Flood Risk Maps Lag Behind Extreme Rainfall Events, Leaving Millions at Risk

As devastating flooding hits Texas, New York City, and other parts of the country, experts warn that many flood risk maps are outdated and fail to account for the growing threat of extreme rainfall events. Climate change is driving more frequent and intense flooding, yet only about half of the world's countries have early warning systems in place. In the United States, over 99% of counties have experienced a flood event over the past 20 years, with more than 40% of National Flood Insurance Program claims coming from outside of high-risk zones.

Key Takeaways:

• FEMA's flood maps, which inform zoning regulations and building standards, underestimate the growing risk of floods and don't account for intense rainfall events.
• First Street's flood risk model estimates more than twice as many properties lie in 100-year floodplains as official FEMA estimates suggest, indicating a significant gap in flood risk assessment.
• Up to 440,000 homes across the country may be underinsured for flood risk, as research from the Consumer Financial Protection Bureau found.
• Independent researchers have run analyses that conflict with First Street's models, highlighting the need for multiple models to understand flood risk.
• State governments are adapting to flood risks by bolstering warning systems and building infrastructure to protect communities, such as New York City's 2.4-mile system of flood walls and floodgates.
• Vermont's emergency management team is focusing on strengthening its alert system and considering new rules requiring homeowners to disclose past flood damage when selling their property.
• Property owners can look to First Street's flood risk model, which feeds into flood risk scores on real estate websites like Zillow, Redfin, Realtor.com, and Homes.com, for more frequently updated information.

Statistics:

• 99% of counties in the US have experienced a flood event in the past 20 years, according to FEMA data.
• More than 40% of National Flood Insurance Program claims come from outside of high-risk zones.
• Up to 440,000 homes may be underinsured for flood risk, according to the Consumer Financial Protection Bureau.
• First Street's flood risk model estimates more than twice as many properties lie in 100-year floodplains as official FEMA estimates suggest.

Sources:

• The New York Times: "Flood Risk Maps Lag Behind Extreme Rainfall Events, Leaving Millions at Risk"
• FEMA: Federal Emergency Management Agency
• First Street: First Street Research Firm
• Consumer Financial Protection Bureau: "Flood Risk Models Conflict With Experts' Estimates"
• National Weather Service: National Weather Service's Flood Mapping Tool