The Federal Emergency Management Agency (FEMA) issued a new floodplain rule in July, requiring construction projects that receive agency funding to be elevated above current and anticipated future flood levels. The rule came as catastrophic flooding hit communities in Texas, Iowa and Vermont, in the latest round of extreme weather events that are posing increasing risks to people and property across the country while also driving up insurance costs.
With this new rule, FEMA will account for the impacts of climate change on increased flood risk and require enhanced resilience for FEMA-funded buildings and other construction projects in at-risk areas. FEMA joins the U.S. Department of Housing and Urban Development (HUD), which adopted a similar rule in April expanding its floodplain definition and increasing elevation requirements for HUD-assisted new housing.
These new flood rules are a critically important step to improve the preparedness of our nation’s infrastructure in the face of growing climate risks and to use taxpayer dollars more prudently in building and rebuilding projects.
The Federal Flood Risk Management Standard
The FEMA and HUD rules both implement the Federal Flood Risk Management Standard (FFRMS). FFRMS is a flexible framework designed to address current and future flood risks and increase the resilience of federally funded infrastructure. Federal agencies are required to select one of three approaches to identify the FFRMS floodplain used for project siting, design and construction:
- Climate Informed Science Approach (CISA): The flood elevation and hazard area that result from using the best-available data and methods integrating current and future changes based on climate science.
- Freeboard Value Approach (FVA): The area that results from adding 2 feet to the base flood elevation (flood event with 1% annual probability) for noncritical facilities and adding 3 feet for critical facilities such as hospitals, power plants and water treatment facilities.
- 500-year floodplain: The area subject to flooding by a 500-year flood (an event with 0.2% annual probability).
FEMA and HUD have prioritized the use of CISA, where data is available and actionable, in their FFRMS implementation. Where data is not available, both agencies will generally defer to the higher result of the FVA or 500-year floodplain approach.
https://www.usgbc.org/articles/federal-agencies-address-increasing-flood-risks-new-rules