MODFLOW-NWT models and calibration files for the Mississippi Alluvial Plain, USA

The existing three-dimensional groundwater flow model (MODFLOW-2005) of the Mississippi Embayment Regional Aquifer system (MERAS), South-Central United States, was updated with: 1) higher stream density; 2) more spatially refined recharge; 3) better estimates of water use; 4) more recent time period simulated; 5) more realistic storage conceptualization; and 6) more robust handling of dry nodes through use of MODFLOW-NWT. For this study, the MODFLOW-NWT groundwater flow model was used to evaluate four parameter estimation algorithms with lower computational burdens. This work was performed to update the previous version of the MERAS groundwater flow model for decision making in the Mississippi Alluvial Plain (MAP), USA.This USGS data release contains all of the input and output to run the model simulations described in the associated Hunt et al. (2021) journal article (https://doi.org/10.1111/gwat.13106).