Senior Geologist
Utah Geological Survey
Bio:
Paul Inkenbrandt has been a Senior Geologist and hydrogeologist with the Utah Geological Survey since September 2009. He has a M.S. in geology from Utah State University and a B.S. in geology from the University of Southern Indiana. Paul is experienced in database management, geographic information systems, and Python scripting. He also teaches introductory geology at Salt Lake Community College. In his personal time, he is actively involved in the Utah Geological Association, maintains his vegetable garden, and spends time with his family.
Title: Groundwater Conditions around Great Salt Lake
Abstract: (by Paul Inkenbrandt and Stefan Kirby)
We compiled groundwater level data, and potentiometric contour maps for every watershed immediately adjacent to Great Salt Lake. The groundwater level data points we compiled include U.S. Geological Survey National Water Information System groundwater levels, Utah Division of Water Rights well drilling information, National Hydrography Dataset spring locations, and borehole and piezometer data from wetlands studies. When multiple measurements were recorded at a well, the median groundwater elevation was used as the representative groundwater elevation for that well. Using the compiled datasets, we interpolated groundwater elevations across the region. We used empirical Bayesian kriging with regression prediction, a modified geostatistical technique to interpolate the data.
The resulting surface represents the regional potentiometric surface map around Great Salt Lake, and a more detailed examination of the East Shore area, where water level data density is highest. The groundwater gradient, and subsequent groundwater flow, are highest along the East Shore region of Great Salt Lake. Localized cones of depression exist in the East Shore area. Groundwater level changes coincide with changes in Great Salt Lake elevation. Many of the contributing groundwater basins show a loss in groundwater over time, coincident with drought and increased groundwater pumping. Estimates of total groundwater contribution to the lake vary between 7 and 136 thousand acre-feet per year. The new potentiometric surface allows for estimates of groundwater influx using a Darcy flux method to calculate total groundwater inflow to Great Salt Lake. Our flux estimate was discretized and used with a previous estimate of groundwater TDS to estimate a total annual solute input from groundwater.
Modeling, potentiometric surface contours, chemistry data, and salt lake analogs indicate that convective groundwater flow driven by salinity gradients is likely occurring near the margin of Great Salt Lake. Monitoring efforts near Pilot Valley, west of Great Salt Lake, show evidence of groundwater convection. Groundwater level decline can lead to issues like encroachment of saline water on relatively fresh groundwater.