Twenty-first century discharge and sediment yield predictions in a small high Arctic watershed

Abstract

Discharge and suspended sediment flux are predicted for the 21st century for the 8 km 2 West River, Cape Bounty, Melville Island in the Canadian High Arctic. Discharge predictions are made using a distributed hydrologic model, and sediment yields are predicted using a rating curve based on monitored relationships between discharge and suspended sediment concentration. Models were forced using statistically downscaled air temperature and precipitation from the A1b and A2 scenarios from the global climate model CGCM3. Under the A2 scenario, total seasonal runoff is expected to double by 2100, daily maximum discharge rates will double, and the melt season will increase in length by 30 days, mostly in autumn. Sediment yield increases will be much more extreme, and are expected to increase by 100 to 600%, but these are almost certainly minimum estimates. Variability between and within global climate models is assessed for the grid cell closest to Cape Bounty, and variability within CGCM3 is assessed by examining data from five of its runs. Intra-model variability is relatively small, but inter-model variability is large. The impact of this variability is minimized, and the applicability of results is broadened by assessing relationships between weather variables, hydrologic variables, and sediment yield for multiple model runs.