The Everyday Risk of Flooding
Flooding is not limited to coastal homes and epic storms. Throughout New York City, street flooding affects the daily lives of millions.
Floods look like waves crashing into beach houses. They look like hurricanes turning roads into rivers. They look like cars floating down the street. But what many discount is that they also look like waterlogged intersections after routine rain. They look like unusable crosswalks in densely packed inland neighborhoods. And they look like basements at high risk of becoming swimming pools even though their owners are miles from the closest river or ocean. In this project, I combine data from FEMA and NYC's 311 hotline to tackle the common misconceptions that drive underestimation of flood risk.
Note: In all of the below maps, you can view the legend by clicking the icon in the bottom lefthand corner.
FEMA refers to areas at 'high risk' of flooding as 100-year floodplains.
This is because these areas have a 1 in 100 chance of flooding each year.
This might seem improbably small.
Many in high risk areas believe this means their house has a 1% chance of flooding over the next century.
This is a common misconception.
Because the yearly flood risk compounds, a house in a high risk flood zone has a 63% chance of flooding in the next century. This is equivalent to a 1 in 4 chance of flooding in the next 30 years.
Many homeowners in New York City face these odds. FEMA estimates that about 80 square miles of New York City are at 'high risk' for flooding.
An additional 20 square miles are classified as 'moderate risk'.
FEMA's estimates appear to be conservative.
In the past five years, New Yorkers have filed over 50,000 complaints of flooding. They have not been limited to high risk areas.
On average, there have been over 200 flooding incidents reported via 311 in each New York zip code since 2015.
Only 14% of these flooding complaints fall in the high risk zone defined by FEMA.
Some of the areas most affected by routine street ponding and flooding, the focus of most 311 complaints, are home to more than 70,000 people per square mile.
Neighborhoods in central Brooklyn, eastern Manhattan, and northern Queens are some of the most densely populated and heavily affected.
Flatbush, Brooklyn
Between 2015 and 2020, Flatbush residents logged 401 complaints. That's 284 flooding complaints per square mile.
Flooding in Flatbush isn't due to crashing waves or overflowing rivers. The nearest coastline is 2.5 miles away.
Research suggests that overbuilt areas are more likely to flood. With concrete, asphalt, and buildings blocking natural drainage, storm drains can easily become overloaded. Flatbush notably has very little space to devote to permeable green space.
This affects hundreds of thousands of people. Flatbush is home to about 75,000 people per square mile.
Street flooding is not a once in a lifetime phenomenon for these people. It affects their daily lives.
We see similar rates of routine flooding in other densely populated areas of New York.
You can explore these areas using the tool below.
Slide divider, pan, and zoom to explore the underlying satellite imagery of each zip code in NYC. Use icon in lower left hand corner of map to view legend. Click (single click) on any zip code to learn more. The neighborhoods that are most densely populated and commonly flooded are marked with pins.
