Evaluation of Future Streamflow Patterns in Lake Simcoe Subbasins Based on Ensembles of Statistical Downscaling

Abstract

Future streamflow patterns of three subbasins, i.e., East Holland, Beaver, and Pefferlaw River basins, located in the upstream of Lake Simcoe of Canada are assessed for 2021–2099. The individual set of parameters of a conceptual hydrological model, HBV (Hydrologiska Byråns Vattenbalansavdelning)-light, are first calibrated for these three subbasins. The calibrated model was validated and further used to estimate the future streamflow driven by statistically downscaled projected precipitation and air temperature from the Pacific Climate Impacts Consortium under Representative Concentration Pathways 8.5 and 4.5 scenarios. The uncertainty of annual streamflow, hydrograph, flow duration curve (FDC), and flood frequency were evaluated. The results reveal that the annual streamflows of the Beaver and Pefferlaw River Basins (PRB) are projected to slightly increase in 2020–2099 while the annual streamflows of the East Holland River Basin (EHRB) are expected to be similar in 2020–2099. The monthly streamflow in winter is projected to increase but to decrease in spring across three subbasins. Based on the projected FDCs, daily streamflow of EHRB and PRB will likely increase by 2070–2099.