Rainfall thresholds for the initiation of slope failures at Jelapang and Gua Tempurung area

For countries located near to the Equator Line, slope failures always associated with the presence of high volume of water due to heavy rainfall. The objective of the study was to find the rainfall threshold that potentially trigger slope failures. These thresholds were to be used as the trigger level to issue Warning Alert and Critical Alert in slope monitoring system. Two (2) study areas were selected i.e. Jelapang area and Gua Tempurung area, as both have substantially large catchments areas with steep natural slopes located beyond the Right-of-Ways (ROW) that feeds into the engineered slopes along the PLUS expressway although they depicted different geology and bedrock underlying the area. The development of Real Time Monitoring System (RTMS) was based on three (3) main elements i.e. complete field stations with sensors (site equipment), central database server and the medium of transmitting the field data to the server at Headquarters. Based on two (2) case studies for both areas and the analysis against rainfall data collected, slope failures occurred during/after rainfall event with intensity of more than 50mm/hour whereby this intensity can be used as the threshold for the RTMS to trigger Warning Alert.