Name
Simulation of hydrological impact of future changes in climate and glacier cover for Bow River headwater basins in the Canadian Rockies
Description
This study diagnoses the impact of projected changes in climate and glacier cover in Bow and Elbow river headwater basins using the Cold Regions Hydrological Modelling platform. Hydrological models were parameterised from research basin observations, DEMs and remote sensing, then forced with 4-km near-surface meteorology from the Weather Research and Forecasting model for the current climate with current glacier coverage and for an RCP8.5 scenario late 21st C climate with reduced glacier coverage. Under climate change, the Bow River at Banff and Elbow River at Calgary warmed up by 4.7 and 4.5°C and received 12% to 15% more precipitation, with a greater proportion as rainfall. Peak snow accumulation and annual snowmelt volume rose by 3 and 43 mm in Bow River but dropped by 20 and 55 mm in Elbow River. The shorter snowcover periods and warmer, wetter climate resulted in increased evapotranspiration, decreased sublimation and reduced lake levels, soil moisture and groundwater levels in both basins. Mean annual water yield increased by 11% and 18% for the Bow River and Elbow River, and mean annual peak daily discharge increased by 12 m3 s-1 in the Bow River but decreased by 3 m3 s-1 in Elbow River. This shows complex and compensatory hydrological process responses to climate change with lower glacier contribution reducing the impact of higher precipitation in high elevation headwaters and drier soil conditions reducing peak discharges despite greater precipitation in Front Range and foothills headwaters under a warmer climate.