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Title: Identification of recharge zones in the lower Mississippi River alluvial aquifer using high-resolution precipitation estimates

Author
item DYER, JAMIE - Mississippi State University
item MERCER, ANDREW - Mississippi State University
item Rigby Jr, James
item GRIMES, ALEXANDRIA - Mississippi State University

Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2015
Publication Date: 7/26/2015
Publication URL: http://handle.nal.usda.gov/10113/62696
Citation: Dyer, J., Mercer, A., Rigby Jr, J.R., Grimes, A. 2015. Identification of recharge zones in the lower Mississippi River alluvial aquifer using high-resolution precipitation estimates. Journal of Hydrology. 531:360-369.

Interpretive Summary: Water resources in the lower Mississippi River alluvial valley are critical to maintain productivity for irrigated agriculture in the region. The lower Mississippi River alluvial aquifer (LMRAA) has been the primary source for irrigation water to the extent that groundwater levels have been in steady decline. To help develop sustainable groundwater withdrawals it is first necessary to understand the processes governing aquifer replenishment from precipitation and streamflow. It is well known that replenishment of the aquifer does not occur evenly throughout the region, but the spatial distribution of aquifer recharge has remained poorly understood. This work sheds light on the areas in which precipitation most directly reaches the underlying aquifer and finds the Tallahatchie River Basin to be of particular importance. The identification of these areas is the first step to managing them to maintain or enhance the quantity of recharge received to the aquifer and thus made available for irrigation.

Technical Abstract: Water resources in the lower Mississippi River alluvial valley play a critical role in agricultural productivity due to the widespread use of irrigation during the growing season. However, the unknown specifics of surface-atmosphere feedbacks in the region, along with diminishing groundwater availability and the non-sustainable trend in irrigation draws from the alluvial aquifer, makes it difficult for water resource managers to make sound decisions for future water sustainability. As a result, it is crucial to identify spatial and temporal associations between local rainfall patterns and groundwater levels to determine the influence of precipitation on regional aquifer recharge. Specifically, it’s critical to define the recharge zones of the aquifer so that rainfall distribution can be used to assess potential groundwater recovery. This project addresses the issue of defining areas of recharge in the lower Mississippi River alluvial aquifer (LMRAA) through an assessment of historical precipitation variability using high-resolution radar-derived precipitation estimates. A rotated principal component analysis (RPCA) of both groundwater and precipitation data from October through April is used to define locations where aquifer levels show the greatest variability, with a stepwise regression approach used to define areas where rainfall and groundwater levels show the strongest association. Results show that the greatest recharge through direct rainfall is along the Tallahatchie River basin in the northeastern Mississippi Delta, with recharge along the periphery of the LMRAA likely a result of direct water flux from surface hydrologic features.