Understanding Flow and Storage between the Wasatch Mountain Block and the Salt Lake Valley using GPS, Satellite Gravity, and Terrestrial Gravity

The water budget of the Great Salt Lake (GSL) relies on surface water and groundwater inflows from snowmelt in the Wasatch Mountain Block (WMB).  Existing estimates of direct groundwater inflows to GSL are essentially derived from water budget residuals (i.e. inflow needed to balance the water budget) and are therefore subject to large uncertainty.  Independent measures of groundwater inflows are needed to verify and improve water budgets and to evaluate the complex interplay between lake water and groundwater.  Groundwater modeling, stream chemistry, streamflow modeling, and stream hydrograph analyses indicate that groundwater inflow (both directly into GSL and into streams within the GSL watershed) have been underestimated.  Recent research has documented that most snowmelt infiltrates soils and recharges groundwater in the WMB before contributing to surface water supplies in the Salt Lake Valley. However, subsurface water storage and its role in water budget calculations remain difficult to quantify based on traditional hydrologic observations.  Geophysical observations (GPS and satellite- and terrestrial-gravity) provide independent constraints on the flow and storage of water mass in the Mountain Block- Valley hydrological system. We demonstrate that geophysics data combined with land surface energy balance models, stream hydrograph data, and snowpack are suited to quantify the amount and time scales of water storage in seasonal snow, soil moisture, groundwater, and surface water storage in reservoirs and the GSL.