LANDSLIDE RISK ASSESSMENT AT PIYUNGAN - PATUK AREA, YOGYAKARTA SPECIAL PROVINCE, INDONESIA

PROCEEDINGS JOINT CONVENTION BALI 2007
The 32^nd HAGI, The 36^th IAGI, and The 29^th IATMI Annual Conference and Exhibition

LANDSLIDE RISK ASSESSMENT AT PIYUNGAN - PATUK AREA,
YOGYAKARTA SPECIAL PROVINCE, INDONESIA

Leang Sopheap¹, Dwikorita Karnawati¹, Kenji Aoki², Teuku Faisal Fathani³

¹Geological Engineering Department, Faculty of Engineering,
Gadjah Mada University, Yogyakarta, Indonesia
²Urban and Environmental Engineering Department, Kyoto University, Kyoto, Japan
³Civil and Environmental Engineering Department, Faculty of Engineering,
Gadjah Mada University, Yogyakarta, Indonesia

ABSTRACT

Field inspection revealed that several geological conditions and old landslide traces present in Piyungan-Patuk indicate that the area is vulnerable to landslide occurrences. As a means of identifying and classifying the areas in Piyungan-Patuk which are in danger during landslide events, this research is carried out to generate a landslide risk map.

Data layers used for the preparation of landslide risk map were obtained from different sources such as topographic and geologic maps. All the above data layers were converted to raster format in the GIS, each representing an independent variable of a constructed spatial database. Landslides’ locations were identified from satellite image and field survey. According to their relative importance, the various classes of different data layers were assigned weights between 0 and 1, and the subdivisions of each parameter maps are also given the score. The overall susceptibility and risk were calculated as Index, expressing the combination of the different weighted layers into a single map using a certain combination rule. By reclassifying the susceptibility and risk index value, the susceptibility and risk zones, namely very high, high, moderate, low and very low can be drawn. Verification of results by overlaying susceptibility map and landslide inventory data and adjustment of zone’s boundaries were the last stage of the mapping process, allowing the reconsideration in some cases of the weights given.

The results reveal that the high risk and susceptibility zones were located along the steep slope showing the coincidence with the landslides locations. This research outcome will beneficially provide the recommendation for appropriate landuse management in the landslide prone area as well as identification the most potentially susceptible area for landslide mitigation.

Keyword: landslide susceptibility map, landslide risk map, landslide impact prediction.