WEST-WIDE CLIMATE RISK ASSESSMENTS: BIAS-CORRECTED AND SPATIALLY DOWNSCALED SURFACE WATER PROJECTIONS

摘要

Public Law 111-11, Subtitle F (SECURE Water Act), section (§) 9503 authorizes the U.S. Department of Interior's Bureau of Reclamation (Reclamation) to assess climate change risks for water and environmental resources in "major Reclamation river basins." Section 9503 also includes the authorities to evaluate potential climate change impacts on water resource management and development of strategies to either mitigate or adapt to impacts. This paper provides an overview of the analysis that was conducted as part of the West-Wide Climate Risk Assessments (WWCRA) in the eight major Reclamation river basins including the Colorado, Columbia, Klamath, Missouri, Rio Grande, Sacramento, San Joaquin and Truckee. The analysis included translating bias corrected and spatially downscaled (BCSD) climate projections to hydrologic projections for these eight basins and characterizing hydroclimate impacts in terms of changes in runoff volumes and timing, and changes to precipitation, temperature and snowpack (measured using snow water equivalent or SWE) for three look ahead decades, 2020s, 2050s and 2070s from the 1990s. Overall it was found that precipitation distribution varies across basins, but temperature shows a persistent increasing trend, decrease in April 1st SWE, an increasing trend in winter season runoff, and decreasing trend in spring-summer season runoff. Also, all the data used in the analysis is being made available through a web service at the Lawrence Livermore National Laboratory's Green DataOasis facility.