Modeling the Hydrology of the Great Salt Lake: What makes the Great Salt Lake go up and down?
The Great Salt Lake is a closed basin lake in which level and volume fluctuate due to differences between inflows and outflows. The only outflow is evaporation, which depends directly on lake area and salinity, both of which depend on lake volume. The lake’s level, volume and area adjust to balance, on average, precipitation and streamflow inflows by evaporation. This presentation will describe the hydrology of the Great Salt Lake, examining the sensitivity of lake volume changes to precipitation, streamflow and evaporation and the interactions among these processes and lake area and salinity related to volume. A statistical model is used to simulate representative realizations of future climate and streamflow inputs. Climate and salinity are used to compute salinity adjusted evaporation from the lake. These then drive a mass balance model of the lake that projects volume, area and salinity and quantifies the sensitivity of the lake to changes in inputs, due to fluctuations in climate as well as development in the watershed, and withdrawals for mineral extraction. Our findings show that variability in lake level and volume are dominated by variability in streamflow inputs and the area dependence of evaporation volume, with smaller sensitivities to precipitation directly on the lake, salinity and withdrawals. These provide a context for understanding future fluctuations in lake level that impact the lake ecosystem, economy and environment.