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Simulation of steady-state groundwater flow and evaluation of groundwater level fluctuations in the Mississippi Delta using GMS-MODFLOW
Year: 2016 Authors: Nekooei M., Paz J.
In recent years, significant water withdrawal from the Mississippi River Valley Alluvial Aquifer (MRVA) for irrigated agriculture in the Mississippi Delta region have caused considerable declines in aquifer water levels, to the extent that withdrawals have outstripped the recharge. Therefore, water managers have a major concern about the ability of aquifers to meet increasing water demand in the Delta. In this research, the MODFLOW groundwater flow model with GMS software was used to compare the simulated daily groundwater levels with the water-level measurements in the period of the growing season from April through September between 2016 to 2021. The daily groundwater data for 11 observation wells were collected from USGS for the period, along with a few available pumping data from the irrigated wells in the Delta. In addition, the data for areal recharge, rivers, adjacent aquifers, boundaries, and the characteristics of the aquifer were considered as the other GMS packages to construct the model. The discretized was established by using a single layer rectangular-grid and oriented north-south with 1-kilometer square cells to represent the alluvial aquifer. The part of the grid covering the Delta area has 76,039 active cells. The model-generated April to September water levels for each year of the simulation were compared to the corresponding measured water levels. The average root-mean-square (RMS) error determined for the calibrated model was 1.4 meter. Assessing the daily data, a declining trend in groundwater levels was observed during the growing season throughout the studied area. However, the aquifer experienced a more reduction in the water table in 2016 and 2017 in comparison with the other years. In addition, the counties of Sunflower, Leflore, and Washington experienced more fluctuations in the water table due to the excessive withdrawals. Overall, the model results indicated that the simulated hydrographs in all the wells are reasonable representations of the measured water levels. A long-term modeling scenario that assumes the same 2021 pumping rate will likely result in the depletion of grid cells located in the three counties. Based on the model results, the net recharge from the Mississippi River and from the adjacent aquifers was small.
Biogeochemical Impacts of Altered Freshwater Flow to the Mississippi Sound
Year: 2016 Authors: Dillon K.S., Milroy S.P., Shiller A.M., Gilbert M.
The Bonnet Carrè Spillway (BCS) is a flood control structure on the lower Mississippi River that is periodically opened at peak flow to prevent flooding in New Orleans and other municipalities. Since its construction in 1931, the spillway has only been opened fourteen times. However, in recent years, spillway openings have become more common with four openings since 2016. In 2019, the BCS was opened twice for a combined total of 123 days, sending large amounts of Mississippi River water into the Mississippi Sound resulting in large reductions in salinity, extensive algal blooms and nearly 100% mortality of oyster reefs. Weekly water quality assessments were conducted from June thru August 2019 to measure nutrients, dissolved organic carbon and nitrogen, chlorophyll a, and particulate organic matter as well as the stable isotopic composition of water (δ18O and δD) for water source tracking. River water had high nitrate concentrations (92 μM) and low ammonium and soluble reactive phosphate (SRP) concentrations (<2 μM). Water isotope results show that water from some regions of the Sound was composed of nearly 50% Mississippi River water. Dissolved inorganic nitrogen (DIN) and chlorophyll concentrations increased by an order of magnitude compared to historical measurements and bottom water hypoxia was measured across large portions of the Sound when bottom water salinity was greater than 12 psu. Bottom water ammonium and phosphate concentrations were elevated at when DO was low (< 4 mg/L) due to anaerobic mineralization of organic matter, dissimilatory nitrate reduction to ammonium or a combination of the two processes however diffusion of these nutrients from sediments cannot be ruled out with the available data. After the BCS closure in late July, nutrient concentrations throughout the Sound returned to low background concentrations within several weeks.
An Interdisciplinary Approach to Community-Engaged Research Surrounding Lead in Drinking Water in the Mississippi Delta
Year: 2016 Authors: Willett K.L., Showalter S.E., Janasie C.M., Rhymes J.P., Dickson K.
Childhood lead poisoning is a problem requiring interdisciplinary attention from toxicology, public health, social sciences, environmental law, and policy. In the U.S., Mississippi was ranked as one of the worst states for lead poisoning with limited childhood screening measures. We conducted community-engaged research by working with leaders in the largely rural Mississippi Delta region from 2016-2019 to collect household water samples and questionnaires and involve their communities in lead poisoning risk awareness and outreach. Drinking water from 213 homes was collected and analyzed for pH and lead concentrations. Highest lead concentrations were from households served by private wells, and detectable concentrations at or above 0.09 ppb were found in 66.2 percent of all samples. Nine samples exceeded 5 ppb, and these households received certified sink filters. Findings indicated that community-engaged research and outreach could be used to address data gaps relating to lead in drinking water in rural decentralized water systems.
Evaluate the effect of BMPs on hydrology and water quality at field scale
Year: 2016 Authors: Risal A., Parajuli P.
In order to implement and regulate water resource management plans in a watershed, it is required to apply some Best Management Practices (BMPs) and evaluate their effects on hydrologic behavior and water quality. Field scale watershed model such as Agricultural Policy/Environmental Extender (APEX) can be applied to access the effect of such BMPs. APEX was applied to a sub-basin of the Big Sunflower River Watershed (BSRW). Calibration and validation of APEX for streamflow was conducted using the flow output from the calibrated Soil and Water Assessment Tool (SWAT) model for BSRW and that for sediment yield, Total Nitrogen (TN), and Total Phosphorous (TP) were conducted using observed data obtained every fifteen days from 2014 to 2016 for two locations within the sub-basin. Modeling scenarios such as crop rotation, tailwater pond, and vegetative filter strips (VFS) were applied and their effects in reducing runoff, sediment yield, TN, and TP concentration were evaluated. A significant difference in the amount of surface runoff, sediment yield, and nutrients concentration were observed for different BMP scenarios. The simulation results obtained from this study will provide a better idea to other modelers and decision makers in formulating decision regarding BMP implementation and proposing a suitable field scale BMPs in the reduction of surface runoff, sediment, and nutrient yield.
Development of a Web-Based Agricultural Integrated Management System (AIMS) for Watershed Management: A case study for the Johnson Creek-Long Creek Watershed in Panola County, Mississippi
Year: 2016 Authors: Pophet N., Ozeren Y., Bingner R., Yasarer L., Smith P., Ramalingam V., Yafei J.
The National Center for Computational Hydroscience and Engineering (NCCHE) and the USDA-ARS-National Sedimentation Laboratory have developed a web-based Agricultural Integrated Management System (AIMS) to provide a powerful watershed conservation management planning tool in easy to use technology. This technology provides modeling capabilities with automated data preparation from seamless geospatial data for use in evaluating runoff, sediment, and agro-pollutant loadings for any watershed in the U.S. via a Web-browser. The ultimate goal of AIMS is to provide capabilities such as (i) viewing and interacting with geospatial layers, (ii) acquiring information describing features from geospatial layers for a user-defined area, (iii) launching modeling tools for topographic landscape analysis (TopAGNPS) and agricultural watershed simulations (AnnAGNPS), and (iv) accessing various Decision Support tools to allow users to compare various simulated conservation planning scenarios. The beta version of AIMS is currently available and can be accessed via the address "aims.ncche.olemiss.edu." In order to evaluate AIMS for adequate input data preparation required for AnnAGNPS watershed simulations, a case study was performed on the Johnson Creek-Long Creek HUC 12 Watershed (155.85 km2) located in northwest Mississippi. The input parameters required for use with the AnnAGNPS model includes soil, climate, land use, and crop data, which can be automatically prepared through AIMS. Soil information was prepared by AIMS from the USDA-NRCS Soil Survey Geographic (SSURGO) Database. The climate generator-GEM6 was used to generate climate data. Land use and crop data were obtained from the USGS 2016 National Land Cover Database (NLCD) and the USDA 2018 Crop Data Layer (CDL), respectively. The performance of the AIMS system to adequately describe this watershed was evaluated by comparing the observed runoff at an in-stream measuring station with the AIMS-AnnAGNPS simulated results.
Effects of cover crops on edge-of-field water runoff in the mid-south
Year: 2016 Authors: Lucore A., Baker B., Aldridge C.
Efforts to reduce nutrient transport from agricultural landscapes has led to research and implementation of numerous conservation practices. Cover crops have been widely documented in certain regions of the country, primarily the Midwest, to provide water quality, soil health, and wildlife benefits to the environment, as well as to the agricultural system in the form of weed and pest suppression. A lesser body of research exists in the mid-south, particularly in respect to water quality where the bulk of the research refers to the benefits to soil and soil structure while the effects on water quality are ancillary. This study investigated the effects of cover crops on runoff in row-crop production systems. This study was conducted on a working farm located in Tippah County, Mississippi, where six plots (0.7–6.5 ha [1.8–16.1 ac]) served as treatments and controls. Four plots were randomly selected and planted with cover crops and the remaining two plots served as controls, all plots had been under no-till for 20+ years. Water quality was monitored via automated storm-based sampling at all locations for two years prior to cover crop implementation at the treatment sites (2014-2015) and for four years post cover crop implementation (2016-2019). Water samples were analyzed for nitrate-nitrite, total nitrogen, orthophosphorous, total phosphorous, and total suspended solids within 48 hours of sample collection. Data analysis indicated reductions among all analytes besides orthophosphorous with nitrate-nitrite concentrations being the most pronounced reduction. Additionally, there was considerable variability amongst season, cover crop type, and cash crop species.
Biogeochemical Impacts of Altered Freshwater Flow to the Mississippi Sound
Year: 2016 Authors: Dillon K.S., Milroy S.P., Shiller A.M.
The Bonnet Carré Spillway (BCS) is a flood control structure on the lower Mississippi River that is periodically opened at peak flow to prevent flooding in New Orleans and other municipalities. Since its construction in 1931, the spillway has only been opened fourteen times. However, in recent years, spillway openings have become more common with four openings since 2016. In 2019, the BCS was opened twice for a combined total of 123 days, sending large amounts of Mississippi River water into the Mississippi Sound resulting in large reductions in salinity, extensive algal blooms and nearly 100% mortality of oyster reefs. Weekly water quality assessments were conducted from June thru August 2019 to measure nutrients, dissolved organic carbon and nitrogen, chlorophyll a, and particulate organic matter as well as the stable isotopic composition of water (δ18O and δD) for water source tracking. River water samples had high nitrate concentrations (92 µM) and low ammonium and soluble reactive phosphate (SRP) concentrations (<2 µM). Water isotope results show that water from some regions of the Sound was composed of nearly 50% Mississippi River water. Dissolved inorganic nitrogen (DIN) and chlorophyll concentrations increased by an order of magnitude compared to historical measurements and bottom water hypoxia was measured across large portions of the Sound. No significant increases in soluble reactive phosphate concentrations were observed resulting in high DIN:SRP ratios (50 - 70) in the western Sound. Under normal hydrological regimes, DON represents the largest nitrogen pool in the Sound; however, DON concentrations concurrently decreased with DIN increases while the BCS was open. After the BCS closure in late July, nutrient concentrations throughout the Sound returned to low background concentrations within several weeks.
Models Supporting Decision Making: The USGS Mississippi Alluvial Plain project
Year: 2016 Authors: Hunt R.J., Pindilli E.J., Fienen M.N., Kress W.H.
The US Geological Survey (USGS) is commonly asked to provide science to inform societal decision-making, including numerical models. Twentieth Century workflows emphasized paper reports and or single discipline information to those charged with making decisions. Such workflows are ill suited for today's decisions, especially those involving adaptive management or large uncertainties. Moreover, as stakeholders have grown accustomed to near instant access to information such as real-time weather forecasts, water-resource support systems have not kept pace. This is the context within which local stakeholders initiated the USGS Mississippi Alluvial Plain (MAP) project in 2016. From its inception, effort was dedicated to formulating a new approach of applying USGS models to decision support involving: 1) dynamic, sophisticated hydrologic-economic model integration, 2) reusable script-based model construction modules; 3) automated conduits that move new field data to the model; 4) high-throughput computing to update calibration and uncertainty outputs; 5) fast-running surrogate models; and 6) web-services suitable for feeding decision-support systems designed by others. The overarching goal is to provide responsive, consistent, and seamless high-quality science even as the decision-making landscape evolves. Challenges to this vision include building an approach that encompasses moving projection targets, ensuring scientific reproducibility, developing a common technology and language across a large, multidisciplinary team, and robust script design extensible for new data types and numerical code updates. However, by the end of the MAP project we believe the workflow and supporting documentation developed will have transferability to many areas outside the MAP.
Does the Sudden Influx of Broiler Production Impact Nearby Surface Water Quality?
Year: 2016 Authors: Moore M.T., Locke M.A.
The United States has the largest broiler chicken industry in the world. Arkansas (1 billion head) and Mississippi (740 million head) are two of the five top broiler producing states. Although poultry is the largest agricultural commodity for both Arkansas and Mississippi, until recently, large-scale broiler production has generally been limited to a small number of clustered counties within each state. In 2014, an industry partner invested $165 million in two northeast Arkansas counties for a significant poultry complex, and by 2017, hundreds of new chicken houses were built within the Current, Upper Black, and Lower Black River watersheds. These were areas new to the broiler chicken industry, as most broiler production had occurred in the middle and extreme northwestern parts of the states. Water quality issues of high levels of phosphorus and nitrate in the Illinois River Basin in northwestern Arkansas had raised the concern of possible surface and ground water contamination by an overwhelming number of chicken houses. In northeast Arkansas, the primary rivers within these watersheds (Current and Black) provide surface water for recreation and agricultural needs. Aquatic diversity is high, and several endangered freshwater mussel species are present in these watersheds. Because of the potential concern for water quality impairment by the sudden influx of chicken houses, a small-scale evaluation began in December 2016 on a six- acre recreation pond immediately downstream of newly constructed chicken houses. Seasonal water quality and sediment sampling are underway for basic physicochemical parameters, nutrient, and pesticide concentrations. Water quality trends will be examined and discussed, along with opportunities and suggestions on research collaborations to ensure continued agricultural commodity production is harmonized with the surrounding natural resources.
Case Studies of Rapid Dam Breach Modeling during Flood Events
Year: 2016 Authors: Crosby W.
The USACE Modeling Mapping and Consequences Production Center (MMC) provides hydraulic modeling, mapping and consequence analysis for USACE dams in support of the USACE Dam Safety and Critical Infrastructure Protection and Resilience (CIPR) Programs. The MMC has developed processes, tools and standards for creating dam breach hydraulic models for use in emergency action plans (EAP), during real-time flood events, and in support of the Corps Dam Safety and Security programs. The MMC-developed standards have been used to provide dam failure modeling for over 500 USACE dams and multiple flood events, involving over 1000's of stream miles throughout the continental U.S. and Alaska. The MMC also provides Flood Inundation Modeling support during real-time flood events with its Flood Inundation Modeling Cadre (FIM). The mission of the FIM Cadre is to assist districts when called upon to run real-time hydraulic models, prepare forecast inundation maps, and develop consequence estimates for significant flood events. Since supporting the flooding efforts during the 2011 flood of record on the Mississippi River and the 2011 flood on the Missouri River, the FIM Cadre has been called in to support multiple flood events across the nation, including support during some hurricanes. This presentation will provide case studies where the MMC FIM Cadre has supported flood inundation modeling during flood events. The presentation will primarily focus on dam break analysis during hurricanes. In 2015 the MMC performed a dam break analysis in South Carolina during Hurricane Joaquin. Additionally, MMC performed 2 dam break analysis during Hurricane Matthew in 2016. The MMC FIM Cadre has also performed numerous levee breach analysis during flood events.
Project Efficiency: Advantages of UAS Technology in Civil and Environmental Engineering
Year: 2016 Authors: Lawson J., Parrish J.
The use of unmanned aircraft systems (UAS) in civilian and non-military sectors has skyrocketed over the past several years with predictions of exponential demand for UAS and related services in the coming years. In this era of disruptive innovation, rapid advances in UAS technology along with implementation of the FAA's 2016 UAS guidelines have boosted the economic development landscape on multiple levels. More UAS and associated features are being produced by manufacturers than ever before, and remote pilot certifications are on the rise. Utilization of UAS technology in the environmental and engineering fields has gained momentum as the capabilities of UAS applications are becoming abundant and more site-specific. What was once seen as too great of a risk to undertake is now considered a valuable investment by environmental and engineering firms. Professionals are increasingly employing certified remote pilots and creating their own UAS divisions. Improved data collection rates and accuracy, lower number of safety risks and costs, and numerous compatible data processing platforms are marked advantages that current UAS technologies allow. Further, UAS software is compatible with global positioning systems and can be manipulated to form 3D models and a surfeit of other outputs. These factors are just a few of the reasons UAS technology is preferred over traditional labor-intensive methods. The versatility of UAS operations over water and unsafe, rugged terrain is ideal for enhancing and accelerating projects such as inspecting inlet and outfall structures at wastewater treatment facilities and detecting leachate leaks at solid waste facilities. A few other examples of areas benefitting from UAS technology include dam spillway condition assessments, erosion monitoring, and natural disaster evaluations involving flooding events. From the water resources standpoint, opportunities are boundless for how UAS technology has and will continue to benefit the environmental and engineering fields.
DSS-WISE Web: A Web-Based Automated Modeling, Mapping and Consequence Analysis Tool for Improving Dams Safety in the USA
Year: 2016 Authors: Altinakar M., MgGrath M., Ramalingam V.
The National Inventory of Dams (NID) includes the records of more than 90,000 dams classified in three hazard classes: high-hazard (HH), significant hazard (SH) and low-hazard (LH). Although required by law, 17.1% of 15,498 HH dams and 13.1% of 11,883 SH dams do not yet have an emergency action plan (EAP). Moreover, some of the existing EAPs are outdated or do not meet the standards set by FEMA and/or the individual states. About 65% listed in the NID are privately owned, but the safety of the dams is under the responsibility of the states. Unfortunately, many dam owners do not fully understand their personal liability in case of a failure and/or may not have the funds to hire professional services of an engineering company to establish an EAP. The state dam safety offices needed a reliable and accurate tool for dam-break modeling to track the hazard classification of their dam portfolio, which may change based on downstream development, and to provide up-to-date EAPs. Funded by FEMA through a sole-source contract, NCCHE developed a web-based, automated two-dimensional dam-break flood modeling and mapping tool called DSS-WISE Lite, which is accessed through DSS-WISE Web secure web portal. The DSS-WISE Web portal was released on November 8, 2016. A graphical user interface with a map server assists the user to set up simulations quickly and efficiently by responding to a small number of questions. The input files needed for the numerical model are automatically prepared using various national data layers, such as NID, USGS 1/3 arc-second digital elevation model (DEM) tiles, National Levee Database (NLD), National Land Cover Database 2011 (NLCD2011), and National Bridge Inventory (NBI). Resampled at the user-specified resolution (20 to 200 ft.), the DEM serves as a regular Cartesian computational grid. The levees from NLD and the estimated reservoir bed topography are burned into the computational grid. The simulation engine uses a shock-capturing upwind scheme to solve the conservative form of full dynamic shallow-water equations discretized over the complex topography using finite-volume method and handles mixed-flow regimes, wetting and drying and discontinuities, such as jumps or traveling positive waves. The results can be viewed on a map server on the Status and Results page of DSS-WISE Web and downloaded onto the user's computer for further analysis. Recently, a post-processing module called DSS-WISE HCOM was released under DSS-WISE Web to provide an estimation of the human consequences of the dam-break floods based on the results of DSS-WISE Lite simulation. This module provides flood danger maps for different categories of population and the evolution of nighttime and daytime population at risk (PAR) by hazard classes using LandScan USA data layers developed by Oak Ridge National Laboratory. This presentation briefly presents the capabilities of the DSS-WISE Web portal, which is being used by 730 users from numerous federal agencies and 35 state dam safety offices. As of mid-February 2019, the system handled 13,836 simulation requests and performed 10,623 dam-break flood simulations for more than 3,000 dams. The computational performances of the DSS-WISE Lite system, which returns 85% of the simulation results to the user within 30 minutes, has made it an extremely valuable real-time emergency management tool. Exampled of the use of DSS-WISE Web as a tool for preparedness and emergency response planning are discussed.
Groundwater Recharge from Oxbow Lake-Wetland Systems to Alluvial Aquifers
Year: 2016 Authors: Gratzer M., Davidson G., O'Reilly A.M., Rigby J.R.
Knowing recharge rates and understanding recharge mechanisms are crucial to managing water resources. Groundwater recharge from oxbow lake-wetland systems to alluvial aquifers is poorly understood. The aim of this study is to determine whether Sky Lake, an oxbow lake-wetland system in northern Humphreys County, Mississippi, provides significant recharge to the Mississippi River Valley Alluvial Aquifer (MRVAA). To answer this question, we monitored lake-wetland stage and groundwater levels in the wetland and around the entire lake-wetland system from December 2016 to October 2018. Our analysis indicates that Sky Lake provides significant recharge to the MRVAA, based on a groundwater ridge located beneath the lake, groundwater responses to surface-water changes, and a higher correlation between groundwater level and lake stage than between groundwater level and rainfall intensity. Possible recharge mechanisms include preferential flow paths created by tree limbs and roots buried in the wetland sediment as well as coarse-grained point bar deposits near the east side of the lake. Oxbow lakes are created as river meanders and tend to have forested wetlands in the Lower Mississippi River Valley. Therefore, the recharge observed at Sky Lake likely occurs at other oxbow lakes. Similar studies could be carried out at these other lakes, monitoring lake-wetland stage and groundwater levels over time to test whether these lakes significantly recharge the alluvial aquifer.
The State of Groundwater Assessment in Alabama
Year: 2016 Authors: Guthrie G.M.
The Geological Survey of Alabama (GSA) Groundwater Assessment Program has two priorities in support of the development of a state-wide water management plan. The first priority is to monitor the state's groundwaters by: (1) conducting bi-yearly water level sampling, (2) expanding the real-time and continuously monitored well network, and (3) developing a GIS-based well database. The second priority is to utilize information from the initial assessment report entitled "Assessment of Groundwater Resources in Alabama 2010-2016", published as GSA Bulletin 186 in 2018, in conjunction with new data to develop a comprehensive integrated and calibrated water model for the state that will incorporate groundwater, surface water, land use, water use, and climatic data. Alabama's water resources are distributed in diverse settings, so the model will be a composite of subareas defined by HUC-8 boundaries rather than a singular state-wide model. The modeling process will utilize pilot projects representative of the state's aquifers to develop procedures that will be used in subsequent modeling of comparable aquifer environments. Two pilot projects have been initiated: the north Alabama Wheeler Lake HUC-8 and the west Alabama Middle Tombigbee-Choctaw HUC-8, representing the Appalachian Plateau and Gulf Coastal Plain aquifers, respectively. Future pilot projects will focus on basins located in the Valley and Ridge and Piedmont areas of the state. The model is being developed to allow responsible parties to make water-related and policy decisions in response to changing water stresses.
The influence of Submarine Groundwater Discharge on the quality of Mississippi coastal waters: example of hypoxic events in summer 2016 and 2017
Year: 2016 Authors: Sanial V., Shiller A., Moore W.
The quality of the Mississippi Sound and Bight ecosystem, and as a consequence of economic activities such as tourism and fisheries, is directly affected by land-derived chemical elements. Rivers supply large amounts of allochthonous nitrogen that impact the ecosystem by stimulating primary production, which sometimes leads to coastal eutrophication as well as harmful algal blooms. The Mississippi Sound and Bight, located to the east of the Mississippi River Delta, experience hypoxia that is often attributed to nutrient-rich Mississippi River waters. However, oxygen isotopes show a limited influence of the Mississippi River waters in the Mississippi Bight in spring and summer 2016, but rather a dominant freshwater source originating from local rivers with much lower nutrient concentrations. Therefore, we hypothesize that there is likely an additional factor, namely submarine groundwater discharge (SGD), that significantly impacts the quality of Mississippi coastal waters by playing a role, in particular, in hypoxia. SGD is a hidden pathway for the transfer of chemical substances (such as nutrients, metals, and pollutants) from the land to the coastal ocean. Unlike rivers, SGD is difficult to monitor due to its diffuse nature, which limits the use of direct physical measurements. Tracing techniques, measuring geochemical species such as radium isotopes (Ra) that are naturally enriched in groundwater, constitute a powerful tool to assess the extent of SGD influence in the coastal zone. Hypoxic Mississippi Bight bottom waters in summer 2016 were enriched in Ra, but also in barium (Ba), and nutrients that cannot be accounted for sediment diffusion or river inputs, which suggests the presence of SGD. Spatial distribution in bottom water concentrations of certain dissolved trace elements (e.g., Mn, V, REEs) also suggests spatial differences in fluxes of species from the sediments are affected by bottom oxygen. Further evidence of SGD comes from the increase of Ra associated with a rise in nutrients and methane in coastal Mississippi Sound waters shortly after a Jubilee event in July 2017.
Improving the Corn Crop Coefficient Method in the Mississippi Irrigation Scheduling Tool (MIST)
Year: 2016 Authors: Buka H., Linhoss A., Tagert M.L., Pote J., Wax C.
This study examines the value of improving the crop coefficient method being used in the Mississippi Irrigation Scheduling Tool (MIST). Due to an overall increase in irrigated acreage, irregular distribution of rainfall during the summer growing season and continual decline of the Mississippi Alluvial River Valley Aquifer (MARVA), it is important to implement irrigation management practices that minimize water use without compromising crop production, yield, and quality through use of scientific models and soil monitoring devices. The objectives of this study were to 1) adjust and examine the Food and Agriculture Organization (FAO) crop coefficient method and the adjusted "SCS polynomial crop coefficient" method adapted and digitized from the former Soil Conservation Service (SCS, 1970) using a growing season of 120 and 150 days, 2) determine corn emergence and physiological maturity using 50 Growing Degree Days (GDD50) for use in adjusting the length of the growing season, 3) examine the importance of initiating the model at planting and emergence date, and 4) compare MIST modeled results to measured soil moisture data from Watermark soil moisture sensors for the 2014, 2016 and 2017 growing seasons. Currently, MIST uses a FAO crop coefficient with a growing season of 150 days, while the adjusted SCS method allows the growing season to be adjusted based on crop, variety, and maturity stages. Results showed that even though the adjusted SCS method called for irrigation earlier in the season, irrigation water was applied during the critical growth stages and did not trigger irrigation events after the crop reached physiological maturity. Results also showed that by using the adjusted SCS method and GDD50 to determine the growing season, fewer irrigation events and less total crop water use were indicated when irrigation was terminated at 2,700 and 2,900 GDD physiological maturity, depending on the variety used, as compared to the FAO crop coefficient. In addition, changing the timing of model initiation (planting vs emergence) was not important on the total crop water use, but it may have other benefits. Lastly, even though Watermark soil moisture sensors installed in the study field generally did not report similar results, especially around the mid-season, shallower sensor depth somewhat matched and showed similar trends with the MIST modeled results.
Evaluation of Methods for Relating Continuous Streambed Resistivity Data and Hydraulic Conductivity in the Mississippi Delta
Year: 2016 Authors: Killian C., Rigby J.R., Barlow J., Kress W.H., Schmitz D.
Data worth and uncertainty analyses of an existing regional groundwater-flow model that includes portions of the Mississippi Alluvial Plain (MAP) identified streambed hydraulic conductivity as a notable parameter that affected model uncertainty, influencing the model's ability to evaluate groundwater and surface-water interactions. The streambed hydraulic conductivity of each stream reach is currently represented by one value in the existing model due to the paucity of existing data, resulting in high uncertainty in model outputs. Waterborne continuous resistivity profiling (CRP) data was collected by the U.S. Geological Survey in 2016 and 2017 along selected streams within the Mississippi Delta to: (1) characterize near-surface lithology of the Mississippi River Valley alluvial aquifer for improved understanding of groundwater and surface-water interactions; and, (2) allow for increased variability of streambed hydraulic conductivity within the existing model. Multiple methods to translate resistivity values to estimates of streambed hydraulic conductivity were evaluated. Two-dimensional profiles of estimated streambed hydraulic conductivity data were aggregated vertically to develop one-dimensional streambed hydraulic conductivity values and horizontally to the scale of the existing model. Estimated streambed hydraulic conductivity values from the methods were incorporated into the existing model and model estimates of predicted streamflow and groundwater levels were compared to measured values to evaluate model performance for each translation method. This exercise to improve streambed hydraulic conductivity values will allow for reduction in model uncertainty by allowing the model to better estimate groundwater/surface-water interaction and improve tools to make informed decisions when creating and implementing best water-use management practices.
Evapotranspiration Measurement Using Eddy Covariance Systems for Irrigation Scheduling
Year: 2016 Authors: Sui R., Anapalli S., Baggard J., Murrell C.
Irrigation plays a critical role in crop production. Irrigated crops produced more and stable yields than dryland crops. In the Mississippi Delta, acreage of irrigated land has increased rapidly in recent years. Uncertainty in the amount and timing of precipitation has become one of the most serious risks to crop production in this region. Crop producers have become increasingly reliant on irrigation to ensure adequate yields. Excessive withdrawal of the groundwater resulted in water level decline in the Mississippi River Valley Alluvial Aquifer. Ongoing depletion and stagnant recharging of the aquifer jeopardize the long-term availability of the aquifer and place irrigated agriculture in the region on an unsustainable path. Novel irrigation techniques and tools are needed for improving water use efficiency to maintain Mississippi water resource sustainability. Eddy covariance (EC) method is capable of measuring exchanges of water vapor between the surface of the earth and the atmosphere, and have been used for monitoring agroecosystems and measuring crop evapotranspiration (ET) for irrigation scheduling. Objectives of this project were to use EC systems to monitor the agroecosystem and measure evapotranspiration in Mississippi Delta for water management research and agroecosystem assessment. Five EC systems were set up in the Mississippi Delta for ET measurement and agroecosystem monitoring. Three of them are located in Stoneville, MS and two others in Arcola, MS. The EC system consisted of a CH4 analyzer for measuring methane gas flux, CO2/H2O analyzer for measuring carbon dioxide and water vapor fluxes, three-dimensional sonic anemometer for determining wind speed in three dimensions, and biomet (biological & meteorological) sensors to collect ancillary data for filling measurement gaps and interpreting flux results. Installation and preliminary field tests of the EC systems have been completed in 2016. These systems are being used to collect data in 2017 season. This presentation will report the ET measurement results with corn, soybean, and cotton in different locations in Mississippi Delta.
Impact of Different Ratios of Surface Water and Groundwater for Row Crops Irrigation on Groundwater Level in Mississippi Delta
Year: 2016 Authors: Gao F., Feng G., Dash P., Ouyang Y.
Groundwater resources in Mississippi Delta have been overexploited for agricultural irrigation for a number of years. Over 700,000 hectares of row crops in this region was irrigated by using groundwater. As a result, groundwater level has declined > 6.5 m (20 ft) since 1970, which threaten the sustainability of irrigated agriculture in this region especially in Big Sunflower River Watershed. Surface water resources can be used as an alternative source for irrigation. Limited information was reported regarding groundwater level as affected by different ratios of surface water and groundwater for irrigation in this region. The objectives of this study were to employ a coupled SWAT-MODFLOW model and simulate the change in groundwater level and storage as affected by a) no irrigation scheme; b) conventional irrigation scheme; c) water-saving irrigation scheduling by using different percentages of surface and ground water. An analysis from 2000 to 2016 showed practically achievable reductions in weekly pumping (<22%) and replacement by surface water for irrigation would stabilize the groundwater levels in the Mississippi Delta. This study suggested that the conjunctive use of surface water in addition to groundwater can be a sustainable way for future to continuously grow major row crops soybean, corn, cotton and rice in the Mississippi Delta.
Long-Term Effect of Cover Crop on Water Use Efficiency in Manured and Rainfed Soybean-Corn Rotations
Year: 2016 Authors: Yang W., Feng G., Adeli A., Jenkins J.
Planting winter wheat cover crops in corn and soybean rotations is an effective to improve the effective utilization of soil moisture and enhance water use efficiency. However, the longer-term impact of this practice needs to be further investigated. The hybrid RZWQM-DSSAT model calibrated with 5 yr (2013-2017) field data was used to simulate the effects of this practice on crop evapotranspiration, yield, and water use efficiency under a rainfed condition in no-till corn-soybean cropping system at Mississippi Agricultural and Forestry Experiment Station in Pontotoc Mississippi. The poultry litter (13.4 Mg ha-1) was applied to corn field with cover crop (CC) and no cover crop (NCC) in May 2014 and 2016. The model was calibrated well in terms of crop yield and biomass, plant N uptake, and soil moisture with percent error (PE) was within ±15%, Nash-Sutcliffe model efficiency (EF) > 0.7, and relative root mean square error (RRSME) < 15%. Longer-term simulations showed that planting a winter wheat cover crop increased corn yield by on average 1,560 kg ha-1 (12%) and did not change soybean yield. The simulation also indicated that the practice increased annual evapotranspiration by 3.5 cm (9%) in corn years but did not affect evapotranspiration in soybean years. Simulated grain water use efficiency was increased by 17% for corn, and it was not changed in soybean. This study demonstrated that introducing winter wheat cover crops in a corn-soybean cropping system is a promising approach to increase corn water use efficiency in the subtropical agro-ecosystem.
A Confluence of Water and Interdisciplinary Education: The Mississippi Water Security Institute
Year: 2016 Authors: Ochs C.
Social-ecological systems (SES) are comprised of humans, human cultures and perspectives, human institutions, and multitudes of diverse non-human residents. Clean water is the solvent of social-ecological systems, a resource upon which the components of these complex systems are linked and dependent for their economic prosperity, heath, and sustainability. To meet and protect the resource requirements of SES, governance and management approaches are necessary that account for and promote the interests and needs of diverse stakeholders. The Mississippi Water Security Institute is an undergraduate program designed to provide interdisciplinary education in the methods and challenges of water use and management in Mississippi, and the opportunities for new approaches to best meet present and future needs in support of the state's economic development. Emphasizing the complex, interdisciplinary nature of the topic, students in MS WSI represent a university of majors, from business and the social science to the natural sciences, and are recruited from Honors College programs across the state. In its first year (2016), MS WSI focused on water use and management in the rural Mississippi Delta, and last year we examined these issues with respect to the well-being of urban communities such as Jackson. This coming year, we turn our attention to water resource issues affecting well-being, prosperity, and resilience along coastal Mississippi. The MS WSI program involves in-class presentations by expert guests, discussion, and extensive time in the field. In both years of the program, students composed a White Paper detailing their individual and group learning experiences. Student assessment indicates strong satisfaction with the MS WSI interdisciplinary approach, experiential design, and the practical application of the subject matter, with several students stating that the program had reinforced interests in some aspect of water security as a career.
The Development of a Hydrodynamic/Water Quality Model for Oyster Restoration in the Western Mississippi Sound
Year: 2016 Authors: Armandei M., Linhoss A.
This study presents the development of a hydrodynamic and water quality model for the western Mississippi sound. The model was developed using the Visual EFDC program, which is an "advanced, 3D, time variable model" that links hydrodynamics with sediment transport and water quality modules. A computational grid has been generated consisting of 4 layers, each having 3000 cells. The cell size range is 1000m < DiameterCell < 3000m. The input data for the hydrodynamic model are water level, water temperature, salinity, and other meteorological data such as precipitation, and were mostly collected from the measurement stations of NOAA (National Oceanic and Atmospheric Administration) and USGS (United States Geological Survey). The hydrodynamic model was calibrated for the time period of Jan 1 to Dec 31, 2016. A sensitivity analysis is being performed in the light of which the parameters that most impact oysters in the western Mississippi sound will be identified. The model will be useful in identifying appropriate locations for oyster restoration in the western Mississippi Sound.
Trend Analysis of Streamflow to Support Bay and Estuary Restoration in Gulf States
Year: 2016 Authors: Rodgers K.
The discharge of freshwater from rivers and streams to estuaries is important for biological and economic endpoints. The estuaries of the Gulf of Mexico represent one of the most diverse and important ecosystems in the United States. These systems are also heavily influenced by anthropogenic effects within upstream watersheds. Understanding systematic changes in streamflow can provide decision-support for water resources managers to help ensure that estuaries of the Gulf of Mexico receive the critical supply of freshwater needed. In 2016, the U.S. Geological Survey began an effort to characterize freshwater discharge in U.S. tributaries to the Gulf in support of the initiatives prioritized by the Gulf Coast Ecosystem Restoration Council. As part of this effort, daily mean streamflow data were aggregated to monthly, seasonal and annual means at 1,389 gaging stations for streams that drain to the Gulf of Mexico. These values were used to test for monotonic trends in streamflow using the non-parametric Mann-Kendall Trend test. Streamflow trends were synthesized by watersheds representing four-digit hydrologic-unit codes (HUC4). Initial analysis of monthly mean discharge at 28 gaging stations (the most downstream station in each of the 28 HUCs draining to the Gulf) indicate increasing trends at 14 percent (4 sites) of the sites and decreasing trends at 32 percent (9 sites) of the sites. Fifty-five percent of the sites indicated no trend in streamflow. A calculation of area based on land use in the 28 HUC4s does not indicate a dominant land use classification associated with increasing or decreasing streamflow trends. Future work will also evaluate trends in low and high flows, relate streamflow trends to changes in land use or other causal influences, and examine the relationship between streamflow trends and biological or economic endpoint within the Gulf of Mexico.
Evaluating Change in Intermittent Streams Monitored by the Mississippi Delta Nutrient-Reduction Strategy Efforts: Successes and Challenges
Year: 2016 Authors: Hicks M.B.
Evaluating the effectiveness of on-field implementation of agricultural best management practices (BMPs) to improve downstream water quality is a challenge due to seasonal and temporal fluctuations in streamflow and water chemistry and to the limited resources available to monitor these two variables. Yet consistent monitoring and evaluation of collected data is the ideal way to document water-quality changes. In 2010, the U.S. Geological Survey began monitoring in several small drainages in northwestern Mississippi as part of nutrient-reduction strategy efforts in the Mississippi Delta. Various BMPs were implemented to reduce sediment and nutrient runoff in the drainages. Water quality and streamflow were monitored for 5-10 years and data were evaluated and then correlated with observed changes in BMPs. Data analysis progressed in a two-step approach. First, exploratory analyses were completed to evaluate the general hydrologic and water-quality conditions of each site. Then, inferential analyses including tests of differences and equivalences were completed using bootstrapping or an assumed distribution based on the available data. Finally, a power analysis was completed to evaluate the minimum detectable change in water quality possible based on the collected data and to determine the ideal number of samples that need to be collected in the future for similar studies. An example of these data-analysis results will be presented for an intermittent tributary that drains into Bee Lake. This particular tributary has had several BMPs installed over the study period. The results of the analysis and "lessons learned" during monitoring, summarized as successes and challenges presented by this approach, will provide relevant information for forthcoming analyses and similar future studies in this area.
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Community-Based Research Strategies to Analyze Risk of Lead Contamination in Public Water Supplies in the Mississippi Delta
Year: 2016 Authors: Fratesi M.A., Woo L., Green J.J., Otts S.S., Janasie C., Rhymes J., Thornton C., Avula B.
This project includes community-based participatory research and an assessment of residential drinking water supplies and water supply infrastructure in the Mississippi Delta. Additionally, we aim to assess multiple social science approaches to engage stakeholders and influence policy on the current state of lead contamination in drinking water in Mississippi. The 2016-2017 cohort of students enrolled in the Tri-County Workforce Alliance and their parents served as our initial community partners. The participants came from four counties (primarily Coahoma) and 14 municipalities and all reported being on public water systems (e.g. not wells). Participants collected their home drinking water (first catch of the day from kitchen sink, cold water) and samples were analyzed for pH and lead concentrations. Sixty-eight of the 87 distributed bottles (78%) were returned. The pH of the drinking water samples ranged from 7.04-8.23. Notably, lower pH is associated with higher potential to leach lead. Of the samples tested so far from the Delta cohort, only 20 of the samples had lead concentrations above the detection limit, with the highest concentration being 3.45 ppb. All concentrations were well below the EPA 15 ppb action level. Letters were sent to each participant notifying them of their water results. The study is ongoing: demographic data is being analyzed for risk factors associated with lead detects; water sampling data from public water systems is being collected and analyzed; and additional community cohorts are being engaged. For example in the cohort, 85% of the residences were houses (vs. apartments or mobile homes) and 47% of the respondents who estimated the age of their home indicated that it was built before 1985. Ultimately, this project has the potential to help safeguard public health because survey and sampling results will help assess the risks of lead contamination in the Mississippi Delta, assist with the identification of lead service lines and lead plumbing within the distribution systems, and design and guide scalable research and outreach efforts to minimize lead exposure through use of filters and/or behavioral changes.
Cost Analysis of Water Management Scenarios for the Mississippi Delta
Year: 2016 Authors: Falconer L., Tewari R., Johnson J.
The objective of this study is to provide the Mississippi Department of Environmental Quality with a report comparing the cost of reduced pumping or increase in recharge per acre-foot in the Mississippi River Valley Alluvial Aquifer as a result of 5 proposed groundwater management alternatives with scenarios. It is important to note that the cost data available for some of the alternatives are more detailed and current than the data for others. The cost data for the RISER and the Tailwater Recovery and Onfarm Storage scenarios are detailed, current, and based on recently implemented projects and practices. The cost estimates for the Enhanced Aquifer Recharge scenario are detailed and based on research on current materials and construction and ancillary costs for a project with similar components, but no comparable project has actually been built. The cost estimates for the Tallahatchie-Quiver Intra-basin Transfer scenarios are based on a U.S. Army Corps of Engineers (USACE) report issued in September, 2016. The cost estimates for the Instream Weir scenarios are based on itemized costs provided by USACE personnel.
Preliminary results indicate that at 33%, 66% and 100% adoption rates in the service area for the Instream Weir alternative scenarios, this alternative provides the lowest cost per acre foot per acre-foot in reduced pumping from the aquifer.
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CHANGE is Coming: An Introduction to the Next Generation of Hydraulic Modeling
Year: 2016 Authors: Hendon D.L.
Recent developments in hydraulic modeling and 3D computer visualization provide engineers, scientists, CFMs and other users with the tools for a more comprehensive understanding of complex flow patterns that are commonly associated with river crossings and in coastal environments. These tools help locate and illustrate patterns of flow, water surface elevations, depth, velocity, and shear stress. The proper use of these tools allows a more realistic estimation of hydraulic conditions (e.g., scour); floodplain impacts (e.g., FEMA floodplain); aquatic and terrestrial habitat impacts; and extreme weather event scenarios. There is a shift coming in our professions to move from one-dimensional models, such as HEC-RAS, to two-dimensional models. This presentation will cover the differences, applications, and visualizations that are associated with this change. Attendees will be provided an introduction to these new tools so they may have a better understanding of what they look like, what they can do, how they work, and how to use the results.
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Groundwater availability of the Coastal Lowlands aquifer system - refinement of a regional-numerical model
Year: 2016 Authors: Clark B., Duncan L., Foster L., Kress W.
The Coastal Lowlands Aquifer System (CLAS), a large, regional aquifer comprised of multiple hydrogeologic units, is located along the Gulf of Mexico from the Texas/Mexico border through the Florida panhandle. Groundwater withdrawals from the aquifer system are primarily for public supply, irrigation, and self-supplied industry. As withdrawals from the system have increased, some areas along the Gulf have experienced water-level declines, saltwater encroachment, and land subsidence.
The U.S. Geological Survey (USGS), as part of the Water Availability and Use Program, is developing a regional groundwater-flow model (~99,000 square miles) to simulate past, present, and projected conditions and to improve understanding of groundwater availability in the CLAS. The model incorporates a refined hydrogeologic framework, as well as improved estimates of aquifer recharge, water use, and groundwater-surface water exchange.
The refined hydrogeologic framework builds on work from the 1980s and 1990s for the USGS Gulf Coast Regional Aquifer System Analysis, and our agency is working with other locate, state, and Federal agencies to integrate data and knowledge gained since the original model was created. Improved land-surface-altitude data and methods to estimate recharge, additional driller's log information, and data extracted from multiple smaller-scale models are a few of the sources for new information. After incorporation of these data and other model parameters, initial estimates of uncertainty will be calculated to help guide additional model refinement as an iterative process. The resultant model (or model ensemble) will quantify groundwater resources in the system and provide uncertainty ranges to better evaluate the predictive capability of future simulations.
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Policy dimension of adopting wetlands assimilation to increase the NPDES compliance rates for municipal wastewater plants in Mississippi
Year: 2016 Authors: Ko J.Y., Day J.W.
The Clean Water Act has been contributing to water quality improvement and enhanced ecological integrity of natural ecosystem in the United States. However, water pollution driven by poorly treated municipal wastewater still has been significant deterrent factor in achieving the goals of the Clean Water Act, especially in the economically depressed Southern Region, causing harms to the human health, and the aquatic ecosystems. Academicians and government officials have advocated incorporating ecosystem services as a tool to increase compliance rates of the environmental regulation.
Economically poor communities across the Southern Region show poor compliance records of the NPDES regulation. For example, as of 2008, the compliance rate among the 1,437 NPDES permits of the wastewater treatment plants in State of Mississippi was below 50%, and so far, no significant compliance improvements have been reported. Wetlands assimilation is one of the Best Available Technology (BAT), allowed by the EPA. However, the State of Mississippi has not adopted the wetlands assimilation as a policy tool. On the contrary, the State of Louisiana has adopted policy guidelines of using natural wetlands to assimilate nutrients in secondarily treated municipal effluent, thus utilizing ecosystem services of natural wetlands, and improving the EPA regulation with reduced financial burdens to local communities.
We reviewed the state policy formulation process of wetlands assimilation in Louisiana by analyzing the implementation of the Clean Water Act from an inter-governmental relation among federal, state, and local governments for expansion of wetlands assimilation, and we found that the communities which have adopted the wetlands assimilation method have complied their NPDES permits successfully, with reduced financial burdens.
Local communities in Mississippi have been under serious financial burdens, resulting from declining residential population, and declining property tax base. In addition, increasing regulations and unfunded mandates, compounded with political pressures of no-property tax increase have been declining local government's capacity to comply with the environmental regulations.
State of Mississippi may need more active and trustworthy dialogues among State and local governments, scientists, and local community leaders, with results from science-based field studies, and the case studies available from neighboring states. We believe that the wetlands assimilation method is a strong alternative for cost-effective ways in increasing the NPDES compliance in Mississippi.
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Calibration and comparison of forest canopy interception models
Year: 2016 Authors: Linhoss A., Siegert C., Levia D.F.
Rainfall interception by the forest canopy plays an important role in the water budget by removing water from the terrestrial hydrologic cycle. Effective models of canopy interception are critical for simulating the water budget and river flows. Over the years, several models have been developed to simulate canopy interception. Few comparative studies have been conducted that assess how well these models simulate measured interception. The objective of this study was to compare five mechanistic canopy interception models including the Rutter, Rutter Sparse, Gash, Sparse Gash, and Liu models. Each model was calibrated independently using PEST, and automatic parameter estimation routine. The five models were calibrated for American beech and yellow-poplar stands as well as under leafed and unleafed conditions. Overall, the models behaved somewhat similarly. Cumulative error ranged between 0.0% and 14.9%. The models were also assessed for their ability to accurately simulate interception during individual rainfall events. The coefficient of determination (R2) between measured and modeled interception events ranged between 0.21 and 0.48. An important reason for the low R2 values is the fact that the models were unable to simulate very low or very high levels of interception. Measured interception ranged between 0.2 and 12.2 mm while modeled interception only ranged between 1.2 and 6.9 mm. These results indicate an important gap in our ability to simulate a substantial portion of the water budget.
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Multi-species environmental DNA screen of aquatic species in the Sipsey River in Alabama
Year: 2016 Authors: Mangum C., Homyack J., Atkinson C.
The Southeastern U.S. is rich in biodiversity with over 1000 species of fish, mussels and crayfish alone Aquatic species are often cryptic, found in low densities, and their current geographic distribution not well-described. Environmental DNA (eDNA) is an emerging technique to detect and identify species-specific DNA fragments in water and soil samples. Modern genome sequencing technology can obtain millions of DNA sequences from a single sample, making it possible to identify organisms by the residual DNA (e.g., feces, urine, skin cells) they shed in their environment. A pilot project was conducted to use data and samples from a freshwater mussel study for eDNA analysis, to evaluate both the effectiveness of the technology to identify known species and to refine field methods. Dr. Carla Atkinson, University of Alabama, is conducting a field study examining abundance and diversity of freshwater mussels in the Sipsey River, Alabama. The Sipsey River is one of the last free flowing rivers in Alabama and it is considered one of "Alabama's Ten Natural Wonders." The river has a 37 mussel species and 102 fish species reported and represents one of the best remaining and most intact mussel communities left in the United States. Water samples were collected in the vicinity of identified mussel species, and submitted for eDNA analysis. An overview of the mussel study and year one data collection will be presented, as well as eDNA field methodology. This non-invasive screening tool has many uses ranging from verifying presence or absence of threatened and endangered species to monitoring of invasive species. Collecting information on aquatic species is difficult and labor intensive with federal permits need for threatened and endanger species. This method is fast, cost effective, and does not require a permit.
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Drawdown II: Water quality and ecological responses to a managed hydrologic drawdown during autumn
Year: 2016 Authors: Lizotte R.E., Jenkins M.B.
A water drawdown of Roundaway Lake, a tributary of the Big Sunflower River, was initiated in mid-autumn to alleviate critical low river flow. While water releases have been demonstrated to alleviate critical low flows, effects of these releases on water quality in contributing tributaries is necessary to improve water resource management decisions. The purpose of the present study was to assess the responses of lake surface water chemical and ecological components including nutrients, phytoplankton and ecoenzyme activities. Lake drawdown began on October 17, 2016 and finished after 14 days when outflow was <0.1% of peak flows and shallowest depths occurred 35 days after drawdown with decreased depths of 56%, 23% and 90% at upstream, lake, and downstream sites, respectively, relative to pre-drawdown depths. Control pond depths during the study period ranged from 82-113% relative to pre-drawdown depths with changes due to evaporation and rainfall. Water samples were collected on days -3, 0, 1, 2, 3, 7, 14, 21, 28, 35, and 42 at the three drawdown sites and an adjacent control pond site (no drawdown) to account for natural seasonal variations. Chemical analyses included soluble nutrients (PO4-P, NH4-N, NO2-N, NO3-N), total nutrients (TP, TN) and organic carbon. Ecological analyses included algal chlorophyll, phycocyanin and photosynthetic efficiency as well as a suite of five ecoenzyme activities. Nutrient changes were greatest at sites with the largest changes in water depth. Upstream dissolved organic nitrogen (NH4-N, NO2-N, NO3-N) increased by >100%, while organic carbon exhibited bimodal changes. Downstream PO4-P, C:N ratios, and C:P ratios all increased by >100%, organic carbon increased by 50% and TP decreased by 45%. Lake nutrients exhibited modest bimodal changes in NH4-N, NO2-N and organic carbon while control pond NO2-N decreased by 50%. Similar to nutrients, algal responses were strongest upstream and downstream. Upstream phycocyanin concentrations increased by >70% while photosynthetic efficiency decreased by 75-80%. Downstream chlorophyll and phycocyanin concentrations decreased by 75-85% and photosynthetic efficiency decreased by 66-90%. Lake and control algal responses were modest with chlorophyll concentrations decreasing by 22-30% and photosynthetic efficiency decreasing by 25-45%. Ecoenzyme activity responses were modest at most sites with bimodal changes to Β-glucosidase:alkaline phosphatase ratios upstream and leucine aminopeptidase in the lake. Greatest changes occurred downstream where Β-N-acetylglucosaminidase, fluorescein diacetate and alkaline phosphatase decreased by 76%, 77% and 98%, respectively. The study contributes valuable information supporting water resource management goals to sustain river and lake ecosystem integrity.
Surface-Geophysical Surveys to Characterize Lithological Controls on Aquifer Recharge and Surface Water-Groundwater Exchange
Year: 2016 Authors: Miller B.V., Kress W.H., Ladd D.
The U.S. Geological Survey (USGS) developed a groundwater-flow model of the Mississippi Embayment Regional Aquifer System (MERAS) that incorporated multiple aquifers including the Mississippi River Valley alluvial (MRVA) aquifer. In addition to groundwater withdrawal, two major fluxes in the model are recharge from precipitation and surface water-groundwater exchange. In order to determine appropriate values for recharge to the MERAS model, the USGS has utilized two published datasets- the geomorphology of Quaternary deposits and local soil surveys. At a regional scale, recharge in the MERAS model correlate well with large-scale geomorphological features. However, there is little spatial variability, so local-scale variations in recharge are not adequately represented. Higher resolution data such as soil coverages provide a more spatially-variable estimates of recharge, but, soil-survey data often characterize the shallow soil horizon and do not reflect the generalized geomorphological features in which the horizon lies. In addition, streambed sediments may differ greatly from the mapped geomorphologic areas and shallow soils due to alteration from stream mechanics. Thus, geomorphologic maps and soil information are both types of surficial information that may not accurately reflect the underlying hydrogeology that controls infiltration of recharge water or the composition of streambed sediments.
In 2016, the USGS conducted a surface-geophysical survey to characterize the near-surface (<15 m) lithology that controls recharge to the MRVA aquifer and surface water-groundwater exchange at selected locations in northwestern Mississippi. Two-dimensional vertical profiles of resistivity identified differences in geoelectrical properties of the streambed for reaches of the Tallahatchie (60 km), Quiver (50 km), and Sunflower (70 km) Rivers. Resistivity profiles of each stream were able to detect boundaries of individual geomorphic features. In addition, terrestrial-based resistivity surveys identified variations in geoelectrical properties from Money to Steiner, Mississippi, a distance of approximately 68 km. The terrestrial-resistivity survey showed distinct differences in surface soil resistivity based on lithology. Drilling logs of wells along the Sunflower River confirmed that lithologic descriptions correlated positively with the resistivity profiles.
Characterizing groundwater and surface-water interaction throughout the Mississippi Delta using hydrograph-separation techniques combined with near-st
Year: 2016 Authors: Killian C., Barlow J., Barlow P., Kress W.H., Schmitz D.
The Delta, an area dense in agriculture, is situated between the Mississippi and Yazoo Rivers in northwest Mississippi. Stream and groundwater levels in the Delta have shown declines with the increase in irrigation to support agricultural production. In 2016, the U.S. Geological Survey (USGS) began a study to better understand the effects of pumping on groundwater and its availability in the Mississippi River Valley alluvial (MRVA) aquifer. The alluvial aquifer is the uppermost hydrologic unit in the Delta and supplies most of the groundwater used for agricultural irrigation. Understanding the relation between withdrawals and groundwater response in the alluvial aquifer could allow for the estimation of changes in groundwater availability over time and can help to determine the best water-resource-management practices for the study area. A spatially-distributed network of paired groundwater and surface-water streamgage sites provided hydrologic data to characterize groundwater/surface-water interaction throughout the Delta. Baseflow, the amount of groundwater that contributes to streamflow, was estimated for each site using hydrograph-separation methods. The USGS Groundwater Toolbox open-source software provides several techniques for hydrograph separation and was used for this study. Recently collected geophysical data along selected streams in the Delta provided insight to the hydraulic conductivity, or ease with which water moves through the soils and unconsolidated sediments, was coupled with the hydrograph-separation results. This combination of techniques allowed for better characterization of groundwater/surface-water interaction at the selected sites. Characterizing and defining these types of hydrologic relations will help USGS scientists refine a regional model of the Delta that will be used to aid water-resource managers in future decisions pertaining to the alluvial aquifer.
Quantifying Recharge to the Mississippi River Valley Alluvial Aquifer from Oxbow-Lake-Wetland Systems
Year: 2016 Authors: Gratzer M., Davidson G., O'Reilly A., Rigby J.R.
Irrigation-related groundwater withdrawals have caused declining water levels in the Mississippi River Valley Alluvial Aquifer (MRVAA) since the late 1920s. To manage this resource, recharge sources must be quantified. This study examines recharge through oxbow lakes, which are numerous in the Mississippi Delta. Previous investigations at Sky Lake, an ancient Mississippi River oxbow with an associated wetland, near Belzoni, Mississippi, suggest that oxbow wetlands may contribute significant recharge to the MRVAA. Multiple methods using geologic, hydrologic, and temperature data are being employed to identify and quantify recharge from the Sky Lake oxbow lake-wetland system. Two wetland soil cores were collected to depths of approximately 7 m, encountering 6 m of clay and silt before penetrating into sands and gravels. Monitoring of MRVAA water levels in two piezometers in the wetland and nine monitoring wells in Sky Lake's vicinity began during the 2016 drought and will continue through the rainy season to track groundwater responses. The potentiometric surface will be mapped to identify possible groundwater mounding beneath the lake, which would indicate vertical recharge. Preliminary results from mid-December, 2016, indicate a general groundwater flow direction to the west beneath the lake. Wells are outfitted with temperature-recording data loggers at specific depth intervals. The groundwater temperature profiles have the potential to differentiate localized wetland-recharge from regionally distributed infiltration, or from recharge from the nearby Yazoo River. Soil temperatures 30 and 60 cm below ground at ten points in the wetland are also being monitored over time to characterize small-scale variations in downward flux. Preliminary results are consistent with earlier work indicating preferential flow pathways through the fine-grained bottom sediments due to an abundance of buried trees and limbs in various stages of decomposition.
Water consumption and yield variability of nonirrigated and irrigated soybeans in Mississippi dominant soils across years
Year: 2016 Authors: Feng G., Ouyang Y., Reginelli D., Jenkins J.
Soybean is the most important crop in Mississippi in both acreage and value. In 2015, the Mississippi soybean harvested area was 2.27 million acres and a total value of $1.04 billion, surpasses other major crops combined. Approximately one-half of Mississippi soybeans are grown under rainfed conditions and another half are irrigated. In order to stabilize dryland soybean yield and improve yield by irrigation, it is essential to determine yield, water requirement and consumption of both non-irrigated and irrigated soybeans in Mississippi dominant soils under different climate conditions over years.
Field experiments were conducted in Noxubee county for those objectives on Vaiden clay, Okolona silty clay, and Demopolis clay loam at a private Good Farm in 2014 and on the Brooksville silty clay at Mississippi State University Black Belt Branch experiment station in 2015 and 2016.
During the entire soybean growing season from 1895 to 2014, the average long-term reference evapotranspiration and crop water requirement (ETc) were 720 and 542 mm, mean rainfall was 432 mm, rainfall of wet, normal and dry category years was 597, 421 and 280 mm.
During soybean season in 2014, 2015 and 2016, rainfall were 365, 388 and 284 mm, soybean water requirement were 428, 455, and 504 mm. In 2014, 2015 and 2016, rainfed soybeans consumed 402, 417, and 347 mm water and produced 5672, 2736, and 1806 kg ha-1 grain, in contrast, irrigated soybean consumed 440, 526, and 478 mm water and yielded 6264, 3109, and 3031 kg ha-1 grain.
The APEX (Agricultural Policy/Environmental eXtender) model was applied on nine soil types (Vaiden clay, Catalpa, Okolona, Griffith, Sumter, Kipling and Brooksville silty clay, Demopolis clay loam, and Leeper sandy loam) in Eastern Central Mississippi from 2002 to 2014.
APEX simulated grain yield of rainfed soybean ranged broadly from 2.24 to 6.14 Mg ha-1 on nine soil types over the 13 years. The average yield in wet, normal and dry years was 4.88, 4.51 and 3.74 Mg ha-1, respectively. Simulated yield potential without water stress due to irrigation varied from 4.47 to 6.51 Mg ha-1. Compared with rainfed soybean, the average increase in yield by irrigation ranged from 0.34 to 1.60 Mg ha-1 among the nine soils. Griffith, Sumter and Demopolis had the highest average yield gap (difference between yield potential and the rainfed yield), ranged from 1.37 to 1.60 Mg ha-1. Average irrigation amount required to achieve potential yield ranged from 16 to 377 mm across the nine soil types. High variability of water consumption as well as grain yield was observed for both nonirrigated and irrigated soybeans on different soils and on a given soil over different years. Therefore, it is necessary to explore production/management options for different soils that will increase opportunities for consistent yields and profits across years without irrigation.
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Quantifying crop water requirements in the MS Delta using eddy covariance and energy balance methods
Year: 2016 Authors: Anapalli S.S., Fisher D.K., Reddy K.N., Ruixiu S.
With competing demands for fresh water from human, urban, and industrial sectors, water available for irrigated agriculture is rapidly declining; this calls for a more judicious use of the limited share of water available for crop irrigations. Accurately quantifying crop water requirements and providing crops with the right amount of water at the right time to optimize crop water productivity holds the key to addressing this challenge. While large field lysimeters allow us to grow crops for quantifying ET directly from the crop-field, they are expensive and time-consuming to install successfully and maintain for long-term data collection for analyzing climate variability impacts on crop water requirements. Eddy covariance (EC) and energy balance (EB) methods are easier to install in crop fields and are portable, and provide two scientifically sound methods for indirect, accurate measurements of water requirements (ET; evapotranspiration) of cropping systems. Nonetheless, the EC method has been widely known to have energy balance closure problems — imbalance in matching energy inputs to the outputs. In the evolving scenario, we embarked on a research program for monitoring ET from corn and soybean crops using both EC and EB approaches, for comparison with each other and accounting for energy balance non-closure artifacts on the EC data generated. In the EB method for quantifying ET, a surface energy balance equation is applied to a soil-plant surface using ground-based and remote-sensing measurements of the system variables, and ET (expressed as latent heat flux) is estimated as the residual term of the energy balance equation when other fluxes in the equation are either measured or calculated. The EC system consists of an omnidirectional sonic anemometer and an open-path infrared gas analyzer with data recorded at a frequency of 10 Hz on a data logger and analyzed with Smartflux software (LiCor, Lincoln, NE, USA). In this project, crops were grown in 40-ha fields planted to soybean and equipped with the EC and EB systems in 2016. In general, computed daily values of ET from EB and EC methods deviated from the computed short grass (ETo) and alfalfa (ETr) reference crop ET. However, total seasonal ET from both EB and EC methods were comparable with ETr and ETo. The EC and EB methods tested show high potential for quantifying crop ET in cropping systems in the MS Delta region.
Rice irrigation strategies: Alternate wetting and drying and methane reductions
Year: 2016 Authors: Runkle R.K., Suvocarev K., Reba M.
Approximately 11% of the global 308 Tg CH4 anthropogenic emissions are currently attributed to rice cultivation. In this study, the impact of water conservation practices on rice field CH4 emissions was evaluated in Arkansas, the leading state in US rice cultivation. While conserving water, the Alternate Wetting and Drying (AWD) irrigation practice can also reduce CH4 emissions through the deliberate, periodic introduction of aerobic conditions. Seasonal CH4 emissions from a pair of adjacent, production-sized rice fields treated with continuous flood (CF) and AWD irrigation were estimated and compared during the 2015 and 2016 growing seasons using the eddy covariance (EC) method on each field. The seasonal cumulative carbon losses by CH4 emission significantly less for the AWD treatment. The substantial decrease in CH4 emissions by AWD supports previous chamber-based research and offers strong evidence for the efficacy of AWD in reducing CH4 emissions in Arkansas rice production. Plans for the 2017 measurement season will be discussed, including a mixture of EC and surface renewal micrometeorological techniques on 16 adjacent 40-acre fields under various irrigation practices in northeast Arkansas. The AWD practice is incentivized by several USDA-NRCS conservation programs and is used for carbon offsets trading, so reductions of both water use and CH4 emissions are encouraged on a regional scale.
Variable pathways and geochemical history of seepage under the Mississippi River Levee: Observations from the 2011, 2015, and 2016 floods
Year: 2016 Authors: Voll K., Davidson G., Kelley J., Corcoran M., Borrok D., Ma L.
Seepage beneath levees during flood stage becomes a concern when piping occurs, opening up channels beneath the levee and forming sand boils where transported sediments discharge. Along the lower Mississippi River, the pathway beneath the levee varies with surface geology, following deeper paths where the levee sits on channel fill deposits, and shallower paths where it sits on sand bar deposits. A preliminary investigation north of Vicksburg, MS, during the 2011 flood, demonstrated the potential for using aqueous geochemistry to differentiate sand boils forming at the end of deep and shallow flow pathways. Deeper flow through the geochemically stratified Mississippi River Valley Alluvial Aquifer (MRVAA) produces discharge low in oxygen and high in redox sensitive elements such as iron and arsenic. Shallow flow contains measureable oxygen and much lower iron and arsenic concentrations. Sampling during the 2015 and 2016 events for bulk chemistry, trace metals, tritium, and stable isotopes of oxygen, hydrogen, iron, and strontium, is enhancing our understanding of the nature of flow and the geochemical evolution of the local groundwater.
Oxygen and hydrogen isotopes suggest that river water experiences significant evaporation before recharging to the MRVAA. Shallow flow pathways beneath the levee are characterized by lower iron isotope ratios, and higher strontium isotope ratios, reflecting interaction with unique mineral phases and distinct reaction pathways. Sand boil discharge following deeper flow pathways group isotopically and geochemically with relief wells, or between relief-well and river end-members. Boil discharge following shallow pathways does not just plot closer to river water. River water passing through the shallow aquifer is altered in ways that will require installation and sampling of dedicated shallow wells to fully understand. Tritium results reveal a dynamic system, where flow paths may vary over between floods or within a continuous flooding event.
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Enhanced Characterization of the Mississippi River Valley Alluvial Aquifer Using Surface-Geophysical Methods - a Pilot Study near Money, Mississippi
Year: 2016 Authors: Adams R.F., Kress W.H., Minsley B., Kass M.A.
The Mississippi River Valley alluvial (MRVA) aquifer is a complex and poorly understood near-surface aquifer system used to supply irrigation for agriculture across the alluvial plain of the Lower Mississippi River basin. The thickness and extent of the aquifer units are typically determined by evaluating geophysical and driller logs from test holes at spatially discrete points. Surface-geophysical data, along with borehole-geophysical and lithologic data from test holes, can be used to provide high-resolution three-dimensional characterization of the aquifer system. In 2016, the U.S. Geological Survey (USGS) conducted a pilot study to demonstrate the use of surface-geophysical methods for delineation of near-surface geologic features, characterization of alluvial aquifer properties, and evaluation of surface water/groundwater exchange in the MRVA. The area chosen for this pilot was a 100-acre plot in Money, Mississippi. The study approach integrated waterborne and terrestrial resistivity and nuclear magnetic resonance (NMR) surveys to develop a three-dimensional geoelectrical model of the site. This integrated approach helped define the 100-150 feet of sand aquifer and the contact of the clay-confining unit beneath it. Shallow terrestrial-resistivity surveys confirmed that the clay-rich loam at the land surface continues as a clay-rich alluvial deposit approximately 25-50 ft thick beneath the study area. The presence of this relatively impermeable layer above the alluvial aquifer has the potential to limit vertical recharge from precipitation or irrigation. The NMR survey was used to determine that the aquifer volume consists of 30% water with two-thirds of that available for use. Comparisons of the waterborne- and terrestrial-resistivity surveys were used to identify that a hydraulic connection or potential for water exchange, between the Tallahatchie River and the MRVA is possible. These geophysical observations provide a more accurate understanding of the local hydraulic properties and hydrology of the MRVA aquifer at this site, and will contribute new data to constrain a regional, numerical groundwater model.
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Simulating cotton water use and yield under rainfed and full irrigation conditions using RZWQM2 model in the Lower Mississippi Delta Region
Year: 2016 Authors: Ma X., Feng G., Sui R., Jenkins J.
Sustainable agricultural water management requires knowledge of crop water use and productivity under both rainfed and Irrigation conditions. Our objective was to determine the yield and water use of both nonirrigated and fully irrigated cotton in the Lower Mississippi Delta Region. The CSM-CROPGRO-Cotton v4.6 model within the Root Zone Water Quality Model (RZWQM2) were applied. The model was calibrated and validated using measured data at Stoneville Experimental Station in 2015 and 2016 Results suggested that the calibrated model simulated cotton yield and water use had good agreement with measured data in field. Simulation study discovered that the lowest rainfed yield was less than 2500 kg ha-1, and the highest irrigated yield were more than 3600 kgha-1.
The Mississippi Water Security Institute: Report on Year 1; Plans for Year 2
Year: 2016 Authors: Ochs C.A., Young D.B., Sullivan-Gonzalez D.
Earth, Air, Fire, and Water. Ancient Greeks considered these the essentials to support life on earth - a wise observation. From Earth, nourishment is derived. From Air are provided the gases of respiration. From the Fire of our Sun we are bathed in the catalytic energy necessary for complex organization. But only where there is also Water can we "live long and prosper". In May 2016, we completed the first workshop of the Mississippi Water Security Institute (MS WSI). Our purpose was to introduce undergraduate honors students to the challenges and complexities of how we use and manage the state's water resources to meet present and future needs. The 2016 MS WSI involved 16 students from four Mississippi universities. The regional focus in our first year was on the Mississippi Delta, a place of great importance to the state's economy but also of striking contrasts; high agricultural production at the expense of enormous resource use; an historically wet wilderness with only remnants remaining outside the levees; islands of economic prosperity in a sea of rural poverty; where water seems inexhaustible but in fact can be consumed faster than it is replenished. Over our two-week Institute, we investigated the means by which we might use water in this vast region to jointly promote broad economic development, and human community health, while supporting ecosystem health. We were visited by numerous speakers representing different areas of expertise related to water use and management, from farming to law to conservation, and we made several field trips to sites of interest in the Mississippi Delta. In this talk, we will present outcomes of student learning from the 2016 workshop, and discuss plans for the upcoming 2017 MS WSI workshop on urban water systems in Mississippi.
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Overview of Gulf of Mexico Hypoxia Policy in 2017
Year: 2016 Authors: Daigle D.
Doug Daigle, Coordinator of the Lower Mississippi River Sub-basin Committee, will give an overview of current policy to address the Gulf of Mexico hypoxic zone, focusing on the national Action Plan and Task Force that Mississippi and other lower river states are participants on. The revised Goal and Interim Target of the Action Plan will be explained, since they set the direction for joint action among Task Force states and agencies for the next decade, and provide the broader context for the work of SERA-46 and state and federal agencies described by other speakers in this session.
Doug Daigle has coordinated the Lower Mississippi River Sub-basin Committee, part of the national Mississippi River/Gulf of Mexico Watershed Nutrient Task Force, since organizing it in 2003. The Sub-basin Committee consists of Arkansas, Louisiana, Mississippi, Missouri, and Tennessee, along with federal partner agencies, researchers, and stakeholders in the region. He also coordinates the Louisiana Hypoxia Working Group, a monthly forum held at Louisiana State University.
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Social Indicators: a New Metric to Guide, Measure, and Accelerate Implementation of State-Level Nutrient Reduction Strategies
Year: 2016 Authors: Guzman S.M., Cossman R.E., Ingram R.
Major barriers in water conservation are the development of effective strategies to improve the quality of freshwaters, and management of the current nutrient loads released by agricultural production. Decision makers require a set of technical, environmental, landscape, and social measurements to restore the quality of their watersheds. Social metrics contribute to the understanding of how individuals and communities perceive, and incorporate, nutrient management plans in their agricultural processes. They are also short term metrics in which change (i.e., delta) can be quantified quickly. Individual producers and users have a set of beliefs and attitudes that make them respond differently to a specific situation. In this project we refine social indicator metrics for agricultural and water management with an emphasis on nutrient reduction, promote an expansion of the existing Social Indicators Planning & Evaluation Systems/Social Indicators Data Management & Analysis Tool (SIPES/SIDMA) throughout the Mississippi Atchafalaya River Basin, and lay the groundwork for an active social indicators users community among policy researchers and regulatory agencies. The overall goals of this project include 1) identifying social science experts and potential users of social indicators in the existing Hypoxia Task Force (HTF) states to build the foundation for establishing a community of practice at the state-wide and Mississippi/Atchafalaya River Basin (MARB)-wide scales, 2) incorporate a fully developed suite of social indicators that are tested, standardized and, most importantly, can be compared across watersheds and at varying spatial scales through the expansion of SIDMA, and 3) expand the use of social indicators to guide, and accelerate implementation of state-level nutrient reduction strategies. Social indicators provide consistent measures of social change and can be used by planners and managers to assess change in attitudes towards the implementation of water conservation practices. Social indicators can also accelerate the effective implementation of nutrient reduction strategies.
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Role of SERA-46 in fostering collaboration and improvement toward nutrient reduction goals in the Mississippi/Ohio River Basin
Year: 2016 Authors: Baker B., Burger W., Ingram R.
The Southern Extension and Research Activities committee number 46, is one of a group of formal USDA Nation Institute of Food and Agriculture (NIFA) and Land Grant University funded committees designed to promote multistate research and extension activities. SERA-46 was created to provide a framework for collaboration and advancement of priorities with the Mississippi River Gulf of Mexico Watershed Nutrient Task Force (Hypoxia Task Force). Land Grant Universities (LGU) throughout the Mississippi/Ohio River basins are uniquely positioned to assist state agencies and the Hypoxia Task Force in the development and implementation of state level nutrient reduction strategies. Researches as these universities participate in interdisciplinary research ranging from soil science, nutrient transport, water quality, and human behavior, which offer support toward the mitigating nutrient pollution to the Gulf of Mexico to secure water quality for environmental and economic enterprises. In addition to a diversity of scientists, LGUs each have expansive extension units that can assist in disseminating innovative best management practices and solutions to farmers across the basins. Recent strides made by SERA-46 in support of state and Hypoxia Task Force nutrient reduction goals include securing extramural funds to develop a framework for tracking progress toward nutrient reduction goals via reductions in nonpoint sources of pollution, securing funds for watershed capacity building, developing social indicators related to nutrient reduction, and a large-scale transforming drainage project in the Midwest. Mississippi State University has contributed significantly toward advancement of priorities within the state through a semantic analysis of all Mississippi/Ohio River basin Nutrient Reduction Strategies to develop a guideline for optimizing plans toward goals of the Hypoxia Task Force, leading the social indicator development efforts, farmer engagement, farm system sustainability trainings, and BMP efficiency investigations.
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Application and validation of STWAVE in the nearshore of Deer Island, MS
Year: 2016 Authors: Dillon C., Linhoss A.
Waves are the driving force for many coastal processes. The process of sediment transport along a beach face is highly tied to the presence and action of waves. Therefore, due to the constant sediment transport occurring along Deer Island in Harrison County, MS, and the costly procedures required to maintain the sediment budget of the area, an accurate and full understanding of the wave parameters in the area is important. To date, no validation of a local model or any other published data on the waves for the area exists. Therefore, the purpose of this study is to validate a local model which will be able to be used to forecast or hindcast wave information for present or future work done on Deer Island. To quantify wave parameters of the area a wave model is the best option for its ability to generate high resolution information. For this study, the STWAVE model was chosen because of the mild and uniform conditions of the area and for STWAVE's fast computational efficiency. Field data of recorded wave information was taken from a Nortek Vector which recorded wave and current data between the months of June and September, 2016. The raw data of the Vector will be processed using the PUV method to produce wave height, wave period, and wave direction information. Wave data was also taken during this same time period through littoral environmental measurements (LEM) made at the shoreline. Both sets of gathered wave information will be used to validate the STWAVE model.
Overview of Water Availability in Mississippi
Year: 2016 Authors: Phillips P.
The abundant water supplies in Mississippi constitute one of the most important and valuable natural resources in the state. These resources contribute directly to the quality of life and economic prosperity of the state. Throughout the state, there is a need for accurate assessment of groundwater resources to allow wise long-range planning and development. The water resources available in areas of the state can vary significantly depending on various hydrogeologic conditions that may affect baseflow in streams, water quality, and the amount of water local aquifers can supply. The highly variable nature of these resources means that a concerted effort must be maintained to collect related groundwater and surface water data that will allow proper decisions to be made regarding the management and development of the state's water resources.
In Mississippi, precipitation averages about 54 inches annually. About 10% of this infiltrates to the water-saturated zone and becomes groundwater. Fresh groundwater in Mississippi occurs principally in unconsolidated sand and gravel deposits interbedded with thick, extensive layers of clay that form aquifer boundaries and is available throughout the state. Groundwater supplies 90% of water used in the state, for everything from drinking water supplies, agriculture, fish culture, to commercial and industrial uses.
The total volume of fresh water stored in Mississippi's aquifers, which has been conservatively estimated to be in excess of 6 billion acre-feet, dwarfs the total volume of all surface water resources, but surface water is still a valued source of water supply in the state. Mississippi has 10 major river basins with 86,000 miles of streams. Surface water supplies drinking water to five entities: the City of Jackson, the City of Corinth, Short Coleman Water Association, the NE MS Regional Water Supply District, and the Jackson County Port Authority. Surface water is also used for agriculture, industries, and wildlife management, among other uses.
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Effects of water use on fish biodiversity: a decision-support framework
Year: 2016 Authors: Cartwright J., Wolfe B.
Despite increasing awareness of the importance of streamflow variability to fish communities and efforts to create regional standards for environmental flows, methods are lacking that explicitly translate water-use decisions into predicted ecological outcomes. The U.S. Geological Survey has developed ecological limit functions in the Tennessee River basin relating hydrologic departure from reference conditions to species richness for key fish groups based on trophic and habitat characteristics. These ecological limit functions have been incorporated into a hydrologic accounting framework to allow water-resource managers to examine the consequences for fish biodiversity of water-use decisions, such as withdrawals for municipal or agricultural use. This approach allows various management scenarios to be compared, with the goal of maintaining ecological health of streams and conserving fish biodiversity while optimizing water availability for human use.
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Nutrient and phytoplankton changes in Roundaway Lake after a managed hydrologic drawdown
Year: 2016 Authors: Lizotte, Jr. R.E., Taylor J.M., Locke M.A.
A late summer drawdown of Roundaway Lake in the Mississippi Delta was initiated to help improve downstream flows within the Big Sunflower River. Although such water releases are important to help improve downstream water quality, a better understanding of the changes and processes within the contributing water bodies is needed to aid water resource management decisions. Consequently, we examined the influence of the lake drawdown on surface water nutrients and phytoplankton within the system before, during, and after drawdown. Lake drawdown was initiated on September 15, 2015 and was completed within six days when outflow was <5% of peak flows and channel water depths decreased by 40%, 28%, and 82% at upstream, lake, and downstream sites, respectively. Surface water samples for nutrient and phytoplankton analysis were collected on days -7, -1, 0, 1, 2, 3, 6, 13, 20, 28, and 34 at all three sites. Nutrients included soluble reactive phosphorus (SRP), dissolved inorganic nitrogen (NH4-N, NO2-N, and NO3-N), total nitrogen (TN), total phosphorus (TP), and dissolved organic carbon (DOC). Phytoplankton measurements were: chlorophyll a and in-vivo chlorophyll (phytoplankton biomass); in-vivo phycocyanin (blue-green algal biovolume); chlorophyll:phycocyanin ratio (Chl:PC, blue-green algal bloom); phytoplankton photosynthetic activity (Chl Fv/Fm); and blue-green algal photosynthetic activity (PC Fv/Fm). Surface water nutrient responses were modest with the exception of SRP. Bimodal changes in SRP occurred with decreases at all sites during the initial drawdown phase (days -1 to 6) followed by increasing SRP levels 13 to 34 days after drawdown. No clear trends were observed for dissolved inorganic nitrogen while TN increased with time and changes in turbidity and TP varied with turbidity. Regression analysis identified some of the physical and chemical factors driving phytoplankton responses to the drawdown. Chlorophyll a was associated with TN and N:P ratios (R2 = 0.571), in-vivo chlorophyll was associated with depth, TN, and N:P ratios (R2 = 0.785), and in-vivo phycocyanin was associated with SRP, TN, and N:P ratios (R2 = 0.750). Blue-green algal blooms (Chl:PC) were associated with SRP, NO3-N, and C:N ratios (R2 = 0.645). Chl Fv/Fm and PC Fv/Fm were associated with C:N ratios (R2 = 0.351) and NO3-N + C:N ratios (R2 = 0.338), respectively. These results will provide valuable information that will help water resource managers make better informed decisions to sustain surface water resources and ecosystem integrity of Mississippi Delta rivers and lakes.
Connecting water level to biological health in Alabama streams
Year: 2016 Authors: Rose C., Knight R.R., O'Neil P.
Water is critical to the survival of aquatic biota, but little has been done to quantify the minimum water level in a stream that provides adequate support for aquatic biological communities. Most research in this field has focused either on connections between various streamflow measures and aquatic habitat, linkages between aquatic habitat and the biological health of streams, or using the annual or monthly 7Q10 or other low-flow measures to establish minimum flows. Resource managers need a better understanding of the interaction and linkages between streamflow, water level, channel morphology, physical habitat availability (streambed), and biological health to establish scientifically-defensible flow requirements. The proposed analysis will be based on existing streamflow, channel morphology, physical habitat availability, and biological health (richness, diversity, or IBI score) data at each site. The analysis will include, but is not limited to: daily value streamflow time series, streamflow measurement data (cross-section data), game and non-game fish community data, available habitat data, and stream cross-sectional surveys. Existing data from 15 to 20 streams in different physiographic regions of Alabama will then be used to answer the following questions: Is physical habitat quantity maximized at low, yet consistent streamflow? Is the streamflow associated with maximized physical habitat predictable and does it vary regionally according to published geologic and physiographic boundaries? Does biological health of fish communities appear to be correlated with the amount of time streamflow is lower than that associated with the maximized physical habitat?
Prioritizing the restorability of impaired water bodies: A case study of four watersheds in the Delta region in the state of Mississippi
Year: 2016 Authors: Sinshaw T., Surbeck C.
The restorability potentials of four impaired water bodies (Lake Washington, Harris Bayou, Coldwater River, and Steele Bayou) in the Delta area of Mississippi were compared in this study using the EPA Recovery Potential Screening tool. A variety of selected indicators under ecological, stressor, and social fields were evaluated. The studied water bodies' restorability potential was ranked based on the most influential indicator score, the aggregated indicator score under each field, and the integrated recovery potential score of the three fields. Restorability scores were calculated based on two scenarios; (1) with indicators assigned with equal weight and (2) with indicators assigned with unequal weight. Agricultural activity, covering 70 to 80 % of the total land use of the studied water bodies' drainage area, was found as the most stressful single indicator. In that regard, Harris Bayou was observed as the most difficult to restore. Based on the aggregated indicator under each field scores, Steele Bayou and Lake Washington were observed with the most and the least favorable biophysical conditions for restorability, respectively. The Coldwater River was observed with the highest social capacity for restorability. The water bodies were also compared based on an overall integrated recovery potential score (IRPS) of the three fields. Coldwater River and Steele Bayou were found as the first and second most restorable water bodies in both the equally and unequally weighted scenarios. Harris Bayou and Lake Washington were ranked as the third and fourth, respectively in the equally weighted scenarios, and fourth and third, respectively in the unequally weighted scenarios. Remarkable rank change between Harris Bayou and Lake Washington in the unequally weighted scenario implies the significant effect of assigning indicator weight on restorability ranking. Based on this rationale, this research suggests further study is needed on the EPA Recovery Potential Screening tool to understand the sensitivity of the restorability potential based on indicator weights.
Brown pathways in green systems: source, habitat and nutrient effects on organic matter breakdown in Mississippi Delta agricultural bayous.
Year: 2016 Authors: Testa III S., Taylor J.M., Lizotte R., Dillard K.
Excess nutrient runoff can impact agricultural water bodies but little is known about the role of agriculturally derived organic matter in mediating water quality impacts associated with nutrient enrichment in agricultural landscapes. We compared source, habitat and nutrient enrichment effects on breakdown rates of agricultural field (corn residue) and riparian (willow oak) organic matter in natural bayou ecosystems and stream mesocosms. Field data indicated that breakdown rates for corn were high (k = 0.0321 ± 0.0027 d-1) compared to willow oak (k = 0.0109 ± 0.0033 d-1) in bayous, and, for both species, more hydrologically dynamic inflow sites had significantly lower breakdown rates than lentic sites. Mesocosm results indicated corn residue breakdown rates did not increase with phosphorus (P) enrichment, increased with nitrogen (N) enrichment, but were highest when mesocosms were enriched with N and P (N+P). Willow Oak had much lower breakdown rates than corn residue in mesocosms, confirming species effects observed at field sites. The highest oak breakdown rates were observed in mesocosms enriched with N and P which were significantly higher than control or P enriched streams. Oak breakdown rates in N enriched mesocosms were also significantly higher than control streams but intermediate between P enriched and N+P enriched mesocosms. Respiration rates for corn residue were double that of willow oak and enrichment effects varied with time, but there was clear experimental evidence that N + P enrichment increased respiration for both species. Our results demonstrate that changes from riparian species to more labile crop residue sources of organic matter, combined with nutrient runoff, may impact agricultural water bodies by increasing microbial respiration associated with faster organic matter breakdown rates. However, reductions in nutrient runoff from agricultural areas, as well as increasing buffers of natural vegetation through agricultural best management practices, have the potential to reduce high inputs of crop residue and decrease microbial respiration rates associated with corn residue and nutrient enrichment in bayous of alluvial plain agroecosystems.
Application of AnnAGNPS for Evaluating the Nutrient Loading Control of an On-Farm Water Storage (OFWS) system in East Mississippi
Year: 2016 Authors: Karki R., Tagert M.L., Paz J., Bingner R.L.
Irrigation tailwater and storm runoff events from agricultural watersheds are a major source of nutrient loading in rivers and streams. According to the 2012 Mississippi Quality Assessment Report, nitrogen, phosphorus, sediments, and biological oxygen demand are the major pollutants of the Middle Tombigbee-Lubbub Watershed, which includes the study area. An On-Farm Water Storage (OFWS) system is a constructed best management practice (BMP) consisting of a tailwater recovery ditch or terraces and a water storage pond. These OFWS systems have demonstrated the ability to both reduce downstream nutrient loading and provide water for irrigation by capturing and recycling irrigation tailwater and rainfall runoff. The Annualized Agricultural Non-Point Source (AnnAGNPS) surface runoff model is a continuous simulation, daily time step, pollution loading model. This poster will present the preliminary results from the application of AnnAGNPS to estimate nitrate and phosphorus losses from a small agricultural watershed in East Mississippi over a one-year period from fall 2014 to fall 2015. Storm runoff events were captured using an ISCO auto sampler and will be used to calibrate and validate the model results. AnnAGNPS will also be used to estimate the nitrogen and phosphorus loads captured by the OFWS system during the study period. In addition, alternative management practices that could potentially decrease nutrient losses from the agricultural fields will be evaluated using the model.
Water use of dominant Pinus taeda and mid-canopy Liquidambar styraciflua and consequent implications of forest succession
Year: 2016 Authors: Hornslein N.
As southeastern forests undergo succession from Pinus taeda (loblolly pine) to hardwoods, differences between water use for these different tree types could alter future conditions of water available in the ecosystem. Investigating loblolly pine and sweetgum (Liquidambar styraciflua) transpiration rates is a necessary step in order to determine if significant changes in water availability in the system will occur during succession. This will have future implications for streamflow, groundwater, and flooding. We hypothesize that sweetgum will use more water per unit sapwood area than loblolly pine and that sweetgum will be more responsive to environmental parameters including soil moisture and atmospheric vapor pressure deficit than loblolly pine. This study was performed in an aging loblolly pine plantation undergoing hardwood succession located on clay soils that experience occasional flooding in central Mississippi. The sap flow of 15 loblolly pines and 12 sweetgums were measured from July to November, 2015 using thermal dissipation probes. The trees sampled vary in size with DBH values ranging from 10.16 cm to 40.13 cm in sweetgums and 35.56 cm to 60.45 cm in loblolly pines. Additionally, environmental variables of vapor pressure deficit and soil moisture were measured to compare with tree-level water use. The slope of sap flow vs. soil moisture was higher in pines, demonstrating that they were more responsive to soil moisture than sweetgums. Both species demonstrated more significant relationships between sap flow and soil moisture than with vapor pressure deficit. On average, during the summer growing season, pine water use was approximately 571 kg m-2 sapwood area day-1 whereas sweetgum water use was approximately 793 kg m-2 sapwood area day-1. Therefore, forest succession from loblolly pine to hardwoods such as sweetgum would result in higher tree water-use leaving less available water in the system.
Research Program at the USDA-ARS National Sedimentation Laboratory: At the Interface of Agricultural and Natural Resource Management
Year: 2016 Authors: Locke M.A., Dabney S.M.
For over 50 years, the USDA-ARS National Sedimentation Laboratory, Oxford, MS, ("Sed Lab") has served as a center for research on sediment and erosion issues and is currently the lead USDA-ARS facility addressing (1) watershed erosion and sedimentation processes, and (2) watershed ecological functions as impacted by agricultural practices. The Sed Lab consists of two research units: (1) Water Quality and Ecology, and (2) Watershed Physical Processes. The research program emphasizes interdisciplinary studies dealing with physical, chemical, and biological processes related to natural resources in agricultural watersheds, and assessing strategies for sustaining and enhancing the integrity and function of agro-ecosystems. Specific topics of study include: (1) soil erosion, transport and deposition of sediment in watersheds including stream stability and bank protection; (2) agricultural practice and stream structure impacts on water quantity, water quality, and ecosystem services; (3) movement and fate of chemicals within the landscape; (4) ecosystem integrity of streams and adjacent riparian zones, lakes and wetlands; and (5) processes controlling surface and groundwater movement. The NSL also serves as the lead research facility in the Lower Mississippi River Basin for the USDA-ARS Long Term Agro-ecosystem Research (LTAR) network.
Remediation of Oriented Strand Board (OSB) Process Water
Year: 2016 Authors: Dowlatabadi L., Borazjani H.
The process of manufacturing OSB involves a pressing process that releases water and extractives from wood. This type water is known as process water and contains wood extractives, phenol/urea formaldehyde resins, terpenes, and other organic compounds which increase the biological oxygen demand (BOD) and total suspended solids (TSS). In order to discharge this water, it must be treated to reach a regulated discharge levels for BOD and TSS. A 30 day laboratory study with bioreactors filled with OSB process water and treated with air only, air plus fertilizer and air with fertilizer and duckweed were conducted to evaluate the removal of BOD and TSS from this type process water. Three untreated controls were used in this experiment. Significant reduction of BOD occurred for all treated replicates after 30 days. No significant differences observed among treated samples. For TSS, again all treated treatments showed significant reduction but reactors treated with only air showed the highest reduction of TSS. Bacterial population remained sufficient throughout this experiment.
Introducing the Mississippi Water Security Institute (MSWSI)
Year: 2016 Authors: Ochs C.A., Sullivan-González D., Young D.B.
Through a generous grant from the Robert M. Hearin Foundation, The University of Mississippi Sally McDonnell Barksdale Honors College has established the Mississippi Water Security Institute (MSWSI). MSWSI is developing an intensive two-week workshop on water security issues in the state, which will be offered to a select group of undergraduate students in honors programs in Mississippi. With abundant natural resources and a growing population, Mississippi is an increasingly favorable place to invest, start a business, and raise a family. MSWSI recognizes that with population and economic growth there will be increasing demand on our freshwater resources. The term "water security" refers to challenges inherent in promoting and linking strong business development with community health with natural resource protection. Clearly, this is a challenge requiring communication among multiple fields and interests - the business community, agriculture, law and public policy, urban planning, engineering, and conservation. Reflecting this complex mosaic of water security concerns, the workshop will facilitate interdisciplinary study and problem solving, and include travel, guest speakers, and independent research. Students in the workshop will become knowledgeable in the availability and quality of freshwater resources in Mississippi, learn to assess how these resources can be used wisely in support of business and community development, and environmental stewardship, and work on skills to effectively communicate what we learn to a broad constituency. In this talk, we will present the framework of our first workshop in May, 2016.
A Dynamic Legal Case Study: Mississippi v. Tennessee - The Interstate Dispute Over Groundwater Resources
Year: 2016 Authors: Janasie C.
Water is one of the most essential natural resources globally, nationally, and locally. In the United States, access to and management of water resources are becoming more deliberated, and often contested, as states strive for stakes in this shared natural resource. As the legal framework looks to respond to evolving water issues, interstate disputes are in the forefront as pending United States Supreme Court cases. This talk will discuss existing water laws and policies throughout the continental United States and distinguish between regulation of surface water and groundwater. When people think of water, images of surface water like the Mississippi River come to mind, but a large amount of the water we use on a day-to-day basis is groundwater. The role of states in managing water resources, and especially groundwater, is heating up as consumption and science advance. While states can, and do, work together to share interstate water resources, the Supreme Court of the United States must preside over cases where states disagree. This talk will provide a general overview of water law and the interstate water disputes currently before the Supreme Court, notably Mississippi v. Tennessee. While interstate water disputes are common, Mississippi v. Tennessee is a significant legal case because the Supreme Court has never before decided a state dispute over groundwater. This talk will provide an overview of each state's argument and how interstate water disputes have traditionally been treated by the Supreme Court. In conclusion, the talk will discuss the relevance of pending litigation, as well as thoughts on the future of water law.
Catalpa Creek Watershed Restoration & Protection Project and Watershed DREAMS Center
Year: 2016 Authors: Schauwecker T.
The Catalpa Creek Watershed is located in Oktibbeha and Lowndes counties in the northeast region of Mississippi and is part of the larger Tombigbee River Basin. The 28,928 acre watershed contains 31 miles of mainstream perennial stream length. At the HUC-12 level, the watershed includes part of the Mississippi State University Campus, the MSU South Farm research facility and dairy farm, as well as a number of privately owned lands. Research activities of the university and continued development and construction of university lands appear to be a primary driver of stream, ecosystem, and water quality degradation. Catalpa Creek is currently listed by the Mississippi Department of Environmental Quality (MDEQ) as impaired by sedimentation and a TMDL has been developed that sets challenging targets for sediment load reductions. Two MSU facilities on the South Farm are permitted point sources - the Poultry Science Research Center and the Ag Center and Horse Park. MDEQ has ranked the watershed as having a high stressor potential, which means compared to other watersheds in the area Catalpa Creek is a watershed in need of restoration. MDEQ supports four sites in the watershed to monitor its biological health.
A comprehensive suite of management practices has been selected to address the agricultural resource concerns identified for the watershed, sedimentation, grazing lands, sustainable forestry, and declining wildlife habitats. In addition to the agricultural resource concerns, urban storm water management is a key need for the watershed and a focus for restoration and protection. MSU's Master Plan (MSU, 2010) contains numerous urban storm water management techniques and approaches, which will be leveraged into the project.
The project has a number of unique features. These include an education, experiential learning, and outreach approach that begins by better understanding the behaviors, perceptions, and beliefs of watershed stakeholders; creation of experiential learning opportunities for students; a comprehensive monitoring and assessment approach that includes traditional physical/chemical water quality monitoring, macroinvertebrate habitat assessments, use of indicator species to evaluate ecosystem restoration progress; and social indicators to understand improvements in stakeholder behaviors and perceptions and the effectiveness of educational and outreach activities. Other unique features include analyses and designs to restore the structure and function of Catalpa Creek and for siting storm water retention basins to mitigate downstream storm water impacts. Also, incorporated into the project is a focus on watershed sustainability. Probably, the most ambitious component of the project is to leverage these restoration and protection activities into the establishment of a Watershed DREAMS (Demonstration, Research, Education, Application, Management and Sustainability) Center. Supported by over 18 university units, it is envisioned that the DREAMS Center will demonstrate innovative applied research, sustainable water resources management, and effective and quantifiable education and experiential learning for students, educators, and federal/state conservation agencies and organizations.
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Collection and analysis of water quality and benthic macroinvertebrate and algal community data to support nutrient criteria development in northweste
Year: 2016 Authors: Hicks M.
The Mississippi Department of Environmental Quality (MDEQ) is in the process of developing scientifically defensible nutrient criteria to protect designated uses of three types of waterbodies: lakes, streams/rivers, and estuaries/coastal waters. Data collection and analysis efforts in support of nutrient criteria have been ongoing in some ecoregions in the State since about 2002, and separate Technical Advisory Groups (TAGs) have been formed to oversee criteria development for each waterbody type. Developing nutrient criteria has proven to be particularly challenging in the Mississippi Delta region in northwestern Mississippi. Reference or best attainable conditions have not been fully identified in this region, and complex relations between nutrient concentrations and biological integrity are not well understood.
In 2015, the U.S. Geological Survey (USGS) partnered with MDEQ and the U.S. Environmental Protection Agency (USEPA) to conduct a study in wadeable streams that originate in the Bluff Hills along the eastern boundary of the Mississippi Delta for the primary purpose of supporting nutrient criteria development. The main scope of the study involves collection of algal community and biomass data along with concurrent and antecedent physical, chemical and other biological data to characterize stressor-response relationships. The study purpose, strategy, design, and timelines will be presented.
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Water Quality in Bangs Lake: effects of recurrent phosphate spills to a coastal estuary: Year 2
Year: 2016 Authors: Dillon K., Caffrey J., Carmichael R.H., Dzwonkowski B., Holcomb S., Berry T., Baine G., Sleek J.
In 2015 we continued to examine the effects of industrial phosphate spills to Bangs Lake in the Grand Bay National Estuarine Research Reserve. Higher phosphate concentrations in sediments and porewater were measured in Bangs Lake compared to the reference site in Bayou Heron (while other nutrient concentrations were similar or lower). Peaks in particulate organic phosphorus (POP) concentrations in southeastern Bangs Lake corresponded in time to at least one known major phosphate spill (2005). In an effort to examine transport of a contaminant plume we also conducted a fluorescent dye tracer study using fluorescein in the northern portion of Bangs Lake. Transport and dilution rates on the day of the study were strongly affected by tidal action and a very strong western wind. Although the known source of phosphorus to the estuary is on the western side of Bangs Lake, hydrological processes that flush sediments and nutrients from the Lake may concentrate finer sediments and associated particulate phosphorus in the southeastern part of the Lake. Pb 210/ Cs dating conducted on the sediment cores were corroborated by Th isotope data, which confirmed greater pollution associated with spill material from the facility at sites in Bangs lake. Phytoplankton nutrient bioassay experiments showed that phytoplankton in Bangs Lake were very strongly limited by nitrogen. Preliminary results suggested that both ammonium and nitrate were effective at stimulating growth, and grazing by microzooplankton was sometimes significant. Benthic microalgae in Bangs Lake appeared to be decreasing, although they were still generally higher than at the reference site. Benthic microalgal growth was not stimulated by addition of ammonium, phosphate or both.
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Improving water quality through cost-effective marsh restoration
Year: 2016 Authors: Sparks E.L., Cebrian J.
Marshes provide many ecosystem functions and services that are integral for coastal health. One of the most valuable ecosystem services provided by coastal marshes is the removal excess nutrients prior to entering coastal waters. Unfortunately, marsh degradation has led to drastic reductions in the capacity of marshes to provide this nutrient buffering service. As an attempt to mitigate for this reduced nutrient removal capacity, many restoration projects have been and will continue to be conducted. However, the majority of these projects are limited in evaluation of the ecosystem services they provide, cost-effectiveness, and how climate change will affect them. Given the high cost associated with these projects, evaluating the cost-effectiveness and resilience of different designs is necessary for making restoration a more ubiquitous and effective practice. We constructed and evaluated experimental marshes at the Grand Bay and Weeks Bay National Estuarine Research Reserves to test the effectiveness of different initial planting densities at removing nutrient pollution. At the Grand Bay site, we had initial planting densities of 0%, 50%, and 100% of Juncus roemerianus (black needlerush). At the Weeks Bay site, we created marshes in abandoned canals and, within them, planted black needlerush at 5 different densities (0%, 25%, 50%, 75%, and 100%). In half of the Weeks Bay plots, we simulated short term sea-level rise to approximate levels projected at 2030. At both sites we compared porewater concentrations of dissolved inorganic nitrogen (DIN) and used this measurement as a proxy for nutrient removal across all plots. Our findings indicate the 50%, 75%, and 100% planting densities suppress porewater DIN concentrations to similar levels and at significantly greater levels than the 0% and 25% planting densities. Therefore, the 50% planting density is suggested as the most cost-effective design for nutrient removal. Effects of short term sea-level rise on DIN concentrations varied by marsh location, but, in general, did not have a large effect. This information can be used by managers to design more cost-effective restoration projects that take into account the potential effects of sea-level rise.
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Optimizing carbon to nitrogen ratios to improve nitrogen removal in agricultural drainage ditches
Year: 2016 Authors: Faust D.R., Króger R., Miranda L.E., Cox M.S., Moore M.T., Rush S.A.
The annual occurrence of a hypoxic zone in the Gulf of Mexico is caused by nitrogen loads from the Mississippi River Basin, which includes agricultural drainage ditches. The objectives of these studies were: (1) evaluate how organic carbon amendments affect nitrate-nitrogen removal in agricultural drainage ditch systems using laboratory microcosms, (2) determine effects of organic carbon amendments and flow rate on nitrate-nitrogen removal in a semi-controlled field setting using experimental drainage ditches, and (3) assess relationships between organic carbon and nitrogen content of overlying water, pore water, and sediments of drainage ditches throughout the Lower Mississippi Alluvial Valley. In laboratory experiments, nitrate-nitrogen removal in dissolved and particulate organic carbon treatments was greater than 90% compared to as low as 60% in control treatments. The optimal carbon-to-nitrogen ratio of organic carbon amendments for efficient nitrate-nitrogen removal was 5:1. Experiments in experimental drainage ditches revealed that flow substantially lowered the ability of organic carbon amendments to remove nitrate-nitrogen with a maximum percent nitrate-nitrogen reduction of 31.6% in a dissolved organic carbon treatment, although implementation of low-grade weirs in experimental drainage ditches did result in removal of nitrate nitrogen in all treatments and at all flow rates. Examining the nitrogen and organic carbon contents in agricultural drainage ditches throughout the Lower Mississippi Alluvial Valley revealed that organic carbon content in overlying water, pore water, and sediments are lower than observed in other wetland-like ecosystems and indeed may be limiting denitrification and other nitrogen removal processes. Increasing organic carbon content overall could be achieved by using organic carbon amendments, but this body of research highlights that additional studies are necessary to ensure successful implementation of organic carbon amendments that reach their greatest potential as a management practice to effectively remove nitrate-nitrogen in the realistic settings of agricultural drainage ditches.
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Mississippi's Approach to Address Declining Groundwater Levels
Year: 2016 Authors: Whittington K.
Groundwater levels in the aquifer used for irrigation in the Mississippi Delta are declining as irrigation demands have increased. By law, the Mississippi Department of Environmental Quality (MDEQ) is charged with conserving, managing, developing, and protecting the state's water resources. MDEQ is working with those in the Delta through the Delta Sustainable Water Resources Task Force to identify solutions. A Voluntary Metering Program is being implemented to get accurate withdrawal information and irrigation water management practices proven to save water, time, and money are being promoted. Progress must be made now with voluntary measures while all options continue to be investigated.
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Water availability in the Mississippi River alluvial plain: optimized monitoring and modeling for water management
Year: 2016 Authors: Barlow J.R., Haugh C.J.
The Mississippi River alluvial plain in northwestern Mississippi (referred to as the Delta), once a floodplain to the Mississippi River covered with hardwoods and marshland, is now a highly productive agricultural region of large economic importance. Water for irrigation in the Delta is supplied primarily by the Mississippi River Valley alluvial aquifer, and although the aquifer has significant storage capacity, there is evidence that the current rate of water use is exceeding the available supply. Groundwater modeling has shown that increasing withdrawals from the aquifer are having a direct impact on the interaction between the groundwater and surface-water systems. Groundwater level declines in the aquifer have resulted in decreased discharge to streams within the Delta to the extent that many stream reaches are presently net-losing streams throughout the year. This decrease in available groundwater discharge is directly impacting many ecosystem services such as maintaining baseflow conditions in streams; regulating temperature regimes for aquatic biota; and buffering contaminant transport at the streambed interface.
To better understand and optimize water management and monitoring activities in the Delta, the U.S. Geological Survey and the Mississippi Department of Environmental Quality are collaborating to update and enhance an existing regional groundwater flow model. The model will be used to develop and assess conjunctive water-management optimization scenarios as well as improve and optimize current and future monitoring activities within the Delta. Key revisions include updating the model through 2014 with more recent water use, precipitation and recharge data, and streamflow and water-level observations. In fiscal year 2016, the updated model will be used to develop selected alternative water-supply scenarios to assess relative impacts to the alluvial aquifer and identify data needs for future optimization modeling.
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Irrigation Water Management Strategies that Improve Crop Yield and/or on Farm Profitability
Year: 2016 Authors: Krutz L.J., Pickelmann D., Atwill R., Leininger S., Bryant C., McNeal J., Wood W., Henry M.
The Row-crop Irrigation Science Extension and Research (RISER) program has demonstrated how Irrigation Water Management (IWM) practices including computerized hole selection, surge irrigation, soil moisture sensor (SMS) technology, and alternate wetting and drying (AWD) reduces irrigation water use up to 40% while improving profitability by $40/acre. However, very few Mid-South irrigators are using IWM practices. The objectives of this session are to 1) illustrate how computerized hole selection and surge irrigation improves irrigation application efficiency; 2) describe how SMS technology improves irrigation scheduling decision for initiation and termination; 3) inform practitioners how AWD impacts water use, yield, weed control, and N uptake 4) examine on-farm case studies where IWM practices significantly improved corn, soybean and rice yield/profitability.
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Managed Aquifer Recharge and the Mississippi River Alluvial Aquifer: On-farm and Regional Perspectives
Year: 2016 Authors: Rigby J.R., Barlow J.
Groundwater from the Mississippi River Valley Alluvial Aquifer (MRVAA) is the primary source for irrigation in the Delta. Withdrawals in excess of recharge in recent decades have resulted in declining groundwater levels, particularly near the central Delta. Irrigated agriculture has reached the point such that to achieve sustainability the aquifer must be managed carefully as a finite, yet renewable, resource. Management of groundwater resources is most often associated with managing withdrawals, e.g., through more efficient water use and development of alternative surface water resources. Equally, though, aquifer recharge is a part of the management equation. Managed Aquifer Recharge (MAR) is increasingly the guiding paradigm for groundwater resources in arid regions. MAR has not received the same attention in humid regions where the supply of water usually far exceeds the demand. In an intensively developed system like the MRVAA, however, emphasis on managing recharge is a crucial component of sustainable water resources. This presentation will examine the hydrologic dynamics of recharge to the MRVAA at farm and regional scales. The merits and challenges of a suite of techniques for managing aquifer recharge including recharge basins, vadose wells, aquifer storage and recovery, and groundwater transfers will be outlined as they relate to the MRVAA.
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Bio-inspired energy and water recovery from low substrate wastewaters
Year: 2016 Authors: Gude V.G., Stuart-Dahl S.
The energy and water production issues are intertwined and cannot be addressed in
isolation. Wastewater treatment and desalination, in particular, are energy consuming processes
which can have detrimental effects on the environment. Integrated solutions that utilize waste
sources to generate energy, which in turn, can be used to produce freshwater are attractive options
to address current energy and water issues. In this context, bioelectrochemical systems have
evolved as a novel technology to convert wastes into valuable forms of energy. Bioelectrochemical
systems can be employed to generate clean electricity, or high value energy or chemical products
from various wastewater sources and organic or inorganic wastes that can serve as fuel feedstock
for electroactive bacteria. Microbial desalination cells (MDCs) are based on an integrated
configuration in which, wastewater and saline water sources can be treated simultaneously without
any external power input or mechanical energy or pressure application. This process offers
multiple benefits of energy and resource (water and nutrients) recovery while eliminating
environmental pollution.
In this research, low substrate synthetic wastewaters with chemical oxygen demand (COD)
less than 300 mg/L were treated at different concentrations in microbial desalination cells. A
process optimization model was utilized to study the performance of the photosynthetic microbial
desalination cells. The variables include substrate concentrations, total dissolved solids, and algae
concertation in the cathode chamber. Relationships between the COD concentrations, algae and
salt concentrations was evaluated. Power densities and potential energy benefits from algal
biomass growth were calculated. This presentation will provide a discussion on the suitability of
MDCs for treating low substrate wastewaters such as agricultural wastewaters, anaerobic digester
effluents and septic tank effluents for net energy production and water desalination.
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Solar powered multi-stage natural vacuum low temperature desalination process
Year: 2016 Authors: Steinwinder J., Martinez-Guerra E., Guerra H., Spiller B., Byrd C., Solis M., Gude V.G.
Desalination has emerged as a viable alternative for water supply in many water-stressed
regions of the world. In US, some of the states such as California, Texas and Florida are faced with
major challenges of ensuring adequate water supplies to meet the demands as a result of population
growth, severe drought, decreasing aquifer levels and increasing industrialization. Desalination
can be performed through membrane and thermal processes. These processes are energy-intensive.
Powering the desalination processes through conventional energy sources is not a sustainable
approach as these sources are not renewable. Utilization of renewable energy such as solar energy
for water desalination is an ideal approach for thermal desalination processes.
In this research, a low temperature desalination process operating at near-vacuum pressures
was studied. Near vacuum pressures are created by exploiting the barometric head and
gravitational force. As a result, this process reduces the specific energy consumption for freshwater
production due to reduced heat losses to the ambient. This allows for efficient utilization of solar
energy.
Preliminary data of a multi-stage (3 stages) solar powered low temperature desalination
process will be presented. Working principles of the novel desalination process as well as energy
and mass balances, heat and mass transfer analysis will be presented. Solar collectors will be used
to provide the thermal energy required for the desalination process. Our preliminary economic
analysis shows that when this desalination system is powered by a low grade flat plate solar
collector heat source, the desalination costs are less than $7/m3 which falls in acceptable range for
small scale desalination systems of similar capacity. When using a cheap waste heat source
purchased at $0.5/GJ, the desalination costs can be reduced to $3/m3. Most small scale domestic
desalination systems are designed in combination with a renewable energy source.
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Mississippi Private Well Populations
Year: 2016 Authors: Barrett J.
Most residents of Mississippi are served by one of the over 1,200 public water systems. Having access to a public water system provides citizens with safety and quality of water through the regulatory enforcement of the Mississippi State Department of Health-Bureau of Public Water Supply. Mississippi citizens on private wells do not have the luxury of knowing the quality and/or quantity of their water on a regular basis. Unfortunately, a reliable method for determining the population that depends on a private well for their water supply has not existed since the 1990 census. This presentation will compare currently available methods and present a new methodology for estimating private well usage in Mississippi. This method uses connections reported to the Safe Drinking Water Information System adjusted to account for non-residential connections, along with census data to generate improved estimates that are quite different from other available sources. This method has been used to generate well usage estimates for all counties in Mississippi. The concluding data can be utilized to better strategize water infrastructure improvements and well monitoring programs.
This study should be of interest to representatives of local municipal water systems, local communities, and rural water associations for potential expansion of their water systems. The expansion of a public water system may achieve multiple goals. Additional customers generate more revenue of the public water system, as well as provide a larger customer base in which to spread costs. The regulatory oversight of public water systems should promote and produce a safer drinking water supply for Mississippi residents.
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Mississippi's Priority Framework
Year: 2016 Authors: Clark S.A.
The Mississippi Department of Environmental Quality (MDEQ) has developed a new collaborative framework for implementing the Clean Water Act. The new framework is designed to help coordinate and focus various efforts to advance the effectiveness of the water program. Given resource constraints and competing program priorities leveraging resources and coordinating efforts is crucial. This new framework does not change regulation, policy or issue new mandates. It is intended to provide focus for MDEQ water programs to better manage the activities and promote collaboration to achieve water quality goals for the streams, rivers, lakes and estuaries of Mississippi.
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The Gulf of Mexico Alliance Water Resources Team Update
Year: 2016 Authors: Caviness-Reardon K.
The Gulf of Mexico Alliance (GOMA) was established in 2004 by the Gulf State Governors in response to the President's Ocean Action Plan. It is a State-led network of partners working together on projects related to the priority issues identified by the Governors of the five Gulf States. GOMA is a partnership of the five U.S. Gulf States, federal agencies, academic organizations, businesses, and other non-profits in the region. GOMA's mission is to significantly increase regional collaboration to enhance the environmental and economic health of the Gulf of Mexico. In 2014, after careful consideration and evaluation, the GOMA Alliance Management Team elected to modify the priorities supported by the GOMA partnership. Important to note is that none of the existing focus areas were eliminated, but were redistributed within the new team structure. One of the new teams to emerge from GOMA's restructure is the Water Resources Team, a combination of the former Nutrients and Water Quality Teams. The GOMA Water Resources Team is led by the Mississippi Department of Environmental Quality and will focus its efforts within three areas: (1) protection of human health, (2) protection of aquatic health, and (3) protection of economic health. The team will be focusing on various water resources issues across the Gulf including but not limited to hypoxia, nutrient pollution, pathogens, harmful algal blooms, freshwater inflows, and ultimately, working to increase understanding regarding how impacts to human health and aquatic health tie in directly to the economic health of the region. GOMA is currently developing Governors' Action Plan III for Healthy and Resilient Coasts, the third in a series of action plans to address issues common to all five Gulf States in a voluntary and cooperative way.
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Land-use impacts on water quality in Beasley Lake Watershed, Mississippi using AnnAGNPS
Year: 2016 Authors: Yasarer L.M., Bingner R.L., Locke M.A., Lizotte R.
Land-use in agricultural watersheds has a fundamental role in shaping hydrologic processes, erosion, and nutrient export. However, changing land-use can be a challenge when assessing the effects of specific agricultural management practices on overall watershed water quality. On a practical level, this challenge often arises from a lack of data describing field-scale land-use and management practices over time. In this study, detailed land-use and management data from 1995-2009 are utilized to conduct AnnAGNPS watershed simulations for Beasley Lake Watershed located in the Mississippi Delta. AnnAGNPS is capable of estimating field-scale sediment and nutrient export on various spatial and time scales, which allows for spatial and temporal analysis of the effects of land-use change. Two major changes in land-use occurred in the watershed over the study period: 1) a change from predominantly cotton to soybean-rotations in 60% of total watershed cropland, and 2) a change from predominantly cotton to Conservation Reserve Program (CRP) practices in 23% of total watershed cropland. The impacts of these two land-use changes will be examined by comparing nutrient and sediment export at the field-level, as well as overall watershed loads throughout the study period. Results from this study will help understand the effect of overall land-use changes on pollutant loads impacting water quality in the Mississippi Delta, where a general decrease in cotton land-use has occurred from 1999 - 2009, coinciding with an increase in soybean and corn land-use. The information from this study can be helpful to conservationists when developing management plans that incorporate effective conservation practices to improve watershed water quality.
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Functions of wetland plant assemblages in water quality improvement
Year: 2016 Authors: Windham E.L., Shoemaker C.M., Ervin G.N.
As wetland restoration continues, an understanding of drivers of natural wetland function becomes increasingly important for effective wetland restoration planning. Many studies have shown that wetlands act as filters for nutrient rich waters, in part due to macrophyte properties. Differences in plant characteristics such as biomass production, root oxygen release, and surface area available for microbial colonization have been suggested as possible contributors to greater nutrient removal. Thus, it is assumed that water quality parameters will vary among plant species assemblages, and that differences observed will correlate with one or more aspects of plant species biology or ecology that may prove useful in planning future restorations. Differences have been found in nitrogen removal rates among plant species in studies of monocultures grown in mesocosms mimicking wastewater treatment constructed wetlands, but almost no research has been done on assemblages in natural or restored wetlands. This study aims to identify the differences in water quality improvement among plant assemblages in natural and restored wetlands. Thirty natural and restored wetlands in the Mississippi portion of the Mississippi Alluvial Valley were sampled four times. Dissolved oxygen, temperature, pH, conductivity, turbidity, and oxidation-reduction potential were measured on-site, and water samples were taken for analysis of nitrogen and total suspended solid content.Results showed that water quality parameters such as nitrate and phosphate concentrations, and pH were significantly correlated with plant growth form, in addition to being influenced by wetland type or by nutrient inputs on the surrounding landscape.
Interspecific ecological and meteorological controls on forest canopy-derived hydrology and biogeochemistry in the southeastern United States.
Year: 2016 Authors: Siegert C.M., Limpert K.E., Karunarathna A.A.
During storm events, as precipitation moves through the forest canopy it is transformed in both quantity and quality, thus delivering highly enriched water to the forest floor. Throughfall is spatially distributed beneath the forest canopy while stemflow is localized to the roots and soils in the immediate vicinity of individual tree trunks. Previous research has demonstrated that storm characteristics (e.g., intensity, duration, and magnitude), canopy structural parameters, and species composition have a significant control on canopy-derived nutrient fluxes. However, in the southeastern United States, contributions of the forest canopy to nutrient cycling have largely been overlooked, although the magnitude of tree biodiversity in the region separates these forests from their more-studied counterparts. Therefore, a field study was established in an oak-hickory forest in Mississippi to categorize the interspecific control on canopy-mediated nutrient cycling during precipitation events. Throughfall collectors and stemflow collars were located underneath the canopies of four oak (Shumard, Southern Red, Post, and White) and two hickory species (Shagbark and Pignut), with three replicates for each species. Hydrologic flux and nutrient samples were collected following individual precipitation events beginning in Fall 2014 and continue to present. Meteorological characteristics and precipitation chemistry were collected at a nearby open site.
Preliminary results indicate that stemflow volumetric flux was significantly different between species (p<0.001) but throughfall volumetric flux was not (p=0.624). Among the oak species, Shumard oak partitioned an average of 73.6% of incident precipitation into throughfall and 1.6% into stemflow, the largest among all species, with the remaining 24.8% partitioned into canopy interception. Mean concentrations of total nitrogen (TN) in throughfall were greatest in Shumard oak (1.44 mg/L) and post oak (1.39 mg/L) while stemflow concentrations were greatest in shagbark hickory (1.81 mg/L) and white oak (1.20 mg/L) and intermediate in Shumard oak (0.96 mg/L). Dissolved organic carbon (DOC) concentrations in throughfall were significantly different than precipitation (p=0.038) but not between species (p=0.342), while DOC concentrations in stemflow were significantly different than precipitation (p<0.001) and between species (p<0.001). Results suggest that Shumard oak canopies facilitate the largest hydrologic fluxes in oak-hickory forests that correspond to intermediate biogeochemical fluxes of nitrogen, enabling this species to directly modify the substrata and its growing conditions. Improved understanding of species-specific roles in nutrient cycles in highly diverse southern forests is critical to developing effective management strategies to mitigate shifts in species composition and ecosystem functions as regional climates change.
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Effects of land use on wetland plant diversity in Mississippi
Year: 2016 Authors: Shoemaker C.M., Windham E.L., Ervin G.N.
Restoration of former agricultural lands to wetlands has increased in the past 25 years, with public and private programs subsidizing the conversion of marginal farmland into wetlands. These wetlands were constructed with structural and functional goals in mind, such as increasing biodiversity and water quality within local and regional watersheds. While successful in terms of area restored, restored wetlands frequently do not meet desired management goals; often, these wetlands resemble highly degraded wetlands in terms of structure and function. While on-site parameters and management recommendations have recently received much attention, desired structural and functional components continue to fall short of management expectations. This study examined relationships between wetland site characteristics, measures of plant diversity, and land use. Data were collected in a total of 30 restored and naturally occurring wetlands in the Delta region of Mississippi during the 2014 and 2015 growing seasons. Wetland sites were surveyed twice during each growing season (May and August) from 50 evenly spaced observation points per wetland. Lower levels of plant diversity were observed in natural, compared to restored wetlands, with hydroperiod and management activities clearly affecting assemblages. Additionally, land use impacted observed plant community metrics, with the prevalence of agricultural and developed lands showing a negative relationship with plant species diversity. Wetland plant diversity showed a strong positive correlation with fallow land cover surrounding wetlands, with fallow land most often corresponding to land placed in conservation easements. Results thus suggest that low-intensity land use buffers associated with conversation easements are having a positive impact on wetland plant species diversity in the Mississippi Delta.
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Tapping into Underground Water in Mississippi
Year: 2016 Authors: Killebrew R.
An adequate supply of safe water is essential to the public health and welfare. The use of that supply through properly constructed and maintained water wells is an important component in the protection of our groundwater resources. The MDEQ Office of Land and Water Resources is responsible for licensing and regulating all drillers and pump installers operating in the state. Individuals desiring to engage in the business of water well contracting in the state must obtain a water well contractor's license. Those who drill boreholes or wells must obtain a restricted driller's license that will be valid only for a specified drilling purpose. Individuals who service or install water well pumps must obtain a pump installer's license. All licensees must meet specific requirements and demonstrate their competency in drilling and/or pump installation by passing various tests administered either by the MDEQ or by the National Groundwater Association (NGWA). Driller's logs submitted in accordance with our laws and regulations are essential in providing important information for the characterization of our resources and for the proper abandonment of wells.
Irrigation in North Mississippi?
Year: 2016 Authors: Tagert M.L., Karki R., Paz J.
The majority of water permits in the state of Mississippi, by far, are for groundwater wells used to supply water for irrigated cropland in the Delta. These wells are fed by the shallow Mississippi River Valley Alluvial Aquifer (MRVAA), which is easily accessible and has supplied water for irrigation since roughly the 1970's. Groundwater levels in the MRVAA have been declining in recent years as the number of irrigated acres in the Mississippi Delta continues to increase each year. As a result, much attention has been placed on maintaining the sustainability of the MRVAA and thus the sustainability of agriculture in the Mississippi Delta. However, an increasing number of producers in North Mississippi have been implementing irrigation to reduce risk during periods of drought and also to increase crop yields. North Mississippi producers face somewhat unique challenges when converting from dryland production to an irrigated system. This presentation will better quantify irrigation practices in North Mississippi and discuss some of the challenges and opportunities North Mississippi producers encounter when implementing irrigation.
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An Overview of Dam Safety and Impoundment Permitting
Year: 2016 Authors: Myers D.
There are approximately 7,000 dams in the State of Mississippi that form lakes that are 5 acres or greater in surface area. The State Dam Safety program which is part of the Department of Environmental Quality's Office of Land and Water Resources is responsible for regulating these dams. These dams and lakes not only pose potential threats to lives and property, but can also alter the flow regime of Mississippi streams. Dams which are on inventory are classified as high, significant, or low hazard depending on what would be flooded downstream if the dam were to fail. One aspect of permitting impoundments includes consideration of impacts to minimum flows. Many impoundments are small and located in the upper reaches of watersheds. The small watersheds they impound typically have very low 7Q10 flows and have not been required to have minimum flow devices installed to bypass the 7Q10.
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Office of Land and Water Resources: Overview of Water Use In Mississippi
Year: 2016 Authors: Hawkins C.
Currently, there are approximately 23,000 groundwater withdrawal permits and 2,600 surface water permits that are active in the state. Seventy-six percent of these permits are issued for irrigation purposes, with the other twenty-four percent leaning heavily on public water supply and other various beneficial uses. The Mississippi Water Law states that all water, whether occurring on the surface of the ground or underneath the surface of the ground, is among the basic resources of this state, belongs to the people of this state, and is subject to regulation. The general welfare of the people of the State of Mississippi requires that the water resources of the state be put to beneficial use to the fullest extent of which they are capable, that the waste or unreasonable use, or unreasonable method of use of water be prevented, and that the conservation of such water be exercised. With only a few exceptions, anyone who wishes to use the waters of the state must obtain a permit from the Mississippi Environmental Quality Permit Board. The OLWR is charged with the task of permitting all groundwater and surface water withdrawals in the state. Other laws that impact the use of water in Mississippi include water well licensing and impoundments, which are also regulated by the OLWR.
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Overview of Water Availability in Mississippi
Year: 2016 Authors: Phillips P.
The abundant water supplies in Mississippi constitute one of the most important and valuable natural resources in the state. These resources contribute directly to the quality of life and economic prosperity of the state. Throughout the state, there is a need for accurate assessment of groundwater resources to allow wise long-range planning and development. The water resources available in areas of the state can vary significantly depending on various hydrogeologic conditions that may affect baseflow in streams, water quality, and the amount of water local aquifers can supply. The highly variable nature of these resources means that a concerted effort must be maintained to collect related groundwater and surface water data that will allow proper decisions to be made regarding the management and development of the state's water resources. In Mississippi, precipitation averages about 54 inches annually. About 10% of this infiltrates to the water-saturated zone and becomes groundwater. Fresh groundwater in Mississippi occurs principally in unconsolidated sand and gravel deposits interbedded with thick, extensive layers of clay that form aquifer boundaries and is available throughout the state. Groundwater supplies 90% of water used in the state, for everything from drinking water supplies, agriculture, fish culture, to commercial and industrial uses. The total volume of fresh water stored in Mississippi's aquifers, which has been conservatively estimated to be in excess of 6 billion acre-feet, dwarfs the total volume of all surface water resources, but surface water is still a valued source of water supply in the state. Mississippi has 10 major river basins with 86,000 miles of streams. Surface water supplies drinking water to five entities: the City of Jackson, the City of Corinth, Short Coleman Water Association, the NE MS Regional Water Supply District, and the Jackson County Port Authority. Surface water is also used for agriculture, industries, and wildlife management, among other uses.
Current Surface Water and Groundwater Studies in the Central Mississippi Region
Year: 2016 Authors: Henley L.
The Central Mississippi Region encompasses twenty counties and is home to many major cities, including the Jackson Metro area. Both surface water and groundwater studies are currently being conducted in the Central Region. The Office of Land and Water Resources conduct streamflow measurements in order to obtain surface water discharges to complement data collected by the Office of Pollution Control for the M-BISQ (Mississippi Benthic Index of Stream Quality) Program. The 2015-2016 M-BISQ study has approximately forty sites selected within the central region of the state. Regional groundwater studies are also performed by the Office of Land and Water Resources' Water Resources Management Division. The data collected for the regional studies include water level measurements, which are used to create potentiometric surface maps and hydrographs, water quality samples, and using geophysical logs to create geologic cross-sections and maps. Due to rapid expansion in Madison County in both the residential and industrial sectors, Central Region studies are presently being focused on the Gluckstadt area. Primary aquifers utilized in Madison County, specifically in the Gluckstadt area, are the Cockfield and Sparta Aquifers, with some minor use of the Meridian-Upper Wilcox aquifer. Population, water use, and water level data will be assessed to determine any impacts on water availability in the area.
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Regional Overview of Work by the Water Resources Division in Northeast Mississippi
Year: 2016 Authors: Banks J.
Groundwater and surface water resources in the northeast region are monitored by a regional hydrogeologist assigned to the twenty counties included in the area. Historically, the primary focus in the region has been monitoring of water levels in the area's aquifers. Potentiometric mapping of the Paleozoic and Cretaceous aquifers was completed in 2011. Work in the region involves aquifer characterization, including subsurface mapping, water quality sampling and continued water level monitoring. A study of the Wilcox aquifers in Lafayette County will be completed when water quality sampling at selected locations is finished and the data have been analyzed. Smaller, more localized projects for water supply analyses have also been completed, including monitoring water levels in the Tupelo area and in the Wilcox aquifers of Choctaw County. OLWR also works with the Office of Pollution Control collecting surface water discharges for the M-BISQ (Mississippi Benthic Index of Stream Quality), with approximately 56 sites selected within the northeast region of Mississippi.
Beginning in July, 2015, each of the four regions is responsible for adequately characterizing the water resources for one area in the region per fiscal year. These areas can be from the size of a small town to as large as a county. Characteristics to be analyzed include water availability, water quality, and water use.
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Evaluations of Groundwater Resources of Southern Mississippi
Year: 2016 Authors: Hoffman J.
Virtually all water used for public and domestic drinking water supplies in southern Mississippi is derived from underground sources. Much of the area is underlain by a thick section of fresh water-bearing sediments and multiple aquifers are available at most locations. Although some wells in Wayne and Jones Counties are screened in other aquifers, the most widely used aquifers in southern Mississippi are developed in beds of sand that occur within sediments above the Vicksburg Group. Southwest of a line from Warren County through Wayne County, these sediments dip in a general gulfward direction at rates ranging from 30 to 100 feet per mile and form a wedge thickening southward to more than 5,000 feet in southern Hancock County and southwestern Wilkinson County. The aquifers within this interval have been termed the "Miocene aquifer system". Because these deposits range from late Oligocene to Pliocene age, it is proposed that the name Grand Gulf aquifer system is more appropriate. Fresh water is available from these aquifers nearly everywhere within the 17,000 square mile area of their occurrence, even extending out from the coast beneath the barrier islands along Mississippi Sound and beyond, possibly as deep as 2,500 feet at Ship and Cat Islands. For years, there was little effort to systematically subdivide the many sand intervals that function as separate aquifers within the Grand Gulf system, an interval often consisting of 2,000 feet of fresh water-bearing sediments. Because of the growing need to make informed decisions concerning water use, staff initiated a study to delineate the individual aquifer units within the Grand Gulf system from interpretations of borehole geophysical logs. Office of Land and Water staff members have measured water levels and collected water samples in wells throughout southern Mississippi for many years. In early 1992, investigation of the potential for intrusion of saltwater into the aquifers that are sources of drinking water along the coast started. Results of this investigation found no evidence of saltwater intrusion in the confined aquifers that are sources of water supplies along the coast. In 2011, after reports of increased mineral leasing activity in southwestern Mississippi associated with fracking and its attendant requirements for water, the staff began a study focusing on potential groundwater availability in Amite and Wilkinson Counties that identified the specific aquifer intervals already being used for public and domestic drinking water supplies and those which might supply water for fracking without resulting in adverse impacts upon others.
Quantifying water dynamics in a no-till vs. conventional-till corn field in the Mississippi Delta
Year: 2016 Authors: Anapalli S.S., Fisher D.K., Reddy K.N., Sui R., Gowda P.H.
Conventional-till (CT) cropping system reportedly conserve less soil water compared with no-till (NT) soil-residue management. Reductions in evapotranspiration (ET) and runoff (RO) result in increasing infiltration rates of precipitation and irrigation water inputs; however, location-specific benefits from such systems vary with soil texture and presence or absence of restrictions to water movement such as hard pans in the soil profile. One of the primary benefits of NT over CT comes from its potentially decreasing the ET loss of water from the system. Also of importance is the amount of water infiltrated into the soil and available for crop uptake, and how much water is percolated beyond the root zone of the crop contributing to ground water re-charge as this ground water is the main irrigation water source in the region for crop production. Limited research on ET and soil water dynamics beyond the crop root zone in these cropping systems in the Mississippi Delta region preclude farmer tillage recommendations in cropping systems, especially under corn, a relatively new crop in the region. To fill this gap, we embarked on a research program to monitor ET and soil water dynamics along with crop growth physiology changes in corn under NT and CT in a Dundee silt loam soil at Stoneville, MS. The ET estimation is by solving an energy balance equation representing a crop canopy-land surface for latent heat flux from estimates of sensible, soil heat, and net radiation fluxes. Soil heat flux was quantified from measurements of heat flux using a soil heat flux plate installed at a depth of 8 cm and soil temperature and moisture measurements above the plate. The sensible heat was quantified by modeling aerodynamic and boundary layer resistance corrected for atmospheric stability and wind speed effects from measurements of net radiation, air temperature and relative humidity, land surface-canopy temperature, and wind speed at a constant height of 1 m above the crop canopy, and similar data from a nearby eddy-covriance station. We have tested the ET algorithm developed, with simulataneous measurements of ET using a field lysimeter (3X3X2.4m) and energy balance in the center of a 4.4 ha cotton field at Bushland, TX, and found good agreement between the two estimates.
Eddy Covariance Systems for Water Management Research and Agroecosystem Monitoring
Year: 2016 Authors: Sui R., Reddy K., Anapalli S., Murrell C.
There is around 1300 mm of annual precipitation in Mississippi. However, uncertainty in amount and timing of precipitation during the crop growing season becomes a serious risk to Mississippi producers. To reduce the risk and optimize crop yield, the producers have become reliant on irrigation. In recent years, irrigated acreage is rapidly increasing in Mississippi. Almost all irrigation water in this region is pumped from the Mississippi River Valley Alluvial Aquifer, and excessive withdrawals of underground water have resulted the level of the aquifer declining. Novel irrigation techniques and tools are needed for improving water use efficiency to maintain Mississippi water resource sustainability. Eddy covariance (EC) method is capable of measuring exchanges of carbon dioxide, water vapor, methane, and energy between the surface of the earth and the atmosphere. Eddy covariance systems have been widely used for monitoring agroecosystems and measuring crop evapotranspiration (ET) for irrigation scheduling. Objectives of this project were to use EC systems to monitor the agroecosystem and measure evapotranspiration for research on water management technologies and agroecosystem assessment. Three EC systems were set up in the Mississippi Delta for agroecosystem monitoring and assessment, and evapotranspiration (ET) measurement. One EC system is located in Stoneville, MS and two others in Arcola, MS. The EC system consisted of a CH4 analyzer for measuring methane gas flux, CO2/H2O analyzer for measuring carbon dioxide and water vapor fluxes, three-dimensional sonic anemometer for determining wind speed in three dimensions, and biomet (biological & meteorological) sensors to collect ancillary data for filling measurement gaps and interpreting flux results. Installation and preliminary field tests of the EC systems have been completed. The systems are being used to collect data for research on water management technologies and climate change impact on agroecosystems in the Mississippi Delta.
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Towards an Improved Understanding of On-Farm Water Storage Systems in Mississippi: How Much Water Is Lost from These Systems?
Year: 2016 Authors: Perez-Gutierrez J.D., Paz J.O., Love M. Tagert M.
On-farm Water Storage (OFWS) systems can mitigate downstream nutrient-enrichment pollution originating from agricultural landscapes. In the Mississippi Delta, an OFWS system usually combines tail-water recovery (TWR) ditches and on-farm reservoirs. The surface runoff and irrigation tail water is collected by ditches, and most of this water is pumped to reservoirs to be stored for future irrigation needs. The remainder of the in-ditch water evaporates, infiltrates, or flows out of the system. Previous studies have focused their attention on the spatial and temporal water quality changes throughout OFWS systems to quantify their nutrient reduction capacity. However, less attention has been placed on measuring the volume of water that is effectively lost from these systems, which is important to investigate so we can better understand the net environmental benefits of using OFWS systems. This study presents preliminary results of water quantity monitoring at the outlet pipe of an OFWS system implemented on a farm located in Porter Bayou Watershed, Mississippi. This data obtained from this study will help to better quantify and provide additional insight on the benefits of OFWS for nutrient reduction and water storage in agricultural watersheds.
Assessment of tailwater recovery system and on-farm storage reservoir water and nutrient harvesting
Year: 2016 Authors: Omer A.R.
The Lower Mississippi Alluvial Valley is economically important due to its highly productive agricultural land. However, producers in this region face two predominant environmental issues that are inherently linked to the intensity of the agricultural industry in this region. First, intensive agriculture practices have resulted in increased surface transport of nutrient-laden sediments, contributing to eutrophication in receiving waters and to the Gulf of Mexico Hypoxic Zone. Second, current water withdrawals from the Mississippi Alluvial Aquifer for irrigation are not sustainable. These issues threatening environmental resources necessitate use of best management practices and groundwater conservation. This research investigates systems of best management practices as water resource conservation methods. Such practices include surface water capture and irrigation reuse systems. Referred to as tailwater recovery systems (TWR), this practice consists of a tailwater recovery ditch which may be paired with on-farm storage reservoirs (OFS). Seven case studies of different TWR were monitored for nutrients during the 2014 and 2015 growing season at: inflow, edge of field, TWR, OFS, and overflow locations. Investigations highlight functionality for nutrient recycling, and descriptions of nutrient loss mitigation. Preliminary results for seven TWR in 2014 and 2015 show a mean of 94.05 mega liters of water being recycled applying a mean of 0.86 kg/ha total nitrogen and 0.2 kg/ha total phosphorus back onto the tillable landscape. These systems are proving successful in holding water on the landscape, recycling that water, and therefore nutrients; thereby preventing those nutrients from being lost to downstream waters. This suggests that TWR, or systems with similar water holding capacity, have potential for water resource conservation in the Lower Mississippi Alluvial Valley.
MDEQ's Mississippi Comprehensive Ecosystem Restoration Tool
Year: 2016 Authors: Strange T.
As a result of the Deepwater Horizon Oil Spill (DWH), Mississippi is working to restore the health and ensure sustainability of the coastal landscape affected by the spill. To ensure sustainable restoration is achieved, the National Fish and Wildlife Foundation (NFWF) Gulf Environmental Benefit Fund (GEBF) agreed that an ecosystem restoration plan was needed in Mississippi. They approved to fund the development of the Mississippi Restoration Plan. One of primary goals of the Plan is to develop the Mississippi Comprehensive Ecosystem Restoration Tool (MCERT), which is a science-based tool for identifying and examining ecological resources and stressors at a landscape/seascape scale and that allows for improved restoration planning and informed decision making. MCERT represents a suite of geospatial analysis models that provide data products to describe the terrestrial landscape and the marine and water quality conditions in south Mississippi. Two of the MCERT components deal directly with water quality and watershed characterization. The water quality model integrates the Soil and Water Assessment Tool (SWAT). We calculated a 2006-2013 simulation of water, sediment, and nutrient flow in the Pearl, Pascagoula, and Mississippi Coastal basins, as well as indices of change between these and the outputs from an earlier 1987-1994 simulation of the same area to highlight broad indicators of water quality change within the study area using three primary parameters: sediment, nitrogen, and phosphorus at the subwatershed and stream reach level. Stream gauge data from the USGS and observed sediment and nutrient loading data points from the MDEQ are used to calibrate the model to better reflect field conditions. The watershed characterization component of the tool uses derived spatial data, including environmental resource and stressor/threat data, as inputs and aggregates the information to characterize subwatersheds by quantifying the amount, weighting, scoring, and normalizing of the input data. Within each subwatershed, various datasets are assigned values and are adjusted, normalized, and ranked relative to one another. Data inputs include but are not limited to SWAT outputs, dam storage ratios, protected areas, T & E species presence, ecological hubs and corridors, and a landscape development index (LDI). The Mississippi Restoration Team uses these tools to identify hotspots and areas of interest as well as simulate best management practices to quantify restoration scenarios across the landscape. Manipulation of climatic, hydrologic, and land use inputs offers further potential for modeling future scenarios, incorporating both agricultural and non-agricultural management practices, at various spatial and temporal scales.
Evaluation of Crop Rotation and BMPs on Water Quality and Quantity using SWAT
Year: 2016 Authors: Ni X.
Corn after soybean is a common crop rotation practices in the Mississippi Delta. Several Best Management Practices are also implemented in the Big Sunflower River Watershed (BSRW). Placement of BMPs and crop rotation practices will affect water quality and quantity in the BSRW. This study will simulate the impacts of different placements of BMPs and corn after soybean rotation in the BSRW using SWAT model. Soil and Water Assessment Tool (SWAT) model was calibrated at Harris Bayou, validated at Bogue Phalia and verified at BSRW using 17 years of stream flow, sediment and nutrient data. Model performances during calibration, validation and verification were ranged from 0.61 to 0.63 for R2, 0.46 to 0.62 for NSE. Results of different crop rotation practices and their effects on water quality and quantity will be evaluated and presented in the conference.
Natchez Trace Ecological Forecasting and Water Resources: Utilizing NASA Earth Observations to Assess Current and Historic Wetland Extent along the Na
Year: 2016 Authors: Lynn T.
This project partnered with the National Park Service (NPS) to produce needed land cover mapping products for the Natchez Trace Parkway and to address community concerns involving the past, current, and future wetland conditions of this area. The parkway occurs in Mississippi, Alabama, and Tennessee. Beavers have altered current and historic wetland conditions in the study area by changing streamflow along adjacent rivers and tributaries. While the ecological services provided by these beavers can benefit wetland ecosystems, indiscriminate and excessive dam building has caused issues with flooding, property damage, and road maintenance within the parkway. NASA Earth observations (Landsat 5 Thematic Mapper, 7 Enhanced Thematic Mapper Plus, and 8 Operational Land Imager) and ERDAS IMAGINE were used to generate a time series of land use/land cover (LULC) classification maps from October 1992 to January 2015 showing wetland status occurring along the parkway. A projected LULC classification map was also produced using TerrSet Land Change Modeler software. This LULC time series and modeled projection will aid the NPS in wetland conservation and beaver management plans throughout the Natchez Trace Parkway.
Data-collection efforts by the U.S. Geological Survey during the winter flood of 2015 on the Lower Mississippi River
Year: 2016 Authors: Manning M.A.
In December 2015, the National Weather Service (NWS) began to predict and warn communities in flood prone areas that the Mississippi River would reach record flood levels in many areas. Based on these predictions, the U.S. Geological Survey (USGS) began to deploy flood-measuring crews at many locations on the Mississippi River to confirm and document these higher streamflow's. As flood waters moved southward along the main stem of the Mississippi River, several USGS teams from offices within the Lower Mississippi-Gulf Water Science Center measured streamflow at several locations in the Lower Mississippi River system. In addition to the USGS, other agencies involved with streamflow measurements and flood forecasting in the Lower Mississippi main stem reaches included the NWS, as well as, the U.S. Army Corps of Engineers - St Louis, MO, Memphis, TN, Vicksburg, MS, and New Orleans, LA, districts.
By mid- to late-January 2016, approximately 72 non-routine streamflow measurements were made at various locations in the Mississippi River main stem system. These measurements were used to confirm stage-discharge ratings and support NWS flood-forecast models as the crest moved into the lowermost reaches of the Mississippi River basin near New Orleans, LA. These streamflow data, in combination with other hydrologic measurements, are widely used by local, State, and Federal agencies to predict flood-inundated areas, as well as, to maintain and operate flood-control structures that are used to divert or reduce major flooding near New Orleans, LA. In addition to numerous flow measurements, several USGS crews collected flow-weighted water-quality samples and maintained continuous water-quality monitors that measured water temperature, salinity, pH, dissolved oxygen, nitrate, and turbidity, to characterize changes in water quality due to increased flow. The Tennessee Department of Environmental Conservation (TDEC) assisted the USGS with water-quality-data collection at Memphis, TN.
In mid-January, near peak streamflow on the Mississippi River at Vicksburg, MS, a group of USGS scientists from more than 9 offices throughout the Nation, collaborated to collect extensive streamflow, bathymetry, water velocity, and bedform data at that site to help advance new research regarding the use of remotely-sensed data collected from onsite video, Predator drone recordings, and satellite imagery to compute streamflow. This research effort will help expand the understanding of flood dynamics, as well as, potentially reducing the physical manpower required to measure flood events in the field.
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A demonstration Project: Measurement of Sediment Oxygen Demand and Nutrient Fluxes in on Eckie's Pond, MS
Year: 2016 Authors: Laurens L., Ortega S.L., Martin J.L., Ramirez-Avila J., Martin J.L.
One of the processes long known to impact the water quality of surface waters is the oxygen demand by, and nutrient release from, sediments. Sediment oxygen demand (SOD) and nutrient releases, due to the mineralization (diagenesis) of organic materials in bottom sediments, can contribute to eutrophication, harmful algal oxygen blooms and hypoxia. SOD and nutrient releases are commonly measured using one of two alternative techniques: by in- situ deployment of chambers on the bottom of the water body; or, by the collection of sediment core samples which are transported to the laboratory where SOD and nutrient fluxes are measured under controlled conditions. The main objective of this study was to develop the capability of using the core method, based on methodologies developed by the Horn Point Laboratory at University of Maryland and extensively used in Chesapeake Bay, and to compare results to chamber measurements at a selected site on campus at Mississippi State University, Eckie's pond. Other goals included the development of standard operating procedures (SOP's) for all the processes and the completion of a laboratory setup. The developed methodology could then be applied to other selected Mississippi water bodies to provide flux measurements in support of related oxygen and nutrient management studies. Overall research goal considers long term measurements of sediment fluxes, sediment diagenesis, and water column concentrations in order to evaluate factors influencing sediment diagenesis, to support evaluation and development of diagenesis models such as that included in the USEPA Water Analysis Simulation Program.
Refining Designated Uses For Mississippi's Surface Waters
Year: 2016 Authors: Caviness-Reardon K.
Water quality standards are required by the Clean Water Act and include three essential components: (1) designated uses for the water bodies, (2) criteria (either narrative or numeric) to support those uses, and (3) an antidegradation policy. Water quality standards establish the water quality goals for a water body. Designated uses are a critical component of water quality standards because they specify what a specific water body is being used for in order to define the appropriate water quality goals provide a way to evaluate whether or not these goals are being attained. Mississippi currently has a very simple water body classification structure. Within recent years, the Mississippi Department of Environmental Quality (MDEQ) has identified the need to examine the current water body classification structure and investigate further refinement of the existing water body classification structure. In 2014, MDEQ completed a preliminary analysis to consider potential options for refinement of the current structure. Further refinement of water use classifications will allow MDEQ to provide a more accurate distinction between water bodies around the state and allow for more appropriate criteria (or goals) to be established for those various water bodies. . Water use classification (or designated use) is the basic foundation of the water quality standards program, and improving the accuracy of water body classifications within Mississippi is a program priority for MDEQ's Water Quality Standards Program.
Agricultural Chemical Monitoring Program Overview
Year: 2016 Authors: Billiot J.
Agriculture is Mississippi's number one industry. A wide variety of agricultural compounds are used to support this industry. Since over ninety percent of the population of Mississippi relies on groundwater for drinking water, there has been concern that the groundwater resources of Mississippi may be impacted and degraded by the use of pesticides and herbicides. In an effort to better determine the impact of agricultural chemicals on groundwater resources, the Agricultural Chemical (AgChem) Groundwater Monitoring Program was designed in 1986 and implemented in March of 1989. Since the inception of the program, over 2,100 samples have been taken from wells around the state and analyzed for more than 100 herbicides and pesticides. Of the samples collected to date, 96.6% have no detectable concentrations of agricultural chemicals present. Of these samples with detects, only four were found to have concentrations exceeding the maximum contaminant levels (MCLs) set by the United States Environmental Protection Agency (EPA). Results indicate that Mississippi's groundwater quality is relatively unaffected by agricultural activities.
Source Water Assessment Program
Year: 2016 Authors: Warner J.
The 1996 amendments to the Safe Drinking Water Act mandated states to develop and implement a Source Water Assessment Program (SWAP). The purpose of this program was to notify Public Water Systems (PWS) and customers regarding the relative susceptibility of their drinking-water supplies to contamination. Congress intended for these susceptibility assessments to encourage efforts that would enhance the protection of PWSs by managing identified potential contaminant sources of concern. In 1998, the Mississippi State Department of Health (MSDH) contracted with MDEQ to develop and administer the SWAP in Mississippi. OLWR's Source Water Assessment Program was designed to identify and properly manage potential contaminant sources in Wellhead Protection Areas from which PWS wells capture their water over a specific period of time. OLWR staff ran countless computer simulations and undertook an extensive data review of Mississippi primary drinking water aquifers in order to come up with meaningful Wellhead Protection Areas and a ranking system was implemented in order to inform PWSs of their relative susceptibility.
Assessments of all public groundwater systems and three of the five public surface water systems operating in the state have been completed. The SWAP reports and corresponding maps of delineated Source Water Protection Areas are available online at the MDEQ website: http://landandwater.deq.ms.gov/swap. OLWR now requires that preliminary assessments of proposed public water supply wells site be performed by MDEQ prior to the issuance of groundwater withdrawal permits. These preliminary assessments allow the suitability of proposed well sites to be screened prior to the drilling and completion of PWS wells. The OLWR staff continues its efforts to protect the drinking water supplies of the 1,200 public water systems operating in the state as part of activities related to the Source Water Assessment/Protection Program. MDEQ is working closely with the Mississippi State Department of Health's Water Supply Division to assist in the implementation of the EPA's Groundwater Rule.
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Developing Numeric Nutrient Criteria For Mississippi's Surface Waters
Year: 2016 Authors: Young A.
Over the last 50 years, the amount of nitrogen and phosphorus entering our surface waters across the nation has increased significantly. The degradation of water quality associated with excess levels of nitrogen and phosphorus in our surface waters has been extensively studied and documented. In Mississippi, like many other states, excessive amounts of nutrients, including nitrogen and phosphorus, have been a major cause of surface water impairments. In 2001, EPA developed an Action Plan requiring that all states develop numeric nutrient criteria in order to protect our waters from nutrient pollution impacts. Since 2001, the Mississippi Department of Environmental Quality (MDEQ) has been working diligently to develop appropriate and protective numeric nutrient criteria for Mississippi's waters including (1) the development and implementation of MS's Nutrient Criteria Development Plan, (2) collecting extensive data to derive scientifically defensible nutrient criteria, and (3) developing robust tools to assess the biological condition of our waters. In 2010, MDEQ formed the MS Nutrient Technical Advisory Group (TAG) consisting of members of state, federal, and research scientists to aid the agency in deriving these criteria providing technical knowledge and regional expertise to the criteria development process. In an effort to be more scientifically defensible, MDEQ is applying the multiple lines of evidence approach for nutrient criteria development. The multiple lines of evidence approach involves looking at several lines of analysis, such as distributional analysis, stressor-response, scientific literature, and water quality models to establish a final endpoint. MDEQ is currently working to develop numeric nutrient criteria for the various water body types around our state which have been categorized into (1) Non-Delta Lakes and Reservoirs, (2) Coastal and Estuarine Waters, (3) Non-Delta Streams, and (4) Delta Waters. Non-Delta Lakes and Reservoirs will be the first water body type in which numeric nutrient criteria will be established. MDEQ is aiming for a public notice date no later than June 30, 2016. MDEQ will continue with criteria development efforts within the remaining water body types in a sequential manner. MDEQ recognizes the complexities that will be faced when implementing numeric nutrient criteria across the various water programs within MDEQ. Therefore, the agency is has established an internal nutrient criteria implementation work group that is developing a Nutrient Criteria Implementation Plan to describe how the criteria will be incorporated into programs such as permitting, water quality assessment, water quality monitoring, total maximum daily loads (TMDLs), and waste load allocations (WLAs). MDEQ, along with the support of the TAG and the engagement of stakeholders, continues to make great strides in developing nutrient criteria for Mississippi's surface waters.
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Real Time Groundwater Monitoring: Mississippi River Valley Alluvial Aquifer and the underlying Tertiary aquifers of the Mississippi Delta
Year: 2016 Authors: Parrish P.C.
This Mississippi Delta in the northwest quarter of Mississippi is largely agricultural. It has long been an Office of Land and Water Resources (OLWR) priority for monitoring and research. This focus comes from the high concentration of wells and water use in this portion of the state. There are approximately 23,430 permitted groundwater wells statewide. The Mississippi Delta has 19,410 of those permits. Due to this high water use, hydrologic factors, and geologic factors, there have been growing concerns about dewatering the aquifer. Groundwater model results indicated the need for more information on the possible exchange of groundwater between the Mississippi River Valley Alluvial Aquifer (MRVA), mainly used for irrigation, and the underlying drinking water Tertiary aquifers in the Mississippi Delta. OLWR began mapping areas where there are possible close proximity of sands between the aquifers. The Delta Drilling Project, initiated between the Office of Geology and OLWR, has provided several locations for sand to sand contact. With this research came the impetus for a Delta-wide monitoring network. The traditional monitoring network of semi-annual survey wells would not be adequate for this type of investigation. Real-time monitoring is an innovative technology that has become more affordable. OLWR needs measurements throughout the year (especially during pumping season) to evaluate any exchange of water between aquifers. Paired well nests were installed in five locations to begin the project. These pairs are located around the center of the regional cone of depression where close proximity sands had been mapped. Instrumentation was installed in one location on October 29, 2015. OLWR has ordered two more sets of instrumentation. The data collected include both water quality and water quantity parameters (water level, conductivity, and temperature). These parameters are sent by cellular transmission in data packets every 15 minutes. The data is housed by McCrometer, which manufactures the instrumentation, and is available through a web portal. OLWR will track fluctuations in the parameters especially during high use periods when heads may drastically differ. This will provide more data on upward recharge and any downward losses to help improve modeling inputs and better manage both drinking water and agricultural water in the Mississippi Delta. OLWR hopes to have at least one well pair in each Delta County and to provide web access for stakeholders in the future.
Harvesting Excess water from the rivers of Little Tallahatchie, Big Sunflower, and the Buffalo.
Year: 2016 Authors: Madison J.
Considerable research has been conducted to assess the potential for harvesting rainwater during the off- season in the South, particularly in the State of Alabama (Tyson, T.W., 1999). The correct management strategy for utilization of groundwater and surface runoff is proper allocation of water resources within a catchment. A management strategy utilizing levee embankment ponds for production and rainwater storage has been beneficial in reducing the amount of effluent discharge by as much as 90% and groundwater use by as much as 75% (Cathcart, 1999). Early research (Cathcart et al., 2007) pertaining to rainwater harvesting and storage technologies demonstrated the importance of the implementation of management strategies for conserving groundwater resources. This research will be based upon the utilization of excess floodwaters from Big Sunflower, Little Tallahatchie, and Buffalo rivers using modeling approaches of simulating floodwater capturing methodologies including the use of pumps, siphons, and diversion techniques of streams or rivers along the Mississippi River Basin to augment the water needs for irrigation during the growing seasons (Pote, J., et al. 1988). Additionally, this research will examine 64 years of precipitation data, flood stages, duration of flooding, and will utilize the use of rating curves and back calculations to determine missing data points in the precipitation and flow data records. Data will be obtained from the United States Geological Survey (USGS) and the Army Corps of Engineers (USACE) for the Big Sunflower, Little Tallahatchie, and Buffalo Rivers.
Variable pathways and geochemical history of seepage under the Mississippi River levee: Observations from the 2011, 2015, and 2016 floods
Year: 2016 Authors: Davidson G., Voll K., Corcoran M., Kelley J.
During flood stage on the lower Mississippi River, water levels on the river side of a levee can be several meters higher than the surrounding land surface, creating steep hydraulic gradients that drive seepage of water beneath the levees. Sand boils form when sediment is eroded and transported to the surface on the opposite side of a levee, leaving open conduits that can compromise the structural integrity of the levee. The flow path of seepage beneath the levee may be deep or shallow, depending on the surficial geology, with deeper flow pathways found where a levee sits on top of low-permeability channel-fill deposits. For levees over the Mississippi River Valley alluvial aquifer, deeper flow pathways may encounter anoxic water with distinct geochemistry, raising the possibility that flow pathways for individual seeps or sand boils can be elucidated based on their geochemical signatures. Exploratory sampling north of Vicksburg, MS, from the river, from relief wells, and from sand boils during the 2011, 2015, and 2016 flood events shows considerable promise. Relief wells and a small number of sand boils had high iron and arsenic concentrations, consistent with deeper water being driven up to the surface. Most of the sand boils analyzed had iron and arsenic concentrations more similar to river water, consistent with shallow pathways through sandbar deposits. Many sand-boil samples also showed evidence of redox reactions during transit, not just simple mixtures of river water and groundwater. In select relief wells and sand boils, sampling was repeated after three weeks of continuous flow (2015), and again during a subsequent flood (2016), to identify short term geochemical and isotopic changes that may occur as flood waters move increasingly into the subsurface. Preliminary results show significant changes in tritium concentration over time.
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Prediction of Future Agricultural Water Needs in Mississippi Delta and Blackland Prairie under Surface Water Supply and Groundwater Pumping Scenarios
Year: 2016 Authors: Feng G., Ouyang Y., Reginelli D., Jenkins J.
The total area of Mississippi is approximately 30 million acre, grain crops take 4.6 million acre lands. Mississippi western Delta (5 million acre in total) and eastern Blackland Prairie (total 3 million acre) are two major agricultural regions where 80% of the MS croplands are planted. The Delta region accounts for 67% of the state croplands, over 90% of irrigation water is pumped from groundwater. The ongoing irrigation depletion of groundwater which has already declined to the alarming level in the Delta threaten agricultural productivity and sustainability. Enhancement of surface water supply is the solution to reduction of groundwater usage in the state which is rich with rainfall and surface. Sustainable conjunctive use of surface and ground water resources for irrigation requires knowledge of crop water requirement and deficit as well as prediction of future agricultural water needs. Soybean, corn and cotton are planted on 65% of croplands in Mississippi. Therefore, irrigation water needs of the three dominant crops were predicted. Patterns and trends of rainfall, reference evapotranspiration (ETo), water deficit and irrigation requirement in Delta (1915-2015) and Blackland Prairie (1894-2014) were analyzed using time series statistical models for annual, seasonal, and monthly periods. An AutoRegressive, Integrated, and Moving Average (ARIMA) approach was used to develop monthly and annual models for rainfall and ETo prediction. The ARIMA models forecasted 1319 mm of mean annual rainfall and 1203 mm of mean annual ETo in the two regions from 2016 to 2024. Those models predicted that soybean, corn and cotton need irrigation of 7.1, 6.6 and 6.9 inch yr-1. In 2014, there are 283,535 and 31,654 ac of cotton, 382,935 and 71,428 ac of corn, 1,595,363 and 217,640 ac of soybean in the Delta and Blackland Prairie, respectively. Totally, the three major row crops need 1.3 million acre feet of water in Delta and 0.2 million acre feet in the Blackland Prairie for irrigation each year. Surface water as an alternative option must be taken to place irrigation agriculture on a sustainable path. Our STELLA pond hydrological process model predicted that the ratio of pond size to irrigated crop land is 1:18. There are approximately 251,983 and 77,186 acre of surface water in the Delta and Blackland Prairie. If 19% and 16% of those surface water is used for irrigation in the two regions, at least 37% (481,155 acre feet) and 100% (185,837 acre feet) of groundwater could be saved in the MS Delta and Blackland Prairie, respectively.
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Water Quality in Bangs Lake: effects of recurrent phosphate spills to a coastal estuary: Year 2
Year: 2016 Authors: Dillon K., Caffrey J., Carmichael R.H., Cressman K., Woodrey M.
Grand Bay National Estuarine Research Reserve (GBNERR) is located in a relatively pristine estuary in the northern Gulf of Mexico, with ambient nutrient concentrations often below detection. However, since 2005, periodic breaches in a containment levee from a phospho-gypsum stack have led to high phosphate levels (over 200 µM) while pH dropped from 7.5 to near 4.5. GBNERR staff assembled a phosphate working group to investigate scientific questions related to these phosphate loadings. This working group includes members from GBNERR, regional universities, marine labs, and Mississippi Department of Environmental Quality. They identified four essential questions needed to assess the impacts of repeated phosphate spills on water quality in an otherwise pristine ecosystem. (1) What is the fate of phosphorus after a spill? (2) Is there a preserved sedimentary record of past phosphorus spills? (3) Is there a biological fertilizer effect on benthic microalgae in this shallow photic system? (4) Is dry deposition of gypsum particles from the adjacent fertilizer plant a smaller but constant source of phosphorus to GBNERR? Research results will provide information critical for management of the Reserve.
A preliminary investigation of surface and groundwater exchange within tailwater recovery systems in the Mississippi Delta
Year: 2016 Authors: Baker B.H., Prince Czarnecki J.M., Barlow J.R., Dibble E., Omer A.R., Rogers J.
Substantial withdrawals from the Mississippi Alluvial Aquifer for irrigation have resulted in a long-term trend of decreasing groundwater levels. Agricultural producers are adopting tailwater recovery systems, a best management practice for capturing surface water for re-use, but scientific data is lacking on the ability of these systems to mitigate aquifer depletion. One current area of interest is the potential for these systems to serve as a recharge mechanism. It is proposed that instrumenting tailwater recovery systems of varying age with piezometers, equipped with multiple loggers that measure temperature, atmospheric pressure, and depth, will provide data for a groundwater flow and heat transport model developed using VS2DH. Quantification of ground and surface water exchange indicated that over the observation period some influence from surface water was likely being exerted on groundwater stores. However, gradual changes in well temperature indicate low hydraulic flow rates between compartments. Additionally, gradual temperature changes were observed to change at a greater rate in the new (<1 year old) tailwater recovery system, indicating that age of the system does impact groundwater - surface water interaction. Surface water quality analysis resulted in low nutrient concentrations. Low flow rates and nutrient concentrations result in minimal concern for groundwater leaching from TWR/OFS systems.
Spatial and temporal trends for mercury concentrations in fish from three north Mississippi lakes and human health risk assessment
Year: 2016 Authors: Willett K.L., Cizdziel J.V., Meals K., Brewer S., Thornton C.
Total mercury (Hg) concentrations were determined in the skeletal muscle of 310 fish collected during 2013 and 2014 from three northern Mississippi lakes (Sardis, Enid and Grenada) that are extensively used for fishing and recreation. Largemouth Bass (LMB), Channel Catfish (CC), White Crappie (WC), and Gizzard Shad (GS), that represent a range of trophic levels, were studied. Creel data indicated anglers harvested 372,711 kg of WC, 26,735 kg of CC, and 14,871 kg of LMB, the three most targeted species of fish, from the lakes. Median Hg concentrations (ng/g) were highest in LMB (443, n=64), followed by CC (211, n=72), WC (192, n=101), and GS (49, n=73). Fish-Hg concentrations were lower than those reported in fish >10 years ago, but there were significant differences between lakes consistent across species. Grenada fish-Hg concentrations were higher than those from Enid and Sardis. Because existing consumption advisories for CC are length-based, the lack of a significant relationship between length and Hg concentration indicated that the recommendations may not be protective enough. Furthermore, five different risk assessment paradigms yielded hazard quotient values suggesting that existing fish consumption advisories may be insufficient to protect adults, and especially children, from exposure to Hg.
Exoenzyme activity and algal biomass responses to experimental nutrient gradients identify factors driving nutrient limitation of algal biomass in an
Year: 2016 Authors: Taylor J.M., Jenkins M., Lizotte R., Locke M., Dillard K., McChesney D., Testa III S., Bryant C.
The development of robust algal biomass-nutrient enrichment relationships for lakes within the Mississippi Delta is challenging due to a lack of undisturbed conditions. However, examining long-term water quality datasets linked to best management practices, combined with nutrient enrichment experiments may provide insight into factors that limit algal biomass. We examined seasonal patterns in nutrients, sediments and chlorophyll α (chl. α) over several years in Beasley Lake. Implementation of conservation practices within the watershed resulted in significant reductions in sediments and nutrients, particularly phosphorus (P), within the lake. However, chl. α concentrations continue to remain higher than recommended criteria during the growing season despite reductions in lake P concentrations. Seasonal patterns in activity of exo-enzymes associated with mineralization of nitrogen (N) and P suggest that nutrient demand is greatest at the end of the growing season when algal biomass is high and nutrient inputs are low. Experimental algal bioassays indicated that both chl. α and FDA (a measure of overall microbial activity) increased according to Michaelis-Menten dynamics with increasing dissolved N and P. We only observed maximum chl. α below recommended 20 µg/L concentrations when dissolved inorganic N (DIN = NH4-N + NO2-N + NO3-N) concentrations were below 0.2 mg/L despite high soluble reactive P (SRP) of 0.345 mg/L. In contrast, chl. α concentrations were always higher than the management target when DIN was not limiting (1.6 mg/L) despite very low SRP concentrations (0.015 mg/L) which suggests that N may be the primary limiting nutrient in Delta oxbows. Acid Phosphatase Activity (APA), an exoenzyme associated with mineralization of P, decreased with SRP and increased with DIN enrichment suggesting that P demand was related to availability and N:P ratios. In contrast, NAG and LAP, two exoenzymes associated with mineralization of N, increased rather than decreased with DIN enrichment and were correlated with chl. α. Chlorophyll α and FDA peaked at N:P ratios of 16:1 indicating that optimal elemental ratios for eutrophic oxbow lakes are similar to those observed in marine environments and some freshwater lakes. From a water resource management and monitoring perspective, our results suggest that exoenzyme activities may provide additional insight into complex relationships between nutrients and algal biomass in oxbow lakes. Furthermore, management practices that reduce N inputs to agricultural water bodies may be key to reducing chl. α concentrations below recommended goals for maintaining ecological integrity of Mississippi Delta oxbow lakes.es.
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Ecological Significance of Phyllosphere Leaf Traits on Throughfall Hydrology, Biogeochemistry and Leaf Litter among Quercus Species in the Southeaster
Year: 2016 Authors: Limpert K., Siegert C.M., Karunarathna A.A.
Quercus (oak) is a dominant species in many forest ecosystems across the United States that contribute vital ecosystem services through water and nutrient cycling. The recent decline of Quercus, largely due to fire suppression and forest mesophication, has the potential to alter forest hydrological and biogeochemical cycling. Given the prevalence, persistence, and diversity of Quercus leaves in forest ecosystems, it is likely that this species strongly mediate nutrient cycling when present. The objective of this study was to (1) quantify canopy-derived nutrients contributed to forest ecosystems and (2) determine interspecific temporal distribution of Quercus leaf fall in an oak-hickory forest in Mississippi. Beginning in Fall 2014, throughfall quantity and chemistry were measured during individual storm events under each of the four focal Quercus species and two non-Quercus (Carya) species and canopy litterfall was collected weekly to quantify changes in canopy leaf area index (LAI) and timing of species-specific leaf fall rates, and determine Throughfall depths decreased as leaves were lost but were greatest in Quercus species compared to Carya and were highest in Q. shumardii, and Q. stellata. The average total kjeldahl nitrogen (TKN) content of throughfall was highest in Q. shumardii (1.44 mgL-1) and Q. stellata (1.65 mg L-1) compared to other Quercus and non-Quercus species. Q. stellata had the greatest total organic carbon (TOC) for the majority of rain events with the largest amount reaching 119.43 mg/L-1. Quercus species contributed larger amounts of essential anions (Cl-1, NO3-, SO4-2). During the winter of 2014-2015, Q. shumardii had the highest leaf retention although non-oak species had a higher leaf retention in general. Leaf fall varied during the winter of 2015-2016 with Q. alba species having longer leaf retention compared to other Quercus and Carya species. Quercus shumardii had the lowest average C:N amounts (43.99 mg L-1) in leaf litter content compared to the other Quercus species. Non-oak species had a considerably lower average C:N ratio (Carya spp. 32.58 mg L-1).
Developing a Habitat Suitability Model for Oyster Restoration in St. Louis Bay
Year: 2016 Authors: Adenihun J., Linhoss A.C., Camacho R.A.
Oyster formations in the Northern Gulf of Mexico are declining rapidly due to over-harvesting, pollution, and changes in hydrology. Oysters depend on a number of environmental factors including water depth, the availability of hard substrate, salinity, temperature, dissolved oxygen, and PH. Oyster reefs provide important ecosystem services including fish habitat, water filtration, storm protection, sequestering carbon, providing food security, forming an economic industry, and as a cultural symbol. Oyster reef restoration can add value to the U.S economy with a sack of oysters fetching up to $40 at market. The objective of this research is to use a hydrodynamic model coupled with a water quality model to simulate conditions that are important for oyster reefs along the Gulf Coast of Mississippi. We will use the existing Environmental Fluid Dynamics Code (EFDC) and Water Quality Analysis Simulation (WASP) models that have been developed for Bay St. Louis, Mississippi. EFDC simulates water quality parameters that are required to run the WASP model, such as velocity, flow rate, temperature, diffusion, dispersion, and salinity. Meanwhile, WASP model generates parameters that are important for the growth of oyster reefs in the Northern Gulf of Mexico, such as dissolved oxygen, phosphorus, nitrate, nitrite, phosphorus, and total suspended solids. We will develop a habitat suitability model for oysters based on the exiting mapped locations of oyster reefs along with environmental parameters that are important for oyster growth and survival.
Multidisciplinary Remediation: An Analysis of Chlorinated Metabolites in Groundwater Contaminated by Pentachlorophenol Following 15 Years of Air/Biosp
Year: 2016 Authors: Stratton J.N., Stokes C.E.
Pentachlorophenol (PCP, Penta) got its foothold as a wood preservative in the United States because it extends the lifetime of wood products up to 40 years, even in adverse conditions. It is also an effective herbicide and biocide. Because of this effective nature against pests, it was applied as a protectant in many areas of agriculture and manufacturing. The site utilized in this study has been a receiver of penta wastewater from a wood product treating facility. To comply with mandated cleanup, injection wells for air injection were installed in 2000. These were used until 2011, when they upgraded the airsparging system and included enhanced biosparging. Shortly after this, 400 hybrid poplar and cottonwood trees were planted in the area for an added aspect of phytoremediation. The latest remediation protocol for the site utilizes in-situ chemical oxidation (ISCO) with dilute hydrogen peroxide, started in 2015. A set of nine wells were sampled monthly following ISCO treatment. Metabolites were extracted from water samples using a novel modified liquid microextraction protocol, followed by analysis on an Agilent GC 6890 to determine the presence of chlorinated compounds resulting from the degradation of penta (ongoing through April 2016). We expect to determine the concentration of chlorinated metabolites, analyze the spatial distribution of these compounds across the site, and make recommendations as to the future of remediation treatments for this location.
Using deuterium and oxygen-18 stable isotopes to understand mechanisms of stemflow generation as a function of tree species and climate
Year: 2016 Authors: Siegle-Gaither M., Siegert C., Keim R.
Stemflow (SF) is a type of rain partitioning from the forest canopy that redirects intercepted water down tree trunks. Through this mechanism, SF leaches nutrients from the canopy and bark to deliver highly enriched water to the base of the tree. Few studies have examined the species-specific effects of bark structure and storm meteorological conditions on SF generation by means of stable hydrogen ( δD) and oxygen δ18O) isotopic tracers. This study explores these relationships in an oak-hickory stand and a pine plantation in central Mississippi. The species selected for this project have unique bark characteristics and variable effects on rainfall partitioning centered on their geographic distribution. Specifically, SF volume and isotopic composition are measured over a one-year period. The objectives of this study are (i) to determine origins and pathways of stemflow water using stable water isotopes, (ii) to identify differences in stemflow generation mechanisms between tree species, and (iii) to identify differences in stemflow generation mechanisms between storm events.
Stemflow collars were installed on seven species of trees with three trees per species. Water samples were collected within 12-24 hours after individual storm events. Tree characteristics such as species, height, and bark thickness were measured. Laser ablation spectroscopy was used to analyze δD ad δ18O in the water samples collected. Preliminary results show that bark thickness was greatest in Pinus taeda (1.74 ±0.09cm), followed by Quercus alba (1.56 ±0.08cm), Q. stellata (1.19 ±0.13cm), Q. shumardii (0.95 ±0.08cm), Q. pagoda (0.95 ±0.05cm), Carya glabra (0.83 ±0.09cm), and C. ovata (0.56 ±0.10cm) (n=24 for all species except P. taeda where n=40). Additional preliminary results suggest that the isotopic composition of stemflow is distinct from that of throughfall and bulk precipitation. A better understanding of isotopic composition (δD and δ18O) and stemflow generation mechanisms will allow for more accurate hydrological and biogeochemical models to be established.
Towards an understanding of surface and groundwater exchange through tailwater recovery system
Year: 2016 Authors: Rogers J., Baker B., Czarnecki J.
A long-term trend of depletion of groundwater levels are the result of significant withdrawals from the Mississippi Alluvial Aquifer for irrigation purposes. Tailwater recovery systems, a best management practice to re-use surface water for irrigation purposes, are being implemented by many agricultural producers throughout the Mississippi Alluvial Valley, however, there is very little scientific evidence that proves these systems have the ability to reduce aquifer depletion. To investigate surface-groundwater interactions in these systems, steel piezometers equipped with multiple loggers that measure temperature, atmospheric pressure, and depth were installed in two tailwater recovery systems.It's anticipated that the collection of this data will be appropriate to develop a ground and surface water flow and heat transport mode using VS2DH resulting in the current area of interest that these systems potentially serve as a recharge mechanism. The magnification of ground and surface water exchange could provide the additional data for those estimating Aquifer levels, as well as, assist policymakers in implementing techniques to appropriately manage this critical resource. In addition, the collection of surface and groundwater samples was endeavored to determine any water quality impacts resulting from ground and surface water exchange.
Utilizing My Maps Feature in Google Maps as a Multipurpose Watershed Planning Tool for the Escatawpa River
Year: 2016 Authors: Liao J., Pote J., Wax C., Linhoss A.
This project involved using a tool to coordinate and track activities impacting an entire watershed and producing a synoptic map giving a snapshot in time. This allows multiuser analysis and discussion for setting priorities in future development. The Escatawpa River was selected to demonstrate this capability. Issues addressed were both water quality and water quantity. It has become growingly important to address the accumulation of activities in the entire watershed. For example, in terms of water quality, elevated bacterial counts can impact oyster harvest. In terms of water quantity, decreased flow raises salinity levels impacting the estuarine and coastal ecosystem of the Mississippi Sound. This project mapped activities along the length of the Escatawpa River and its tributaries that might explain variations in water quality and quantity of the river. The method chosen for this multipurpose study was My Maps feature in Google maps. My Maps is an interactive tool that allows users to position markers and leave annotations. The markers have different colors and shapes to help the user stay organized. Furthermore, the users can go back and forth between different types of maps such as satellite and terrain. In this study, several categories were examined which included tributaries, impact analysis, gage stations, golf courses, and septic systems. The categories are differentiated based on color, and the subcategories are separated based on shape. Each marker is assigned its respective color and shape. Furthermore, each marker has a description section to record observations and to keep track of discoveries. These information could be used to prioritize targeted areas of concern and accumulated effects of activities. Discrepancy between terrain and satellite maps were of particular interest, since they could reflect either a flaw in mapping or a change over time. Usually, the discrepancy revolved around bodies of water missing or existing in one type of map and not in the other.
An Examining of the Changes in the Hydrological Environment around a Surface Lignite Coal Mine over the Last 20 Years
Year: 2016 Authors: Foote J.
The population and industrial complexes of Choctaw County utilizes much of its water from an aquifer system in the Tertiary age Wilcox unit of the Mississippi Embayment. Utilizing 20 years of surface and ground water physical chemistry (P-Chem) analysis, potentiometric groundwater records of Choctaw County public water wells as well as industrial P-Chem analysis and surface and ground water level records from an industrial complex, this study examined the changes to the hydrosphere that has taken place since 1995. Analysis of the hydrosphere shows that over the last 20 years, there has been a drop in the potentiometric surface of Mississippi section of the Lower Wilcox Aquifer system. The analysis also shows changes in the surface water physical chemistry of the hydrosphere. These changes include a decrease in the concentration of free CO2 and chloride, and fluctuations of Alkalinity. Comparisons between groundwater records taken from the industrial complex and other locations around Choctaw County, show little variation in the physical chemistry.
Crop water requirement, rainfall deficit and irrigation demand of major row crops in Mississippi Delta
Year: 2016 Authors: Tang Q., Feng G., Ouyang Y., Jenkins J.
The Mississippi Delta is the most productive region in the state where 67% of the state croplands is located. Because irrigation can stabilize and increase crop yield and profit, irrigated acreage is rapidly increasing. Currently, irrigated croplands are not over 30% of its croplands yet, which already consumed groundwater down to the alarming level due to lack of knowledge regarding rainfall deficit and crop water requirement in the region. Objective of this study was to determine rain water deficit, crop water requirement and irrigation demand for improving irrigation management of crops grown in the MS Delta. We developed a STELLA soil water balance model and utilized weather records at Stoneville station for 100-years period, 1915 to 2015. The analysis showed average annual rainfall was 1290 mm with a mean annual reference evapotranspiration (ETo) value of 1202 mm. Most rainfall occurred off-growing season in January to April, November and December, their mean monthly rainfall was 124, 123, 130, 134, 120, and 133 mm, while less rain was received in August (66 mm), September (80 mm), October (81 mm), May (81 mm), June (90 mm), and July (94 mm). Soybean, corn and cotton were typically planted in early May, late March, and late May, harvested in mid-September, late August, and late October in the MS Delta. Rainfall during the growing season for soybean, corn and cotton was 400, 510, and 435 mm, accounted for 31%, 40% and 34% of annual rainfall over the 100-years period. Early seeding can make crops receive more rainfall, therefore, reduce degree and days of water stress during growing season. Averaged evapotranspiration (ETc) of soybean, corn and cotton was 546, 588, 552 mm. Rainfall is no longer to meet water requirement of soybean, corn and cotton since the 6th, 8th, and 7th weeks after planting, which resulted in rainfall deficit (difference between ETc and rainfall) of 262, 237, and 228 mm, respectively, on average over the last 100 years. As expected, more pan evaporation (E) was measured in May (199 mm), June (213 mm), July (205 mm), and August (189 mm). High linear correlation between monthly E and ETo was found (ETo=0.7829E-0.0468, R2=0.98). Monthly ETo can be estimated in terms of the equation by monthly E values which can be easily measured. Results obtained from the 100 years-long historical time-series data can be applied to improve irrigation scheduling, water resources planning and better design cropping system in the MS Delta.
Potential Solutions for Dealing with High Iron Content in Filter Backwash Water of a Municipal Water Treatment System
Year: 2016 Authors: Mealins E., Tagert M.L.
A small drinking water system in central Mississippi uses traditional processes to purify and filter water at their five different water treatment plants. The ground water that the system pumps from the well has a naturally high iron content. When the water goes through the treatment process, the iron flocculates and is eventually captured by large filters. The filters are backwashed regularly, and the backwash discharge is pumped to an onsite basin (an excavated retention pond) in a corner of the property. Currently, the basin is a relatively open system, and it occasionally overfills and spills off of the property. While not harmful to human health at current levels, the area is not aesthetically pleasing during the time the filters are backwashed and shortly thereafter. A design solution for this problem is needed that will effectively keep all of the backwash discharge on site in order to prevent future spillovers. The iron and water may be separated so that the iron can be excavated and used for different potential markets, while the water can be reused for other eco-friendly purposes such as watering the grass on the property. Several potential solution methods are being investigated and will be presented.
Prediction of Bacteria in Recreational Waters Using Artificial Neural Network Modelling
Year: 2016 Authors: Douglas C.
Many scientists and government agencies rely on fecal indicator bacteria (FIB) to determine the risk of exposure to pathogens in water. If there is a presence of these indicator bacteria, pathogenic microorganisms may also be present. These bacteria in recreational water bodies pose a health threat to people if ingested during activities such as swimming or from the consumption of marine life. The most commonly tested FIB are total coliforms, fecal coliforms, Escherichia coli, fecal streptococci, and enterococci. The measurement of bacteria can be time consuming (up to 48 hours) and expensive, creating a difficulty in warning the public of a potential risk. Ideally, a predictive model could determine the FIB concentration in real-time, eliminating the current delays. Many analytical, statistical, process-based, and empirical models exist for water quality prediction, but produce a low level of precision. Artificial neural network (ANN) models create a better model for predicting water resource variables because they are often capable of modeling complex systems of behavioral rules or underlying physical processes that are often difficult to simulate. An ANN is a computational model based on the biological neural networks. ANNs consist of processing units known as neurons or nodes that are joined by weighted connections. The connections are adjusted by determining an error quantity between the newly predicted output and the actual output and then applying the correction to each weighted node allowing the network to "learn" as it applies the correction for all data in the model. By modeling the ANN using easily recorded inputs to predict indicator bacteria, the concentration of bacteria can be provided almost instantaneously through the model. Due to the non-linear behaviors of most water quality parameters and the learning capabilities of ANNs, the development of a model could provide an adequate method for determining the risk for pathogen exposure in a timely manner.
Characterization of Surface Water Quality in Sunflower River Watershed, Mississippi
Year: 2016 Authors: Ouyang Y., Moran M., Parajuli P., Zhao B.
Characterization of water quality is essential to evaluate river pollution due to natural and/or anthropogenic inputs of point and non-point sources. In this study, surface water quality from three monitoring stations at Big Sunflower River Watershed (BSRW) located in Mississippi during the years from 2013 to 2015 was estimated using the YSI meter and laboratory analysis. Results showed that dissolved oxygen was negatively correlated to water temperature, while total dissolved solid was fairly correlated to water temperature. In general, the concentrations of nitrate-nitrogen (NO3-N) and total phosphorus (TP) were highest in spring. Our study further revealed that the minimum, mean, and maximum concentrations in the streams were, respectively, 0.019, 2.31, and 6.43 mg/L for NO3-N, 0.01, 0.08, and 0.16 mg/L for TP, and 2.38, 5.81, and 13.29 mg/L for potassium (K).
A new absorbent from chemically modified powder of Bidens pilosa and its characteristics for Cd removal from solutions
Year: 2016 Authors: Zhao B., Zhang J., He T., Guan A., Gu N., Ouyang Y.
Bidens pilosa is a harmful invasive plant species in many countries. In this study, a cadmium (Cd) adsorbent for water treatment was developed by modifying the Bidens pilosa powder with chemical agents including hydrochloric acid, hydrogen nitrate, sodium hydroxide, sodium carbonate, sodium bicarbonate and potassium permanganate to test the Cd removal efficiency. Results demonstrated that the modified Bidens pilosa (MBP) powder with potassium permanganate was an effective adsorbent to extract Cd from a solution. To further assess the potential application of the MBP in polluted water, characteristics of the MBP and its related interference ions effect were investigated. Results showed that: 1) the Cd removal efficiency exceeded 97% when the dosage of the MBP was > 1g/L; 2) the Cd removal efficiency remained at about 99% when the initial Cd concentration was < 100 mg/L; 3) the Cd removal efficiency of the MBP was > 95% when the pH ranged from 2.5 to 5.5; 4) more than 90% of Cd in the polluted water was removed by the MBP in 5 minutes and about 100% of Cd was removed after 1 h; 5) the addition of Mg ion had no significant negative effect on Cd removal when the concentration of Mg ion was below 50 mg/L; and 6) the Cd removal efficiency was significantly decreased when the concentration of Zn or Cu ion was 100 mg/L. This study proved that the MBP is an effective absorbent for Cd removal from polluted water. Being a harmful invasive plant, the utilization of the MBP is beneficial to the control of Bidens pilosa. Further study is warranted to investigate the ions competitive effect provided that the MBP is used for wastewater treatment.
Application of a Spreadsheet Model to Groundwater Use in the Yazoo River Basin
Year: 2016 Authors: Johnson D.R.
Both the USGS and MS-DEQ have developed intricate groundwater models for the Yazoo Basin in Mississippi. The difficulty in using these models is the amount of time that is required to run the model. A less accurate but faster Excel model was developed to simulate groundwater utilization in the Yazoo Basin. The Excel model can be used to screen many more alternatives than the MERAS model, which then can be applied to the most attractive alternatives. The Excel model was used to explore a range of possible management scenarios to extend the life of the groundwater resources in the Mississippi Delta.
Wastewater management issues of small communities in Jourdan River watershed
Year: 2016 Authors: Rainey B., Gude V.G., Truax D., Martin J.
Wastewater treatment and nutrient removal alternatives for large size communities are very well-established and are feasible in many cases. When it comes to the small rural and especially for low-income disadvantaged communities, this is not the case, particularly with regard to nutrient removal. The alternatives for small communities are often viewed as cost-prohibitive and unreliable. While this is partly true, careful selection and implementation of appropriate technologies can result in high performance, energy and cost efficient and environmental-friendly solutions. Assessment of water and wastewater is very crucial to safeguard public health and the environment. However, water quality data on fresh and marine waters in the Mississippi coastal region, especially in Jourdan watershed are still sparse and uncoordinated. Therefore, monitoring these parameters is important for safety assessment of the environment and human public health and the water bodies. We have identified a few small and decentralized communities in the Jourdan River watershed area to assess the current wastewater treatment and management practices and their impacts on the receiving water bodies. This presentation will discuss the preliminary evaluation and understanding on the local water quality issues of the watershed.
Simulation of transient groundwater recharge in deep water-table settings: A simple water-balance/transfer-function model
Year: 2016 Authors: O'Reilly A.M.
Deep water-table settings are areas where the water table is below the reach of plant roots and virtually all water that is not lost to surface runoff or evapotranspiration eventually becomes groundwater recharge. To simulate transient recharge in these areas, a simple water-balance/transfer-function (WBTF) model was developed. The WBTF model represents a one-dimensional column from the top of the vegetative canopy to the water table and consists of two components: (1) a water-balance module that simulates the water storage capacity of the vegetative canopy and root zone; and (2) a transfer-function module that simulates the traveltime of water as it percolates from the bottom of the root zone to the water table. Input data requirements include two time series for the period of interest, precipitation (or precipitation minus surface runoff if surface runoff is not negligible) and evapotranspiration, and values for five parameters that represent water storage capacity or soil-drainage characteristics. A limiting assumption of the WBTF model is that the percolation of water below the root zone is a linear process. That is, percolating water is assumed to have the same traveltime characteristics, experiencing the same delay and attenuation, as it moves through the unsaturated zone. This assumption is more accurate if the moisture content, and consequently the unsaturated hydraulic conductivity, below the root zone does not vary substantially with time. Results of the WBTF model were compared to those of the U.S. Geological Survey model VS2DT (a physics-based, variably saturated flow model) and to field-based estimates of recharge. Field-based estimates of daily recharge were computed for a 334-day period by analysis of water-table fluctuations at a site with well drained sand and a water table that ranged from 2 to 3.5 meters below land surface. Recharge was simulated for 1- to 2-year periods for eight hypothetical field sites by using VS2DT and synthesized values of precipitation, evapotranspiration, and soil properties for combinations of two soil types (sand and loamy sand) and four water-table depths (2.5, 5, 10, and 20 meters). The WBTF model reproduced independent estimates of recharge reasonably well for the range of soil types and water-table depths tested: coefficient of determination (r2) was 0.80 and standard error (SE) was 3.2 millimeters per day for the field-based estimates of recharge; and r2 ranged from 0.73 to 0.90 and SE ranged from 0.48 to 1.6 millimeters per day for VS2DT-simulated recharge.
A comparison of five forest interception models using global sensitivity and uncertainty analysis
Year: 2016 Authors: Linhoss A.C., Siegert C.M.
Interception by the forest canopy plays a critical role in the hydrologic cycle by removing a significant portion of incoming precipitation from the terrestrial component. While there are a number of existing physical models of forest interception, few studies have summarized or compared these models. The objective of this work is to use global uncertainty and sensitivity analysis to compare five mechanistic interception models including the Rutter, Rutter Sparse, Gash, Sparse Gash, and Liu models. Using a one-hour continuous rainfall simulation and input probability distribution functions of values from the literature, our results show that gross precipitation [PG], the free throughfall coefficient [p], canopy cover [Cc], canopy storage capacity [S], and trunk storage capacity [St] are the most important model inputs. On the other hand, the climatic variables that determine evaporation have relatively low levels of importance in modeling interception based on our rainfall simulation scheme. As such, future modeling efforts should aim to breakdown inputs that are the most influential in determining model outputs into easily measurable physical components. Additionally, low, medium, and high one-hour rainfall scenarios were simulated to determine the sensitivity of input parameters to variable rainfall conditions. Under the low rainfall scenario [PG] was the most important parameter across all five models. Under medium and high rainfall scenarios, parameters that described canopy storage ([S] and [St]) and canopy heterogeneity ([p] and [Cc]) became more important. Because this study compares models, the choices regarding the input probability distribution functions are applied across models, which enables a more definitive ranking of model uncertainty.
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Surface and groundwater modeling in the Platte River watershed to support water resource management
Year: 2016 Authors: Woodward D.
COHYST is a cooperative hydrologic study of the Platte River drainage basin in the central part of Nebraska. One objective of COHYST is to develop a comprehensive suite of tools to aid in conjunctively managing surface and groundwater to: 1) maintain the region's extensive irrigation economy; and 2) protect the river habitats used by endangered species. These tools must provide decision-makers with reliable quantitative information about the hydrologic consequences of alternative water management strategies. There also is a need to quantify past hydrologic changes, such as accounting for historic depletions of streamflow.
COHYST 2010 is the second generation of modeling tools within COHYST that involves developing an integrated computer-based model of basin hydrology to be used to calculate the effects of different management scenarios on stream flows and the regional aquifer. Phase I of COHYST 2010 involved design of the modeling work, and development of an observation based water budget for the study area to be used in model calibration. Phase 2 of COHYST 2010 had the objective of building the quantitative tools. Phase 3 is application of the tools to management scenarios and time period updates to the tools.
The Phase 2 tools were completed in 2014 and included a Watershed model, Surface Operations Model, and a MODFLOW groundwater model. We are in Phase 3 of the COHYST 2010 work effort. Models are being updated thru 2010 and the 2014 Model documentation is being edited to include model changes and integration work. An updated Stream depletion analysis along with Basin Water Supply and Basin Water Demands analysis are nearing completion. Conjunctive water management projects are also being simulated for project development.
Influence of wetland plant community types on water quality improvement in natural and restored wetlands of the Mississippi Delta
Year: 2016 Authors: Ervin G.N.
In an effort to quantify the specific linkages between wetland plants and water quality in Mississippi Delta wetlands, we assessed vegetation and water quality in 30 wetlands, including 24 Wetland Reserve Program (WRP) restorations and six naturally occurring wetlands. Our goal was to examine interactions among water quality parameters and plant species to determine which plant species assemblages appear to most strongly influence nutrient and sediment concentrations in these wetlands. We found substantial differences in the hydrology of restored, versus naturally occurring wetlands, and these differences were correlated with differences in plant species diversity among wetlands. We did not see significant correlations between specific plant species and water quality parameters, but we did find that some plant growth forms were consistently correlated with such water quality parameters as pH, conductivity and nitrate concentrations. We will be working with the USDA NRCS in an effort to translate results of this work into information useful for the design of future restorations, such that they can yield the greatest improvements in water quality while also providing other benefits, such as wildlife habitat, for the Mississippi Delta.
Responses of water quality and wetland plant communities to multi-scale watershed attributes in the Mississippi Delta
Year: 2016 Authors: Ervin G.N., Kroger R.
This project aimed to understand the influence of local and landscape factors in shaping wetland functions within the Mississippi Delta. An understanding of scale effects on function is both critical and timely for Delta wetlands. Recent efforts aimed at restoration of marginal agricultural lands to wetlands have been sponsored through government and private wetland restoration projects. Unfortunately, the outcomes of these projects in terms of conservation goals are unknown. This means that decisions to enroll lands in such programs continue to be made without a full evaluation of specific practices that may result in the greatest conservation benefits. Additionally, with little to no long term monitoring conducted on many sites, the ultimate outcome of restoration efforts is unknown. A better understanding of the influence of local and landscape factors on wetland functions in existing restorations will permit more effective targeting of limited resources towards future restorations.
This two-year study resulted in a large database relating to soil and water variables and plant species inventories of 24 Wetlands Reserve Program (WRP) restorations and six natural wetlands within the northern half of the Delta. Thus far, our analyses have indicated that WRP wetlands harbor high levels of plant species diversity and that surrounding conservation practices may be buffering these wetlands from any potential negative impacts of agricultural land use within the Delta. An experimental study of seed bank responses to flooding suggested that some of the observed differences in wetland plant diversity may be attributed to the duration of flooding in natural wetlands. Ongoing analyses are aimed at more detailed examination of how within-wetland vs. landscape factors may be shaping water quality and plant species assemblages within these wetlands.