KEMAMPUAN KOLAM RETENSI ASRAMA POLDA DALAM MENGURANGI LIMPASAN HUJAN MENGGUNAKAN EPA SWMM 5.2

Abstract

ABSTRACT
High rainfall intensity can cause flooding in the Flamboyan Baru area of Padang City, which has become a major issue requiring sustainable drainage infrastructure solutions. This study aims to evaluate the capacity of the West Sumatra Police Dormitory retention pond in reducing runoff discharge and mitigating inundation in the Flamboyan Baru area. The design rainfall intensity was analyzed using the Log Pearson Type III distribution. The storage capacity of the retention pond was calculated based on contour map data processed with Surfer software to obtain the topographic cross-section profile of the pond. The pond volume was computed using the average cross-sectional area method, resulting in a total storage capacity of 1,114.79 m³ with an average depth of 4 m. The EPA SWMM 5.2 model was developed by creating a schematic of the drainage system, including channels and the retention pond, and incorporating the design rainfall intensity. Simulations for 2-, 5-, and 10-year return periods showed increases in water level from an initial 1.5 m to 0.07 m for the 2-year, 0.10 m for the 5-year, and 0.17 m for the 10-year return periods during a 6-hour simulation. Overall, the West Sumatra Police Dormitory retention pond is effective in reducing flood potential for rainfall events with 2-, 5-, and 10-year return periods. However, for rainfall events with return periods greater than 10 years, the pond’s capacity should be re-evaluated to anticipate further increases in water level that may affect storage volume.