Abstract

Hydrogeology of the Central Delta (East-Central Sunflower County and West-Central Leflore County)

Author(s): Byrd, C.

For the last several years there has been growing concern regarding the declining water levels in Mississippi River Valley alluvial aquifer (MRVA) in the central Delta. Analysis of water levels alone does not answer the question of how much water is actually remaining in the aquifer. The only way to determine this is to know where the base of the aquifer is in relation to the water level at any one site. Therefore, in the summer of 2004 staff of Mississippi Department of Environmental Quality’s Office of Land and Water Resources (OLWR) began a drilling program to gather this type of information.

Twice each year, staff of the Yazoo-Mississippi Delta Joint Water Management District (YMD) collects water level data from wells screened in the MRVA throughout the entire Delta. Most of the drill sites for this project have been very near some of these wells. The minimum depth drilled at all the sites has been 300 feet. This depth allows not only the entire thickness of the MRVA to be penetrated, but a portion of the underlying formation, as well. Data collected from the water level measurements and drilling enables changes in the saturated thickness of the aquifer at each of these MRVA well sites to be monitored through time.

Throughout the Delta, the surface of the formation(s) underlying the MRVA is an erosional surface; therefore, the contact between the two is an unconformity, resulting in an extremely variable MRVA thickness. Most publications report that the average thickness is approximately 135 to 140 feet. In the project area the average depth of the base of the aquifer is 131 feet below ground surface, with the range of depth between 90 and 166 feet. The water level in the MRVA is approximately 50 feet below ground surface. As most irrigation / catfish culture wells have 40 feet of screen, the most serious scenario is where these wells are screened where the MRVA base is less than 100 feet below ground surface. At these sites, the static water level is either only a very few feet above the top of the well screen or at the top of the screen; and during periods of pumping, the water level is below the top of the screen.

Continued investigation of the geology is an important key to understanding the hydrology of the alluvial aquifer in this area. A better understanding of how this aquifer system works will allow officials to properly and effectively manage this tremendous resource.







 

Technical Presentations

  • Delta Water Quality
  • Delta Water and Agriculture
  • Wetlands
  • Water Quality
  • Sediments
  • Non-Point
  • Management and Sustainability
  • Wood Treatment
  • Modeling
  • Soil and Water Treatment

Workshops

Responsible Site Design: Implementing Innovative Stormwater Management Strategies

The primary goal of the workshop is to create a dynamic learning experience that examines the role of stormwater management in the built environment. The workshop will focus on integrating ecologically sound water management approaches into site design. After the workshop, attendees will be familiar with the following concepts and technical issues:

  • Knowledge of the stormwater treatment chain
  • Knowledge of the impact of land use codes on stormwater management
  • Application of a design process that mitigates the effects of stormwater on-site
  • Knowledge of the relationship between land use codes and design for innovative stormwater management

Information

For information contact:
Jessie Schmidt
MWRRI
Box 9680
Mississippi State, MS 39762
662-325-3295
jschmidt@cfr.msstate.edu