Geographic Information System (GIS) Analysis for Landslide Risk Potential Zonation Using Analytical Hierarchy Process (AHP) at Tunggilis Area, Pangandaran, Indonesia (original) (raw)

The flood disaster that swept across districts in Pangandaran on October 9 th , 2016 was followed by the landslide at several points, one of which occurred in the border of Tunggilis-Ciparakan area. This disaster caused a lot of losses. Mapping of landslide risk potential zonation is one of the mitigation efforts for strategic planning in the future. This study intended to map the landslide risk potential zonation of Tunggilis area with the analytical hierarchy process (AHP) method to determine relative ranking of parameters. For the basics, there were two maps, i.e. landslide hazard maps and landslide damage map. The landslide hazard map was composed of six parameters with weights obtained from AHP: slopes (34.09%), structures (20.54%), lithology (20.54%), land use (12.26%), streams (7.62%), and elevation (4.96%). Meanwhile, landslide damage map was composed of land use (53.90%), population density (29.73%), and roads (16.38%). All of the data above were obtained by the combined method of direct and indirect methods. The lithologic and geological structure data were obtained directly with geological mapping of 1:25,000 scale, while the other data were obtained by indirect method: slopes, land use, streams, relief, and roads were obtained from the National Coordinating Agency for Surveys and Mapping (Bakosurtanal), while the population density data was obtained from the village government. The data were first processed by weighting the description of the existing parameters with the pairwise comparison matrix, and then did an evaluation of consistency. The result of each weighted parameter was overlaid with GIS, then the weight of each parameter analyzed was summed. The landslide hazard map and landslide vulnerability map are then overlaid to get the final result in the form of landslide risk map. The final values obtained were then classified into several classes of risk levels. The analysis shows that it produces four zones of landslide risk potential in the study area, which are zone of high landslide risk potential, zone of moderate landslide risk potential, zone of low landslide risk potential, and zone of very low landslide risk potential.