| Description |
Water resources face increasing stress from climate change that may not result in uniform vulnerability to hydrologic response across all watersheds. I compare over 100 years of historical hydrologic data from seven seasonally snow-dominated watersheds near Salt Lake City, Utah to identify how watershed landscapes interact with climate variability to control hydrologic partitioning. Mean annual precipitation (790 mm - 1290 mm) and temperature (3.3°C - 6.9°C) differ primarily as a function of watershed elevation. Mean annual streamflow, normalized by watershed area (150 mm to 820 mm), differs primarily as a function of mean precipitation. Precipitation and temperature exhibit similar interannual variability. However, due to the unique landscape characteristics of the watersheds, streamflow values exhibit large differences in interannual variability between the watersheds. Interannual variability in precipitation explains between 46%-73% of the annual variability in streamflow. Surprisingly, the remaining variability does not correlate to annual or seasonal temperature. Instead, interannual variability in subsurface storage and snowmelt processes further reduce the uncertainty in annual streamflow. Together, precipitation, storage, and snowmelt explain nearly all (96%-98%) of the annual variability in streamflow. Storage accounts for a legacy effect of past climate on streamflow that varies between watersheds based on subsurface characteristics. The rate of snowmelt affects the snowpack's infiltration efficiency and is primarily controlled by solar radiation, varying between watersheds based on hillslope shading characteristics. These controls on hydrologic partitioning indicate that subsurface and topographic characteristics control the differential sensitivity of watersheds to changes in climate. |
