Hydrologic impacts of ensemble-RCM-projected climate changes in the Athabasca River Basin, Canada

Abstract

In this study, the Providing Regional Climates for Impacts Studies (PRECIS) and the Regional ClimateModel (RegCM) system as well as theVariable InfiltrationCapacity (VIC)macroscale hydrologicmodel were integrated into a general framework to investigate impacts of future climates on the hydrologic regime of the Athabasca River basin. Regional climate models (RCMs) including PRECIS and RegCM were used to develop ensemble high-resolution climate projections for 1979-2099. RCMs were driven by the boundary conditions from the Hadley Centre Global Environment Model, version 2 with Earth system configurations (HadGEM2-ES); the SecondGeneration Canadian Earth SystemModel (CanESM2); and the Geophysical FluidDynamics Laboratory Earth System Model with MOM (GFDL-ESM2M) under the representative concentration pathways (RCPs). The ensemble climate simulations were validated through comparison with observations for 1984-2003. The RCMs project increases in temperature, precipitation, and wind speed under RCPs across most of the Athabasca River basin.Meanwhile, VICwas calibrated using the University of Arizona ShuffledComplex Evolutionmethod (SCE-UA). The performance of the VIC model in replicating the characteristics of the observed streamflow was validated for 1994-2003. Changes in runoff and streamflowunderRCPs were then simulated by the validatedVIC model. The validation results demonstrate that the ensemble-RCM-driven VIC model can effectively reproduce historical climatological and hydrological patterns in the AthabascaRiver basin. The ensemble-RCM-drivenVIC model shows that monthly streamflow is projected to increase in the 2050s and 2080s under RCPs, with notably higher flows expected in the spring for the 2080s. This will have substantial impacts on water balance on the AthabascaRiver basin, thus affecting the surrounding industry and ecosystems. The developed framework can be applied to other regions for exploration of hydrologic impacts under climate change.