Landslide Susceptibility Zonation Using GIS-Based Frequency Ratio Approach in the Kulon Progo Mountains Area, Indonesia

Abstract

Landslides cause many casualties, environmental damage, property losses, and psychological impacts. Landslides frequently occur in the Kulon Progo Mountains area of Indonesia and are especially triggered by high-intensity rainfall between November and March. Research on landslide susceptibility in the Kulon Progo Mountains area can be a relevant tool to prevent or reduce the risk of landslide potential. Therefore, this research aims to develop a landslide susceptibility map using the frequency ratio (FR) method. Controlling factors, namely, elevation, slope, aspect, lithology, lineament density, distance from streams, distance from roads, land use, and rainfall, were combined with landslide data to develop a landslide susceptibility map by GIS software. Seven hundred and forty-four landslide data points were acquired from field surveys, Google Earth image interpretation, and the Regional Disaster Management Agency (BPBD) of the Kulon Progo, Purworejo, and Magelang regencies. Landslide data were randomly selected for map modeling (80%) and validation (20%). The FR analysis shows that the research area can be classified into four landslide susceptibility zones based on the LSI value: low (LSI 4.05–7.85), moderate (LSI 7.86–9.85), high (LSI 9.86–12.81), and very high (LSI 12.82–19.46). The landslide susceptibility map was validated using the area under the curve (AUC) method, resulting in a success rate of 80.1% and a predictive rate of 81.3%.