Stormwater Management Adaptation Pathways under Climate Change and Urbanization

: Urban runoff volumes and flow peaks are likely to increase in the future owing to climate change – driven effects on rainfall and continued urbanization. Actionable planning estimates that anticipate these impacts are needed to assess stormwater management infrastructure requirements and to minimize impacts on ecosystem services. This study presents a planning-level simple flow simulation tool and quantifies benefits of green stormwater management practices in small watersheds. Flow simulation was performed using a curve number – based watershed model (CWM). A portfolio approach was used to assess cost-optimal stormwater adaptation pathways considering a suite of alternative practices including both gray and green infrastructure. The CWM provides actionable information for medium to highly urbanized watersheds with percent bias less than 30% for highly urbanized watersheds. Considering projected future stormwater needs, analysis of multiple stormwater management approaches showed that green stormwater management alternatives are less cost-optimal than gray infrastructure at small watershed scales. These results suggest the possible use of CWM for quick planning-level flow estimates and analysis of more green practices for cost-optimal alternatives. DOI: 10.1061/JSWBAY.0000992. This work is made available under the terms of the Creative Commons Attribution 4.0 International license, https://creativecommons.org/licenses/by/4.0/. of BMPs to mitigate increased stormwater runoff resulting from climate change alone or in combination with different degrees of urbanization within several watersheds. The results generally showed that if the sole objective of the BMPs is flood control, gray infrastructure is more cost-effective than green infrastructure. Green infrastructure becomes more cost-effective when including important cobenefits in the evaluation.