Groundwater Availability Model for the northern portion of the Queen City, Sparta and Carrizo-Wilcox aquifers Basin, Texas
GSI led a team to update the northern portion of the Queen City, Sparta, and Carrizo-Wilcox aquifer system groundwater availability model (GAM) to provide a tool for predicting future groundwater availability and assessing water management strategies. The GAM update focuses on providing a better representation of the hydrostratigraphy to better simulate the complicated aquifer connections and the confined and unconfined aquifer conditions in outcrop areas. A Leapfrog geologic model was translated to a numerical model using unstructured grids in MODFLOW 6. MODFLOW 6 was used to simulate complex geologic features, such as faulting, outcrop and down-dip areas, cross-layer connections, islands, and pinch-out layers.
The model is calibrated to 34 years of hydrogeologic data and groundwater / surface-water interaction flux estimates (1980 through 2013) using annual stress periods for recharge and pumping. Sensitivity of the model to model parameters and model stresses are being examined and correlations between parameters and boundary stresses are evaluated.