Development of landslide tolerable and acceptable risk criteria for MalaysiaTools Sim, Kwan Ben (2025) Development of landslide tolerable and acceptable risk criteria for Malaysia. PhD thesis, University of Nottingham.
AbstractLandslide tolerable and acceptable risk criteria are strongly governed by utilitarian concerns i.e. financial power and the need for development and should be developed locally with historical landslide inventory, public perception, and engineering aspects being considered. The risk criteria of Hong Kong and that of the Australian Geomechanics Society are widely employed in many countries. The present study aims to develop and improve the landslide tolerable and acceptable risk criteria for Malaysia by taking into considerations of qualitative and quantitative inputs from various stakeholders. Based on the compiled landslide inventories, the Frequency-Number of fatalities (F-N) curve of Malaysia established from the present study have a similar slope gradient with those of Italy, Colombia, and Hong Kong. The F-N curve is a graphical tool (typically expressed on a log-log scale) used to depict the level of societal risk associated with a particular activity or project, which, in the present study, is landslides. As for the findings from the questionnaire surveys and interviews with landslide experts, public (non-experts) generally expressed the lowest acceptance in landslide risk for all scenarios (from low to high risk), whereas the experts were willing to accept a higher landslide risk as they understand that an ideal low landslide risk environment is not feasible under the current Malaysian scenario. Gender, occupation and educational level were the significant demographic factors influencing landslide risk acceptability in Malaysia. Modifications were proposed to the existing landslide risk criteria with a lower acceptance towards death upon taking into consideration findings from the present study. To demonstrate the application of the newly developed criterion and runout model, quantitative risk analyses (QRA) were performed to quantify landslide risk for a real-life case study. An important part of QRA concerns the development of a simple yet reliable model for predicting the impact / consequence of a landslide. A new empirical model for landslide runout estimation in Malaysia was proposed based on historical landslide data. The reliability of the proposed model was verified through a reasonable agreement between the actual runout and predicted values. Gumbel analysis was utilized to obtain the extreme rainfall scenario with a 10-year return period. It should be noted that Gumbel analysis is typically conducted for the probability distribution of extreme value in hydrologic studies for prediction of maximum rainfall. Seepage and probabilistic slope stability analyses were carried out to determine the probability of landslide occurrence of the studied slope. Using the newly developed empirical model, the runout of the landslide was predicted. The outcomes included a quantification of risks posed to elements within the runout path, such as houses and residents. The findings offer a quantitative estimation of the annual probability of fatalities for people. A F-N curve was employed to articulate the societal risk associated with this specific slope in the case study, which was then compared against the newly established risk criterion. These results carry significant societal implications and will furnish decision-makers and regulators with valuable insights for devising risk mitigation strategies for both existing slopes and forthcoming developments.
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