Flooding & Flash Flooding

Floods are one of the most common hazards in the U.S. and the State of Florida. While flooding does result from hurricanes, flooding can also occur during winter storms as well as prolonged summer thunderstorm activity. All floods are not alike. Riverine floods develop slowly, sometimes over a period of days. Flash floods can develop quickly, sometimes in just a few minutes. Overland flooding occurs outside a defined river or stream, such as when a levee is breached. Flooding also can occur from a dam break, producing effects similar to flash floods.

Flooding also has become the most deadly hurricane impact in the last 30 years. Rainfall associated with hurricanes varies with hurricane size, forward speed and other meteorological factors. The rainfall associated with a hurricane is from 6 to12 inches on average, with higher amounts common. As warnings have increased and coastal evacuation plans have become more sophisticated, the deaths associated with storm surge have been reduced significantly. However between 1970 and 1999, more people lost their lives from freshwater flooding than any other tropical storm hazard.

Flooding, like drought, is a natural event, part of the normal water cycle. Flooding disasters, however, are another matter. They usually result from a failure to understand the natural systems of our environment. In fact, flooding is the most common and expensive hazard facing the State due to our development in floodplains and the frequency of flooding events.

Realizing that tax dollars could be saved and disasters avoided through adequate planning, the National Flood Insurance Program (NFIP) was established. The NFIP provides flood insurance to residents in communities that adopt appropriate standards and land use controls. The Federal Emergency Management Agency (FEMA) through the National Flood Insurance Program (NFIP) has identified areas that have a 1% chance or greater of flooding in any given year, referred to as the 100-year flood plain. These areas have been delineated on Flood Insurance Rate Maps (FIRMs) for most flood-vulnerable jurisdictions in the country. The maps also identify the elevation of the flood waters from the hypothetical 100-year storm. Structures within the floodplain must be built at or above the Base Flood Elevation (BFE).

The big boom of development along the Florida’s coastline in the early 1970’s has left a legacy of existing coastal development built before the floodplain regulation of the NFIP and coastal management legislation. This has resulted in significant property losses for homeowners. Florida has more than 1,500 repetitive loss properties, properties that have had more than 4 flood losses in the last 10 years.

Most communities in the State of Florida (which contain floodplains) are participants in the NFIP. In addition, most of those communities participate in the Community Rating System (CRS) that encourages local governments to enact policy and procedures that further promote preparedness and mitigation. Floodplain managers, CRS Coordinators and LMS Coordinators meet through different committees to address common major issues relating to flood hazard mitigation.

First you must determine if your facility is located in flood-vulnerable areas. Contact your community's flood plain management/planning office to determine if it is in the 100-year flood zone and if there is a history of flooding in the area. Local officials can give you valuable information on how to prevent flood damage through flood proofing, such as:

Locating outside of the floodplain unless the facility and utilities are elevated above the BFE.
Constructing barriers such as levees, berms, and floodwalls to stop floodwater from entering the building.
Sealing walls in basements with waterproofing compounds to avoid seepage.

They will be able to tell you what the policies and regulations are regarding construction and redevelopment.

Flooding Myths & Facts

MYTH: Flooding occurs only at low elevations along the coast.
FACT: Flooding is a result of elevation, drainage, soil type and surrounding development. It occurs along the coast and rivers as well as inland. More than 30% of the land in the State of Florida is in the flood plain.

MYTH: My property insurance policy will cover damage if we are flooded.
FACT: Flood damage is only covered under a separate flood insurance policy.

MYTH: Freshwater flooding is bothersome but not dangerous.
FACT: While traditionally riverine flooding was not considered life-threatening, over the past thirty years, it has become the leading cause of death from tropical storms and hurricanes. These deaths are primarily the result of driving through flooded roadways and children playing in flood waters.

If flood waters threaten...Know the terms used to describe flooding:

Flood Watch - Flooding is possible. Stay tuned to National Oceanic and Atmospheric Administration (NOAA) Weather Radio or commercial radio or television for information. Watches are issued 12 to 36 hours in advance of a possible flooding event.
Flash Flood Watch - Flash flooding is possible. Be prepared to move to higher ground. A flash flood could occur without any warning. Listen to NOAA Weather Radio or commercial radio or television for additional information.
Flood Warning - Flooding is occurring or will occur soon. If advised to evacuate, do so immediately.

Flash Flood Warning

Flood Safety Tips

Purchase a NOAA Weather Radio with battery backup and a tone-alert feature that automatically alerts you when a Watch or Warning is issued (a tone alert is not available in all areas). Purchase a battery-powered commercial radio and extra working batteries.
Be prepared to evacuate. Learn your community's flood evacuation routes and where to find high ground. See the Preparedness Information Center for direction to this important information.
Be prepared to be "on your own" for at least three days. Assemble a disaster supplies kit for each facility. Keep a stock of food and extra drinking water.

For more information, see the Appendices in the Guidebook Flood Safety Checklist (Checklist 7) and Emergency Evacuation Procedures (Checklist 1).

Tips on Flood Insurance

Consider purchasing flood insurance. Flood losses are not covered under standard property insurance policies.
FEMA manages the National Flood Insurance Program, which makes federally-backed flood insurance available in communities that agree to adopt and enforce floodplain management ordinances to reduce future flood damage.
Flood insurance is available in most communities through insurance agents.
There is a 30-day waiting period before flood insurance goes into effect, so don't delay.
Flood insurance is available whether the building is in or out of the identified flood-prone area.
If your community participates in the NFIP, it has adopted a Flood Plain Management Ordinance that regulates development within the 100-year flood plain. This allows residents and businesses to purchase flood insurance through the federal government. The Flood Plain Management Ordinance requires new construction and reconstruction to elevate up to or above the Base Flood Elevation (BFE) to reduce the risk of flooding in the building itself. After a disaster, this can become a major challenge. The rule requires structures damaged more than 50% of the value, to be rebuilt to current standards including elevating the structure above the base flood elevation. Your NFIP flood insurance policies automatically provide this coverage up to $20,000. However, this may not cover the amount necessary to rebuild to current codes. Many other commercial policies do not. Business owners in the flood plain should purchase additional "replacement" coverage in case the facility is damaged by wind or fire.

If you have questions about the program, contact your municipal government. If you work in an unincorporated area, call the County Planning or Building Department.