Ecodrainage System Improvement Design: A Case Study of Anwa Residence, Tangerang

Rapid urbanization in Tangerang has altered land use patterns, increasing flood risk in residential areas such as Anwa Residence. The existing drainage system, originally designed for a 10.10 ha catchment area, currently serves 22.16 ha, resulting in increased runoff and reduced hydraulic performance. This study evaluates hydrological changes and drainage system capacity using ArcGIS-based catchment delineation, drone-derived topographic data, rainfall analysis, and hydraulic modeling. The existing retention pond has a surface area of 1,386 m² and a storage capacity of 2,079 m³ (average depth 1.5 m), allowing it to accommodate only 22.15% of the total runoff volume under the 25-year design storm. To comply with the local zero-runoff policy, two eco-drainage improvement scenarios were evaluated. Hydraulic storage calculations show that deepening the pond to 6.77 m or expanding its area to 6,258 m² provides sufficient storage to accommodate 100% of the total runoff volume of 9,387 m³. The proposed design enables complete runoff retention, contributing to flood mitigation, groundwater recharge, and sustainable urban water management