Modelling spatial and temporal variability of hydrologic impacts of climate change in the Fraser River basin, British Columbia, Canada

摘要

This paper presents a modelling study on the spatial and temporal variability of climate-induced hydrologic changes in the FrasernRiver basin, British Columbia, Canada. This large basin presents a unique modelling case due to its physiographic heterogeneitynand the potentially large implications of changes to its hydrologic regime. The macro-scale Variable Infiltration Capacity (VIC)nhydrologic model was employed to simulate 30-year baseline (1970s) and future (2050s) hydrologic regimes based on climatenforcings derived from eight global climate models (GCMs) runs under three emissions scenarios (B1, A1B and A2). BiasnCorrected Spatial Disaggregation was used to statistically downscale GCM outputs to the resolution of the VIC model (1/16u0001).nThe modelled future scenarios for the 11 sub-basins and three regions (eastern mountains, central plateau and coastal mountains)nof the FRB exhibit spatially varied responses, such as, shifts from snow-dominant to hybrid regime in the eastern and coastalnmountains and hybrid to rain-dominant regime in the central plateau region. The analysis of temporal changes illustratednconsiderable uncertainties in the projections obtained from an ensemble of GCMs and emission scenarios. However, direction ofnchanges obtained from the GCM ensembles and emissions scenarios are consistent amongst one another. The most significantntemporal changes could include earlier onsets of snowmelt-driven peak discharge, increased winter and spring runoff andndecreased summer runoff. The projected winter runoff increases and summer decreases are more pronounced in the centralnplateau region. The results also revealed increases in the total annual discharge and decreases in the 30-year mean of the peaknannual discharge. Such climate-induced changes could have implications for water resources management in the region. Thenspatially and temporally varied hydro-climatic projections and their range of projections can be used for local-scale adaptation innthis important water resource system for British Columbia