Geospatial technology for flood hazard analysis in Comal Watershed, Central Java, Indonesia

Abstract River flood has become a severe disruption toward the community, and it can trigger loss of life, damage infrastructure properties, suffer economic, social cultural, environmental degradation. Flood hazard analysis downstream Comal Watershed in Pemalang Regency, Central Java, was designed to generate map reduce effects disaster. The simulated for five, 10, 25, 50 years using HEC-RAS ArcGIS with HEC-GeoRAS. data input discharge, geometry, roughness. discharge obtained from hydrology modelling by utilizing daily rainfall 22 years. geometry composed topographic measured an echo sounder, while roughness land use along plain. accuracy validation were conducted matching result historical Disaster Management Agency in-depth interview results community. showed feasible disaster risk reduction purposes. levels generated return periods dominated high very low levels. In every period, rising trend inundation width depth occurred high,