The dynamics of permafrost degradation in northern landscapes may vary under different thawing scenarios due to the geological and hydrogeological complexity of the subsurface. Investigating the influence and interactions of key physical processes under varying freeze–thaw conditions may improve the understanding of permafrost degradation. In this study, the relative influence of various physical processes is assessed under different freeze-thaw scenarios. Main processes considered include heat advection, latent heat effects, cryosuction, freeze–thaw hysteresis, and soil deformation. For the current study, specific thawing scenarios considered involve variations in soil characteristics and groundwater flow systems. A numerical testing model (NTM) is developed using COMSOL Multiphysics, which fully couples thermal, hydraulic, mechanical, and solute transport (THMC) processes in a 2D synthetic cross section representative of discontinuous permafrost terrain. Model validation is performed by comparing model results to ground temperature measurements from a small watershed in the Northwest Territories. Process-based sensitivity analyses are then performed under various subsurface conditions to assess the role of individual physical processes. Preliminary results suggest that although the incorporation of some processes does not significantly influence the simulation results, the interaction between various processes is critical to model performance under certain subsurface conditions. For example, the simulations suggest that heat advection has negligible effects in less permeable soils but significantly accelerates permafrost thaw when lateral groundwater inflow is considered. The overall results may facilitate prioritizing field monitoring activities and selecting the key processes that should be incorporated within larger-scale models used for applications in discontinuous permafrost terrain.