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. Here in Sea Isle City we are located on a barrier island and are at risk of coastal flooding. Coastal flooding usually occurs when severe or extreme weather events combine with high tide conditions. Storm surge is the most common cause of coastal flooding. It happens when winds from a large storm or other hydrometeorological event cause the ocean to “surge” onshore.
What is a flood zone?
Flood zones are defined by FEMA and delineated on Flood Insurance Rate Maps (FIRMs). Within these maps, 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). The Federal Emergency Management Agency has classified Sea Isle City, in its entirety, as a Special Flood Hazard Area due in part to the fact that the City is a barrier island completely surrounded by water. 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 Sea Isle City are required to be elevated to or above the BFE. If you have questions about 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?
The areas in the north end of town and many of the ocean front properties are the most vulnerable to hurricane and storm damage. For construction purpose they are still considered "V" zones. The "V" zones are high velocity flood prone areas. In a “V” zone one can expect wave action greater than 3 feet in height. Although your property may be high enough that it has not recently flooded, all properties located in the City are located within a floodplain.
Flood maps and the flood protection reference materials are available at the Construction Office, located at 233 JFK Blvd. 2nd floor. At the Construction Office you can get advice about all elevation certificates we have on file, flood insurance, drainage issues, flood depths during recent flooding events, determining if your property is located in a Coastal A or COBRA Zone and selecting an architect, engineer or contractor familiar with local flood issues.
Flood maps are available for review and questions about how they will affect your property can be answered. These materials are available at the Sea Isle City branch of the Cape May County Public Library, located at 200 48th St. You can also find digital links to FIRM maps below.
If requested, the Construction Office’s Floodplain Administrator will visit your property to review a flooding problem and explain possible corrections to prevent continued flood damage. Please call the Construction Office at (609) 263-1166 or use this form to make an appointment. These services are free!