Landslide susceptibility mapping using GIS and FR method along the Cagayan de Oro-Bukidnon-Davao City route corridor, Philippines

Landslides along highways in Mindanao including the Cagayan de Oro (CDO)-Bukidnon-Davao City (Buda) highway pose high risk to many motorists and passengers. It also hampers the flow of transportation affecting the economy of the region not counting the cost of road maintenance and rehabilitation. This study aimed to evaluate the casual factors of rainfall-induced landslide along the study area using Geographic Information System (GIS) and Frequency Ratio (FR) approach. Global Positioning System (GPS) was used to determine the coordinates of 78 landslide locations recorded. Map layers of different parameters with FR values were overlaid to produce the rainfall-induced Landslide Susceptibility Index (LSI) map. The generated LSI map was classified into low, moderately low, moderate, moderately high and high risk. Results showed that rainfall coupled with soil type and slopes were the main triggering parameters of based on their corresponding FR values. Majority of high risk areas for rainfall-induced landslides were located along the southern portion belonging to Davao City and Kitao-tao and Arakan Municipalities. Validation using Receiver Operator Characteristic (ROC) revealed a model accuracy rate of 76.4% at 0.05 level. Hence, the LSI map generated can be a useful input in planning out projects for road repairs and maintenance along landslide prone areas so that cost, disturbances and exposure to such hazards may be minimized.