<![CDATA[Urban drainage infrastructure consists of minor systems, such as drainage channels, and major systems, such as retention/detention basins and receiving water bodies. The city of Bekasi, as part of the Jabodetabek metropolitan area, is prone to flooding due to high rates of land conversion and the shrinking of green open spaces. Data from the Bekasi City Disaster Management Agency (BPBD) shows an increase in flood-prone areas from 20 locations across 7 subdistricts in March 2025 to 28 locations in January 2026, with the Danita Irrigation Housing Complex in East Bekasi being a consistently affected area. Current conditions show sediment buildup in drainage channels ranging from 5 to 40 cm and a reduction in retention pond capacity due to sediment deposits 2.71 m thick. Topographically, this area is situated at an elevation of 11–18 meters above sea level and has a bowl-shaped topography, which causes water flow to concentrate at a single point, thereby exacerbating the potential for flooding. This study aims to evaluate the performance of the existing drainage system and redesign the retention pond through hydrological analysis of design rainfall events and EPA SWMM 5.2 simulations. Simulations of existing conditions yielded a flood volume of 3.525×10⁶ liters, indicating that the system’s capacity is inadequate. The retention pond was redesigned with a minimum capacity of 2,863 m³ and a design capacity of ±4,300 m³ using a safety factor of 1.5, with a pond depth of 5 m, resulting in a planned pond area of 860 m². The results of the post-redesign simulation show that the basin is capable of reducing flooding by up to 100% within the basin area, with a remaining storage capacity of approximately 50% of the design flood volume; thus, the system is deemed feasible and has adequate resilience against extreme rainfall events. The estimated construction cost for the redesign of the retention basin is Rp1,119,315,000.00.]]>
