The Federal Emergency Management Agency (FEMA) has conducted the first comprehensive review of flood zones throughout Broward County in 14 years, using a new “vertical datum,” that enables consistent comparisons of land and water elevations across the nation.

Flood maps, also known as Flood Insurance Rate Maps or F.I.R.M., need to be reviewed periodically due to the dynamic nature of flood hazard conditions, the availability of updated elevation data, improved technology for identifying flood hazards and to account for developments that can affect flood zone boundaries.

The new flood maps will help community officials and citizens be better prepared for flood-related disasters by providing an official depiction of flood hazards for Fort Lauderdale and the rest of Broward County.

Following its review, FEMA updated local flood zones on area flood maps. The proposed flood zones will go into effect on August 18, 2014.

Updated flood maps will then be used to:

• determine flood insurance purchase requirements;
• determine flood insurance rates;
• establish minimum finished-floor elevations for new construction and substantial improvements to existing structures.

By adopting the new flood maps, Broward County is assured that FEMA will offer assistance during emergencies and provide flood insurance coverage for county residents.

Determine Your Proposed Flood Zone

Residents and businesses in Broward County are encouraged to look up their property address to compare their current and proposed new flood zone map. Property owners should consider purchasing a flood insurance policy, even if it is not mandated for their location. All areas are susceptible to flooding, although to varying degrees.

Flood Zone Designations

The following flood zone designation determines whether or not flood insurance is mandatory.

About Vertical Datum

In an effort to reduce the effects of flooding, Congress created the National Flood Insurance Program (NFIP) in 1968. The Federal Emergency Management Agency is in the process of updating the Flood Insurance Rate Maps (FIRMs) for Broward County. One of the main goals of this effort is to more accurately define the boundaries of flood hazard areas, which are determined by comparing flood elevations with digital elevation data. To ensure that all the elevations used are based on a common reference system, a FIRM must reference a single vertical datum.

What is a Vertical Datum?

A vertical datum is a set of constants that defines a system for comparing elevations. If someone were to measure to measure the height of the ground you are standing on, they would need a point of reference, or a zero (0.0) point, to measure from. But where is that zero point? A vertical datum establishes a consistent zero point so elevations can be compared with one another even if the elevation measurements are taken by different people at different times or in different parts of the state.

Why is the Vertical Datum Changing?

For many years, the zero point used throughout the United States was based on “mean sea level” at 26 separate tidal stations in the US and Canada. This datum was referred to as the National Geodetic Vertical Datum of 1929 (NGVD 29). The main assumption used to create NGVD 29 - water level is equal all along the coast and thus represents the same zero- later proved to be erroneous and was shown to create errors in the elevation data obtained using this datum. This means that using the outdated vertical datum, two different points measured at 0.0' NGVD 29 can have different actual elevations. In the NFIP, the vertical datum is crucial because all elevations need to be as accurate as possible and referenced to the same zero point. Otherwise, surveys may show different elevations for the same point, which could result in flooded structures and losses. Currently, the old FIRMs reference the outdated National Geodetic Vertical Datum of 1929 (NGVD 29). We can now more accurately measure vertical elevation differences using the new official U.S. vertical datum, the North American Vertical Datum of 1988 (NAVD 88). With the new FIRM updates, this more accurate datum will be used (NAVD 88), resulting in a difference of minus 1.51 feet between elevations shown on the new (2012) FIRM as opposed to the old (1997) FIRM.

When is the Vertical Datum Changing?

Elevations in NAVD 88 should be used for floodplain management and flood insurance purposes (e.g., elevation certificates) as of August 18, 2014. As of January 30, 2011, the new datum must be used for all surveys and plans submitted with Environment Engineering and Licensing applications.

Who Will be Impacted by the Vertical Datum Change?

The change in vertical datum will affect all those using FIRMs or submitting applications for building permits or environmental licenses in Broward County, including engineers, surveyors, developers, homeowners, lenders, insurance agents, realtors and floodplain administrators, especially when comparing elevation data on the new FIRMs, produced using NAVD 88, with data on older FIRMs produced using NGVD 29.

Points to Know

• Changing from a measuring method developed in 1929 to one developed in 1988 will mean greater accuracy in determining land and water elevations.
• Instead of relying on "mean sea level" to determine the elevation of a point, Broward County will utilize the sophisticated elevation reference system for the North American continent. Eventually, all cities and counties in North America will use this same network of vertical reference points to support many diversified uses.
• Broward County databases will retain information in both the NGVD 29 and the NAVD 88 vertical datums in order to maintain historical data.
• Anyone who uses elevation information in Broward County will need to know about, understand and apply the new measuring standards.
• A conversion application is available so that users can readily convert elevation data from NAVD 88 to NGVD 29, and vice versa. You will be able to compare "apples to apples" using the free conversion software VERTCON. In addition, FEMA has computed an average conversion factor of minus 1.51 (-1.51) that may be used to provide a more rough conversion between the two datums.
• It is always more precise to convert elevations from the more accurate NAVD 88 vertical datum to the NGVD 29 vertical datum. Because of inherent flaws in the NGVD 29 datum, values converted from NGVD 29 to NAVD 88 will not exceed the accuracy of the source data. If exacting elevations are required, a new survey utilizing NAVD 88 values should be considered.

Conversion Factor Example

A building finished floor elevation is shown on an existing elevation certificate as 10.0’ NGVD. The equivalent NAVD 88 elevation can be obtained using the FEMA-approved average conversion factor in the following formula:

NAVD 88 = NGVD 29 + conversion factor

NAVD 88 = 10.0’ NGVD + (-1.51)

NAVD 88 = 8.49

If you have any questions regarding vertical datum changes or the NFIP in general, please contact the FEMA Map Assistance Center toll free at 1-877-FEMA MAP (1-877-336-2627). Learn more about vertical datums and vertical datum conversion:

• South Florida Water Management District Vertical Datum Webpage
• FEMA Vertical Datum Conversion Factor Guidance Document (PDF)
• FEMA Vertical Datum Conversion Instructions (PDF)
• FEMA Datum Conversion Brochure (PDF)
• Vertical Datum Conversion Software (VERTCON)

Frequently Asked Questions

What is a Flood Zone Map?
Flood zone maps, also called “Flood Insurance Rate Maps” or “FIRMs” are used to determine the flood risk to properties. The low- and moderate-risk zones are represented on the maps by the letter “X”, "0.2 PCT" or an “X” that is shaded. The inland high-risk zones will be labeled with designations such as “A”, “AE”, “AO” or “AH”, and coastal high-risk zones that have additional risk from storm surge will be labeled “V” or “VE”.

Who is responsible for modernizing the maps?
Currently, there is a nationwide effort by the Federal Emergency Management Agency (FEMA) to update the nation’s flood hazard data and provide it in a detailed, digital format. This FEMA effort is referred to as map modernization and has evolved as a growing number of industries were impacted by out-of-date flood data.

What's a floodplain? How do I determine if my property is in one?
A floodplain is the part of the land where water collects, pools, and flows during the course of natural events. Such areas are classified as Special Flood Hazard Areas (SFHA), and are located in a 100-year flood zone. The term “100-year flood” does not indicate a zone that will flood every 100 years. The term describes a zone with a flood elevation that has a 1 percent chance of being equaled or exceeded each year; it is not the flood that will occur once every 100 years. The likelihood of a flood occurring within a 100-year stretch of time is high, but there is no way to predict when the next flood will occur. The redrawn maps indicate the floodplain as a “high-risk” area, officially classified as an A, AE, AH, VE zone.

What are the benefits of the new flood hazard maps?
The map modernization project will benefit numerous groups of people in different ways:

• Community planners and local officials will gain a greater understanding of the flood hazards and risks that affect Broward County and can therefore improve local planning activities.
• Builders and developers will have access to more detailed information for making decisions on where to build and how construction can affect local flood hazard areas.
• Insurance agents, insurance companies, and lending institutions will have easy on-line access to updates and upcoming changes in order to serve their customers and community more efficiently.
• Home and business owners will have the ability to make better financial decisions about protecting their properties.

How will the new flood hazard maps affect me?
Neighborhoods across Broward County will be affected differently by these map changes. There will be some properties that aren’t affected and their risk remains the same. Other properties will now be mapped into a higher-risk area and/or show a new Base Flood Elevation.

Will the new flood maps affect me financially?
When new maps are officially adopted, if your structure is mapped into a high-risk area and you have a mortgage with a federally-regulated lender, you will need to purchase flood insurance. If your property is mapped into a low-or moderate-risk area, you are not required to purchase or maintain insurance, but are strongly encouraged to do so. The cost of properly protecting your home and contents from flood damage is far less expensive than the cost to repair or replace it after a flood has occurred.

Through the National Flood Insurance Program, coverage can often be obtained at significant savings. The average cost for a flood insurance policy is around $500 per year. Further, homeowners may qualify for a Preferred Risk Policy that covers both a structure and its contents for as little as $112 per year. Coverage for renters starts at just $39 a year. Talk to your insurance agent to determine the appropriate level of protection you need and the money savings options that are available.