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WSGS Develops Model to Estimate Groundwater Baseflow, Publishes Results
The Wyoming State Geological Survey (WSGS) has published results of a statewide groundwater study after developing a new model to estimate baseflow, a significant component of groundwater recharge.
Groundwater is an important resource across Wyoming. Open File Report 2016-8, “Wyoming State Geological Survey Statewide Groundwater Baseflow Study,” is intended to provide a preliminary approximation of baseflow levels.
The primary objective of the WSGS project was to develop a straight-forward model capable of making reasonable large-scale estimates of baseflow for the state of Wyoming using precipitation data, other readily available environmental data and Geographic Information Systems techniques.
Baseflow is groundwater that discharges directly to stream channels, tributary springs, wetlands, lakes and seeps. It represents an effective measure of total recharge, which is the most difficult component of the groundwater system to measure because most of the process occurs below ground surface.
“The gravity-driven movement of precipitation from the surface to the water table (groundwater recharge) is subject to a series of complex geologic and meteorological properties,” says WSGS hydrogeologist Karl Taboga. “In Wyoming, the recharge process can occur within a few days in moist mountainous regions where soils are thin and bedrock is heavily fractured or may take hundreds of years in semi-arid basins, which have thick impermeable soils and bedrock.”
Baseflows constitute an important water resource first accessed through groundwater wells and then by surface water users. Baseflow represents an interconnection between surface and groundwater resources that is recognized in Wyoming water law and is the subject of increasing U.S. Geological Survey (USGS) research.
“Using established techniques and updated spatial data, the model generates statewide estimates at a scale previously unavailable,” says WSGS natural resource analyst James Stafford.
The WSGS model generated reasonable estimates of baseflow that compare favorably with results obtained from USGS models in selected areas.
“Baseflow estimates from the new WSGS model should prove useful to federal, state and local water managers and to environmental personnel,” says Taboga.
The 16-page report, authored by Taboga and Stafford, details methods used in the study, including geospatial data, evapotranspiration rates, observation-based watershed baseflows and baseflow rates. The study is an open file report and therefore will be supplemented periodically as new information becomes available. It is available as a free download. More information about Wyoming groundwater can be found on the WSGS website.