Empirical Analysis and HEC-HMS Modeling of Green Stormwater Infrastructure: Stormwater Capture, Ponding, and Infiltration in Urban Tucson
Eden Harper1, Neha Gupta2, Justin Warlick3, Eleonora Demaria3, Yoga Korgaonkar4, Ty P.A Ferré1
1Department of Hydrology and Water Resources, The University of Arizona
2Arizona Institute for Resilience, The University of Arizona
3Pima County Regional Flood Control District
4School of Geography, Development and Environment, The University of Arizona
Green Stormwater Infrastructure (GSI) provides an opportunity to mitigate urban flooding while supporting vegetation growth and urban recharge in arid regions. However, observational research on GSI remains limited despite its increasing implementation. A major challenge is the complexity of these systems, which depend on local urban heterogeneity (e.g. roads, buildings, drainage infrastructure). When retrofitting within highly developed urban areas, GSI placement is frequently constrained by land availability, and as such GSI are often placed adjacent to roadways which act as floodwater conduits. Despite indirect placement within flood prone neighborhoods, it is visually apparent that GSI sites capture stormwater, evidenced by the vegetative growth. This study examines four GSI sites in Tucson, Arizona: Richey Park, Cherry Park, Seneca Park, and Alvernon Park. GSI sites were monitored with pressure transducers installed in basins (July 2022-April 2024). Pressure transducer data and data from nearby rain gauges were used to estimate stormwater capture volumes, identify precipitation thresholds causing basin ponding beyond 24-hours, and assess infiltration capacity over time. Four HEC-HMS models were developed using ArcGIS Spatial Analyst and Arc Hydro extensions, calibrated using rainfall data and subsequent transducer responses, then applied to simulate stormwater behavior under varying storm frequencies. Over the study period, Richey Park in total harvested 0.6 acre-ft; Cherry Park 0.2 acre-ft; and Seneca Park 1.3 acre-ft. Alvernon Park’s transducer placement is at the outlet of a channel, where 2.4 acre-ft was determined to flow through the channel.