Physically based numerical modelling to identify permafrost degradation due to climate change in Northern Manitoba
A critical factor in permafrost degradation is the hydrological processes' changes, which result from free-flowing water, such as soil water or groundwater, and their associated flow paths. Hydrological models calibrated under current climate conditions are less likely to accurately predict the water budget of a catchment under permafrost degradation under future climate conditions. However, such models are used to help manage large watersheds in northern Canada, which are used for hydropower generation, and are essential for strategic planning on the future supply of energy. This research was conducted to understand and identify the potential impact of permafrost thawing on the hydrological regime within the Nelson-Churchill River Basin (NCRB) due to climate change. Numerical models were developed using HYDRUS-1D and Hansson’s module to analyze potential changes in ground temperature resulting from climate change to establish a detailed physical-based understanding of the changes in the active layer. The calibration process was carried out using soil temperature data for 2014-2015 and validated by 2011-2012 data. Data from two Global Circulation Models (GCMs), namely, CanESM2 (Canadian Center for Climate Modelling Second Generation Earth System Model) and MIROC5 (Model for Interdisciplinary Research on Climate), were used to analyze potential future changes in active layer thickness due to climate change under two emission scenarios (RCP8.5 and RCP4.5). The investigation showed that permafrost remained stable in sites with peat layers. The lower emission scenario forcing predicted up to 1 m increase in active layer thickness whereas up to 5 meters increase of the active layer thickness was observed for both GCMs under high emission scenarios by 2080.
Permafrost degradation, Climate change, Numerical modelling