Conjunctive Management for Groundwater-Surface Water Resources: Numerical Modeling and Potential Assessment of Managed Aquifer Recharge (MAR) at Lower Rio Grande Valley in South Texas
Texas is well known to frequent floods and droughts, and yet has mounting concerns in very imbalanced water availability and water demands from growth in population and economical activities. Capturing and storing water is essential to long-term and climate-smart management of the “already-scarce” water resources. This study aimed to apply numerical modeling to evaluate potentials and impacts of Managed Aquifer Recharge (MAR) to regional groundwater systems in the Lower Rio Grande Valley. Using Visual MODFLOW Flex 3D package, different scenarios were simulated for groundwater flow patterns and storage capacities. Water injections tested ranged between 7.30x105 ft3 to 3.65x109 ft3 , which were comparable to existing ASR capacities in Texas. This study examined flow patterns and water table changes at one selected MAR site with injected water volume equivalent to 3~5% of flood water from Hurricane Hanna (major flood event in LRGV). Giving current assumptions and limited scenarios ran, study results showed that MAR injections had minimal impacts to regional coastal aquifers. LRGV are suitable for MAR using treated water or when there is surplus water, i.e., water from flooding as alternative mitigations. More studies such as data and simulations are needed to better plan and build water resilience
