Mississippi River Alluvial Aquifer Groundwater Availability Study

 

Project Sponsors: U.S. Geological Survey, Charles Lamar Family Foundation

Investigator: Frank Tsai (LSU)

Graduate Student: Ramazan Karakullukcu, Jina Yin

Award Length: 2016-2018 (USGS-104B), 2018-2020 (CLFF)

 

Project Summary: The Mississippi River Alluvial Aquifer (MRAA), extend from Louisiana-Arkansas border in the north to central Louisiana in the south, is one of the most-pumped aquifer in Louisiana. The aquifer provide about 390 million gallons of water per day to supply demands ranging from irrigation, public supply, and industrial usages in the region. The MRAA is of high economic importance to the state of Louisiana. However, the aquifer is vulnerable to over-pumping, water table declining, and aquifer salinization. To optimize usage and avoid over-exploitation of the aquifer, a comprehensive and conjunctive modeling of the MRAA is necessary. In this study, a groundwater flow model of MRAA is constructed, following the flowing procedure: (1) a hydrogeological model is constructed using 7,259 well logs along with natural neighbor method, to characterize subsurface hydrogeology of the study area; (2) hydrologic setting of the model is configured by pumping rate of wells and river/stream recharge, which was estimated from a hydrologic model; (3) the model was calibrated using groundwater level data collected by USGS. A groundwater flow model with root-mean-square error of 1.14 m was achieved in this study, which indicate: (1) strong interaction between surface water (Mississippi River and streams) and groundwater (alluvial aquifer); (2) declining trend of groundwater level in recent years, caused by increased pumping for agricultural irrigation in the region; (3) necessity of a conjunctive groundwater model and management strategies to recover groundwater storage and promote sustainable usage of the groundwater resources in the region.