EVALUASI KINERJA SALURAN DRAINASE MENGGUNAKAN APLIKASI HEC-RAS (Studi Kasus Desa Sei Alam, Kecamatan Bengkalis)

Abstract

Flood inundation is one of the problems occurring in Sei Alam Village, Bengkalis District, Bengkalis Regency, which is influenced by the relatively low elevation of the area, limited drainage system capacity, and tidal effects. This study aims to analyze the capacity of the drainage system in conveying design flood discharge and to determine the pattern and extent of flood inundation in the study area. Hydrological analysis was conducted to determine design flood discharges using the Rational, Weduwen, Haspers, and Nakayasu methods for 5-, 10-, and 25-year return periods. Hydraulic analysis was conducted using HEC-RAS software through 1D Steady Flow and 2D Unsteady Flow modeling. The results show that the design flood discharges obtained using the Rational method were 44.12 m³/s, 51.24 m³/s, and 59.31 m³/s for the 5-, 10-, and 25-year return periods, respectively. The HEC-RAS 2D simulation results indicate that the inundation area increases with increasing design flood discharge and tidal effects. Flood inundation mainly occurs in low-elevation areas, residential areas, and local road networks. The required mitigation measures include increasing drainage capacity, channel normalization and maintenance, runoff control, and tidal management.