Characterizing the Decline of the Great Salt Lake during the Current Exceptional Drought in Utah using MODIS Satellite Data Products
Abstract
The megadrought that is afflicting much of the western U.S. is especially dramatic in the state of Utah, with almost 100 percent of the state experiencing either Extreme Drought or Exceptional Drought (https://droughtmonitor.unl.edu/) (early August 2021). Drought is negatively affecting the Great Salt Lake (GSL) which is the largest terminal lake in the Western Hemisphere. A terminal lake loses water almost exclusively through evaporation. Since the middle of the 19th Century, the volume and area of the GSL decreased by ~48 percent and ~50 percent, respectively, mainly because of upstream diversions of water for agricultural and other uses, but also because of climate warming (https://doi.org/10.1038/ngeo3052; https://doi.org/10.1016/j.rse.2020.112106). The GSL surface-water elevation is at or near the lowest ever recorded, at ~1277.4 m (https://waterdata.usgs.gov/ut/nwis/current?type=lake) and will likely get lower later this year. Time-series of data products from the MODerate resolution Imaging Spectroradiometer (MODIS), beginning in 2000, provide an excellent record of conditions associated with the drought and its effect on the GSL. Surface-water elevations of reservoirs in Utah, e.g., Lake Powell can be tracked using the MODIS water-reservoir data product, MOD28C2 (https://doi.org/10.3390/rs13040565). The mean number of days of snow cover in the GSL basin decreased by 18 days, and snow melted ~9.5 days earlier since Water Year (WY) 2001 according to the MODIS snow-cover data product, MOD10A1F (https://modis-land.gsfc.nasa.gov/snow.html) and associated snowmelt-timing maps (https://daac.ornl.gov/CLIMATE/guides/Snowmelt_timing_maps_V2.html). Daytime (MYD21A1D) and nighttime (MYD21A1N) land-surface temperatures (https://modis- land.gsfc.nasa.gov/temp21.html) show statistically significant (=0.05) increases of 2.07C and 1.50C, respectively (WY 2003-2020) in much of the GSL basin, and monthly mean air temperature data from the Salt Lake City International airport show an increase of ~1.93C since October 2001. Additionally, the mean rate of evapotranspiration in the basin, measured using the MOD16A3 data product (https://modis-land.gsfc.nasa.gov/ET.html), is ~2.7 mm/yr (2000-2020), with trends in much of the basin being statistically significant ( = 0.05).
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.H52G..08H