Abstract

Recharge in the Water Budget of the Delta’s Alluvial Aquifer

Author(s): Mason, P.

The Missisippi River Valley Alluvial Aquifer (MRVA) is a highly productive aquifer which supports vast amounts of Delta agriculture and commerce. Maintaining an adequate future water supply requires understanding of the water budget. Stated simply: current water levels + recharge - discharge = future water levels. Focusing on the recharge term in the equation, existing evidence about recharge to the MRVA is reviewed, and current active research is described.

Normal direct recharge by precipitation is extremely restricted in the MRVA because of a widespread impermeable unit just below the soil profile. Direct recharge is, however, active in localized areas, particularly through the conduit of the alluvial fans along the eastern boundary of the Delta plain. An estimated 220 square miles of land surface is covered by fans, with vertical relief ranging from 4 to 66 feet. Drilling reveals much greater thicknesses of alluvial fan deposits occur below the surface, coeval with deposition of the MRVA.

Recharge from streams is also a significant factor in the bluff margin area, where streams cross fan sediments which lie in connection with the MRVA. In summer, many smaller streams can be observed to lose flow and disappear as they traverse fans. Direct discharge measurements of larger streams have recorded every condition as streams cross the fans, from gains on clay dominated fans, to significant losses over sandy materials, suggesting that the variable source geology of the reworked sediment making up each fan tends to control the amount of gain or loss of flow from any given stream to the aquifer.

Efforts are underway to characterize and quantify water heads and pathways along the Bluff Hills boundary for use in a large flow model. These include data collection regarding the size and hydraulic conductivity of the alluvial fans, the role of Yazoo headwater streams and other surface watersheds, and the involvement of the several geologic formations adjacent to the MRVA.







 

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