ABSTRACT

Gembong Watershed is one of the watersheds frequently affected by floods every year. Flooding in the Gembong Watershed often occurs due to high rainfall. Besides rainfall, several other factors contribute to flooding, such as land cover, slope gradient, elevation, soil type, and river density. These six factors are used as flood-prone parameters in this study. The purpose of this study is to determine the flood-prone level in the Gembong Watershed and its mitigation efforts, which can be utilized to obtain information about the level of flood-proneness in the Gembong Watershed area and to determine mitigation actions. The method used involves scoring and weighting the flood-prone parameters according to their classifications and will be overlaid using ArcGIS 10.4.1 software. Based on the flood-prone mapping analysisin the Gembong Watershed, five levels of flood vulnerability were identified: very high with an area of 4.26 km2 (7.36%), high with an area of 22.96 km2 (39.66%), moderate with an area of 24.10 km2 (41.63%), low with an area of 5.07 km2 (8.76%), and very low with an area of 1.50 km2 (2.59%). For structural mitigation efforts, five small reservoirs and two retention ponds are planned. For non-structural mitigation, an early warning system will be implemented with four flood status levels: normal, moderate, critical, and emergency.