Pemanfaatan digital elevation model (DEM) dan citra ALOS AVNIR-2 untuk pemodelan longsor: studi kasus DAS Ciliwung hulu

Abstract

In acordance with the development of society in upper Ciliwung river, land convertion usage depending of what the society needs, such as settlements, agricultural land, etc. The most happening of land convertion usage at upper Ciliwung river is the changing of the land which used to the agricultural needed into the non-agricultural statements. One of the impacts of the high intensity of land convertion was the occurance of landslide which could became a disaster. the objectives of this research were to asses the development of DEM and making a landslide model based on what DEM produced. To carry trough all of those things up, it is generated some main datas. There are non-optical remote sensing (SRTM) as well as optical remote sensing data (ALOS AVNIR-2), topographic map, also the meteorological and soil data. The usages of all those datas are to obtain the necessary parameters that needed to calcute the slope, slope aspect, elevation, vegetation index, rainfall, soil type, relief, and soil material. The first three parameters derived from the DEM, while the vegetation index derived from analysis of ALOS AVNIR-2 imagery. The last three parameters obtained from 1:50,000 soil maps scale (Puslitanak, 1992). Field observation was conducted to determine the points of landslide and to locate them with GPS, while the method of overlay of GIS used to analyze the relationship between the landslide point with parameters assessed. Further statistical analysis (LDA) using Tanagra 1.4 software to determine the effect of those parameters in landslides possibility with 5% interval accuracy. The result showed that the parameters that significantly affected to the danger of landslide were rainfall and elevation, while the slope, vegetation index and slope aspect had no significant effect. This may be caused by a lack of precision (accuracy) of the DEM results (with interval contour 12,5 meter) which could the interval contour at landslide point less than 12,5 meter.