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 Bay Head we are bordered by the Atlantic Ocean to our East, which means that we 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.
Bay Head is also bisected by Scow Ditch and Twilight Lake and situated at the head of Barnegat Bay. Along with the ocean, each of these bodies of water contributes to our flood risk. These hazards are especially dangerous because, given the variety of water bodies surrounding our community, we are at risk of flash flooding. It is difficult to give prior warning before flash floods and when they occur they can be very fast moving, with a large amount of water entering a waterway over a short period of time.
To help mitigate this risk, Bay Head has oceanfront dunes (our first line of defense during a storm or flood event). To encourage the protection and preservation of these dunes, we’ve adopted Ordinance No. 1993-8, Article II (amended as Ordinance No. 2010-10). We’ve also required homeowners residing on the oceanfront to install snow fences and dune grasses to help build the dunes. If you’re an oceanfront resident and want additional information about these regulations, contact us via our Get Help form.
What is a flood zone?
Flood zones are defined by FEMA and delineated on Flood Insurance Rate Maps (FIRMs). FEMA issued a revised FIRM for our Borough in 2006. 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). Most of the Borough of Bay Head lies in or near a 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 Demoville 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?
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. If you would like further assistance, we’re here to help. You can reach us via our Get Help form or via phone at: (732)-892-0636.
The Bay Head Reading Center is also a great resource for learning more about flooding. Publications found there cover topics like: flood proofing, elevation, flood mapping, emergency procedures, flood insurance, retrofitting, and flood hazard mitigation.
Note: The Borough of Bay Head is included in the NY and NJ Coastal Restudy. To find out more about restudy progress, take a look at FEMA Region II’s Restudy Newsletter.