Enhanced warming and amplified hydrologic response in a sub-arctic mountainous river basin

The magnitude and extent of snowpack and permafrost in the high-latitude region are intrinsically related to temperature and precipitation, and enhanced warming and amplified moisture fluxes to the region could lead to significant changes in the hydrologic regime. In this study, we evaluated potential future hydrologic changes for the Liard River basin in Canada, which is a large (277,100 km2) mountainous river basin in the sub-arctic, draining into the Mackenzie River. Future projections indicate significant increases in the annual and seasonal temperature and precipitation in the basin. We employed the variable infiltration capacity hydrologic model with the future climate inputs derived from the CMIP5 GCMs, downscaled using a multivariate bias-correction method that explicitly accounts for the inter-variable dependence between precipitation and temperature. Preliminary results indicate a shortened snow cover duration, a declining trend in the April 1 snow water equivalent and a shift to earlier snowmelt driven peak discharge. Despite the decline in the magnitude and duration of snowpack, peak discharge is projected to increase attributable to the enhanced spring/early summer rainfall. Additionally, significant increases in the autumn, winter, spring as well as annual flows are projected while the summer flow is projected to decline. This suggests changing interactions of the temperature, precipitation, snow and streamflow in the basin.