Evaluation of the Drainage System Regarding Water Inundation on Karadenan Main Road, Cibinong District, Bogor Regency, West Java Province

Abstract

The drainage system along Karadenan Road in Cibinong District, Bogor Regency, plays a crucial role in conveying stormwater runoff to prevent pooling that could disrupt the function of this collector road and impede traffic flow. Field observations revealed that water pooling persists at five locations for durations exceeding two hours; the existing rectangular channels measure 0.50 m × 1.00 m, and sediment deposits were found at the channel bottoms. This study aims to evaluate the capacity of the existing drainage channels against the design flood discharge and to formulate recommendations for adjusting channel dimensions. A descriptive quantitative approach was employed for a catchment area of ​​22.31 hectares. Hydrological analysis utilized maximum daily rainfall data from 2015 to 2024 recorded at the Cibinong, Ranca Bungur, and Sumur Batu stations. Areal rainfall was calculated using the arithmetic mean method, while rainfall distributions were analyzed using Normal, Log-Normal, Gumbel, and Log-Pearson Type III distributions, followed by Chi-Square and Smirnov-Kolmogorov goodness-of-fit tests. Design flood discharge was calculated using the Rational Method for a five-year return period, whereas channel capacity was calculated using Manning’s equation and simulated via HEC-RAS. The study results yielded a design rainfall of 145.88 mm, a rainfall intensity of 46.9 mm/hour, a runoff coefficient of 0.56, and a design flood discharge of 1.63 m³/s. The existing channel capacity was only 0.26 m³/s—insufficient to handle the design discharge—and simulations indicated overflow. Adjusting the channel dimensions to 1.20 m × 1.00 m resulted in a capacity of 1.74 m³/s; HEC-RAS simulations showed the water level remaining below the channel rim, indicating no overflow under the proposed design scenario.