Stormwater management and climate change: vulnerability and capacity for adaptation in urban and suburban contexts

Managing stormwater under climate uncertainty is a concern in both built-out communities and those continuing to undergo land use change. In this study, a suite of climate change scenarios were developed to represent a probable range of change in the 10-year recurrence interval design storm. The Environmental Protection Agency's Stormwater Management Model was used to predict flooding due to undersized drainage components within watersheds representing a traditional, built-out urban area and a developing suburban area with intact green infrastructure corridors. Despite undersized infrastructure and flooding in both study watersheds, the risk of property damage in the suburban watershed was negligible across the range of scenarios even at projected build-out, due in part to flood storage capacity of the green infrastructure network. Adaptation approaches - including pipe upsizing, underground storage, and bioinfiltration - and costs were also modeled in both watersheds. In the built-out site, bioinfiltration practices were predicted to moderate both flooding and total adaptation costs even when implemented over a relatively modest (10 %) portion of the watershed; however, a substantial upgrade to gray stormwater infrastructure (pipes and storage chambers) was also needed to mitigate impacts. In the urbanizing community, maintaining an intact green infrastructure network was surmised to be the most cost-effective approach for enhancing the resilience of urban stormwater systems to climate uncertainties and urbanization.