Landslide Analysis Using Geographic Information System (GIS) in South Tapanuli Regency

Landslide is a natural disaster that often occurs in Indonesia. Landslide is defined as a movement of soil or rock substances, or a mixture of the two substances that move down out of the slopes which is caused by stability disturbances of soil and rock making up the slopes. Losses that can be incurred include loss of life, damage to residences, loss of property, and psychological impacts. In this study, the development of landslide-prone area map was carried out in South Tapanuli Regency based on the estimation model of Pusat Penelitian Tanah dan Agroklimat, Department of Agriculture (2004). The parameters used in this study were rainfall, rock type, slope, land cover, and soil type. Scoring and overlapping method was used to obtain landslide susceptibility levels by using QGIS 3.24 application. According to the study results, there were 4 landslide susceptibility levels in South Tapanuli Regency, namely low landslide susceptibility (142.0093 km2), moderate landslide susceptibility (1528.4674 km2), high landslide susceptibility (2314.9484 km2), and very high landslide susceptibility (379.5909 km2). There were 3 districts dominated by moderate landslide susceptibility levels, namely Aek Bilah, Batang Angkola, and Muara Batang Toru districts. Then, there were 10 districts classified in high landslide susceptibility level, namely West Angkola, South Angkola, East Angkola, Angkola Sangkunur, Arse, Marancar, Saipar Dolok Hole, Sayur Matinggi, Sipirok, and Tano Tombang Angkola. Only Batang Toru district classified in very high landslide susceptibility level.