Mapping of Flood Hazards to Affected Areas in South Batipuh District, Tanah Datar Regency

Abstract

Flash floods in South Batipuh District, Tanah Datar Regency, continue to recur and threaten settlements around Lake Singkarak. This study aims to map the level of flood danger and analyze the distribution of flood-affected areas to land use in the sub-district. The research uses a quantitative descriptive method with a Geographic Information System (GIS) approach. The flood danger level is calculated using the Paimin method by scoring and weighting five physical parameters of the area, namely watershed shape, slope slope, land use, land shape, and drainage density. The distribution of the affected area is analyzed through an intersect overlay technique between flood hazard maps and land use maps using ArcGIS 10.8. The results showed that the low-hazard class dominated the study area of 10,851.20 hectares or 68%, the medium class of 4,744.37 hectares or 30%, and the high class of 473.02 hectares or 2%. Forests dominated the low-hazard class, while rice fields and built-up areas dominated the high-hazard class, especially in Nagari Guguak Malalo and Nagari Padang Laweh Malalo. This study produced the latest data by combining the Paimin method, post-disaster field data, and Sentinel-2A imagery at the sub-district scale, which was not available in the previous study. These results can be a reference for the Tanah Datar Regency Government and BPBD in formulating spatial planning and disaster mitigation policies.