16 Worst U.S. Cities for Flooding
June 24, 2020
Flooding can come in many different shapes and sizes.
Flash floods can happen quickly and with little notice, while hurricanes can move slowly, leaving tremendous property damage in its wake. There are also coastal floods due to high tides, and storm surges commonly occur after east coast hurricanes. However, those who are inland are not without risk, and river flooding and floodplain geography present recurring challenges in some regions.
Even though the cause of a flood may be different, often the results are similar.
Basements and crawl spaces will begin to take on water. Streets can turn into rivers. Houses will be damaged, and property owners will face major cleanup.
The force of floodwaters is nearly unstoppable. For example, outside of St. Louis, MO, flooded rivers can flow at a rate of 1.27 million gallons per second, overtaking multiple highways, knocking out utilities, and causing significant damage. And that's not one of the worst flooding areas.
What are the worst U.S. cities for flooding? Let's take a look at the data to find out.
Measuring Flood Risk
Identifying the worst cities for flooding starts with measuring flood risk.
In the United States, the longtime standard for assessing flood risk is FEMA's flood maps. The government analysis considers information about hydrology, land use, and infrastructure.
Determinations are then made about what land areas fall into a 100-year floodplain where there's a 1% annual chance of flooding or a 500-year floodplain where there's a 0.2 percent chance of annual flooding.
The maps determine who needs flood insurance, inform local floodplain management, and affect real estate decisions.
Yet the number of floods doesn't always line up with perceived risk. Between 2015 and 2019, a St. Louis suburb had three flood events that were considered 100-year floods. Similarly, North Carolina had two 500-year floods in the span of two years.
In part, the frequency of these major floods is a factor of probability. It's a coin toss if the 0.2 percent chance of it occurring will happen twice in a row.
However, other researchers argue that FEMA's flood maps are flawed. Risk measurements are calculated based on past water events including the relation to nearby bodies of water. The maps do not take into consideration future predictions of changing weather patterns, rising sea levels, and increased storm velocity. Estimates show that 66 to 80 percent of annual flood losses occur outside of special hazard flood zones.
New Orleans is a key example of how floodplains only tell part of the story of flood risk. Only one percent of homes in the New Orleans/Metairie area are in a 100-year flood plain. However, during Hurricane Katrina, 80 percent of the city was flooded after the levees and floodwalls failed.
The methodology of Identifying the Worst Cities for Flooding
Despite the potential flaws in these risk models, floodplain maps remain the best possible tool we have for measuring flood impact.
To understand the flood risk for each city, we used data from NYU's Furman Center which combines the National Flood Hazard Layer (NFHL) with Census data to calculate how many homes are at risk.
We then grouped together nearby metro areas that had high scores. In many cases, cities with high flood risk were clustered together.
Here are the worst metropolitan areas for flooding and the percent of houses in a 100-year floodplain.
1. Fort Myers, FL, Area
- Punta Gorda, FL: 53%
- Naples, FL: 49%
- Fort Myers, FL: 47%
2. Coastal Georgia
- Brunswick, GA: 50%
- Savannah, GA: 28%
- Hinesville, GA: 20%
3. Coastal Louisiana
- Baton Rouge, LA: 30%
- Hammond, LA: 27%
- Lake Charles, LA: 22%
- Lafayette, LA: 16%
- Gulfport-Biloxi-Pascagoula, MS: 29%
5. Florida Panhandle
- Panama City, FL: 28%
- Crestview, FL: 18%
6. Tampa, FL, Area
- Tampa, FL: 28%
- Homosassa Springs, FL: 20%
- Sarasota, FL: 12%
7. San Joaquin Valley, CA
- Merced, CA: 21%
- Porterville, CA: 12%
8. Coastal North Carolina
- New Bern, NC: 20%
- Wilmington, NC: 15%
9. Southern Atlantic Florida
- Miami, FL: 20%
- Vero Beach, FL: 18%
- Port St. Lucie, FL: 14%
10. Chesapeake Bay Peninsula
- Salisbury, MD/DE: 20%
11. Alabama Coast
- Daphne-Fairhope-Foley, AL: 20%
12. Inland Louisiana
- Monroe, LA: 18%
- Shreveport, LA: 13%
13. Cape Cod, MA
- Barnstable Town, MA: 18%
14. Central Texas
- Abilene, TX: 17%
- Odessa, TX: 12%
15. Orlando, FL, Area
- Deltona, FL: 16%
- Orlando, FL: 15%
- Jacksonville, FL: 14%
- The Villages, FL: 14%
- Titusville, FL: 13%
16. Virginia Beach Area
- Virginia Beach-Norfolk-Newport News, VA-NC: 12%
Living in a Floodplain
As Virginia Beach foundation experts explain, the ground level of your home is your first line of defense against flooding. As water levels in your community begin to rise, your basement or crawl space will likely begin to take on water first before the flooding reaches the first level of your home.
A free inspection can determine whether you need basement waterproofing, better drainage, a sump pump, or flood vents.
People living in Florida may need a completely different set of flood mitigation systems. The slab foundations that are common in the state combined with the different geology and weather patterns mean Florida foundation experts would likely design a different type of solution, focusing on crawl space waterproofing and exterior drainage solutions.
It's also important to remember how your risk level compares to flood insurance costs.
In Florida, 1.7 million people have flood insurance policies, which is about 22% of homeowners. One analysis revealed that the average flood insurance premium in Florida costs less than $500 per year. However, a two-foot flood in a one-story 2,500 square-foot home would cost about $87,326.
One spokesperson from the National Oceanic and Atmospheric Administration (NOAA) said he still gets flood insurance for his South Florida home, even though it's not in a flood zone. "You never know what’s going to happen. Most Floridians choose not to have it, but we’ve seen the price floods can bring to households when a storm comes along."