Flood Prediction due to Land Cover Change in the Ciliwung River Basin

Abstract

Located in the Special Capital Region of Jakarta (DKI Jakarta), which serves as the government capital and national capital of Indonesia, the Ciliwung River plays a major role in Indonesia. The increasing population of the Jakarta and Bogor area has resulted in an increase in the level of land ownership, which has had an impact on increasing areas of settlement and decreasing green open spaces. This rapid urbanization and change in land use has directly affected the hydrological nature of the area, causing an increase in the flooding volume in this region. This research was conducted in four stages: hydrological analysis, hydraulic analysis, flood hazard mapping, and flood assessment of land cover. To estimate the impact of the land cover change that has occurred, the Soil Conservation Service Unit Hydrograph was used along with the West Java rainfall distribution method. Hydraulic modeling uses the Hydrologic Engineering Center-River Analysis System, with 1D for channel runoff and 2D for surface runoff. Two projected land cover changes from a previous study and spatial plan were used to analyze design discharges. The results found that, for every 13 km2 of forest or agricultural area converted into urban or bare soil area, the flood peak discharge, flood area, and flood volume would increase by 3.6%, 15%, and 16%, respectively. The hydrological analysis showed that, based on historical data trends, the land cover change in 2030 would lead to an increase in peak discharge, flood area, and flood volume of 25%, 101.7%, and 91%, respectively. However, this impact could be minimized by following Bogor District Spatial Planning, which has a wider forest area than the future projection land cover.