Effects of Snow Water Equivalent Products on Streamflow Volume Forecasts and Climate in the Colorado River Basin

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Date
21-May
Keywords
Authors
Butler, Zachariah J.
Description
The Colorado River Basin (CRB) provides water resources to millions of people in the western United States and northern Mexico. Efficient and effective water management is needed to sustain the economy, human life, and the environment. The water cycle in the CRB is dominated by high elevation snowpack, seasonal (April through July) snowmelt-driven runoff, and is critical for hydrologic forecasters and water managers. Anthropogenic climate change combined with natural variability are warming and drying the CRB, which has put new stresses on the water cycle. The Colorado Basin River Forecast Center (CBRFC) forecasts streamflow within the CRB to provide actionable decision support tools and information to resource managers within the basin. To properly forecast and model the hydrology in the region, frequent spectral and temporal data is needed. The CBRFC currently uses the SNOW-17 accumulation and ablation model to develop and forecast mean areal snow water equivalent (SWE) values. A relatively new SWE dataset is available from the University of Arizona, the Snow Water Artificial Neural Network (SWANN). With help from the CBRFC, SWANN and SNOW-17 SWE datasets are run through the CBRFC's framework to model spring streamflow volumes in headwater basins throughout the CRB from 1982-2015. Observed streamflow volumes are compared with model results to determine that SNOW-17 proves to be more accurate, although the two SWE datasets are statistically similar. The two SWE datasets are used with observed streamflow volumes to show declines throughout the CRB. Additional in-situ datasets are used to confirm warming and drying through observed temperature, precipitation, and SWE through the year 2020. Model SWE and observed in-situ data show warming and drying are affected more at higher elevations and lower latitudes. Minimum temperatures are shown to be warming more than maximum temperatures. Finally, upper-level atmospheric reanalysis data of 500 hPa geopotential heights and 300 hPa scalar winds are analyzed to show and confirm the warming and drying trends observed in the CRB. This study illuminates the uses of SWE datasets combined with hydrologic and meteorologic data to relate climate changes impacts on the region, which the CBRFC can use to inform the public and stakeholders. Results from this study are supported by past documentation of climate trends in the CRB which are critical to properly manage and understand with a growing need and concern for water management.
Identifier
psu-etd-213