Drought Induced Groundwater Loss in and Around Great Salt Lake, Utah, Inferred from 3D GPS Displacements

Zachary M. Young, & Corné W. Kreemer

Submitted August 15, 2019, SCEC Contribution #9855, 2019 SCEC Annual Meeting Poster #199 (PDF)

Poster Image: 
The American Southwest experienced a massive drought between 2011 and 2016 with significant impacts to regional water storage. During this period, the Great Salt Lake (GSL), Utah, lost 1.85 meters of water and Global Positioning System (GPS) data show significant changes in nearby station positions during the same time. Although the GPS data show expected uplift and extension localized on the GSL, preliminary analysis suggests that the observed GSL unloading alone cannot fit the GPS displacements and contributions from groundwater loss surrounding the GSL are likely. This study applies a damped least squares inversion to determine the amount and distribution of groundwater removal consistent with the observed deformation. We test a large number of load distributions over a range of radial load rings and compare both the predicted vertical and horizontal displacements to the data. We estimate the loading coefficients of load rings using the code of D’Urso and Marmo (2013). Three dimensional inversion provides the most realistic distributions, compared to horizontal and vertical only solutions, and yield GSL unloading comparable with the observed 2 meters of water loss (i.e., a volume of 8.7 km^3). The best model implies a radially decreasing mass loss up to 78 km from the edge of the lake at a volume of 50.6 km^3, over twice the volume of the entire GSL. The maximum localized unloading is on the lake itself; however, the contribution of exterior groundwater loss is substantial and greatly improves the fit to the data. In conclusion, we find that there is groundwater loss up to 78 km away from the lake and that the total amount of water loss surrounding the lake is ~6 times that for the lake itself.

Key Words
Drought, GPS,

Citation
Young, Z. M., & Kreemer, C. W. (2019, 08). Drought Induced Groundwater Loss in and Around Great Salt Lake, Utah, Inferred from 3D GPS Displacements. Poster Presentation at 2019 SCEC Annual Meeting.


Related Projects & Working Groups
Stress and Deformation Over Time (SDOT)