Validation of Meteorological Parameters From Global Circulation Models Used to Drive Future Flow Projections of the Fraser River in British Columbia, Canada (PAP014999)

Código

PAP014999

Autores

Daniel Betancourt, Paul Whitfield, Ronald Stewart

Tema

Floods in a changing climate

Resumo

Large scale flooding along the Fraser River in British Columbia, Canada, as occurred in 1948 and 1972, produced considerable economic and societal impacts on the region. Current model projections indicate the potential for a greater occurrence and magnitude of hydrometeorological extremes, fueled by higher moisture availability and potential changes in storm tracks and cyclone intensity. Any such trends will play a large role in modulating the future occurrences of catastrophic flood events including those along the Fraser River. Several studies have used downscaled data from coupled Global Circulation Models (GCMs) to drive projections of flow rates for the future climate in the Fraser basin. In general, findings reveal a trend for increased total annual discharge (due mainly to increased winter precipitation), but a reduced and earlier annual peak flow. However, given the potential for increased cold season precipitation and available moisture, some uncertainty exists in future trends of the largest flooding events (which are dependent on a complex interaction of key hydrometeorological variables). In this study, a validation of GCM data from the Coupled Model Intercomparison Project 5 (CMIP5) will be conducted for mid to upper range representative concentration pathways. Daily temperature and precipitation data for selected locations in the Fraser basin (representative of different regions and sub-basins) will be compared to historical observations using empirically derived cumulative distribution functions and quantile to quantile plotting. Particular attention will be paid to the heaviest precipitation events through the application of extreme value analysis. Model performance will be assessed by utilizing an adjustment factor calculated for different time slices throughout the base period simulation. These analyses will provide insight into the spatial and temporal evolution of GCM performance for parameters used to drive hydrologic models of the future climate. Such information is necessary in order to express a degree of confidence in flow projections, and to provide a clearer picture of the potential for future catastrophic events in the Fraser basin.