Know Your Flood Risk

If you have ever bought a house you should have some idea of what a flood zone is. If the house you bought is within the “100 year flood zone” which is really a 1% annual risk of flooding. It is said to be in Special Flood Hazard Area, SFHA; and requires flood insurance. Moderate flood hazard areas, are the areas between the limits of the base flood and the 0.2% annual chance of flooding (or 500-year) flood. The areas of minimal flood hazard, which are the areas outside the SFHA and higher than the elevation of the 0.2-percent-annual-chance flood, are labeled Zone C or Zone X (unshaded). However, according to FEMA, more than 20% of flood claims come from homes located outside of a high-risk flood zone. Floods can happen anywhere, flood zones just have a higher probability.

FEMA has worked in recent years to update its flood maps, especially in coastal zones, but FEMA’s flood maps are intended for flood plain management, not for mitigation of flood damage for homeowners. The FEMA's maps align with First Street's analysis of current and future flood risk in many areas. However, there are some areas, parts of South Florida and much of the Mid-Atlantic coast, that face higher flood risk than FEMA's maps currently indicate, partly because seas are rising and ocean water is growing warmer, the perfect conditions for more severe storms and hurricanes.

First Street Foundation is a non-profit research and technology group committed to defining America’s flood risk. They have developed a model to evaluate flood risk from multiple sources while also including current and future environmental considerations that may change storm intensity. They have identified this risk on a 1 to 10 scale at the individual property level. This combination of high-resolution scale and national scope brings to homeowners and the public in general a more exhaustive and comprehensive flood risk. According to First Street, FEMA, has undercounted nearly 8 million homes and businesses that face substantial risk of flooding, placing more Americans in jeopardy from coastal storms, rising rivers and flash flooding..

First Street’s Flood Factor model was produced in partnership with researchers and hydrologists from First Street Foundation; Columbia University; Fathom; George Mason University; Massachusetts Institute of Technology; Rhodium Group; Rutgers University; The University of California, Berkeley; and University of Bristol. According to First Street this collaboration makes use of open government data and builds upon decades of research, modeling, and expertise, brought together to develop a high-resolution, property-specific flood risk information at a national scale.

The top five states showing the greatest proportion of properties currently with substantial flood risk* include:

• West Virginia (24.4%),
• Louisiana (21.1%),
• Florida (20.5%),
• Idaho (14.8%) and
• Montana (14.2%),

The states with the lowest proportions of properties that currently have substantial risk are:

• Arizona (3.7%),
• Nevada (3.7%),
• Washington D.C. (5.3%),
• Colorado (5.7%), and
• Maryland (6.2%).

When adjusting for future environmental changes, by 2050 the number of properties with substantial risk across the country will increase by 10.9% to 16.2 million. Louisiana (69.7%), Delaware (21%), New Jersey (19.1%), Florida (18.6%), and South Carolina (16.7%) will see the greatest proportional increase of properties with significant flooding risk over the next 30 years.

The Foundation provides this information for every property in the contiguous U.S., in a format that is publicly and freely accessible via Flood Factor™, (www.floodfactor.com), all you have to do click the link and type in your address or the address of any property you are interested in and the model gives you the flood risk. The tool presents past, present and future flood risk with particular attention paid to recent and projected climate changes that contribute to flood risk. Also, remember that homeowners insurance does not cover damage from flooding, that is a separate flood policy.