MODFLOW-NWT model used in Simulation of Groundwater Flow, and Analysis of Projected Water Use for the Washita River Alluvial Aquifer, Western Oklahoma

The U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, constructed a finite-difference numerical groundwater-flow model of the Washita River alluvial aquifer using MODFLOW-2005 with the Newton formulation solver (MODFLOW-NWT). The 1973 Oklahoma Water Law (82 OK Stat § 82-1020.5) requires the Oklahoma Water Resources Board to conduct hydrologic investigations of the State's aquifers to support a determination of the maximum annual yield (MAY) for each groundwater basin. A permanent MAY and EPS have not been established for the Washita River alluvial aquifer; thus, the U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, conducted calibration and simulations of a numerical groundwater-flow [...]