Evaluasi Kapasitas Efektif Saluran Drainase Eksisting Berdasarkan Debit Limpasan Di Ruas Jalan Lingadan–Batas Kota Tolitoli

Abstract

Road drainage channels are an important part of transportation infrastructure, serving to convey stormwater runoff and reduce the potential for inundation. Sedimentation, narrowing of the cross-section, and variations in channel dimensions can reduce hydraulic capacity, so an evaluation of existing drainage channel conditions is needed. This study aims to estimate stormwater runoff discharge and to evaluate the effective hydraulic capacity of the drainage channels along the Lingadan–Tolitoli City Boundary road section, Kalangkangan Village, Tolitoli Regency, Central Sulawesi Province. A quantitative approach was used through measurement of effective channel dimensions and hydrological and hydraulic analysis. Runoff discharge was calculated using the Rational Method, while channel hydraulic capacity was calculated using the Manning equation. Preliminary data show a catchment area of 3.43 ha, a composite runoff coefficient of 0.64, a daily rainfall of 193.2 mm, and a time of concentration of 33.31 minutes. Based on a rainfall intensity of 99.16 mm/hour, the estimated runoff discharge is 0.605 m³/s. Preliminary calculations at 11 observation points, P0 to P10, show hydraulic capacities ranging from 0.061 to 0.758 m³/s. The lowest capacity is at point P5 (0.061 m³/s) and the highest at point P0 (0.758 m³/s). A provisional comparison with the runoff discharge shows that the capacities of P0 and P10 exceed the reference discharge, while those of P1–P9 are lower. However, these results cannot yet be used to determine the final performance of the network because the catchment delineation, flow direction, inter-segment connections, and source rainfall data still require verification. This study provides an initial overview of variations in channel hydraulic capacity and the need for further evaluation of existing drainage conditions