Application of the HBV model for the future projections of water levels using dynamically downscaled global climate model data

The Hydrologiska Byråns Vattenbalansavdelning (HBV) model was used to project the future water levels of the Mackenzie River at selected stations. The Weather Research and Forecasting (WRF) model was utilized to dynamically downscale the Global Climate Model data. The calibrated and validated HBV model was run with the WRF downscaled CanESM2 data and with the PCIC data for the historical (1979–2005) period, and then compared with the observed flow data at the Fort Simpson station and the Arctic Red River station. The simulated streamflow showed a good correlation with the observed streamflow (R value was around 0.85). The HBV model was then forced with the bias-corrected WRF downscaled daily rainfall and temperature data driven by the CanESM2 RCP 4.5 and RCP 8.5 climate scenarios to simulate the future streamflow for the 2041– 2070 period. Rating curves were used to convert streamflow to water levels. At the Fort Simpson station, mean flow was projected to decrease by about 5% under both RCP 4.5 and RCP 8.5 scenarios, whereas the peak flow was likely to reduce by about 12 and 9% for RCP 4.5 and RCP 8.5 scenarios, respectively, in the 2050s. The projected lower water levels could affect the navigability and the northern ferry operations of the Mackenzie River.