According to the National Weather Service, floods/flash floods are the #1 cause of weather-related fatalities in the United States, and many victims die in their cars. It only takes 6” of swiftly moving water to knock you off your feet, and only 2’ of water to float a car.
The causes of flash flooding can include -
- heavy rainfall in a short period of time - one inch per hour or more
- over-saturation of the ground, when the soil cannot absorb any more water
- prolonged rainfall that results in high water levels in rivers and streams
- debris jams in rivers and streams, which cause water to back up and overflow the banks
- urbanization - lots of buildings and parking lots where fields and woodlands used to be
It is important to consider these last two, as they are within our collective control. How we choose to develop our land, and whether or not we dispose of trash and debris properly, can have a tremendous impact on the possibility of flash flooding in our county.
"Human activity that changes the surface of the Earth also affects the water cycle, and can cause floods. Buildings, parking lots and roads, replace grass and dirt with concrete. Under normal circumstances, soil acts like a sponge and soaks up a fair portion of rainwater. But in crowded towns and cities, rainwater flows into storm sewers and drainage ditches, and, at times, overloads them. An urban area can be flooded by an amount of rainfall that would have had no impact in a rural area.
The destruction of the nation's wetlands may also contribute to moderate floods. The wetlands are the swampy land along the edges of some rivers. When it rains, the wet soil and mud of a wetland acts like a sponge and stores the extra water. But much of America's wetlands have been drained for farmland or to build houses. The only place flood water can go is up and over its normal riverbanks and into areas where it can cause major damage." PBS Newshour
Old North Knoxville leads a cleanup of First Creek twice per year, and I am always amazed at the amount of trash we pull out of the creek. And we're not just talking about fast food bags and plastic drink bottles - we pull out shopping carts, clothing, building materials, furniture, and at the last cleanup, a pay phone!
The issue of flooding is closely related to the proposed Knox County Stormwater Ordinance, which is scheduled for a vote at this month's County Commission meeting. Tomorrow I plan to attend the Commission's workshop on the Stormwater Ordinance, and will write more about this issue then.
In the meantime, you might want to check out the following website to learn more about floods/flash floods and how to prepare, survive, and recover from them:
http://www.disastercenter.com/guide/flood.html
Flood Safety
Stay out of areas subject to flooding. Dips, low spots, canyons, washes, etc., can become filled with water.
If outdoors, climb to high ground and stay there. Move away from dangerous floodwaters.
If you come upon a flowing stream where water is above your ankles, stop, turn around, and go another way. Never try to walk, swim, or drive through such swift water. Most flood fatalities are caused by people attempting to drive through water, or people playing in high water. If it is moving swiftly, even water six inches deep can sweep you off your feet.
What to Do if You Are Driving During a Flood
Avoid already flooded areas, and areas subject to sudden flooding. Do not attempt to cross flowing streams. Most flood fatalities are caused by people attempting to drive through water, or people playing in high water. The depth of water is not always obvious. The roadbed may be washed out under the water, and you could be stranded or trapped. Rapidly rising water may stall the engine, engulf the vehicle and its occupants, and sweep them away. Look out for flooding at highway dips, bridges, and low areas. Two feet of water will carry away most automobiles.
If you are driving and come upon rapidly rising waters, turn around and find another route. Move to higher ground away from rivers, streams, creeks, and storm drains. If your route is blocked by flood waters or barricades, find another route. Barricades are put up by local officials to protect people from unsafe roads. Driving around them can be a serious risk.
If your vehicle becomes surrounded by water or the engine stalls, and if you can safely get out, abandon your vehicle immediately and climb to higher ground. Many deaths have resulted from attempts to move stalled vehicles. When a vehicle stalls in the water, the water's momentum is transferred to the car. The lateral force of a foot of water moving at 10 miles per hour is about 500 pounds on the average automobile. The greatest effect is buoyancy - for every foot that water rises up the side of a car, it displaces 1,500 pounds of the car's weight. So, two feet of water moving at 10 miles per hour will float virtually any car. Many persons have been swept away by flood waters upon leaving their vehicles, which are later found without much damage. Use caution when abandoning your vehicle, and look for an opportunity to move away quickly and safely to higher ground.
What to Tell Children
If you come upon flood waters, stop, turn around, and go another way. Climb to higher ground.
If it is moving swiftly, even water six inches deep can knock you off your feet. Many people are swept away wading through flood waters, resulting in injury or death.
Stay away from flooded areas. Even if it seems safe, flood waters may still be rising. Never try to walk, swim, drive, or play in flood water. You may not be able to see on the surface how fast flood water is moving or see holes and submerged debris.
If you are in a vehicle and become surrounded by water, if you can get out safely, do so immediately and move to higher ground. Vehicles can be swept away in two feet of water.
Watch out for snakes in areas that were flooded. Flood waters flush snakes from their homes.
Stay away from creek and stream banks in flooded and recently flooded areas. The soaked banks often become unstable due to heavy rainfall and can suddenly give way, tossing you into rapidly moving water.
Never play around high water, storm drains, ditches, ravines, or culverts. It is very easy to be swept away by fast moving water.
Throw away all food that has come into contact with flood waters. Contaminated flood water contains bacteria and germs. Eating foods exposed to flood waters can make you very sick.
From http://www.disastercenter.com/guide/flood.html
Make sure your children know not to play in rising waters around creeks, ditches, and drains in your neighborhood. Not only could they be swept away, they could come into contact with bacteria, chemicals, and other contaminants that could be dangerous to their health!
