Flood Preparation – Prepare – Activate
Did you know:
Floods are one of the most common hazards in the United States.
Not all floods are alike. Some floods develop slowly (overland flooding), while others (flash floods), can develop in just a few minutes and without visible signs of rain. Additionally, floods can be local, impacting a neighborhood or community, or very large, affecting entire river basins and multiple states.
Flash floods occur suddenly and often have a dangerous wall of roaring water carrying rocks, mud and other debris. They often occur within a few minutes or hours of excessive rainfall, a dam or levee failure, or a sudden release of water held by an ice jam.
Overland flooding is when when waterways such as rivers or streams overflow their banks as a result of rainwater or a possible levee breach. Overland flooding is the most common type of flooding event. It can also occur when rainfall or snow melt exceeds the capacity of underground pipes, or the capacity of streets and drains designed to carry flood water away from urban areas.
Be aware of flood hazards no matter where you live or work, but especially if you are in low-lying areas, near water, behind a levee or downstream from a dam. Even very small streams, gullies, creeks, culverts, dry streambeds or low-lying ground that appear harmless in dry weather can flood.
Causes of Flooding
Tropical Storms and Hurricanes –
Hurricanes pack a triple punch: high winds, soaking rain, and flying debris. They can cause storm surges to coastal areas, as well as create heavy rainfall which in turn causes flooding hundreds of miles inland. While all coastal areas are at risk, certain cities are particularly vulnerable and could have losses similar to or even greater than those caused by the 2005 hurricane, Katrina, in New Orleans and Mississippi.
When hurricanes weaken into tropical storms, they generate rainfall and flooding that can be especially damaging since the rain collects in one place. In 2001, Tropical Storm Allison produced more than 30 inches of rainfall in Houston in just a few days, flooding over 70,000 houses and destroying 2,744 homes.
Spring Thaw –
During the spring, frozen land prevents melting snow or rainfall from seeping into the ground. Each cubic foot of compacted snow contains gallons of water and once the snow melts, it can result in the overflow of streams, rivers, and lakes. Add spring storms to that and the result is often serious spring flooding.
Heavy Rains –
Several areas of the country are at heightened risk for flooding due to heavy rains. The Northwest is at high risk due to La Niña conditions, which include snowmelts and heavy rains. And the Northeast is at high risk due to heavy rains produced from Nor’easters. This excessive amount of rainfall can happen throughout the year, putting your property at risk.
West Coast Threats –
Although floods can occur throughout the year, the West Coast rainy season usually lasts from November to April. This window increases the chance of heavy flooding and flash flood risks.
Wildfires have dramatically changed the landscape and ground conditions on the West Coast, causing fire-scorched land to develop in to mudflows under heavy rain. Experts believe it will take years for the vegetation to be fully restored, which in turn will help stabilize these areas.
In addition to the heavy rains and wildfires, the West Coast has thousands of miles of levees, which were constructed to help protect homes and land in case of a flood. However, levees are not fail-proof and can, weaken, or overtop when waters rise, often causing catastrophic results.
Levees & Dams –
Levees are designed to protect hold back a certain level of water. However, levees can and do fail; and when they fail, they can fail catastrophically. Weakening of levees over time, or as a result of weather events exceeding the levee’s level of support, can cause the levee to be overtopped or breached, thus increasing the chance for flooding. Homeowners and renters insurance policies usually do not cover flood loss, therefore FEMA strongly encourages those who live and work behind levees to consider flood insurance as a dependable financial security from a flood event.
Flash Floods –
Flash floods are the #1 weather-related killer in the U.S. since they can roll boulders, tear out trees, and destroy buildings and bridges. A flash flood is a rapid flooding of low-lying areas in less than six hours, which is caused by intense rainfall from a thunderstorm or several thunderstorms. Flash floods can also occur from the collapse of a man-made structure or ice dam.
New Development –
Construction and development can change the natural drainage and create brand new flood risks. That’s because new buildings, parking lots, and roads mean less land to absorb excess precipitation from heavy rains, hurricanes, and tropical storms.
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The following are important points to remember
Flood Watch – Flooding is possible. Tune in to NOAA Weather Radio, commercial radio or television for information.
Flash Flood Watch – Flash flooding is possible. Be prepared to move to higher ground; listen to NOAA Weather Radio, commercial radio or television for information.
Flood Warning – Flooding is occurring or will occur soon; if advised to evacuate, do so immediately.
Flash Flood Warning – A flash flood is occurring; seek higher ground immediately.
When driving in flood conditions:
- Six inches of water will reach the bottom of most passenger cars causing loss of control and possible stalling.
- A foot of water will float many vehicles
- Two feet of rushing water can carry away most vehicles including sport utility vehicles (SUV’s) and pick-ups.
- Do not attempt to drive through a flooded road. The depth of water is not always obvious. The road bed may be washed out under the water, and you could be stranded or trapped.
- Do not drive around a barricade. Barricades are there for your protection. Turn around and go the other way.
- Do not try to take short cuts. They may be blocked. Stick to designated evacuation routes.
- Be especially cautious driving at night when it is harder to recognize flood dangers.
To prepare for a flood, you should take the following measures:
Build an emergency kit
Make a family communications plan.
Know your surroundings.
Learn the elevation level of your property and whether the land is flood-prone. This will help you know how your property will be affected when storm surge or tidal flooding are forecasted.
Identify levees and dams in your area and determine whether they pose a hazard to you.
Avoid building in a floodplain unless you elevate and reinforce your home.
Elevate the furnace, water heater and electric panel in your home if you live in an area that has a high flood risk.
Consider installing “check valves” to prevent flood water from backing up into the drains of your home.
If feasible, construct barriers to stop floodwater from entering the building and seal walls in basements with waterproofing compounds.
Learn community flood evacuation routes and how to find higher ground. Determine where you would go and how you would get there if you needed to evacuate.
While spring brings the promise of warm weather and longer days, it also brings a variety of conditions that can include heavy rains, severe weather, and rapid snowmelt that can increase your flood risk.
Don’t be caught off guard, get the facts and know the risks. Take action to protect yourself, your family, your business, and your finances—before a weather event occurs and it’s too late.
Use the tools here to learn the steps you can take before, during and after a flood to prepare yourself and your family.
Interactive Flood Risk Resources
For more information about floods, risk of financial loss due to flooding, and flood insurance check out
To promote Flood Safety Awareness, FEMA’s Emergency Management Institute (EMI) has developed a series of training programs to encourage flood safety. This guide provides readers with an easy way to identify and access self-paced courses designed for people who have emergency management responsibilities and the general public.
- IS 22: Are You Ready? An In-depth Guide to Citizen Preparedness
- IS 279: Engineering Principles and Practices for Retrofitting Flood-Prone Residential Structures
Printer Friendly Information You Can Use & Share
FEMA has developed these resources to educate and inform communities about the importance of flood safety awareness.
Outreach Toolkit Materials
As a leader in public information response to emergency situations, the National Flood Insurance Program (NFIP) has developed this valuable tool designed to assist your efforts to educate and inform communities about the importance of flood insurance coverage.