Review of site-specific quantitative risk assessment practice for natural terrain landslide hazards in Hong Kong

Abstract

A review of quantitative risk assessment (QRA) practice for site-specific natural terrain landslide hazards in Hong Kong over the last some ten years was undertaken. The objective of the review is to consolidate the recent development in local practice by synthesising and critically analysing various approaches in undertaking the assessment. The review also aims to compare the practice between Hong Kong and other places to benchmark the performance of local practice. The review is primarily literature-based. The reviewed literature covered government publications, consultants’ reports and academic papers. The review consists of an introduction of the fundamental concepts of QRA for landslide hazards and the application in Hong Kong, followed by discussion about the various approaches for QRA in practice, and a brief comparison between Hong Kong and overseas approaches. The review found that the QRA practice has been enhanced through the use of advanced modelling techniques such as LiDAR-derived Digital Elevation Model (DEM) and numerical debris mobility modelling, as well as the development of rationalised approaches for both hazard and consequence assessment. A wide range of techniques has been applied for some QRA elements including the delineation of hillside units, the use of empirical/numerical approach to assess debris travel distance, and the construction of F-N curve. The merits and limitations of these techniques were evaluated with work examples where necessary. Practical considerations and recommendations are made for the use of these techniques. The comparison with overseas practice reflected the uniqueness of site-specific studies in Hong Kong. Some techniques being developed overseas merit attention for continuous enhancement of the assessment are highlighted.