Kajian Risiko Banjir Kawasan Kabupaten Langkat Berbasis Sistem Informasi Geografis

Abstract

Langkat Regency, located in North Sumatra Province, is an area prone to flood disasters, especially during the rainy season. This vulnerability is due to high rainfall intensity, inadequate secondary and tertiary drainage systems, and poorly managed riverbank areas. Recurrent floods have caused damage to infrastructure, agricultural land, and disrupted community activities in the region. This study aims to assess the flood risk level in Langkat Regency by using a Geographic Information System (GIS) approach. The method used involves overlaying flood hazard maps with flood vulnerability maps. Hazard analysis was conducted using rainfall data for 10, 25, and 50-year return periods. Meanwhile, physical vulnerability was assessed based on land use, landform, slope gradient, and drainage density. Social vulnerability was determined by calculating the population density in each sub-district. The results of the study show that for the 50-year return period, areas with low risk cover 2153 km² (82,17%), and high risk 467 km² (17,82%). For the 25 year return period, areas with moderate flood risk dominate Langkat Regency, covering an area of 2080 km² (79.39%), while high-risk areas cover 540 km² (20.61%). For the 10-year return period, moderate-risk areas reach 2381 km² (90.88%) and high-risk areas 239 km² (9.12%). These findings are expected to provide significant input for local governments and related stakeholders in formulating flood risk management policies, spatial planning control, and flood disaster mitigation in Langkat Regency.