Landslide risk microzonation and the mechanism of landslide in tropical volcanic area, Kulon Progo Region, Yogyakarta, Indonesia

KYI, Su Su, Promotor Prof.Dr.Ir. Kabul Basah Suryolelono, Dip.HE.,DEA

2007 | Disertasi | S3 Teknik Geologi

The research area is located in the watershed area along Kalibawang channel of Kulon Progo region, Yogyakarta, Indonesia. It is situated at the foot of Kulon Progo hilly mountains and has been disrupted by the landslides in the rainy season. The ruin of houses and loss of lives were experienced due to landslides in this area. The dominant factors of landslides are investigated rigorously and identified the input parameters for multivariate statistical analysis by using quantification theory type II. The weighted scores resulted from this analysis are input to GIS to construct the landslides hazard map and construct the landslide risk microzonation. The critical rainfall is identified based on historical rainfall with landslides for hazard warning criteria. This warning criterion has its own tropical mechanism and related rainfall. In research area, the typical mechanism of landslide is analyzed by using one of the Distinct Element Methods of Particle Flow Code 2 D and the Finite Element Method (PLAXIS). From the result, the slope, valley side effect and the lithology especially the colluvial material, highly weathered Andesitic breccia intercalation of clay layers that was once experienced from the ancient landslides in upper steep slope region are the critical factors govern in this area. The repetition of landslides in colluvial material is the typical type phenomena of landslide in this tropical area. Their heterogeneity, the intercalation of clay within the slope, facilitates the failure condition. When the daily rainfall 80mm with the antecedent rainfall over 134 mm, the high-risk area should be taken caution of landslides.

Kata Kunci : Tanah Longsor,SIG,PLAXIS