LANDSLIDE SUSCEPTIBILITY ZONATION BASED ON FREQUENCY RATIO METHOD, IN KARAHA BODAS GEOTHERMAL FIELD, WEST JAVA
Abstract
Abstract – Indonesia has the potential for geothermal energy which is quite unique because of the location of geothermal sources in mountainous areas with fairly steep slopes and quite complex geological structures. In general, high temperature geothermal fields are located in volcanic areas with high relief, steep morphology, thermal alteration rocks that produce thick soil, and high rainfall. This is a threat in geothermal development that causes landslides. This study aims to map the landslides susceptibility in the Karaha Bodas geothermal area using the Frequency Ratio (FR) method and evaluate the parameters that have a strong influence on landslides in the study area. Based on the inventory of landslides, there were 538 landslides in the study area. The landslide event data is then divided randomly into two groups, namely 70% training data (377 landslides) and 30% test data (161 landslides). There are 16 parameters used to determine their effect on landslides, including elevation, slope, aspect slope, curvature, lithology, flow direction, distance from the road, lineament density, distance to lineament, drainage density, distance to drainage, stream power index (SPI), topographic wetted index (TWI), rainfall, normalized differential vegetation index (NDVI) and Land Use and Land Cover. The value of the area under curve (AUC) of the parameters causing landslides that affect landslides is ≥ 0.6.
Based on the AUC value, the parameters that affect the occurrence of landslides in the study area using the FR method are the slope, LULC, drainage density, elevation, distance to road, lithology, distance to drainage, rainfall, TWI, NDVI, and curvature. The results of the evaluation of the AUC success rate value show the FR method (0.786) and the evaluation results of the AUC prediction rate value show the FR method (0.793). Based on the results of the study, it was concluded that the FR method has an accurate AUC value which affects the landslide susceptibility zoning in the Karaha Bodas geothermal area and its surroundings.
Key words: Karaha Bodas, landslide, frequency ratio