Urban stormwater management is a growing challenge in many U.S. cities. Continued population growth, urbanization, and inadequate investment in storm- and wastewater infrastructure have left many cities exposed to sewer overflows, stormwater flooding, and reduced water quality. Climate change is expected to add to this challenge by increasing the intensity or volume of rainfall from storms in many regions. There is also a growing acknowledgment that these vulnerabilities are environmental justice and equity challenges, as flooding and other negative outcomes disproportionately affect low-income or majority-minority neighborhoods.
Pittsburgh's Negley Run watershed is a prime example of these stormwater management challenges, draining a diverse area of Pittsburgh's East End, including neighborhoods that have suffered heavily from underinvestment. It also represents an urgent flood-risk challenge in the city, as heavy rainfall in the area leads to regular flooding of a key road corridor. In this project, RAND researchers use simulation modeling to evaluate present and future risks in Negley Run from sewer overflows and flooding given future rainfall uncertainty. The authors then evaluate proposals for a phased series of green stormwater infrastructure (GSI) investments.
In addition to estimating stormwater benefits and implementation costs, the authors provide economic estimates of recreational, amenity, and other cobenefits to local residents; compare total benefits to costs; and explore potential trade-offs. Results show that a centralized system of stormwater management in Negley Run could yield cost-effective sewer-overflow reduction, reduce street flooding, and provide positive net economic benefits across a range of assumptions about future rainfall and implementation costs.