Hydrostratigraphic Modeling of the Lower Mississippi-Gulf Region

A regional hydrostratigraphic model has been developed to provide a common framework for assessing groundwater availability in the Lower Mississippi-Gulf (LMG) region. This modeling effort includes three principal aquifers the Coastal Lowlands and Mississippi Embayment aquifer systems (CLAS and MEAS) and Mississippi River Valley alluvial aquifer (MRVA) in portions of Alabama, Arkansas, Florida, Kentucky, Louisiana, Mississippi, Missouri, and Tennessee (although portions of CLAS and MEAS also occur in Texas, currently it is outside the scope of this study). This integrated three-dimensional hydrostratigraphic model incorporates 16 hydrostratigraphic units to a maximum depth of about 5,800 feet. Developing an integrated hydrostratigraphic model is challenging because of the spatial scale of the study area (approximately 180,000 square miles), non-uniformly in the spatial and vertical distribution of boreholes, presence of various structural features (for example, syncline, unconformities, and faulting), and the need for computational resources. This study adopts the USGS National Hydrogeologic Grid (NHG) with a 1 km resolution as the base model grid. To reduce computation time, the modeling domain is partitioned into subdomains based on the USGS HUC8 watershed boundaries. Geostatistical approach is used to develop stratigraphic surfaces by interpolating hydrostratigraphic horizons from more than 5360 geologic and geophysical logs. A hydrostratigraphic database and the data analytic tools developed in this study will be modularized to allow flexibility to incorporate new data as they come available. This regional hydrostratigraphic model will provide water resource managers and researchers with a common framework for conducting water availability assessments within the LMG region.