Interaction Assessment Between Tallahatchie River-Mississippi River Valley Alluvial Aquifer and Low Flow Management

The amount of flux exchange between a river and an aquifer mainly depends on the river stage, groundwater level, and hydraulic properties of the aquifer and river bed material. Typically, river flow during high-flow periods is controlled by surface runoff, but during low-flow periods river flow is often influenced by the river-aquifer flux exchange. The objective of this study is to identify the spatial-temporal variation of interaction between the Tallahatchie River and the Mississippi River Valley alluvial aquifer (MRVAA) in northwest Mississippi, USA, and compute the quantity of flux exchange and effects of river-aquifer exchange on low river flows. For this study, groundwater data collected between 2020 and 2021 in the vicinity of the Tallahatchie River near Shellmound, Mississippi, is used to develop a groundwater-surface water model. During this period, the Tallahatchie River was a perenially losing river because the aquifer water level was below the stage of the river, which is due in part to the long-term depletion of groundwater storage in the MRVAA from intensive agricultural irrigation. In 2018, the United States Geological Survey conducted an airborne electromagnetic study for this area to establish high-resolution subsurface resistivity profiles, which is used for model conceptualization and development. Net seepage will be calculated by subtracting outflows and evaporation loss from inflows. Results of the study will help inform operation and assessment of a managed aquifer recharge facility combining riverbank filtration adjacent to the Tallahatchie River and subsequent transfer of extracted groundwater to an area of greater groundwater depletion and injection in the MRVAA. The United States Department of AgricultureAgricultural Research Service is conducting the aquifer recharge pilot project for supporting a sustainable groundwater-irrigated agroecosystem in the region, and potential impacts during low river flow will be an important determinant of feasibility.