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Development of the CCHE1D Looped Channel Network Model
Year: 2011 Authors: Zhang Y., Chao X., Al-Hamdan M., Bingner R., Vieira D.
The CCHE1D model, developed by National Center for Computational Hydroscience and Engineering (NCCHE), is designed for dendritic 1D channel networks to efficiently simulate unsteady flows with non-equilibrium and non-uniform sediment transport and channel morphological change, general pollutant transport and fate, nutrient dynamics and water temperatures. However, the dendritic channel network allows only one outlet and junctions of flow confluence, which is not applicable for more general and realistic cases that can be described only by looped channel networks with multiple outlets and junctions of both flow confluences and divergences, such as agricultural irrigations, natural river networks and urban floods. To expand its capabilities in handling looped channel networks, CCHE1D model needs new developments on the numerical solver and the generation tools for looped channel networks.
In this study, the junction-point water stage prediction and correction (JPWSPC) method proposed by Zhu et al. (2011) will be integrated into CCHE1D model to resolve the general 1D channel networks, either looped or dendritic. In JPWSPC, each branch is computed independently, which guarantees the simplicity, efficiency, and robustness of the numerical model. In addition to the digitization tool, the CCHE1D model plans to modify a delineation tool of dendritic channel network based on the watershed-merging algorithm (Zhang and Jia, 2020) for looped channel network generation. The observation that the loops only exit between junctions would make it possible to enable the watershed-merging algorithm for looped channel network generation.
This paper will present some preliminary results from selected test cases of looped channel networks to demonstrate the developments at the current stage for the CCHE1D looped channel network model. More results will be reported in the future.
Effect of Land Management on Surface Runoff Water Quality in Beasley Lake Watershed
Year: 2011 Authors: Locke M.A., Lizotte Jr. R.E., Yasarer L., Bingner R.L., Moore M.T.
Assessing best management practices in the landscape is needed to better understand their potential to mitigate sediment and nutrient loss in runnoff. Runoff and sediment and nutrient losses in Beasley Lake Watershed were monitored from 2011 to 2017. Landscape management in monitored catchments included areas under row crops with (CropBuff) and without (Crop) edge-of field buffers and under the Conservation Reserve Program (CRP). The study demonstrated that edge-of-field vegetated buffers and conservation reserve can be integral components in an agricultural landscape to reduce topsoil loss and transport of nutrients downstream concomitantly mitigating water quality impacts on rivers and lakes. Overall, efficacy in mitigating runoff losses of soil and nutrient resources, significant within-lake processes may limit the effectiveness of land management in improving downstream water quality. Results from this study should be providing additional information to improve and sustain water quality and overall environmental quality using combined conservation practices.
Case Studies of Rapid Dam Breach Modeling during Flood Events
Year: 2011 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.
Evaluating the Use of sUAS-Derived Imagery for Monitoring Flood Protection Infrastructure
Year: 2011 Authors: Dietz E., Yarbrough L.D.
In the U.S. there are approximately 33,000 miles of levee. This includes 14,500 miles of levee systems associated with U.S. Army Corps of Engineers programs and approximately 15,000 miles from other states and federal agencies. More than 14 million people live behind levees and associated flood prevention infrastructure. Monitoring and risk assessment are an on-going process, especially during times of flood conditions. The historic events such as those in the City of New Orleans with Hurricane Katrina in 2005, Red River floods of 2009 and 2011, Ohio River flooding of 2018, the 2017 California Floods have profoundly impacted lives and communities. Climate change and increasing population are likely to make flooding events more frequent and costly. As new technologies emerge monitoring and risk assessment can benefit to increase community resiliency. In this research, we investigate the use of the structure from motion photogrammetric method to monitor positional changes in invariant objects such as levees, specifically, I-walls. This method uses conventional digital images from multiple view locations and angles by either a moving aerial platform or terrestrial photography. Using parallel coded software and accompanying hardware, 3D point clouds, digital surface models, and orthophotos can be created. By providing comparisons of similar processing workflows with a variety of imaging acquisition criteria using commercially available unmanned aerial systems (UAS), we created image sets multiple times of a simulated I-wall at various flight elevations, look angles, and image density (e.g. effective overlap). The comparisons can be used for sensor selection and mission planning to improve the quality of the final product. The results can optimize current equipment capabilities with respect to client expectations and current FAA limitations.
Distributions of Dissolved Trace Elements in Mississippi Coastal Waters: Influence of Hypoxia, Submarine Groundwater, and Episodic Events
Year: 2011 Authors: Ho P., Shiller A.
A multi-year (2007-2011) chemical time series of eight stations in the western Mississippi Sound and northwestern Mississippi Bight was undertaken to examine the factors affecting the distributions of trace elements in this estuarine-coastal system. Key findings include the frequent development of bottom water hypoxia in this part of the Bight during late spring and summer, the likely contribution of submarine groundwater discharge (SGD) to the material flows (i.e., Ba, V and nutrients), and the effects of episodic events (i.e., tropical storms, cold fronts, the opening of the Bonnet Carr Spillway) on trace element distributions. A variety of trace metals (i.e., Ba, Mn, V and Cs) in Mississippi Sound surface waters were largely regulated by the temporal and spatial variations of riverine sources. For instance, in fall and winter, high concentrations of dissolved Mn at the most nearshore stations followed by a sharp decline in concentrations offshore, are indicative of Pearl River influence in the Mississippi Sound. Cs-rich water coming from St. Louis Bay is evident in the Mississippi Sound, but not observable in Mississippi Bight. In hypoxic bottom waters, enriched Mn and Ba as well as depleted V were commonly observed. Consideration of the mass balances of dissolved Ba and V suggests that SGD can be a significant contributor to the chemical mass balance in this region, not just for certain trace elements, but for nutrients, too. Interestingly, a seasonal change in the direction of the V flux from the sediments suggests that the chemical conditions (i.e., pH, EH, and/or DOC) of the groundwater are changing. During the study period, the Bonnet Carr Spillway was opened in April 2008 and May 2011. The spillway discharges Mississippi River water to Lake Pontchartrain and ultimately to our study area, which is supported by the observation of an extended freshwater signal and low Cs across the Mississippi Sound and Bight during these two spillway openings. Important remaining questions from this study include the extent to which SGD and/or Mississippi River water are necessary for establishment and maintenance of hypoxia in the Mississippi Bight and the reasons for the seasonal change in the direction of the sedimentary V flux.
DSS-WISE Web: A Web-Based Automated Modeling, Mapping and Consequence Analysis Tool for Improving Dams Safety in the USA
Year: 2011 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.
Effects of Varying Suites of Agriculture Conservation Practices on Water Quality in the Mississippi Delta
Year: 2011 Authors: Baker B., Prince Czarnecki J.M., Omer A.R., Aldridge C.A., Kroger R., Prevost J.D.
Increasing concern regarding environmental degradation and annual hypoxic zones has led to the need for mitigation of nutrient laden runoff from inland landscapes. An annual occurrence of a hypoxic zone in the Gulf of Mexico has led to the development and implementation of nutrient reduction strategies at the state level throughout the Mississippi River Basin (MRB). With federal, state, and private financial and technical assisstance, landowners have implemented best management practices (BMPs) to reduce nutrient and sediment loading; however, the effectiveness of these BMPs to improve water quality, alone or utilized together, has not been widely documented. This research includes a field-scale, paired watershed approach in two watersheds in the Mississippi Alluvial Valley to test for differences in sediment and nutrient runoff concentrations between four management systems. Baseflow and stormflow samples were collected from 2011 to 2015 and analyzed for nutrient and sediment concentrations. Median baseflow concentrations across all sites were 52 mg L-1 for total suspended solids (TSS), 0.38 mg L-1 for total phosphorus (TP), 0.09 mg L-1 for nitrate-nitrite (NO3--NO2-), and 0.81 mg L-1 for ammonium (NH4+). Median sediment and nutrient concentrations from stormflow samples across all sites within the study were greater than baseflow concentrations, where median stormflow concentrations were 985 mg L-1 for TSS, 1.21 mg L1 for TP, 0.32 mg L-1 for NO3--NO2-, and 1.04 mg L-1 for NH4+. Results showed no strong improvements in water quality from agricultural landscapes where suites of BMPs had been implemented. Rather, the data presented variability in runoff concentrations indicative of strong influences from environmental and management variables. Study outcomes highlight opportunities to better capture nutrient dynamics at the field scale through adaptive management of BMPs and the importance of in-field practices for improved water quality to improve nonpoint source pollution reduction.
Sources of Hypoxia in Mississippi Delta Streams
Year: 2011 Authors: Lizotte R.
Rivers and streams in watersheds with intensive row-crop agriculture are vulnerable to ecological impairment associated with non-point source runoff. Agricultural watersheds impacted by elevated nutrients can exhibit eutrophication, producing periods of severe oxygen stress or hypoxia (dissolved oxygen concentrations<2 mg/L). Additional factors such as hydrology and channel morphology as well as sporadic influxes of dissolved organic matter (sometimes referred to as blackwater) can exacerbate oxygen stress. From 2011-2017, we monitored biweekly summer and fall nutrients (total nitrogen and total phosphorus), chlorophyll α, dissolved organic carbon, and daily dissolved oxygen (one-week deployments) within three low-gradient, low-flow stream bayous in the Mississippi Delta. Eutrophication-induced hypoxia exhibited diel dissolved oxygen patterns with hypoxia primarily occurring during late night to early morning hours throughout the summer months. Periods of eutrophication-induced hypoxia lasted an average of 29 h or 17% of a 168 h (one-week) deployment period. In contrast, blackwater-induced hypoxia occurred sporadically following intense rainfall events typically >25.4 mm falling on dry row-crops prior to harvest (late summer to early fall) producing dissolved organic matter-laden runoff and dissolved oxygen sags. Periods of blackwater-induced hypoxia lasted an average of 84 h or 50% of a one-week deployment period. Classification and Regression Tree (CART) analysis of eutrophication-induced hypoxia produced a model indicating that stream morphology as channel width and elevated nutrients and total nitrogen worsened hypoxic conditions. CART analysis of blackwater-induced hypoxia produced a model indicating that elevated dissolved organic matter, decreased water depth and inhibition of photosynthesis worsened hypoxic conditions. Monitoring results indicate that reduction of both nutrients and sporadic dissolved organic matter pulsed inputs to low-flow Mississippi Delta streams is necessary to help mitigate hypoxic conditions and improve summer to fall dissolved oxygen concentrations in agricultural streams.
Variable pathways and geochemical history of seepage under the Mississippi River Levee: Observations from the 2011, 2015, and 2016 floods
Year: 2011 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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Regional Overview of Work by the Water Resources Division in Northeast Mississippi
Year: 2011 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: 2011 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.
Variable pathways and geochemical history of seepage under the Mississippi River levee: Observations from the 2011, 2015, and 2016 floods
Year: 2011 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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Multidisciplinary Remediation: An Analysis of Chlorinated Metabolites in Groundwater Contaminated by Pentachlorophenol Following 15 Years of Air/Biosp
Year: 2011 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.
Enhancing Agricultural Water Management Through Soil Moisture Monitoring and Irrigation Scheduling
Year: 2011 Authors: Rawson J.C., Linhoss A., Tagert M.L., Sassenrath G., Kingery W.
Increasing reliance of crop producers on water for irrigation coupled with expansion of irrigated acreage has resulted in the overdraft of the Mississippi River Valley alluvial aquifer (MRVA). As water resources continue to decline, there is an immediate need for more efficient water management and greater implementation of water conservation practices. Mississippi's Natural Resource Conservation Service (NRCS) has been working with farmers to increase voluntary implementation of water conservation practices, but these systems often require financial input from the grower and take time to install and manage. The Mississippi Irrigation Scheduling Tool (MIST) uses a "checkbook" water balance calculation and offers producers a free online irrigation management tool that indicates a need for irrigation when the soil water available to the plant falls below the level needed for crop growth.
The overall objective of this study has been to evaluate and refine data requirements and inputs needed to calibrate and validate of the model for testing on corn and soybean fields with differing management and soil types. Data collection has been ongoing since May of 2011. Watermark 200SS sensors and dataloggers have been used to continually measure and record soil moisture at six-inch depth increments to three feet at various sites throughout the growing season of each year. Soil water retention curves were generated for each field from detailed soil testing at each depth increment and used to convert soil tension data to actual soil water balance, which was then compared to the MIST-calculated soil water balance. In addition, comparisons were done between sets of soil moisture readings within the same field to characterize the precision of the measurements. Next Generation Radar's (Nexrad) four-kilometer precipitation data were used along with farm irrigation data to calibrate the model for a soybean field under pivot irrigation and a cornfield under furrow irrigation.
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Tillage and Cover Crop Effects on Runoff Water and Soil Quality
Year: 2011 Authors: Locke M.A., Krutz J., Steinriede W., Dabney S.
Conservation management systems need to be assessed in the lower Mississippi River alluvial basin to balance production goals with environmental concerns. Complementary approaches for assessing effects of tillage and cover crops on water and soil quality in cotton (Gossypium hirsutum L.) production are reviewed here. In Study 1, no-tillage (NT) or minimum tillage (MT) with or without cover crop (rye [Secale cereale], balansa clover [Trifolium michelianum ssp. Balansae], or none) treatments were assessed from 2001 to 2006 for changes in soil characteristics and production. In 2007, a rainfall simulation study was conducted to evaluate treatment effects on runoff. In Study 2, NT, MT, MT with rye cover, and conventional tillage (CT) were assessed for effects on soil changes (2003 to 2011) and runoff water quality (2007 to 2011). Synthesis of results from these studies indicated that: (a) Cover crop and reduced tillage resulted in modest increases in soil organic matter and soil nitrogen; (b) Soil biological activity was enhanced by cover crops (e.g., enzymes, mycorrhizae); (c) Total runoff sediment loss was reduced by no-tillage and cover crop; (d) Nitrogen and phosphorus associated with runoff sediment were reduced in no-tillage and cover crop; (e) Soluble nitrogen and phosphorus in runoff was variable, sometimes higher in no-tillage and cover crop plots.
Refinement and regionalization of phosphorus assessment tools in Mississippi
Year: 2011 Authors: Ramirez-Avila J.J., Oldham J.L., Ortega-Achury S.L., Osmond D., Martin J.L., Locke M., Read J.J.
Phosphorus is a major nonpoint source pollutant that causes eutrophication in surface waters. Phosphorus (P) Indices are applied assessment tools used to identify agricultural fields most vulnerable to P loss by accounting for major source and transport factors controlling P movement. There is a wide range in formulation and management recommendations of P Indices among the southern states leading to differences in P-management recommendations under relatively similar site conditions. This situation creates the need for rigorous evaluations of P Indices to determine directional and magnitudinal correctness. Mississippi State University-based investigators participate in a southern multistate research program with the objectives to coordinate and advance P management in the region by ensuring that P assessment tools developing using guidance in the 2011 NRCS 590 standard are compared to water quality data. The research goals include producing tools that provide more consistent results across physiographic regions that will encourage greater similarity between southern state P Index ratings and ensuing recommendations. Values of annual P loss measured in two Mississippi physiographic regions, i.e. agricultural fields in the Mississippi Delta and pastures in the poultry production counties in South Mississippi, are used to compare southern P Index assessments against water quality data, and to calibrate and validate the Agricultural Policy/Environmental eXtender (APEX) model. Results will show the assessment for P loss vulnerability estimated by different southern P Indices and the performance of the APEX model before and after calibration and validation procedures for the proposed scenarios.
Nutrient Reduction In Mississippi: Partnering For Success
Year: 2011 Authors: Bhowal P.
Mississippi is blessed with abundant water resources, and protection of these water resources is essential to ensure sustainability of Mississippi's ecosystems and economies. One of the biggest challenges for Mississippi's surface waters, the Mississippi River and the Gulf of Mexico is the presence of excess nutrients in these waters. The Gulf of Mexico contains a hypoxic zone that is a result of nutrient-rich water from the Mississippi River flowing into the Gulf. Nutrients, in the form of nitrogen and phosphorus, come from a variety of sources including farmlands and lawns where fertilizers are used, wastewater treatment facilities, animal wastes from farms and pasturelands. Accordingly, the issues of nutrient pollution and Gulf Hypoxia have become priorities for Mississippi's Delta, Upland and Coastal regions that contribute significant nutrients loading to the Gulf. Mississippi's approach to reduce nutrient loadings within basins and to the Gulf of Mexico is a highly collaborative, stakeholder supported process centered on development and implementation of comprehensive nutrient reduction strategies for the Delta (December 2009), Coastal (March 2011), and Upland (March 2011) regions of the state. These strategies identified 11 strategic elements to help reduce nutrient loading to Mississippi's surface waters. Over 50 staff from multiple state and federal resource agencies and other organizations in Mississippi have been working together to help develop and implement these comprehensive nutrient reduction strategies. Implementation includes engaging stakeholders, characterizing watersheds, determining status and trends, documenting management programs, establishing quantitative targets, selecting analytical tools, identifying/implementing established and innovative best management practices (BMPs), designing monitoring work, providing incentive and funding, and communicating results. These nutrient reduction strategies are currently being implemented in 10 priority watersheds in the Delta (7), Upland (2), and Coastal (1) regions of the state.
Benefits of On-Farm Water Storage Systems in Porter Bayou Watershed
Year: 2011 Authors: Tagert M.L., Paz J.O., Pote J.W., Kirmeyer R.L.
Since the 1970's, groundwater levels in the Mississippi Alluvial Aquifer have decreased as the number of irrigated acres in the Mississippi Delta has increased. Today, there are roughly 18,000 permitted irrigation wells dependent on water from the Mississippi Alluvial Aquifer, with approximately 50,000 new irrigated acres added both in 2011 and 2012. As concern has grown over groundwater declines and increasing fuel costs to run irrigation pumps, farmers have been implementing more irrigation conservation measures, such as on farm water storage (OFWS) systems. These systems began appearing in the Mississippi Delta in 2010 in conjunction with the implementation of the Mississippi River Basin Healthy Watersheds Initiative (MRBI). OFWS systems typically are surrounded by fields that are padded and piped, directing rainfall and runoff to a tailwater recovery ditch, from where it is then pumped into a pond for storage. Water is pumped from the pond and used for irrigation at a later date. These systems offer farmers the dual benefit of providing water for irrigation and also capturing nutrient rich tailwater for on farm reuse. This presentation will give an update on the project, which has monitored water savings and nutrient levels at two OFWS systems, one each at Metcalf Farm and at Pitts Farm, in the Porter Bayou Watershed, Mississippi. Data collection began in February 2012 and is ongoing, with water samples collected for analysis every three weeks throughout the growing season from March-October and every six weeks through the off season. Cumulative readings were also taken on flow meters to measure water use from the storage pond. The ability of these systems to reduce downstream nutrient concentrations has been mixed, with systems performing better when the tailwater recovery ditch is not full and can contain runoff on site. Thus, better management will improve the nutrient reduction potential of these systems. The water savings potential of these systems has been substantial. Metcalf Farm used 42 and 17 million gallons of water from the storage pond in 2012 and 2013, respectively; Pitts Farm used 60 and 56 million gallons of water from the storage pond in 2012 and 2013, respectively. These amounts reflect savings in groundwater that was not pumped from the Mississippi Alluvial Aquifer.
The Red Creek Consolidated Mitigation Bank and the Challenges of Stream Restoration in Gulf Coastal Plain Soils and Weather
Year: 2011 Authors: Maurer B.
Since the Mobile and Vicksburg districts of the Corps began regulating impacts to streams, the Mississippi Department of Transportation has been proactive in acquiring advance credits for future impacts in several watersheds. One such project is the Red Creek Consolidated Mitigation Bank, located in coastal Jackson County and established in partnership with The Nature Conservancy. Approved in 2011, this wetland and stream bank is providing credits on wet pine flats, bayhead and bottomland hardwood forest, and 3,345 linear feet of stream restoration primarily on two reaches of a tributary to Red Creek. The site is part of an ecologically-significant conservation area in the Pascagoula River watershed. The two restoration reaches have distinctive features; a Priority 2 Restoration was completed on steep and highly entrenched section of the upper stream to arrest severe headcutting. In the second reach, Priority 1 stream relocation was completed in a low-gradient bottomland forest to prevent active downcutting. Completed in the spring of 2012, the stream restoration work was subject to several substantial rain storms (including Hurricane Isaac, which dropped 15-20 inches on the site) before soils had settled and vegetation was fully established. In addition, unforeseen seepage areas developed on some of the steeper slopes causing slumping in the toe areas. Significant damage from storms in these seepage areas and later universally throughout much of the project forced a re-evaluation of the design before repairs were completed. This presentation will discuss and contrast the two restoration reaches, including the challenges of choosing Best Management Practices (BMPs)for stream restoration, and establishing vegetation in erodible, relatively low-nutrient soils and unfavorable weather conditions (hot and dry with periodic intense rainfall). Finally, we will evaluate the damage and repairs to restoration reaches, and how the untimely storms quickly taught us what worked best and what needed improvement.
Crayfish Harvesting: Alternative Opportunities for Landowners Practicing Moist-soil Wetland Management
Year: 2011 Authors: Alford A.B., Grado S.C., Kaminski R.M.
Harvest of crayfish (Procambarus spp.) for human consumption in the United States and beyond is considerable, amounting to an annual value of $150-170 million annually in the southern United States alone. Most crayfish harvested for human consumption are cultivated in rice fields in southern Louisiana. Management of emergent vegetation in moist-soil wetlands is similar to cultivation of rice where the seasonal wet-dry cycle of these wetlands encourages the growth of annual plants that produce abundant seeds and tubers for waterfowl forage. Recent aquatic invertebrate studies in moist-soil wetlands suggest that populations of crayfish in these habitats may be large enough to warrant a harvest for human consumption. To estimate the economic potential of crayfish harvests in moist-soil wetlands, crayfish yield was estimated from moist-soil wetlands on public and private lands in the MAV in Arkansas, Louisiana, Mississippi, and Missouri in spring-summer 2009-2011 using typical crayfish harvest strategies practiced in commercial rice-crayfish fields of Louisiana. Average daily yields of crayfish from moist-soil wetlands ranged from 0.08 kg/ha to 23 kg/ha with an overall mean yield of 2.73 kg/ha (n = 42, CV = 21%). Whereas the mean daily yield of crayfish from moist-soil wetlands was >3 times less than the yield expected from a high production rice-crayfish culture system (e.g., 8-10 kg/ha), estimated cost associated with harvest of crayfish from moist-soil wetlands were $529/ha and were lower compared to costs associated rice-crayfish harvest practices which were estimated to be $1,856/ha. However, the estimated break-even selling price for crayfish harvested from moist-soil wetlands was $4.90/kg compared to $2.75/kg estimated for rice-crayfish practices. The estimates of break-even selling prices for crayfish harvested from moist-soil wetlands were higher than the 2012 estimate of $2.75/kg price for single crop production of crayfish in Louisiana. However, in areas where crayfish markets are sparse, such as the North Mississippi Delta, landowners may still realize economic potential from this fishery. Harvesting crayfish from moist-soil wetlands may provide a small profit to landowners but will likely provide additional recreational opportunities and can serve as additional extension vehicles to encourage wetlands conservation throughout the MAV.
Teaching How Water Works: Informal Science Education through Exhibit Design
Year: 2011 Authors: Brzuszek R.
The mission of the Crosby Arboretum, Mississippi State University Extension (located in Picayune, Miss.), is to preserve, protect and display plants and their communities native to the Pearl River Drainage Basin. The Crosby Arboretum's nationally award-winning master plan has designated a portion of its facility for the creation of a small stream swamp forest educational exhibit. Small stream swamp forests are wetlands situated on bottomlands of small streams that are predominated in species type and frequency by black gum (Nyssa biflora) and sweet bay magnolia (Magnolia virginiana). As specified in Mississippi's Comprehensive Wildlife Conservation Strategy by the Mississippi Department of Wildlife and Fisheries (MDWF), small stream swamp forests are considered vulnerable in the state of Mississippi. The proposed swamp forest exhibit will address MDWF priorities through the construction and management of the habitat type, as well as providing a venue for public education and experience in this vulnerable forest.
The Crosby Arboretum Foundation was awarded a grant to create a small stream forest educational exhibit. Graduate students in the Department of Landscape Architecture at Mississippi State University utilized a semester-long class project in spring 2011 to research and design the proposed exhibit. Students conducted a literature search on small streams and related wetlands and visited several in situ small stream swamps in Mississippi. Students recorded environmental data at the natural wetlands to inform the restoration design. Students also conducted an environmental inventory and analysis at the proposed exhibit site that recorded the site's hydrology patterns, plant species, soils and other data. A design charrette, or a collaborative session to determine solution to the design problem, was conducted with wetland specialists and landscape architects to develop the preliminary design. This paper will discuss the method used to develop the exhibit design and will exhibit the drawings for the proposed stream and associated wetland types. Long-term vegetation monitoring will be initiated after construction.
Development of the Mississippi Irrigation Scheduling Tool-MIST
Year: 2011 Authors: Sassenrath G.F., Schmidt A.M., Schneider J., Tagert M.L., van Riessen H., Corbitt J.Q., Rice B., Thornton R.
Increasingly variable and uncertain rainfall patterns together with higher production input costs have led farmers to rely on supplemental irrigation to enhance production. While many irrigation methods have been developed for dry climates, few tools are available for humid, high rainfall areas. Moreover, most scheduling tools require extensive data collection, entry and simulation runs, limiting their practical utility during the production season. We have designed the Mississippi Irrigation Scheduling Tool (MIST) as a web-based, easy to use management tool for crop producers. An estimate of crop water use is made using the modified Penman Monteith to calculate daily evapotranspiration. The "checkbook" water balance method sums the water balance of the soil, plus water from rainfall or irrigation, minus water used by the crop or evaporated from the soil. This method indicates the need for irrigation when the soil water available to the plant falls below that which is readily available for crop growth. To enhance utility, the MIST has been implemented in a web interface, allowing producers to access the information from anywhere through tablet computers or smart phones. To reduce the data entry requirements, the system relies on national databases for automated integration with a water balance model. The system was tested at multiple production sites during the 2011, and 2012 growing seasons. This presentation will give details on the development of input parameters for the water balance calculation, including crop water use and soil moisture, and water balance during the growing season for corn and soybeans. Additional presentations in this session will describe the implementation of the user interface (Rice et al.), calibration and validation of the model (Prabhu et al.), and spatial accuracy of national databases (Thornton et al.). The MIST will provide producers, consultants and other professional colleagues with a reliable, accurate, and easy to use tool for improved water management.
Potential environmental risk of the phosphorus status in soils receiving poultry manure applications in Mississippi
Year: 2011 Authors: Ramirez-Avila J.J., Oldham J.L., Kingery W.L., Crouse K.K., Ortega-Achury S.L.
Phosphorus (P) enrichment of surface and ground water involves a combination of source factors such as high soil test phosphorus (STP) levels and site-specific soil and field characteristics that influence P transport by water flow overland and through the soils. Long-term applications of manure have generally increased STP levels to a greater degree than has fertilizer application because manure applied to meet the nitrogen (N) needs of crops provides more P than utilized by crops. Preliminary research found that subwatersheds within the poultry production counties in Mississippi have a high potential for soil and water degradation from manure P and N. An assessment was developed to increase understanding of STP levels in soils of the top 20 poultry production counties in Mississippi. The study performed a descriptive summary and analysis of temporal dynamics of STP in 15,057 soil samples, submitted for forage and pasture crop recommendations, after analysis by the Mississippi State University Extension Service Soil Testing Laboratory for 10 annual periods from 2002-2003 to 2011-2012. There were gradual annual changes in STP level ranges from the first (5 to 3780 lb ac-1) to the last year (5 to 3980 lb ac-1). Individual peak STP values of 5990 and 4840 lb ac-1 were observed in the 2nd and 7th year, respectively. However, mean STP levels increased from 113 lb ac-1 to 302 lb ac-1 from the first to the last year with the highest mean STP level of 356 lb ac-1 in the 7th year. The MSU Extension Service would not recommend additional external P for 69% of the soils sampled in the last year of the dataset; in the first year this value was 38%. These results indicate increased STP in these soils that could contribute P to runoff and leaching flows. Because of the susceptibility of these areas to manure source P leaching and runoff, Best Management Practices should be implemented that manage P source and off-field transport to minimize environmental impacts. Balancing P inputs with crop removal is an essential part of a sustainable practice to controlling P losses. Maintaining moderate STP levels or reducing high STP levels can reduce the potential for transport of P from both particulate and dissolved P. Comprehensive nutrient management plans should be developed and implemented for all poultry production operations for the optimal use of poultry manure.
Spatial distribution of Sediment and Nutrient Loadings from Upper Pearl River Watershed (UPRW)
Year: 2011 Authors: Jayakody P., Parajuli P.B., Cathcart T.P.
Deterioration of surface water quality is one of the most concern issues in the U.S. The knowledge of spatial and temporal variability of water quality parameters may help to formulate mitigation plans to improve water quality. This study was designed to investigate temporal and spatial variability of sediment, total nitrogen (TN), and total phosphate (TP) loadings to the surface water through a modeling approach. The Soil and Water Assessment Tool (SWAT) was applied for Upper Pearl River Watershed (UPRW) in central Mississippi. Water samples were collected from Burnside and Lena USGS gauging stations. The SWAT model was calibrated and validated for daily time steps using manual and automatic (SUFI-2) methods from Feb 2010 to May 2011. Preliminary results showed good to very good model performances with the coefficient of determination (R2) and Nash-Sutcliff Efficiency Index (NSE) from 0.6 to 0.8 (flow), 0.3 to 0.6 (sediment), 0.6 to 0.7 (TN), and 0.5 to 0.6 (TP) during both hydrologic and water quality model calibration and validation. Sub-watersheds were ranked based on water quality pollutants loading to prioritize land areas for watershed management operations.
Factors affecting low summer dissolved oxygen concentrations in Mississippi Delta bayous
Year: 2011 Authors: Lizotte Jr. R.E., Shields Jr. F.D., Locke M.A., Murdock J.N., Knight S.S.
Streams in watersheds supporting intensive row-crop agriculture are vulnerable to ecological degradation due to non-point source discharge of pollutants such as nutrients. Low gradient streams such as bayous are especially susceptible due to increased water residence time, and often result in poor water quality and chronic low dissolved oxygen (DO) concentrations (hypoxia). The goal of the current study was to assess physical, chemical, and biological components affecting low DO during summer of 2011 in three Mississippi Delta bayous. Three sites were selected within each bayou: upstream channel, lake or open water in the water body mid-section, and downstream channel. Dissolved oxygen was monitored at 40 cm depth every 15 minutes for 6-7 days on alternate weeks. Stream surface water samples collected biweekly were analyzed for nutrient and chlorophyll a concentrations. Minimum daily DO levels were frequently below the State instantaneous minimum DO standard of 4 mg/L. Diel DO fluctuation (the difference between daily maximum and minimum DO concentrations) reflected large 24-h DO ranges (=10 mg/L) across all three bayous. Pearson product moment correlations showed minimum DO concentrations to be negatively correlated with total phosphorus (TP) concentrations across all habitats. Total nitrogen (TN) concentrations and dissolved organic carbon (DOC) concentrations were negatively correlated with minimum DO concentrations only in lake habitats. Diel DO fluctuation was positively correlated with water column chlorophyll a concentrations across all habitats. Upstream diel DO fluctuation was also positively correlated with water depth and TP concentrations while downstream diel DO fluctuation was positively correlated with TP but not water depth. Low summer DO concentrations and changes in diel DO fluctuations were affected by both nitrogen and phosphorus driving summer algal blooms (eutrophic to hypereutrophic conditions) in Mississippi Delta bayous. Organic carbon inputs may exacerbate DO minimums in these nutrient-rich systems. As a result, nutrient reduction in all habitats in conjunction with increased water depth in upstream habitats is necessary to improve summer DO concentrations in Mississippi Delta bayous.
Evaluating the Variability of Sediment and Nutrient Loading from Crop and Cattle Fields Located in North Mississippi
Year: 2011 Authors: Guzman S., Salazar G., Diaz-Ramirez J., Schauwecker T.J.
Excess nutrients are known as a primary problem facing Gulf of Mexico estuaries and coastal waters, leading to nuisance algal blooms, depletion of dissolved oxygen, and other water quality impairments. Soil and nutrient losses encourage siltation and eutrophication in Gulf of Mexico waters. Soil and nutrient exported from agricultural fields into water bodies in Mississippi is a major environmental concern by local, state, and federal agencies. This poster presents runoff and sediment & nutrient loads from two fields in north Mississippi: a 8.4-ha cattle drainage area located on the agricultural research property of the Mississippi Agriculture and Forestry Experiment Station (MAFES), adjacent to Mississippi State University (MSU); and a 11.3-ha crop drainage area located in Leflore County. The cattle field is monitored since 2011 by researchers from MSU Departments of Civil & Environmental Engineering and Landscape Architecture. At the outlet of the cattle field, MSU researchers are using a pressure transducer and automatic sampler to monitoring water depth and water quality, respectively. Field data (discharge and sediments & nutrient concentrations) from the crop drainage area were collected by the U.S Geological Survey from 1996 to 1999. The goal of this research is quantify sediment and nutrient loads by storm events yielded from fields managed with crops (soybeans and cotton) and beef production grazing pasture. Currently, we are computing and analyzing sediment and nutrient loads by storm events and planning to show results at the conference.
Assessment of Improved Sensors to Monitor Water Used for Irrigation in the Mississippi Delta
Year: 2011 Authors: Burt D.E.
The Mississippi River Valley alluvial (MRVA) aquifer spans seven states in the central part of the U.S. In northwestern Mississippi, the MRVA underlies a rich, agricultural region known locally as the Delta. Nearly all of the water used to irrigate crops in the Delta is withdrawn from the MRVA aquifer. As more and more wells are drilled to irrigate crops, the need to monitor the amount of water being pumped from the MRVA becomes more critical. Using technologies such as data loggers combined with improved sensors, the U.S. Geological Survey has partnered with the Yazoo-Mississippi Delta Joint Water Management District to monitor irrigation wells throughout the Delta.
Vibration and inductance sensors are being tested on a variety of pumping applications to obtain real-time data for the amount of time that pumps are applying water during the growing season. The sensors were evaluated on about 30 test wells during the 2011 growing season to determine their ability to accurately monitor pump usage based on powering up and down and overall run-time. Once pump usage is determined, and pump rates are measured using a non-intrusive flow meter, then a total water volume pumped at each well can be calculated.
Future plans are to calculate total water volume pumped from a network of wells throughout the Delta during the growing season. Selected permitted wells in every county in the Delta for each of the four main crop types—corn, cotton, rice, and soybean—will form the network. This network can then be used to estimate irrigation water use for all other permitted wells in the Delta, aggregated by crop type and county.
Preliminary Results from a New Ground-Water Network in Northeastern Mississippi
Year: 2011 Authors: Manning M.A., Rose C.E., Welch H.L., Coupe R.H.
In 2010, the U.S. Geological Survey established a new groundwater network to better understand the influence of agricultural land use on shallow groundwater quality. The areal extent of the study spans from southwestern Tennessee southward through the middle of northern Mississippi. A 30 well network overlays the basic recharge area that conforms along the eastern outcrop boundary of the Middle Claiborne Group, (Sparta Sand) within Tennessee and Mississippi. Well locations were randomly selected using a grid of 30 polygons generated by a geographical information system (GIS) model. Monitoring- well locations were then selected for each GIS-generated polygon that best fit both agricultural land use, and location to the outcrop area. These areas of outcrop for the Sparta Sand provide a hydrologic connection between the aquifer, and surface-water sources such as rivers, lakes, and rainfall runoff. This study will investigate the shallow groundwater quality of the Sparta waters on the eastern edge of the formation that could be altered by agricultural land use and will document any unfavorable compounds that may be carried into the aquifer.
During the fall of 2010, 15 of the new 30 well network were drilled and established on private properties located in northeastern Mississippi. These new monitoring wells were installed using a rotary drilling-type rig until the first water was identified. Using historical data, potentiometric surfaces were estimated to range from zero (land-surface) to about 30 feet below land surface. During the initial well drilling, the first water was encountered anywhere from 12 to 40 feet below land surface. All of the wells were screened at a 10 foot interval from the bottom of the well. Each well screen was set within mixed marine/deltaic facies consisting mostly of sand to sandy silty clays which are considered consistent with most Sparta Sands. Most of the wells were drilled within an area consisting of a least 60 percent or more local agricultural land-use. The locations were selected because the landowners were interested in the study, allowed accesses to their property, and they possessed land that had active agricultural activities that included corn, cotton, and /or soybeans.
The lower extent of the two-state study area was sampled for groundwater quality from March through April 2011. Water samples were analyzed for a wide range of constituents, including but not limited to trace elements, inorganics, nutrients, dissolved gases, tritium, and a full spectrum of pesticide compounds. The well network will be re-visited annually to monitor water levels, and a subset of five wells will be sampled every other year. Future plans are to re-sample the entire network for water-quality trends on a 10-year rotation. Land-use surveys were conducted within a 500-meter radius of each well to determine the current land use, and to provide a baseline for future land-use changes.
Hydrologic Regimes of Bottomland Hardwood Forests in the Mississippi Alluvial Valley and Gulf Coastal Plain and the Impact on Red Oak Acorn Production
Year: 2011 Authors: Sloan J., Hatten J.
Red oak (Quercus spp.; Subgenus Erythrobalanus) acorns provide a major food source for many species of wildlife such as ducks, white-tailed deer (Odocoileus virginianus), and wild turkeys. Acorns are also important for the regeneration of these forests. The production of acorns is sporadic and the cause of this is not completely known or understood. Red oaks are prevalent in bottomland hardwood forests throughout the Mississippi Alluvial Valley (MAV) and Gulf Coastal Plain (GCP) and these forests undergo extreme hydrological events annually, from being completely inundated in the winter and spring to very dry in the summer. This study will examine the hydrology and soils of bottomland hardwood systems and the control they have on acorn production. Data has been collected at six sites, covering five states in the MAV and GCP. A well placed at each site was used to measure hydroperiod with an In-Situ Inc. LevelTROLL 300 and an In-Situ Inc. BaroTROLL. With these wells both ground water and surface water were measured. Organic matter input was measured using 10 porcelain sediment tiles at five of the sites and 20 porcelain sediment tiles at one site. Organic matter content of deposited sediment was determined by loss on ignition. Acorn production data was measured at 20 plots per site during the fall and winter of 2011/2012 and will be measured again in the fall and winter of 2012/2013. We will present preliminary hydrology, sedimentation, and organic matter accumulation data collected from September, 2011-February 2012.
Evaluating a Vegetated Filter Strip in an Agricultural Field
Year: 2011 Authors: Young A.
The use of best management practices and low impact development strategies have become common in recent years, leading to the need for the creation of hydrologic models to predict their behavior and effectiveness. A vegetated filter strip at the South Farm Research Park at Mississippi State University was used to test two of these models: the Hydrologic Simulation Program-FORTRAN Best Management Practices Editor (HSPF BMPrac) and the System for Urban Stormwater Treatment and Analysis Integration (SUSTAIN). Water samples were taken during the Spring of 2011 and tested for sediments and nutrients; HSPF was used for computing flows, sediments, and nutrients. The filter strip was not effective at pollutant removal with removal efficiency rates of 68.1, 91.7, 86.3, and 115.4 percent for total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP), and dissolved phosphorus (DP) respectively. Calibration of HSPF was successful for TSS with a R2 value of 0.52; nutrients were not as successful with R2 values of 0.11 and 0.43 for
TN and TP. HSPF's BMP Practice Editor demonstrated an drastic over prediction of pollutant removal. Modeling of the VFS in SUSTAIN was not a success due to technical failures preventing the model from running.
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Analyzing the Hydraulics of a Biofiltration Swale Using HEC-RAS
Year: 2011 Authors: Bassi D., Rivas D., Diaz-Ramirez J., Martin J.
Hydraulic Engineering Center's River Analysis System (HEC-RAS) is a hydraulic model that was developed by the U.S. Army Corps of Engineers to execute 1-D hydraulic calculations. The software is made up of four 1-D river analysis tools that all use the same geometric data that is imputed by the user. It calculates steady flow water surface profile computations, unsteady flow simulation, movable boundary sediment transport computations, and water quality analysis. It comprises of a graphical user interface, data storage and management, and reporting functions. The purpose of this research was to use HEC-RAS to assess a biofiltration swale by calculating the flows, roughness, and sediment loads, as well as evaluating a porous check dam located at the end of the swale. The vegetative swale is a Best Management Practice (BMP) that is located on the South Farm at Mississippi State University. The 50-m long swale contains a rip-rap check dam at the downstream end of the BMP followed by a fiberglass flume. The watershed for the BMP contained cattle pastures and is approximately 8.4 ha. Since summer 2011, flows from storm events were measured using a Son-Tec Flow Meter in the field and water levels were used to measure the gage heights during the events. Rating curves (stage vs. discharge) were developed for the upstream, middle, and downstream (flume) sections of the BMP. Thirteen cross sections of the channel were found using a total station and the geometric data was imputed into HEC-RAS. Water samples were also collected during storm events using an automatic water sampler located at the entrance, middle, and flume sections, and the samples were analyzed in the laboratory for total suspended solids as well as various nutrients. Currently, we're setting up the model and planning to show model results at the conference.
Water quality and other ecosystem services from wetlands managed for waterfowl in Mississippi
Year: 2011 Authors: Kaminski R.M., Alford A.B.
A successful and increasingly applied conservation practice in the Lower Mississippi Alluvial Valley (MAV) to mitigate loss of wetland wildlife habitat and improve water quality has been development and management of "moist-soil wetlands." This conservation practice has the potential to provide ecosystem services critical to restoring wetland functions in the MAV such as reducing dispersal of sediments and nutrients into surrounding watersheds. Moreover, a significant potential exists for native crayfish (Procambarus spp.) harvest in moist-soil wetlands in the MAV. During spring 2011, we estimated average daily yield of crayfish from 18 moist-soil wetlands in Arkansas, Louisiana, Mississippi, and Missouri. Average daily yield in 2011 was 3.64 kg/ha (CV = 33%). This estimate was slightly greater and more variable than the estimated yield from Mississippi wetlands in 2009 (i.e., 1.75 kg ha-1; CV = 16%, n = 9) and wetlands in Arkansas, Louisiana, and Mississippi in 2010 (i.e., 2.18 kg ha-1;CV = 30%, n = 15) . Our estimated daily yield of naturally occurring crayfish from moist-soil wetlands is lower than 10 kg ha-1 which is the average daily yield from commercially operated rice-crayfish ponds in Louisiana. However, our comparisons of operating budgets from the two harvest systems indicated that rice-crayfish systems incur $1455 in direct expenses per hectare whereas crayfish harvest operation in moist-soil wetlands incur $682 direct expenses per hectare. Although fixed expenses are lower in harvest operations from moist-soil wetlands, lower yields increased the break-even selling prices from $2.75 kg-1 in rice-crayfish systems to $6.38 kg-1 in moist-soil harvest systems. These prices, however, are still less than those observed in regions of the Southeastern United States outside of Louisiana. To determine if crayfish harvested from moist-soil wetlands are an acceptable seafood product relative to commercially harvested crayfish, we conducted a consumer acceptability panel in May 2011. We found that crayfish from both sources were well liked and did not differ significantly (p > 0.05) in overall consumer acceptability. In July 2010, we installed water quality monitoring stations at 5 wetlands and 5 agriculture fields. We monitored concentrations of nutrients and sediments exported from these habitats during storm events in December-March of 2010-2012. We determined that wetlands exported significantly less total suspended solids and NO3 than agriculture fields in 2010-2011 whereas all parameters except for NH3 were significantly lower in wetland effluent compared to agriculture fields in winter 2011-2012. We were able to calculate loads (kg ha-1) from wetland habitats during the study years and determined that total annual loads of nutrients were slightly greater than currently assumed loading values of wetlands in Mississippi (i.e., 1 kg ha-1). Quantifying these ancillary ecosystem services of moist-soil wetlands will encourage further establishment and management of these wetlands in the MAV and elsewhere for wildlife and associated environmental and human benefits.
Water-quality of the Yazoo River During the 2011 Mississippi River Flood
Year: 2011 Authors: Woods M.S., Rose C.E., Coupe R.H.
The Mississippi River was above flood stage at Vicksburg, Mississippi, for much of spring 2011. Water samples were collected during this period on a weekly basis from the Yazoo River near Vicksburg, Mississippi, and analyzed for nutrients, sediment, and pesticides as part of a U. S. Geological Survey study to assess water quality of the Mississippi River Basin. High water affected the water quality of the lower Yazoo River, as the Mississippi River stage rose and fell during the flood. Water-quality changes correspond not only to stagnant or reversed flows and accumulation and backwater effects, but also to different sources of water to the Yazoo River before, during, and after the flood. Before the spring 2011 flooding of the Mississippi River, the Yazoo River water came from two sources: the Delta and the Bluff Hills. Along the upper Yazoo River, flood-control structures at Steele Bayou and Little Sunflower Diversion Canal outlets were closed to prevent flooding in the Delta from the Mississippi River; during this time, the Yazoo River source is primarily from the Bluff Hills. During the flood, when the Mississippi River stage was higher than the Yazoo River stage, the Yazoo River flow was impeded and reversed, and mixing of the Mississippi River into the Yazoo River occurred. The Mississippi River was a major source of water to the Yazoo River near Vicksburg during flooding. For much of the 2011 growing season, the control structures along the Yazoo River were closed, thus causing sediment and nutrients to accumulate behind the flood control structures. As the Mississippi River receded following the flood, the flow control structures were reopened, flushing the stagnant and sediment-laden backwater into the Yazoo River, allowing the streams of the Delta to return to normal flow. Following the flood, the Yazoo River water source was primarily from the Delta. The changes in water-quality on the Yazoo River during the 2011 Mississippi River flood can be attributed to the different water sources caused by the flood.
Movement of Agricultural Chemicals and Sediment Through the Lower Mississippi River Basin During the 2011 Flood, April through July
Year: 2011 Authors: Welch H.L., Aulenbach B.T., Coupe R.H.
Extreme hydrologic events, such as floods, can overwhelm a surface water system's ability to process agricultural chemicals (nutrients and pesticides) and can move large amounts of sediment downstream to larger surface water bodies. The Mississippi-Atchafalaya River basin drains approximately 41% of the conterminous United States and is the largest contributor of nutrients to the hypoxic zone that develops along the inner continental shelf of the Gulf of Mexico each spring. From March through April 2011, the lower Mississippi River basin received more than five times more precipitation than normal, which combined with snow melt from the upper Mississippi River basin, created a historic flood event that lasted from April through July. The U.S. Geological Survey, as part of the National Stream Quality Accounting Network (NASQAN), collected samples from six sites located in the lower Mississippi-Atchafalaya River basin, as well as, samples from the three flow-diversion structures: the Birds Point-New Madrid in Missouri and the Morganza and Bonnet Carré in Louisiana, from April through July. Samples were analyzed for nutrients, pesticides, suspended sediments, and particle size; results were used to determine the water quality of the river during the 2011 flood. Monthly loads for nitrate, phosphorus, pesticides (atrazine, glyphosate, fluometuron, and metolachlor), and sediment were calculated to quantify the movement of agricultural chemicals and sediment into the Gulf of Mexico. Nutrient loads were compared to historic loads to assess the effect of the flood on the zone of hypoxia that formed in the Gulf of Mexico during the spring of 2011.
The Great Flood of 2011 and its Influence on the Mississippi River Valley Alluvial Aquifer: Did the River Recharge the Aquifer or What?
Year: 2011 Authors: Byrd C.B.
The flooding along the Mississippi River during the months of April and May, 2011 was among the worst in the last 100 years. According to one source, this flooding event was comparable to the flooding that occurred in 1927 and 1993. Data from five gages that include stations at Memphis, Tennessee down to Vicksburg, Mississippi indicate that an all-time record was set at the gage at Vicksburg, Mississippi, and near-record stages were recorded at the other four stations. Seven states were impacted by the floodwaters, and for the first time in many years, the Morganza Spillway was opened to deliberately flood roughly 4,600 square miles of rural Louisiana so that New Orleans and Baton Rouge could be spared.
With all the record setting stages along the Mississippi River adjacent to Mississippi, one may ask, "What influence did the record-high river stages have on the Mississippi River valley alluvial aquifer (MRVA), which is the shallow aquifer in the alluvial plain (Delta) in the northwest portion of the state?" Unfortunately, the answer is not as straight forward as one may wish.
The Mississippi River is the western boundary for both the Delta and the alluvial aquifer. The depositional history of this river system is very complex, thus the geology of the alluvial aquifer is very complex. As the Mississippi River and its tributaries migrated throughout the alluvial plain, many stream channels were eventually cut off from the main river creating oxbow lakes. Through time, many of these oxbows were filled in with very fine-grained sediments, such as silt and clay. If the fine-grained sediments within an oxbow is of sufficient thickness, a "clay plug" is formed that serves to prevent any flow of water through it. Remnants of these old streams and oxbows are present all along length of the Mississippi River. However, if mostly fine- to coarse-grained sand and gravel was deposited, the river and the MRVA are most likely in very good hydrologic connection.
Water levels were collected during early May (the period of peak flooding) by the Office of Land and Water Resources staff. This data along with water level data collected by the Yazoo Mississippi Joint Water Management District staff during early April and early June were correlated with River stages. Then an analysis of geologic data was combined with the water levels and river stages to try to determine hydrogeologic connection.
Sedimentation Processes in Perdido Bay
Year: 2011 Authors: Sigsby N.J., McAnally W.H., Sigsby N.
Perdido Bay is an estuarine system located along the Alabama-Florida border in the Gulf of Mexico with an estimated 2900 sq. km watershed and a narrow tidal inlet to the Gulf of Mexico. Water quality and hydrodynamics have been examined in some detail, but very little research has been done on the sedimentation processes of the bay. A systematic sedimentation study will contribute to an improved understanding of the processes of the bay.
An investigation into the sediment classifications, distributions, and discharges will be completed as a major part of this sedimentation study. As a first step, a data collection was performed in July 2011. This survey included water and bed sediment sampling, water quality readings, and velocity measurements. Water quality constituents tested included dissolved oxygen, pH, salinity, temperature, turbidity, and depth. Velocity and discharge calculations were recorded using an Acoustic Doppler Current Profiler. Bed sediment samples will be used for grain size analysis and sediment classification. The water samples collected will be used for total suspended solids analysis. Analysis of the tide levels, salinity and turbidity will be completed for the verification of the existence and location of the turbidity maxima in Perdido Bay.
A thorough literature review will be completed to better understand sedimentation processes, sediment budgets, numerical modeling, and historical data. Using this data, along with data collected on-site, a systematic sediment budget will be developed and a numerical model of sediment transport using EFDC will be developed.
Field-Scale Monitoring of Agricultural Ditches as Conduits of Nitrogen, Phosphorus, and Suspended Sediment in Response to Storm Events and Low-Input D
Year: 2011 Authors: Pierce S.C., Kröger R., Prevost D., Pierce T.
Runoff from row-crop agriculture is a major source of non-point source aquatic pollution. High concentrations of inorganic nitrogen and sediment-bound phosphorus that are conveyed in agricultural drainage ditches can lead to eutrophication of receiving waters at both local and regional scales. Concerns regarding accelerated eutrophication have led to a concerted effort toward understanding the movement of nutrients across the landscape and the management of agricultural drainages for water quality remediation. This study monitors field-scale movements of nitrate, nitrite, ammonium, dissolved phosphorus, particulate phosphorus and total suspended solids through agricultural ditches over several months preceding and following the implementation of controlled drainage practices including riser boards, slotted pipes, and low-grade weirs. Water samples were collected during baseflow conditions and storm events via grab sampling and different automated techniques. Pre-implementation data collected from January-July of 2011 is summarized below. Preliminary post-implementation data will be presented as it becomes available. Nitrate concentrations showed a high degree of variability both spatially and temporally, varying from approximately 0 to 15 ppm, with values higher in the watershed tending to be slightly higher than outflows. Storm events generally had nitrate concentrations 50% to 100% greater than baseflow concentrations. Nitrite also demonstrated temporal variation, with some samples approaching 1 ppm. Compared to nitrate, however, spatial differences and total variance was low. In contrast to oxidized nitrogen, ammonia concentrations generally ranged from 0.1 to 0.3 ppm regardless of time or location. Dissolved inorganic phosphorus concentrations ranged from approximately 0 to 1.5 ppm, varying nonlinearly with date the sample was collected, but did not appreciably change in response to storm events. Total inorganic phosphorus and turbidity approached an order of magnitude higher in stormwater samples than baseflow samples, with mean total inorganic phosphorus of less than 2 ppm in baseflow samples compared to mean values greater than 10 ppm in stormwater samples. Total suspended sediment concentrations were also significantly higher in stormwater samples than baseflow samples, indicating the likelihood that erosion or sediment resuspension is a major factor in phosphorus transport in agricultural drainage ditches. Preliminary data following implementation of controlled drainage will be compared with this background data set to determine short-term impacts of ditch reshaping on water quality and to estimate the effects of vegetation establishment.
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Nutrient and Suspended Sediment Mitigation Through the Use of a Vegetated Ditch System Fitted with Consecutive Low-Grade Weirs
Year: 2011 Authors: Flora C., Kröger R.
Mississippi is the largest producer of channel catfish (Ictalurus punctatus) in the United States. Channel catfish ponds cover over 20,000 hectares of land, mainly concentrated in the Alluvial Valley of northwest Mississippi. Water management practices to reduce mass discharge from ponds are currently a major point of concern, especially in light of potential regulations through nutrient criteria development. A vegetated ditch fitted with consecutive low-grade weirs is anticipated to be a practical and effective option of reducing nutrients and suspended solids entering downstream receiving systems. This study assesses the effect of low-grade weirs on chemical retention and settling of aquaculture pond effluent in a single drainage ditch. The efficiency of consecutive low-grade weirs will be compared in and across the system. The experiment was conducted September 26–October 1, 2011 at the aquaculture facilities at Mississippi State University. Three embankment ponds were discharged at 48 hour intervals into a single vegetated drainage ditch fitted with 4 low-grade weirs. Data will be analyzed to quantify the ability of the low-grade weir system to reduce the levels of ammonia, nitrate, nitrite, total inorganic phosphorus, particulate phosphorus, and dissolved inorganic phosphorus. The levels of total suspended solids and volatile suspended solids will be compared across the system. As water passes each weir the nutrient and suspended solid loads should decrease through the system, overall reducing the load entering the downstream receiving systems.
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Management of Coastal Ecosystem Restoration Sites under Increased Climatic Extremes: Effects of Hurricane Katrina on Wetlands Restoration Projects in
Year: 2011 Authors: Foster M.A., Battaglia L.L.
Coastal wetland mitigation banks are at the forefront of climate change and are under strict regulatory requirements regarding plant community composition. As effects from climate change intensify, sea level rise and tropical storms may alter the composition of these communities. We measured aspects of plant community structure and diversity at a 382-hectare wetland mitigation bank in southwest Mississippi in 2005-20011. Rapid monitoring assessment with supplemental recording of all species detected was conducted each year at seven pine savanna monitoring plots. The site was in the eye-path of Hurricane Katrina and received over 2.5m of storm surge in August 2005. Multivariate analyses of the understory composition indicated that the high diversity, pre-Katrina community diverged after the storm to a lower diversity subset assemblage. Some recovery through time was evident, although species composition had neither stabilized nor returned to pre-storm conditions by 2011. Richness of savanna forbs dramatically declined following Katrina and has not yet recovered. The assemblages have continued to shift in composition since Katrina, but the eventual state of these systems is not yet known. The reference species composition for a mitigation site is typically strictly defined by regulatory requirements. As a result of tropical storm activity, these coastal ecosystems may be shifting away from fixed reference standards. The likelihood of a major vegetation state change increases as the effects of sea level rise and intensified tropical storm activity become more pronounced along the northern Gulf of Mexico.
Coles Creek Watershed Assessment and Education
Year: 2011 Authors: Silitonga M., Johnson A.
The Coles Creek Watershed, located in the southwestern quadrant of the state of Mississippi, is listed under the US EPA impaired water section 303(d). Degradation of the ponds/lakes and streams/creeks in this watershed is caused mostly by biological impairment, followed by nutrients, organic enrichment or Low Dissolved Oxygen, sediment/siltation, pesticides, and pathogens (US EPA, 2007). These impairments cause the degradation of water quality thus causing euthrophication or algal bloom that
can lead to fish kills and can also adversely affect human health. The causes of algal blooms have not been studied; therefore, data is needed to evaluate the quality of water and soil in the surrounding areas of the watershed. The data obtained will be used to analyze and determine the situation and find effective methods to solve the problem. Community participation in the area is much needed to improve, maintain, and restore the quality of water. Thus, educational materials are necessary to engage the community in protecting the quality of water in this area.
Each water body is unique depending upon its geological characteristics such as natural
landscape features and human activities
related different land uses and landmanagement
practices. In the Coles Creek Watershed, several identified water bodies have been heavily impaired.
Poor water quality can harm fish, wildlife, and their habitats. Many things are known to cause poor water quality including:
sedimentation, runoff, erosion, dissolved
oxygen, pH, temperature, decayed organic
materials, pesticides, and toxic and
hazardous substances. Therefore, identifying the cause of degradation and finding the best
management practice(s) (BMPs) as well as protection strategies have to be developed for each lake, pond, or river, individually.
The purpose of the study is to investigate, assess, and find solutions to improve the quality of surface water bodies that can be adopted and implemented in the watershed.
Influences of Land Surface/Land Use Characteristics on Precipitation Patterns Over the Lower Mississippi Alluvial Plain
Year: 2011 Authors: Dyer J.
The lower Mississippi River alluvial valley in southeast Arkansas, northeast Louisiana, and northwest Mississippi is characterized by widespread agriculture with few urban areas. Land use is predominantly cultivated cropland with minimal topographic variation; however, the eastern edge of the alluvial valley is defined by a rapid, though small, change in elevation into a heavily forested landscape. This change in land use / land cover has been shown to potentially enhance precipitation through generation of a weak mesoscale convective boundary. This project defines the causes and influence of the land surface on associated precipitation processes by simulating a convective rainfall event that was influenced by regional surface features. Analysis was conducted using a high-resolution simulated dataset generated by the Weather Research and Forecasting (WRF) model. Results show that the strongest uplift coincides with an abrupt low-level thermal boundary, developed primarily by a rapid change from sensible to latent heat flux relative to the agricultural and forested areas, respectively. Additionally, surface heating over the cultivated landscape appears to destabilize the boundary layer, with precipitation occurring as air is advected across the land cover boundary and the associated thermal gradient. This information can be used to define and predict surface-influenced convective precipitation along agricultural boundaries in other regions where the synoptic environment is weak.
A climate-driven model to serve as a predictive tool for management of l groundwater use from the Mississippi Delta shallow alluvial aquifer
Year: 2011 Authors: Wax C.L., Pote J.
The objective of this research was to develop a model that can be used as a management tool to find ways to meet the needs for water use while conserving groundwater. This is the third phase of the project to meet these objectives. In phase one of the project, the growing season precipitation was used to develop a relationship that estimated irrigation use, and this was the driving mechanism of the model that simulated water use to the year 2056. Phase two added the use of surface water when growing season precipitation was 30% or more above normal. In this third phase, a new climatological input was introduced into the model—irrigation demand. Irrigation demand was calculated using daily precipitation, evaporation, and a crop coefficient to estimate daily water needs by crop type. Daily values were summed to one week segments which were added to derive the total growing season irrigation demand. Weekly summations increased temporal resolution, improving model efficiency in accounting for excess daily rainfall, allowing the model to apply excess rainfall in subsequent days.
Water-Conserving Irrigation Systems for Furrow & Flood Irrigated Crops in the Mississippi Delta
Year: 2011 Authors: Massey J.H.
The goal of this project was to improve irrigation water- and energy-use efficiency for one of the most economically important cropping rotations practiced in the Mississippi delta, the soybean-rice rotation. Combined economic activity for the two crops in the delta exceeds $600 million annually while combined irrigation water use approaches 2 million A-ft per season. As a result, a modest reduction in the amount of irrigation water used in the soybean-rice rotation could help reduce the current overdraft of the alluvial aquifer. Results from these 2010 on-farm trials indicate soybean irrigation savings using NRCS Phaucet optimization software ranged from 6 to 18% compared to non-optimized furrow irrigation while associated energy use reductions ranged from 32 to 20%, respectively. (It is important to note that in order to foster comparison, the soybean fields used in these studies were rectangular in shape; water savings are expected to be greater for more irregular (i.e., hard to irrigate) soybean fields.) Irrigation water used in rice grown using straight-levees with multiple inlets and intermittent flood management averaged 23.1 ± 2.4 A-in/A as compared to 32.4 A-in/A for straight-levee rice using multiple inlets without intermittent flood management. These results indicate that by overlaying an intermittent flood regime on practices that are already familiar to rice producers in Mississippi, rainfall capture is increased and over-pumping is decreased such that overall water use is reduced by ~40% over the standard rice irrigation practices. Field trials comparing rough rice yield and milling quality for 15 rice varieties grown on two soil series indicated that commercial rice varieties, grown using standard fertility and pest control programs, well-tolerated a carefully-controlled intermittent flooding regime. Each inch of water not pumped from the Alluvial aquifer onto an acre of rice or soybean saves the energy equivalent of ~0.7 gallon diesel fuel (with concomitant reduction in CO2 emissions by ~200 lbs/A). Assuming a current off-road diesel price of $3.20/gallon, a 9 acre-inch (40%) reduction in rice irrigation translates to a savings of ~$20 per acre while a 1.5 acre-inch (18%) reduction in soybean irrigation represents a savings of ~$3 per acre. By reducing irrigation water and associated energy inputs in soybean and rice production, the producer reduces input costs while reliving pressure on the Alluvial aquifer and also reduces carbon emissions.
Sources, sinks, and yield of organic constituents in managed headwaters of the Upper Gulf Coastal Plain of Mississippi
Year: 2011 Authors: Hatten J.A., Dewey J.C., Ezell A.W.
Sediment, organic matter, and nutrients (particularly nitrogen) are the constituents that most often lead to the impaired designation for rivers in Mississippi (E.P.A. 2000). Headwater streams are very important contributors of water, sediment and nutrients to the downstream fluvial environment. Many studies of non-mountainous systems have focused on the quantity of particulate or dissolved forms of material (e.g. suspended solids, organic matter, and nitrogen); few have examined the source of this material. The relationships among origin, storage, consumption and export of organic matter (OM) with stream discharge and subsurface interflow represent significant gaps in our understanding of headwater processes. This study is part of a larger-scale study investigating the effects of silvicultural best management practices in ephemeral and intermittent drains on hydrologic function in small-scale headwaters. A 30 ha watershed located approximately 8 miles west of Eupora in Webster County, MS has been continuously monitored for water table elevation, precipitation intensity and duration, in-stream TSS, and chemical composition of water and particulates. Data were used to elucidate the transport and source/sink behavior of sediment, and dissolved and particulate forms of organic matter, in the form of nitrogen (N) and organic carbon (OC), over a broad range of hydrographic conditions. Results indicate that particulates in perennial and ephemeral-intermittent stream segments are derived from surface mineral soil horizons as a result of downcutting. The source of water in the perennial stream is dominated by ephemeral stream contributions rather than groundwater during dry periods. During the wet winter months perennial streamwater chemically resembles groundwater whereas ephemeral-perennial segments chemically resemble canopy throughfall waters. Ephemeral drains are significant contributors to downstream perennial streams, especially during dry periods; therefore it is important to consider ephemeral basins within an overall basin management plan.
Mississippi Embayment National Water-Quality Assessment - Cycle II: the Second Decade
Year: 2011 Authors: Smoot J.L., Coupe R.H.
In 2001, the second decade of the U.S. Geological Survey’s National Water-Quality Assessment (NAWQA) Program began. The program has been redesigned, and the second decade is referred to as Cycle II. The number of study units has been reduced from 60 to 42, and each study unit will be revisited in three groups of 14 on a rotational schedule. In 2004, the Mississippi Embayment NAWQA will begin its second decade of the NAWQA Program. Similar to Cycle I, each group will be intensively studied for three years, followed by six years of low-intensity assessment. The primary emphasis of Cycle II (2001 - 2011) is to assess long-tenn trends in water quality and to improve our understanding of the factors and processes that govern water quality. An additional emphasis is to fill critical gaps remaining in the status assessment, the main focus of Cycle I (1991 - 2001).