Perencanaan Normalisasi Sungai Air Putih Desa Air Putih Kecamatan Bengkalis

Air Putih River is located in Air Putih Village, Bengkalis District, Bengkalis Regency, and discharges into the Bengkalis Strait. The river is approximately 800 meters long with a watershed area (DAS) of about 0.578 km². The downstream area of the river is frequently affected by flooding, caused by sedimentation at the river mouth and within the channel, as well as high rainfall intensity. This condition results in the river cross-section being unable to accommodate the incoming water discharge. Therefore, mitigation efforts are needed in the form of river normalization in the downstream section. The initial step of normalization involves hydrological and hydraulic analyses. The hydrological analysis utilizes rainfall data from the past ten years, watershed characteristics, land use data, and the location of rainfall stations. This data is used to calculate the design flood discharge for a 25-year return period (Q25) using the Nakayasu method. The hydrograph generated by this method is then used in hydraulic analysis through the HEC-RAS software, taking into account the river cross-section and tidal conditions. The analysis results show that the Q25design discharge of 3,183 m³/s cannot be conveyed by the existing river section, resulting in overflow at several segments. Consequently, normalization is carried out along a 625-meter stretch in the downstream part of Air Putih River, involving riverbed dredging and cross-section widening to accommodate the design flood discharge.