Integrating Hydrology and Green Infrastructure for Urban Flood Resilience: A Hypothetical Catchment in Bandar Lampung

This paper proposes a screening-level framework that treats hydrological performance as an explicit design criterion for landscape architectural and urban design interventions. The framework is applied to a hypothetical 120-hectare mixed-use catchment in the Kali Balau Kencana area, Bandar Lampung. Two scenarios are compared using an illustrative rainfall event of 120 mm over 120 minutes: an existing-condition scenario (S0) and an integrated scenario (S1) combining rain gardens, bioswales, permeable pavement, a retention pond, and green corridors. Land-cover proportions, runoff coefficients (0.72 for S0 and 0.56 as the S1 target), and intervention dimensions are assumed rather than measured. Screening calculations yield runoff volumes of 103,680 m³ for S0 and 80,640 m³ for S1, equivalent to a 22.2% reduction, with peak discharges of 14.41 and 11.21 m³/s. These values are not EPA SWMM simulation outputs. Estimated geometric storage is 14,150 m³, or 13.6% of S0 runoff, indicating that the reduction target requires simulation-based verification. The study also outlines the required SWMM configuration and discusses implications for planning, regulation, financing, maintenance, and institutional responsibility.