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Landslides are common across Canada and they pose hazards to human safety, economic activities, and the environment. Robust risk management strategies are necessary for sustainable development. A slope risk management framework has been adopted by the geotechnical community for approximately four decades allowing a systematic, consistent and transparent framework for managing risks. Implementing this framework is associated with uncertainties embedded in our estimates of risk. This paper presents a brief summary of the sources and categories of uncertainty in geotechnical slope engineering and focuses on two topics: (1) estimates of uncertainty in risk calculations and (2) temporal changes in landslide likelihood as a function of weather and steps towards estimating landslide risk changes with climate change. The paper argues that a quantitative risk assessment should not focus on the final risk calculation, but the overall knowledge gained. This allows comprehensive documentation of sources of uncertainty and how they impact geotechnical and risk assessments. Furthermore, the paper outlines approaches to define quantitative correlations between rock fall occurrences and weather, which can be leveraged to estimate changes in rock fall risk with climate change. The paper corresponds to, and expands on, the 2021 Canadian Geotechnical Colloquium. [ABSTRACT FROM AUTHOR]

The assessment of rainfall-induced shallow landslide hazards at the catchment scale poses a significant challenge. Traditional empirical approaches for landslide hazard assessment often assume that conditions having caused failure in the past will not change in the future. This assumption may not hold in a climate change scenario. Physically based models (PBMs) therefore represent the natural approach to include changing climate effects. PBMs would in principle require the combination of a three-dimensional (3-D) mechanical and water-flow model. However, a full 3-D finite element model at the catchment scale, with relatively small elements required to capture the pore-water pressure gradients, would have a significant computational cost. For this reason, simplifications to the mechanical (i.e., infinite slope) and water-flow models (i.e., one-dimensional or hybrid 3-D) are introduced, often based on a priori assumptions and not corroborated by experimental evidence. The paper presents a methodology to build a PBM in a bottom-up fashion based on geological surveys and geotechnical investigation. The PBM is initially set as simple as possible and then moved to a higher level of complexity if the model is not capable of simulating past landslide events. The approach is presented for the case study of Sorrento Peninsula and two main landslide events recorded during the winter of 1996–1997. [ABSTRACT FROM AUTHOR]