GSFLOW model simulations used to evaluate the impact of irrigated agriculture on surface water - groundwater interaction

Watershed-scale coupled surface water (SW) – groundwater (GW) flow modeling was used to examine changes in streamflow and SW – GW interaction resulting from irrigation and associated SW diversions and GW pumping. The U.S. Geological Survey (USGS) model GSFLOW, an integration of the USGS Precipitation-Runoff Modeling System (PRMS) and the Modular Ground-Water Flow Model (MODFLOW), was utilized for this effort. Processes represented in the model include daily rain, snowfall, snowmelt, streamflow, surface runoff, interflow, infiltration, soil-zone evapotranspiration (ET), and subsurface unsaturated and saturated GW flow and ET. The upper Smith River watershed, an important agricultural and recreational fishing area in west-central Montana, [...]