State Water Resources Research Institute Program

Project Id: 2010MS113B
Title: A Climate-driven model to serve as a predictive tool for management of groundwater use from the Mississippi Delta Shallow Alluvial Aquifer
Project Type: Research
Start Date: 3/01/2010
End Date: 2/28/2011
Congressional District: 3rd
Focus Categories: Climatological Processes, Groundwater, Water Use
Keywords: water resources development, surface and groundwater management
Principal Investigators: Wax, Charles; Pote, Jonathan
Federal Funds: $ 13,779
Non-Federal Matching Funds: $ 92,837
Abstract: The shallow alluvial aquifer in the Mississippi Delta region is heavily used for irrigation of corn, soybeans, and cotton, as well as for rice flooding and filling aquaculture ponds in the prominent catfish industry. Water volume in the aquifer is subject to seasonal declines and annual fluctuations caused by both climatological and crop water use variations from year-to-year. A recently documented annual water level decline in the aquifer is estimated at 500,000 acre-feet. This may represent a worst-case situation in which severe drought combined with consequent increased demand for irrigation, but the pattern documented since measurements were begun shows a consistent annual growing season use greater than winter/spring recharge. Additionally, producers in the region are continually increasing use of irrigation to stabilize crop production as shown by the 453 new and 120 replacement wells drilled between January 2006 and January 2007.

WRRI-sponsored research in 2008 produced a model that evaluates the effects of climatological variability, crop acreage changes, and specific irrigation methods including use of available surface water on consequent variations in the water volume in the aquifer. The model projected that recommended changes in cultural practices, when simulated over a 45-year period into the future with realistic climatic variability, would decrease the consistent drop in water volume in the aquifer. Groups involved in descriptive modeling of the Delta aquifer (MDEQ, USGS, YMD) have shown a preference for this primarily predictive kind of model—"this action produces this result."

The objective of this current research proposal is to further develop and refine the model, making it a tool for management decisions and water conservation throughout the Delta region. Three new objectives are proposed: 1) improve the rainfall-irrigation use relationship by using weekly amounts of rainfall and subsequent weekly irrigation demand through the growing season in place of total growing season rainfall and total seasonal irrigation use; 2) expand the model to represent the entire Delta region; and 3) attempt to determine a more realistic recharge amount for the aquifer each year, thus increasing the legitimacy and accuracy of the model results. Additional climatological and cultural information through 2009 will be incorporated into the model.

The resulting spreadsheet simulation model will be a tool that can be easily used to reflect climatic variability and changes in the cultural practices in the region, then assess the consequences to the water volume in the aquifer through time. The model can be easily modified as new information becomes available, and it will be a tool that is useful in making management decisions that will allow sustainable use of the groundwater resource.

Progress/Completion Report, 2010, PDF

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