Modeling climate change effects on water balance, streamflow generation, and permafrost dynamics in the Nelson Churchill River Basin: a HYPE model approach

Climate change has been a strong driving force impacting the distribution of global water resources over the past few decades, especially in cold regions at high latitudes. Hydrological models are essential to analyse complex changing cold region’s processes, such as permafrost, seasonally frozen soil, and snow cover, which are prevalent across much of Canada and the pan-Arctic basins. Here, we utilize the Hydrological Predictions for the Environment (HYPE) model with seven discretized vertical soil layers to assess climate change response to different water balance portioning components and permafrost extent. The study also explores seasonal and interannual shifts, examining the implications of model uncertainty associated with streamflow generation for the Nelson Churchill River Basin (NCRB). The calibrated HYPE model is run with a suite of fourteen GCMs and two RCPs (RCP 4.5 and RCP 8.5) scenarios representing 87% of the variability of 154 climate scenarios to discern the relationship between climate projections and water balance components. Increasing precipitation and temperature are anticipated in the future, but reduced, or balanced runoff is projected due to the dominant impact of rising temperature on evapotranspiration from thawing soil layers. Under an extreme scenario (RCP 8.5) 82% reduction in permafrost degradation is projected by the mid-future period (2050s). In this study, the future projections of streamflow, soil moisture, permafrost projection, and interrelationships of water balance processes at a continental scale are presented to aid in large-scale planning and implementation of sustainable development principles and guidelines for decision-making in the NCRB.