Predicting scour risk at hydraulic structures remains a significant challenge in design and safety assessment, particularly as climate change is expected to increase the frequency and intensity of extreme flow events. Scour is commonly mitigated using riprap and rock armouring in areas exposed to high velocities and erosion potential. Evaluation of riprap stability has traditionally relied on physical modelling, as available predictive tools remain limited for complex hydraulic conditions. However, physical testing is often constrained by cost, scale effects, and laboratory limitations. Numerical modelling offers a promising alternative, but most sediment transport and scour models are based on continuum and empirical formulations that are not well suited for simulating the movement and interaction of large rocks used in riprap protection. To address this limitation, this study proposes a coupled Computational Fluid Dynamics–Discrete Element Method (CFD–DEM) framework for assessing riprap stability under extreme hydraulic loading conditions. In this approach, hydrodynamics are resolved using CFD, while rock motion and particle interactions are simulated using DEM through a coupled fluid–particle solution. The proposed framework is applied to the West Timiskaming Dam, where a physical modelling study was previously conducted at the National Research Council Canada hydraulic laboratory in Ottawa. Comparison of numerical predictions with experimental observations shows promising agreement, demonstrating the potential of the CFD–DEM approach as a practical computational tool for evaluating the stability of riprap protection systems under both current and future climate-driven loading conditions.