MONITORING AND ANALYSIS OF LANDSLIDE HAZARD USING DINSAR TECHNIQUE APPLIED TO ALOS PALSAR IMAGERY: A CASE STUDY IN KAYANGAN CATCHMENT AREA, YOGYAKARTA, INDONESIA

Abstract

The differential synthetic aperture radar interferometry (DInSAR) technique is applied to the ALOS PALSAR data to observe surface displacement in Kayangan Catchment area, Yogyakarta, Indonesia. Change detection is implemented to extract information on several landslides that occurred in the region in a time span between 2007 and 2009. The advanced DInSAR processing of images (2007–2009) has shown slight surface movements before the landslide events. These results are compared and validated with available GPS measurements. Our analysis reveals that Kayangan catchment area exhibits clear indication of surface displacements varying from 5.2 to 57.9 cm/year. The occurence of landslides has been analyzed in relation to the following terrain parameters; elevation, slope, distance to stream network, geology, landuse, and distance from road. Among these factors, it is found that 18% of landslides occur in elevation >100 m, 56% in slope 300-400, 34% in <25 m distance to stream networks, 100% in kebobutak formation, 67% in mix garden of land use types, and 100% in <25 m distance from road. The landuse is the most influential factor, since there are only four types of landuse that can lead to landslide occurrence, i.e., mixed garden, dryland agriculture, bush, and settlement. The analysis of land deformation is promising for assessing acceleration caused by a destabilizing anthropogenic change, and relationship between seasonal precipitation and deformation variability.