What is flood risk?
The term “flood” is sometimes confusing because it is used to describe a wide range of environmental conditions. In basic terms, a flood is when water either partially or totally covers land that is typically dry. This means that you are experiencing a flood when your storm drain overflows and fills the street during a storm. You’re also experiencing a flood when your house is underwater due to a dam breach.
Flood risk is a measure of how vulnerable you are to flood. You can think of it as the product of flood event probability and total amount of assets potentially exposed to the event. You’ve probably heard people talk about the probability in this equation in terms of 100-year floods or 500-year floods. These terms are sometimes misinterpreted. A lot of people think they mean that one flood happens every 100 or 500 years. So, if you were recently flooded, you wouldn’t experience another one for another 99 or 499 years. In reality, 100-year flood is a flood event that has a 1% chance of happening every year. Similarly, a 500-year flood is one that has a 0.2% chance of happening every year. These are statistical terms that describe likelihood, which means that, while unlikely, you could plausibly experience a 100-year flood two years in a row!
Local flood hazards
Events that cause flooding are called “flood hazards”. These hazards can be manmade (like a dam failure or levee breach) or they can be natural (like a storm) and are often locally unique.
Being bordered by the Atlantic Ocean on one side and Risley’s Channel on the other, Longport is highly susceptible to flooding. This flooding can be caused by hurricanes, tropical storms, coastal storms, and high tides with heavy rain events. Flood water can fill the street and low lying areas to depths ranging from six inches to five feet of water, depending on the elevation of the ground. During the Hurricane of 1944, March Storm of 1962, December Storm of 1992, and Hurricane Sandy, all of Longport was flooded with between 2 feet and 5 feet of water!
What is a flood zone?
Flood zones are defined by FEMA and delineated on Flood Insurance Rate Maps (FIRMs). High-risk flood zones are described as part of an area known as a Special Flood Hazard Area (SFHA). The SFHA is what must be regulated through floodplain management in order for our community to participate in the National Flood Insurance Program (NFIP). If that’s confusing, think of it like this: the Special Flood Hazard Area (SFHA) is the area of concern for the National Flood Insurance Program (NFIP). While it isn’t the case with all communities in the U.S., Longport happens to fall entirely in the Special Flood Hazard Area. Within the SFHA, there are different zones that correspond to different types of hazards. These are called flood zones. There are many different flood zones but the ones that are most common are:
- X: Areas subject to flooding by the 0.2-percent annual chance flood event. These are considered to be lower risk than A, AE, V, and VE zones and are not included in the Special Flood Hazard Area (SFHA).
- A: Areas subject to inundation by the 1-percent annual chance flood event that don’t have Base Flood Elevations (BFEs) calculated. Sometimes A zones are called “Approximate A” zones.
- AE: Areas subject to flooding by the 1 percent annual chance flood event that have Base Flood Elevations (BFEs) calculated (the E in AE stands for “elevation”!). Coastal AE zones also exist. These are areas of special flood hazards extending inland to the limit of the 1.5-foot breaking wave.
- V: Areas along coasts subject to inundation by the 1-percent annual chance flood event with additional hazards associated with storm-induced waves.
- VE: Areas along coasts subject to flooding by the 1-percent annual chance flood event with additional hazards associated with storm-induced waves. These are different from V zones in that (like AE zones) they have Base Flood Elevations (BFEs) calculated.
In the above list, the Base Flood Elevation (BFE) is referenced often. BFEs are important to floodplain management in that they are often regulatory thresholds for development and building permits. This means that some of the construction in Longport is required to be elevated to or above the BFE. Flood zones can get confusing. If you have questions about any of this, feel free to contact us using the information listed in the next section.
How do I know if I’m in a flood zone?
All of Longport is in the Special Flood Hazard Area (SFHA), so you’re definitely in a flood zone! The majority of the Borough is in an AE flood zone with a few homes Bay Side located in a V Zone.
If you would like more information about your individual flood risk, and to learn more about your flood zone, you can reference FEMA’s Map Service Center. Copies of Longport’s FIRM can also be obtained in the Construction Office located on the second floor of Borough Hall and the Longport Public Library. Both locations also have a wide range of flood-related publications that can further your education about flood risk. If you would like further direct assistance, we’re here to help. You can reach us via our online Get Help form or via phone at (609) 823-2731 ext. 120. We can provide map information services about:
- Whether or not your property is located within the Special Flood Hazard Area (SFHA)~~
- Our Community Number, Flood Map Panel Number, & Suffix
- The date of the Flood Insurance Rate Map (FIRM) Index
- The FIRM Zone you are in
- The minimal base flood elevation for each zone
- The elevation used on the FIRM, if other than the National Vertical Datum (NAVD 1929)
- Elevation Certificates