MODFLOW–6 model of the Shell Valley aquifer, Belcourt, North Dakota, 1980-2022

A MODFLOW-6 groundwater flow model of the Shell Valley aquifer near the Turtle Mountain Band of the Chippewa Indians land area representation in northern North Dakota was constructed to improve the understanding and management of the water-supply resources. The model area included sub-watersheds containing the extent of the Shell Valley aquifer approximately between the towns of St. John, Belcourt, Wolford, Overly, and Dunseith, North Dakota. The model simulated groundwater flow in the Shell Valley aquifer and the adjacent overlying and underlying hydrogeologic units from 1980 through 2022. The data release directories contain ancillary, bin, georef, model, output, and source folders with the necessary executable and input files for the following models: (1) a combined steady-state and transient MODFLOW-6 groundwater flow model; (2) a version of the MODFLOW-6 groundwater flow model used to estimate model water-budget uncertainty; and, (3) a Soil-Water Balance (SWB) model used to estimate spatial and temporal variations of recharge and potential evapotranspiration.