Landslide hazard mapping of Penang Island using dominant factors

Landslide is one of the natural disasters in Malaysia and precipitation is the triggering factors for landslide in Malaysia. Besides rainfall factors, topographical factors also play key role in the susceptibility analysis of landslide. Since there are many available landslide-causative factors involved, selection of dominant factors is a crucial steps in landslide susceptibility analysis. This paper reports the landslide hazard mapping using Frequency Ratio (FR) approach with selected dominant factors in the area of Penang Island of Malaysia. Landslide hazard map of Penang Island is first generated by taking into account of twenty-two (22) landslide-causative factors. Among these twenty-two (22) factors, fourteen (14) factors are topographic factors. They are elevation, slope gradient, slope aspect, plan curvature, profile curvature, general curvature, tangential curvature, longitudinal curvature, cross section curvature, total curvature, diagonal length, surface area, surface roughness and rugosity. The other eight (8) non-topographic factors considered are land cover, vegetation cover, distance from road, distance from stream, distance from fault line, geology, soil texture and rainfall precipitation. After considering all twenty-two factors for landslide hazard mapping, the analysis is repeated by removing one factor at one time to identify the dominant landslide-causative factors. Twelve dominant factors are selected from the twenty-two factors. Landslide hazard map was segregated into four categories of risks, i.e. Highly hazardous area, Hazardous area, Moderately hazardous area and Not hazardous area. The maps was assessed using ROC (Receiver Operating Characteristic) based on the area under the curve method (AUC). Landslide hazard map produced by including all 22 factors has an accuracy of 77.76%. By removing 10 irrelevant factors and employing only 12 dominant factors, the generated hazard map achieves better performance with accuracy of 79.14%.