Following a period of unusually intense rainfall on the 30th June 1995, a catastrophic debris flow occurred in the vicinity of a tunnel by-pass road some 425 m from its junction with the Kuala-Lumpur -Karak highway, Malaysia. This event caused the death of 21 persons along with significant damage to the bypass (access) road and highway. The report into the event recommended the installation of an automatic rain gauge system with rain gauges located at strategic locations along the access road. This system was to have the capability of triggering a warning alarm should certain critical threshold rainfall levels be reached in order to facilitate traffic management and/or road closure to ensure public safety. This paper provides a preliminary review of the rainfall record that is available from the installed system, the relationships between rainfall and subsequent landslide occurrence, and the critical rainfall thresholds identified for landslide prediction. It is found that both 'trigger' rainfall (that occurring over ≤120 minutes) and 'short term' antecedent rainfall (that occurring over ≤6 days), can be used in combination to provide warning against landslide occurrence in real time. An assessment of these threshold rainfall values is undertaken utilising the physically based combined hydrology and stability model CHASM~(TM).
展开▼
