Stress Testing Framework for Managing Landslide Risks Under Extreme Storms

ExtrExtreme storms in the changing climate may trigger a large number of landslides and debris flows. The consequences can be catastrophic but their occurrence probability is rather low. Stress testing is recognized as an efficient tool for managing the risks of low-frequency high-consequence hazards. This paper presents a stress-testing framework for coping with the landslide risks under extreme rainstorms. Stress testing is a targeted reassessment of safety margins of a system under extreme events. It involves testing beyond normal operational capacity, often to a breaking point. The proposed stress testing framework include (1) identifying future critical rainstorm scenarios under the changing climate; (2) evaluating the response of the slope safety system to the critical rainstorm scenarios; (3) assessing the risks posed by the multi-hazard processes; (4) evaluating the bottlenecks of the slope safety system and (5) proposing strategies for improving system performance. A preliminary stress test was performed to evaluate the response of Hong Kong Island to four storms corresponding to 29, 44, 65 and 85% of the 24-h probable maximum precipitation. The testing shows that extreme storms can pose high risks, which require suitable policies and strategies for multi-hazard risk management.