Slope monitoring: an application of time-lapse electrical resistivity imaging method in Bukit Antarabangsa, Kuala Lumpur

Slope monitoring study using 2-D electrical resistivity imaging method was conducted on a slope where a massive landslide occurred in December 2008 in Bukit Antarabangsa, Kuala Lumpur, Malaysia. The main objective of the study is to determine the subsurface resistivity distribution of the study area and to map the risk/potential zone of landslide in the future. To detect the changes in the subsurface resistivity distribution due to variation in water saturation in the subsurface, time-lapse electrical resistivity imaging method was applied in this study. Repeated measurements of electrical resistivity over chosen lines at different times were done to monitor the changes in the subsurface resistivity distribution. The results obtained from the time-lapse electrical resistivity shows that there are significant changes in the subsurface resistivity distribution during different periods. Locations of possible slope failure are identified along the slope and are divided into Zone 1 and Zone 2. Weak zones are characterized by the large proportion of high water saturation zones and low resistivity values which are highly affected by the supply of water into the subsurface as well as the properties of the subsurface materials. These particular regions are more susceptible towards slope failure as high water content will ease the movement of soil in the subsurface. Thus, proper mitigation must be done at the problematic zones to prevent the occurrence of slope failure in the future.