Flood Inundation Distribution Modelling for River Boundary Management in Cisadane Sub-Watershed

Abstract

Cisadane watershed is one of the priority watersheds to be restored immediately. The Cisadane River has the potency to cause floods in the river's border region due to a reduction in river width, river depth, and land-use changes. This study aims to analyze the distribution of flood inundation by employing the HEC-RAS. Flood distribution modeling using components the flood distribution in the steady flow of water level profile component. The permanent flow use is 19 January 2022 discharge. Scenarios discharge was reported with a return period of 5, 10, 25, 50 and 100 years. Digital Elevation Model (DEM), discharge, watershed boundary, and land use maps are included in the data used. The results indicated that 30 districts were affected by the flood. The extent of the annual flood inundation is predicted to expand by 24.41 hectares per year throughout each discharge period. Teluk Naga, Sepatan Timur, Paku Haji, and Neglasari Districts have the broadest and deepest probablility inundation in Tangerang Regency, with a total inundation area 644,7 hectares (permanent flow). The depth will increase from 0.40 to 1.33 m as the return period discharge rises. Tangerang Regency, located in the Lower Cisadane watershed, is the most affected area.