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Streamflow -- Forecasting, Hydrologic models, Uncertainty -- Mathematical models


The impacts of climate change on the seasonality of extremes i.e. both high and low flows in the Columbia River basin were analyzed using three seasonality indices, namely the seasonality ratio (SR), weighted mean occurrence day (WMOD) and weighted persistence (WP). These indices reflect the streamflow regime, timing and variability in timing of extreme events respectively. The three indices were estimated from: (1) observed streamflow; (2) simulated streamflow by the VIC model using simulated inputs from ten combinations of bias corrected and downscaled CMIP5 inputs for the current climate (1979–2005); (3) simulated streamflow using simulated inputs from ten combinations of CMIP5 inputs for the future climate (2040–2080) including two different pathways (RCP4.5 and RCP8.5). The hydrological model was calibrated at 1/16 latitude-longitude resolution and the simulated streamflow was routed to the subbasin outlets of interest. These three cases are compared to assess the effects of forcing by different climate models and different pathways on the three indices. The preliminary results showed significant differences between three cases indicating a shift in streamflow regime and timing of extreme events such as high and low flows in the Columbia River Basin. The results will help to understand the effects of climate change on three important seasonality properties: regime, timing and persistence and associated errors.


Presented at the 5th Annual Pacific Northwest Climate Science Conference, At Seattle, WA



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