An Overview of the Columbia Basin Climate Change Scenarios Project: Approach, Methods, and Summary of Key Results

Abstract

The Columbia Basin Climate Change Scenarios Project (CBCCSP) was conceived as a comprehensive hydrologic database to support climate change planning, impacts assessment, and adaptation in the Pacific Northwest (PNW) by a diverse user community with varying technical capacity over a wide range of spatial scales. The study has constructed a state-of-the-art, end-to-end data processing sequence from "raw" climate model output to a suite of hydrologic modelling products that are served to the user community from a web-accessible database. A calibrated 1/16 degree latitude-longitude resolution implementation of the VIC hydrologic model over the Columbia River basin was used to produce historical simulations and 77 future hydrologic projections associated with three different statistical downscaling methods and three future time periods (2020s, 2040s, and 2080s). Key products from the study include summary data for about 300 river locations in the PNW and monthly Geographic Information System products for 21 hydrologic variables over the entire study domain. Results from the study show profound changes in spring snowpack and fundamental shifts from snow and mixed-rain-and-snow to rain-dominant behaviour across most of the domain. Associated shifts in streamflow timing from spring and summer to winter are also evident in basins with significant snow accumulation in winter (for the current climate). Potential evapotranspiration increases over most of the PNW in summer because of rising temperatures; however, actual evapotranspiration is reduced in all but a few areas of the domain because evapotranspiration is mostly water limited in summer, and summer precipitation decreases in the simulations. Simulated widespread increases in soil moisture recharge in fall and winter in areas with significant snow accumulation in winter (for the current climate) support hypotheses of increased landslide risk and sediment transport in winter in the future. Simulations of floods and extreme low flows increase in intensity for most of the river sites included in the study. The largest increases in flooding are in mixed-rain-and-snow basins whose current mid-winter temperatures are within a few degrees of freezing. The CBCCSP database has been a valuable public resource that has dramatically reduced costs in a number of high-visibility studies in the PNW and western United States focused on technical coordination and planning. « neige ou pluie et neige mêlées » vers « principalement pluie » dans presque tout le domaine. Des déplacements correspondants des caractéristiques d'écoulement fluvial du printemps et de l'été vers l'hiver sont également évi-dents dans les bassins où l'accumulation de neige est importante en hiver (sous le climat actuel). L'évapotranspira-tion potentielle augmente dans la majeure partie de la région du Pacifique et du Nord-Ouest en été à cause des températures plus élevées; cependant, l'évaporation réelle est réduite dans presque tous les secteurs du domaine parce que l'évapotranspiration est principaleme...

Future Climate Change Impacts on Streamflows of Two Main West Africa River Basins: Senegal and Gambia

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A hydrogeologic framework for characterizing summer streamflow sensitivity to climate warming in the Pacific Northwest, USA

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Effects of Climate Change on Extreme Low-Flows in Small Lowland Tributaries in the Skagit River Basin

“…For the largest basins, the lowest monthly flows generally occur in August/ September, before the end of the WY, whereas in the smaller basins, occurrences frequently span across into the new WY. Simulated historical and projected future monthly flows for the Samish River (Gage: 12201500) (Figure 5a) show the characteristic shift in streamflow timing that accompanies warmer air temperatures and shifts in the seasonality of precipitation in many other PNW hydrologic studies (Snover et al 2003, Hamlet et al 2013. All but one of the 2040s ensemble members are above the historical baselines in cool season (Oct-March) and below historical baselines in warm season (May-Sept) (Figure 5b).…”

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