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FLOODS
Floods are one of the most common hazards in the United States. However, 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, without any visible signs of rain. Flash floods also often have a dangerous wall of roaring water that carries a deadly cargo of rocks, mud and other debris, which can sweep away many things in its path. Overland flooding occurs outside a defined river or stream, such as when a levee or dam is breached. Flooding can also occur from a dam break producing effects similar to flash floods.
Be aware of flood hazards no matter where you live, but especially if you live in a low-lying area, near water or downstream from a dam. Even very small streams, gullies, creeks, culverts, dry streambeds or low-lying grounds that appear harmless in dry weather can flood.
What to Do in a Heavy Rainfall
Stay away from stream beds. Natural stream beds, gullies and other drainage channels are not safe during and after rainstorms. Water runs off higher elevations very rapidly. One minute a creek bed is dry, the next minute flood water, rocks, mud, trees and other debris are raging down the hill.
Use your map. Know where you are, and whether you are on low ground, or below a dam. You don’t have to be at the bottom of a hill to be a target for the dangers of flash flooding.
Move to higher ground. Many roads and trails parallel existing drainage patterns, and may be swept away by flood waters. Stay out of these low-lying areas when there is a possibility of flash flooding.
Never attempt to outrun a flood on foot or in your vehicle. You can’t out run or out drive a flood. Stop the car, get out and climb to safety. If you are in a canyon, try to climb directly up the hillside.
Never try to drive through flooded areas. Twelve inches of water will float most vehicles. Flood water can rise up quickly and sweep your vehicle away. If an area is flooded, take an alternate route. Chances are you won’t be able to see how deep the water is, the strength of the current or the condition of the road underneath. Many people have died trying to drive through flooded areas.
Abandon stalled vehicles in flooded areas. If your vehicle stalls in flood water, get out and climb higher as soon as possible—before the water picks up speed and you can’t get out at all.
Before a Flood
1. Know these National Weather Service terms:
w Flash Flood Watch means that heavy rains are occurring or may occur—and may cause flash flooding in certain areas. Be alert. A pending flood may require immediate action.
w Flash Flood Warning means that flash flooding is occurring or imminent on certain streams or designated areas. If you live in the warning area you should act immediately.
w Small Stream and Urban Flood Advisory is issued when minor flooding is occurring or expected. In periods of heavy rain, be prepared to protect yourself against the possibility of flash flooding. If you see any possibility of a flash flood where you are, move immediately to a safer location (don’t wait for instructions to move). Notify local authorities of the danger so other people can be warned, especially during periods of heavy rainfall thunderstorms. For additional information, contact the Jefferson County Emergency Management Office at (303) 271-4900
2. Ask local officials whether your property is in a flood-prone or high-risk area. (Remember that floods often occur outside high-risk areas.) Also ask how you can protect your home from flooding.
3. Identify dams in your area and determine whether they pose a hazard to you.
During a Flood
1. Be aware of possible flash flooding hazards. If there is any possibility of a flash flood, move immediately to higher ground. Do not wait for instructions to move.
2. Listen to radio or television stations for local information.
3. Be aware of streams, drainage channels, canyons or other areas known to flood suddenly. Flash floods can occur in these areas without such typical warning signs as rain clouds or heavy rain.
4. If local authorities issue a flood watch, prepare to evacuate.
w Secure your home. If you have time, tie down or bring outdoor equipment and lawn furniture inside. Move essential items to the upper floors.
w If instructed, turn off utilities at the main switches or valves. Disconnect electrical appliances. Do not touch electrical equipment if you are wet or standing in water.
w Fill bathtubs with water in case water becomes contaminated or services cut off. Before filling the tub, sterilize it with a diluted bleach solution.
5. Do not walk through moving water. Six inches of moving water can knock you off your feet. If you must walk in a flooded area, walk where the water is not moving. Use a stick to check the firmness of the ground in front of you
6. Do not drive into flooded areas. 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 water will wash away almost all vehicles. If floodwaters rise around your car, abandon the car and move to higher ground, if you can do so safely. You and your vehicle can be quickly swept away as floodwaters rise.
After a Flood
1. Avoid floodwaters. The water may be
contaminated by oil, gasoline or raw sewage.
The water may also be electrically charged
from underground or downed power lines.
2. Avoid moving water. Moving water only six inches deep can sweep you off your feet.
3. Be aware of areas where floodwaters have receded. Roads may have weakened and collapse under the weight of a car.
4. Stay away from downed power lines and report them to the power company.
5. Stay away from designated disaster areas unless authorities ask for volunteers.
6. Return home only when authorities indicate it is safe. Stay out of buildings if surrounded by floodwaters. Use extreme caution when entering buildings. There may be hidden damage, particularly in foundations.
