Flood Risk
18% of properties in Southern states (42% in LA, 33% in WV, and 23% in FL) are at major risk of flooding within the next 30 years.
Share of properties at major to extreme risk for flooding, by county
Based on 30-year cumulative flood likelihood and projected depth of flooding
Source: First Street Foundation-Flood Model (FSF-FM). Notes: Properties at “major” to “extreme” risk of flooding have at least an 80% cumulative probability of being flooded over 30 years (at least a 5% chance in any given year). The FSF-FM incorporates flood protection measures (e.g. levees, flood walls, retention ponds, marsh/wetland restoration), multiple types of flooding risks (e.g. tides, rain, riverine and storm surges), as well as future environmental considerations.
Flooding from heavy downpours, swollen rivers, storm surge, or high tides are impacting every state — leading to property damage, business closures, job losses, school closures, and loss of life. The nonprofit First Street Foundation has developed technology that estimates a property’s flood risk, taking into account much of the existing flood protection infrastructure including levees, flood walls, and retention ponds. According to their assessments, 14.6 million properties nationwide are at substantial risk of flooding. 5.9 million of them are not currently within FEMA special flood hazard areas and, thus, not required to buy flood insurance.1 These properties may be in areas that previously were considered safe for development, but the actual risk is now greater than anticipated.
In Louisiana, West Virginia, Florida, more than 1 in 5 properties have an 80% or greater cumulative probability of flooding in the next 30 years. Meanwhile, the cost of flood insurance is set to increase by thousands of dollars each year in many counties (Flood insurance). Increasing flood resilience (e.g. raising buildings and critical equipment, reducing impervious surfaces) and investing in flood protection infrastructure including nature-based solutions (e.g. restoring barrier islands and wetlands) will be critical to climate adaptation.
The First National Flood Risk Assessment: Defining America’s Growing Risk. (2020). First Street Foundation. https://assets.firststreet.org/uploads/2020/06/first_street_foundation__first_national_flood_risk_assessment.pdf
