This modeling study estimates the flood loss avoidance benefits from application of small storm retention practices for new development and redevelopment nationwide. Twenty HUC8 watersheds were modeled in areas where significant growth is expected between 2020 and 2040, using the FEMA Hazus model and national-scale datasets. The area of the watersheds ranges between 500 and 3,000 square miles. The study was conducted in consultation with other federal agencies including the US Army Corps of Engineers (USACE), the National Oceanic and Atmospheric Administration (NOAA), and the Federal Emergency Management Agency (FEMA).
The approach was vetted by a panel of experts from government, academia, and industry. The results show that, over time, the use of green stormwater infrastructure can save hundreds of millions of dollars in flood losses, while just applying the practices to new development and redevelopment only. If retrofitting were to occur, the avoided losses would be even more significant.
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