Landslide Susceptibility Assessment using Heuristic Statistically Method in Kayangan Catchment Kulon Progo Yogyakarta-Indonesia

要旨

This research applied the heuristic-statistic modelling to explorelandslide susceptibility map of the Kayangan Catchment in Kulon Progo, Yogyakarta. The objectives of this research were to study geomorphological situation and to evaluate landslide susceptibility area in Kayangan catchment. Bivariate statistic based on weights of evidence was applied to evaluate the relationship between active landslide and various controlling factors of landslide. Thematic map representing various controlling factors of landslide was generated by field check and GIS techniques. The result of weights of evidence on each controlling factor of landslide was evaluated with geomorphological situation of the study area to confirm the heuristic assumptions. Geomorphology photo interpretation accompanied by ground check was applied to figure out the geomorphological situation of Kayangan catchment. All of thematic maps have been weighted based on weights of evidence and geomorphological condition into landslide susceptibility map. The results of this research showed that geomorphological situation of Kayangan catchment can be divided into three zones. There were northern zone, middle zone and south-east zone. The northern zone was dominated by denudation processes in which intensive weathering, erosion, and mass wasting occurred. The middle zone consisted of structural landform embodied by resistance volcanic breccias. The south-east zone was dominated by fluvial landform. The distribution of landslide had been matched with geomorphological zone of Kayangan Catchment. The largest number of landslide occurrences was found in the northern zone. Moreover, the landslide susceptibility and landslide typology had been also matched with geomorphological zone of Kayangan catchment. The success rates analysis was applied to evaluate accuracy of landslide susceptibility map. It showed that the accuracy of heuristic-statistic model attained 85%.