Hydraulic Conductivity Sensitivity of Vegetated Swale Networks for Urban Stormwater Management in Semi-Arid India: An InfoDrainage-Based Assessment with Design Guidelines

This InfoDrainage v2026.3 simulation-based assessment of a six-unit vegetated swale network in a 2.44 ha semi-arid Maharashtra catchment yields four principal conclusions: •  K-insensitivity for short-duration peak performance: Combined outfall peak and retention at the 25-year/10-minute design storm are practically invariant to K across a 33-fold range (0.0003–0.010 m h⁻¹). Combined peak varies by only 0.3 L s⁻¹ (0.3%) and retention remains 84.7% at all K values, confirming entirely storage-governed behaviour. Media specification tolerances may be relaxed for flash-flood control objectives without hydraulic penalty. •  Strong storm-duration dependence: Retention is 84–91% and peak reduction 77–85% for 10-minute storms, declining to 73–76% and approximately 7% for 1440-minute storms due to storage saturation. This pattern is K-invariant and represents a fundamental physical constraint of swale-only networks in high-volume monsoon environments. •  Swale superiority over conventional pipes: Swales outperform conventional pipe drainage for both peak attenuation (80% vs 12.5% at the design storm) and volume retention (84.7% vs 60.7%), demonstrating that SuDS-based approaches deliver substantially greater hydraulic benefit for semi-arid Indian urban drainage. •  Ten-step design methodology: A replicable design framework is proposed, incorporating Gumbel-based IDF derivation, InfoDrainage multi-storm simulation, K-sensitivity verification (Step 7), CIRIA C753-compliant sizing, and field validation protocols, suitable for direct application by Indian urban drainage practitioners.   Vegetated swales are recommended as flash-flood-control infrastructure in semi-arid Indian urban catchments, paired with storage-based SuDS for long-duration monsoon event management. All results are conditional on modelling assumptions and must be validated against site measurements prior to implementation.

1. Dietz, M. E. (2007). Low impact development practices: A review of current research and recommendations for future directions. Water, Air, & Soil Pollution, 186(1), 351–363. 2. Ahiablame, L. M., Engel, B. A., & Chaubey, I. (2013). Effectiveness of low impact development practices in two urbanized watersheds. Journal of Environmental Management, 119, 151–161. 3. Guptha, G. C., Swain, S., Al-Ansari, N., Taloor, A. K., & Dayal, D. (2021). Assessing the role of SuDS in resilience enhancement of urban drainage system: Gurugram City, India. Urban Climate, 41, 101075. 4. Rangari, V. A., Umamahesh, N. V., & Bhatt, C. M. (2019). Assessment of inundation risk in urban floods using HEC RAS 2D. Modeling Earth Systems and Environment, 5, 1839–1851. 5. Scholz, M., Futter, M., & Smit, H. (2021). Vegetated swales and their role in managing urban runoff. Science of the Total Environment, 746, 141054. 6. He, J., Li, Q., & Wang, L. (2021). Managing urban runoff with vegetated swales. Environmental Pollution, 268, 115539. 7. Woods Ballard, B., Wilson, S., Udale-Clarke, H., Illman, S., Scott, T., Ashley, R., & Kellagher, R. (2015). The SuDS Manual (CIRIA C753). CIRIA, London. 8. Singh, A., Soni, P., & Joshi, M. (2019). Role of vegetated swales in improving urban water quality. Environmental Science and Pollution Research, 26(10), 10122–10133. 9. FAO. (2006). Guidelines for Soil Description (4th ed.). Food and Agriculture Organization of the United Nations, Rome. 10. FAO. (2015). World Reference Base for Soil Resources 2014. World Soil Resources Reports No. 106. FAO, Rome.