Simulation-Based Performance Evaluation of a Vegetated Swale Network for Urban Stormwater Management using Info Drainage

This study presents a simulation-based assessment of a vegetated-swale network for stormwater management in a 2.44 ha semi-arid catchment in Jath taluka, Sangli District, Maharashtra, using InfoDrainage v2026.3. Three scenarios predevelopment, conventional pipes, and a six-unit swale network with engineered media (K = 0.0003 m h^-1) were compared across an eight-storm matrix (2-, 10-, 25-, 100-year return periods at 10-min and 1440-min durations; +20% uplift on the 100-year rainfall). Design rainfall was established by Gumbel (EV1) analysis of a 63-year (1963–2025) IMD annualmaximum daily series. Swale performance is strongly storm-dependent. For 10-minute storms, swales provide 77–85% peak reduction and 84–91% volume retention relative to pre-development; for 24-hour storms, peak attenuation falls to ≈7% and retention converges toward pre-development (73–76%) as transient storage saturates. Conventional pipes attenuate peaks by only 7–14% and retain essentially pre-development volumes. At the 25-year/10-minute design storm, combined outfall discharge falls from 195 m³ to 74 m³ (62% reduction), and combined peak from 588 to 116 L s^-1 (80% reduction). InfoDrainage reports Flood Risk status for two swales at the design storm and four at the 100-year/10-minute climate-uplifted storm; no swale overflows in any of the 48 runs. Results are uncalibrated and require field validation before implementation.