A flash flood is the swiftest, fastest type of flood. The rapid moving waters are very dangerous. Flash flooding is the leading cause of weather-related deaths in the U.S. — approximately 200 deaths per year.
Flash floods occur through torrential rainstorms and can develop in just a few hours or even a matter of minutes.
Flash floods occur within six hours of a rain event, or after a dam or levee failure, or following a sudden release of water held by an ice or debris jam, and flash floods can catch people unprepared. You will not always have a warning that these deadly, sudden floods are coming. So if you live in areas prone to flash floods, plan now to protect your family and property.
What to Do Before Flooding Occurs
- Develop an evacuation plan. Everyone in your family should know where to go if they have to leave. Trying to make plans at the last minute can be upsetting and create confusion.
- Discuss floods with your family. Everyone should know what to do in case all family members are not together. Discussing floods ahead of time helps reduce fear and anxiety and lets everyone know how to respond.
- Keep insurance policies, documents, and other valuables in a safe-deposit box.
- Avoid building in a floodplain unless you elevate and reinforce your home.
- Raise your furnace, water heater, and electric panel to higher floors or the attic if they are in areas of your home that may be flooded.
- Install check valves in building sewer traps to prevent flood water from backing up into the drains of your home. As a last resort, when floods threaten, use large corks or stoppers to plug showers, tubs, or basins.
- Construct barriers such as levees, berms, and flood walls to stop flood water from entering the building. Permission to construct such barriers may be required by local building codes. Check local building codes and ordinances for safety requirements.
- Seal walls in basements with waterproofing compounds to avoid seepage through cracks.
- Consult with a construction professional for further information if these and other damage reduction measures can be taken. Check local building codes and ordinances for safety requirements.
- Contact your local emergency management office for more information on mitigation options to further reduce potential flood damage. Your local emergency management office may be able to provide additional resources and information on ways to reduce potential damage.
When a flood is possible (Flash flood watch)
- Be alert to signs of flooding, and if you live in a flood-prone area, be ready to evacuate at a moment’s notice. Floods can happen quickly and you may need to leave with little or no notice.
- Follow the instructions and advice of local authorities. Local authorities are the most informed about affected areas. They will best be able to tell you areas to avoid.
If you live in a flood-prone area:
- Fill bathtubs, sinks, and plastic bottles with clean water. Water may become contaminated or service may be interrupted.
- Bring outdoor belongings, such as patio furniture, indoors. Unsecured items may be swept away and damaged by flood waters.
- Move your furniture and valuables to higher floors of your home. If flood waters affect your home, higher floors are less likely to receive damage.
- If you are instructed by local authorities, turn off all utilities at the main power switch and close the main gas valve. In some areas, local authorities may advise you to turn off utilities to prevent further damage to homes and the community.
- Get your preassembled disaster supplies ready. You may need to act quickly. Having your supplies ready will save time.
- Fill your car’s gas tank, in case an evacuation notice is issued. If electric power is cut off, gas stations may not be able to operate pumps for several days.
- Be prepared to evacuate. Local officials may ask you to leave if they truly feel your home is at risk from flood waters.
- If you are stopping your vehicle, camp or park away from streams and washes, particularly during threatening conditions. Flood waters can rise quickly and carry you or your belongings away.
- When in or along stream channels, be aware of distant events, such as dam breaks or thunderstorms that may cause flash floods in the area.
- Watch what’s happening. Is the weather getting worse? What are other people doing? Should you be doing the same?
- Move your car to higher ground.
- It only takes two feet of fast flowing water to wash your your car away.
- Check on your neighbors. Do they need your help Someone near you may not be able to escape upstairs. Or they may be unable to move furniture on their own.
- Do as much as you can in daylight. Doing anything in the dark will be a lot harder, especially if the electricity fails.
When a flash flood is happening (Flash flood warning)
- Use a NOAA Weather Radio or a portable, battery-powered radio (or television) for updated emergency information. Local stations provide the best advice for your particular situation.
- If it has been raining hard for several hours, or steadily raining for several days, be alert to the possibility of a flood. Floods happen as the ground becomes saturated.
- Listen for distant thunder. In some types of terrain, runoff from a faraway thunderstorm could be headed your way.
- When there is water reaching across the road you are traveling, turn around and find an alternate route. Vehicles are involved in nearly 80% of all flood deaths. A vehicle can get swept downstream in as little as eight inches of water and 24 inches of water can float most vehicles, even SUV’s.
- Most flash floods occur in the evening or at night when it is difficult to see the water over the road, so it is important to be extra vigilant during the later hours during a storm.
- Never cross a road on foot covered in water. It only takes six inches of water to knock a person down. At this point, you would be at the mercy of the current, and that is never a good place to be.
- If your vehicle stalls, get out and walk to higher ground.
- Block doors and airbricks with sandbags or floodboards. If you cannot get hold of sandbags improvise by filling old pillowcases or carrier bags with earth or sand.
- Try and keep things warm and dry. A flood can last longer than you think and it can get cold. Take some warm clothes and blankets upstairs to a safe place. Take a thermos and flood supplies too.
- If advised to evacuate, do so immediately. Move to a safe area before access is cut off by flood water. Evacuation is much simpler and safer before flood waters become too deep for vehicles to drive through.
- Follow recommended evacuation routes. Shortcuts or alternate, non-recommended routes may be blocked or damaged by flood waters.
- Leave early enough to avoid being marooned by flooded roads. Delaying too long may allow all escape routes to become blocked.
- Your disaster kit
- Your evacuation kit
- Sand bags
For after the flood, have the following supplies on hand:
- Scouring powder
- Rubber gloves
- Strong boots or heavy-soled shoes
- Tools (crowbar,hammer,screwdriver)
- Sponges and cloths
- Scrub brushes
- Throw-away containers for garbage, and container to carry
from house to street
- Water hose
- Sponge mop or mop that is easily squeezed out
- Water hose
- Bushel baskets
- Wash tubs (for soaking objects)
- Emergency building materials: plywood, plastic sheeting, lumber, nails, hammer and saw, pry bar, sand, shovels, and sandbags.
Info from NOAA and FEMA