Evaluasi Kapasitas Drainase dan Box Culvert Terhadap Elevasi Muka Air Sungai di Jalan Parit Bengkok

This study aims to evaluate the capacity of the drainage channel and the box culvert dimensions in relation to the river water surface elevation at Jalan Parit Bengkok, Pematang Duku Timur Village, Bengkalis Regency. Flooding and runoff issues during the rainy season indicate a mismatch between the existing channel capacity and the actual river discharge. The methods used in this study include rainfall data collection, existing channel cross-section measurements, and discharge calculation using the rational method. The results show that the existing channel capacity of 9.205 m³/s is insufficient to accommodate the maximum river discharge of 14.23 m³/s. Therefore, a redesign of the box culvert dimensions was carried out using the Manning formula, considering the channel slope, roughness coefficient, and water surface elevation. Based on the evaluation results, the recommended box culvert dimension is 2 m × 3 m, which can safely handle the discharge. This research is expected to serve as a reference for better drainage system planning in the area