Increasing Stormwater Infrastructure Climate Resilience and Enabling Adaptation Under Deep Uncertainty

Extreme precipitation events have become more frequent over the last several decades, and projections from Global Climate or General Circulation Models (GCMs) suggest that this trend will continue throughout the 21st century due to climate change. Stormwater systems designed in urban

areas to manage precipitation on roadways and protect residents during rainfall events were designed using historical rainfall information that does not reflect observed trends nor future conditions projected by GCMs. Most of these infrastructure systems will continue in service for many more decades, and thus will be exposed to conditions for which they were not designed. Prior research has shown that under climate change, existing stormwater infrastructure might not provide the expected level of protection because of increases in the intensity and frequency of rainfall

extremes. Research is needed to understand to what extent and under which conditions are existing and proposed stormwater systems vulnerable to climate change, and what engineered and natural solutions could increase the climate resilience of stormwater systems. Location-specific projected changes in rainfall extremes remain deeply uncertain, sometimes with conflicting change signals from

GCMs projections and numerous downscaling methods to match the spatial resolution required for stormwater engineering design. The type of climate information used and how stakeholders incorporate this information into designs can affect the resilience performance of infrastructure and can result in assets either performing better or worse than originally required or intended.

This dissertation contributes to the understanding of the impacts of climate change on stormwater infrastructure assets and advances the exploration of solutions to increase resilience. It characterizes uncertainties in future rainfall projections from commonly-used public sources of downscaled climate projections in an effort to understand stormwater infrastructure climate resilience and preparedness and possible strategies to increase resilience where needed. The research also analyzes the implications

of data input choices used by local U.S. cities’ climate adaptation plans for infrastructure design decisions. Overall, this research advances the understanding of stormwater infrastructure systems’ vulnerability to climate change and provides valuable and actionable guidance to aid local

decision-makers and stakeholders to increase infrastructure resilience.