HEC-RAS MODEL FOR DRAINAGE CAPACITY ANALYSIS AND PEAK DISCHARGE SIMULATION OF CIMANDE RIVER

Abstract

Flooding occurs in Rancaekek District annually, affecting residential and industrial areas, particularly those along the Cileunyi-Nagrek highway. This research focuses on the drainage channel along the Cileunyi-Nagrek highway, which is always overpopulated by flood water. Given that the drainage channel empties into the Cimande River, the water level of the drainage channel is influenced by the Cimande River flow. The shallowing and narrowing of the river and the narrowing of the channel width and bridge abutment across the Cileunyi-Nagrek highway cause overtopping and inundation. Peak discharge of the Cimande River in various return periods is simulated for the analysis of existing drainage channel capacity and water level profile. Peak discharge in various return periods is determined using the Hydrological Engineering Centre – Hydrology Modeling System (HEC-HMS) 3.5.  River and drainage channel hydraulic modeling are carried out simultaneously by using the cross section option of geometric data in Hydrological Engineering Centre – River Analysis System (HEC-RAS) 4.1. The river overtopping leads to backwater because of peak discharges: 36 m³/s (10 years) and 52.9 m³/s (25 years). The existing drainage channel dimension is insufficient for all simulated flood discharges. The drainage channel capacity must be increased to 0.80 m² fit to peak discharge in a 10 year return period.