Date of Award

5-2023

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Plants, Soils, and Climate

Committee Chair(s)

Lawrence Hipps

Committee

Lawrence Hipps

Committee

Nancy Huntly

Committee

Wei Zhang

Abstract

As a terminal basin lake, the Great Salt Lake (GSL) is known to act as a barometer for low frequency climate variability for the Western United States. As thus, there are naturally occurring large changes to GSL elevation levels that vary on time scales from years to decades. However, amongst these naturally occurring interannual changes there has been a significant declining trend in the elevation levels since a string of anomalous pluvial years in the early 1980s. In the summer of 2022, the Great Salt Lake reached its lowest levels in recorded history, which coincided with a two-decades long regional drought in the Western United States. Though climate forcings have been speculated to be a primary source of this decline, the exact contribution and magnitude of drought impacts on the Great Salt Lake decline have been understudied. Analysis here addresses this question by utilizing observational climate records to establish the relationship between precipitation and drought metrics on the GSL elevation levels since the 1980s, as well as utilizing gridded reanalysis datasets to provide insights into the large-scale atmospheric conditions associated with these regional climate changes. Correlation analysis between streamflow and regional drought metrics reveals that the GSL has become more responsive to drought and less correlated with streamflow. Analyzing atmospheric conditions during the period of record reveals that a strengthened high-pressure system, associated with an intensified upper-level ridging pattern since 1980, has resulted in this pattern of increased aridity. Finally, the future of drought in the GSL watershed is analyzed using a suite of CMIP5 downscaled climate model outputs under two future warming scenarios, of which results indicate that the strongest variable associated with recent GSL decline (annual number of days without precipitable moisture) will increase in the future. Given the GSL’s economic and ecological importance, in addition to growing air quality concerns of newly exposed toxic dust from the desiccated lakebed, diagnosing the contributions of regional hydroclimate forcings on the lake's decline is timely. Results from this analysis provides insights into the growing role that drought plays on the GSL’s decline and the likelihood of regional drought patterns to intensify in the future.

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