Application of Hydrological Model, RS and GIS for Flood Mapping of Citarum Watershed, West Java Province, Indonesia

Abstract

Citarum River Basin is considered as one of the vital and strategic river basins for the country’s development, particularly for the West Java Province and Metropolitan City of Jakarta. Flooding is almost occurred annually in Upper Citarum in Bandung area, the Capital City of the West Java Province and in Lower Citarum. This article presents the flood map of lower Citarum watershed delineated using hydrodynamic model and satellite image analysis. HEC-RAS was selected to model the flood. The ArcView program and the HEC-GeoRAS module were used to extract the geometric data and export to the RAS GIS Import File in the HEC-RAS import file format. This file was then imported in HECRAS model. The correction of geometric data such as adjusting the location of river banks, filtering the number of cross section point, etc. was then performed in HEC-RAS model. After the correction, the maximum discharge was used as input to simulate the flood event. Two images of ALOS PALSAR, one taken on a dry date (January 19, 2009) and the other on a wet date (March 26, 2010), were selected to be analysed using ENVI platform. One Dimension Hydrodynamic model HEC RAS has been used for flood inundation mapping using two different DEMs for the lower Citarum watershed. Flooded area for year 2007 (From existing map) is 105.11 km and simulated area from HEC RAS is 95.63 and 25.68 km with DEM-1 (extracted from spot height and contour data) and DEM-2 (extracted from ASTER data) respectively. ALOS PALSAR (year 2010) has been utilized for the flood extent mapping of year 2010. A threshold of -3 dB gives an area of 57.27 km of flooded areas. Keywords-Hydrological Model; Flood Inundation Model; ALOS-PALSAR; Citarum Watershed