Flooding may be caused by the overflowing of rivers, lakes, and reservoirs initiated by unexpectedly heavy rain fall. Keep in mind that the rain does not necessarily have to be in the area of the flooding itself. It may have rained elsewhere with the subsequent waters flowing to the flood location. Flooding may also be caused by the build up of sea or lake water due to the effects of an underwater earthquake, hurricanes, freak high tides and winds or even by the collapse of dams or dykes.
Heavy rain can rapidly produce torrents in once-dry riverbeds, or build up in a narrow channel of behind a barrier that subsequently collapses due to the force of rushing water that envelopes everything in its path.
Persistent rain over a long period of time, especially after a prolonged dry spell combined with heavy storms should alert you to keep clear of water channels and low-lying ground. However, do not be deceived, a flood can affect much wider areas. It is always safer to camp on a spur and move to higher ground if you detect rising waters. In hilly areas, keep out of valley bottoms which are particularly prone to flash floods.
Food is not likely to be a problem at first because animals will also head to higher ground. Both predators and prey are likely to focus on getting to safety. However, beware of possible injury from panic-stricken animals in the water.
Drinking water may be difficult to obtain as the water swirling around is may be contaminated. Collect rainwater to drink and boil any other water before use.
Flooded Buildings
If you are in a solid building when the water begins to rise, stay where you are if it is rising rapidly. You will be at less risk to injury than trying to evacuate on foot. Turn off the gas and electricity, prepare emergency food supplies, warm clothing and drinking water in screw-topped plastic bottles or other well-sealed containers.
It is important to keep all containers sealed to avoid any accidental contamination or spillage. If you can collect the following items:
- Flashlight
- Whistle
- Mirror
- Brightly Colored Flags or Cloths (for signaling)
- Camp Stove (for heating food and drinks for warmth)
- Candles
- Matches
It is a very good idea to obtain an emergency kit that has all of these items already included and to keep it in a safe, but quickly accessible place in case there is little time to react, much less gather necessary items.
Move Upwards
Move to an upper floor, if possible, and to the roof if you are in a single story building. If you are forced to the roof, create some kind of shelter. If the roof is sloping, tie everyone to the chimney stack or other roof structure that can be expected to remain firm. In the event the water continues to rise, prepare some kind of raft. If there are no ropes available, use bed sheets. Unless the water threatens to wash your building away, or rises so high that you are forced to evacuate, stay until it stops rising.
Flood Readiness
If you live in a river valley or a coastal region that is prone to flooding, find out how high you are above the normal water levels. Familiarize yourself with the easiest route to high ground. It won’t necessarily be the commonly used highway route as major roads tend to follow drainage channels in valley bottoms. In rainy periods be aware of flood warnings which will often predict the levels to which waters may be expected to rise and the areas that are likely to be affected.
A few inches of floodwater may not sound like much but it can do an enormous amount of damage. I remember one Christmas morning at my Grandmother’s house where the basement flooded due to an unseasonably powerful thunderstorm. There was only about two inches of water, but it took us all morning to get the basement cleared, and that is with an in-ground drain.
Trust me, It is definitely worth the time to lay sandbags or plastic shopping bags filled with earth along the bottom of doorways and windows to keep the water out. If you are in a really solid building and the doorways, windows and other apertures are well blocked, water will not enter. Also, the central heating flue, ventilation blocks and other spaces must all be sealed.
If a high flood is expected, there is no point in trying to keep water out of basements – trust me on this, I’ve tried. Indeed, in some houses with basements this could cause extra damage due to uneven pressure on the walls. Personally, I’ve seen flood damage cause concrete walls to “shed” their outer skin and reveal the more vulnerable interior. If this flooding is consistent (as it was in my case), the walls begin to thin, lose strength and cause the house to settle unevenly.
If you are bound to be flooded anyway, you could consider flooding the basement yourself with clean water so that the pressure is equalized. Bottom line is that you will have less filth and debris to clean up later.
Evacuation
If you are abandoning your home, bring in all outdoor furniture and other mobile objects as this will reduce the amount of debris floating or being swept along outside.
Be careful when walking or driving to a safer location: a small drop in the level of the roadway down a hill can make a considerable difference to the water depth.
Do NOT attempt to cross a pool or stream unless you are CERTAIN that the water will not be higher than the center of the car’s wheels or higher than your knees.
If you MUST cross: use river-crossing techniques (see On the Move: under Make Camp).
If crossing bridges which are underwater: take special care – you may not be able to see that the flood has already swept part of the bridge away.
Flash Floods
When incidents of heavy rain occur, stay out of valley bottoms and stream beds both during and after the rainfall. Always remember that you don’t have to be at the bottom of a hill to be caught by rushing water – often carrying mud and a deadly debris combination of broken trees and rocks among other things.
I’ve experienced flash flooding, it’s a surreal experience. Solid ground becomes covered with water almost immediately and it’s EVERYWHERE. There is no place to run or hide unless you can find higher ground. I’ve seen cars swept away along with people and items I considered unmovable. As mentioned in the Tsunami section, there is no defense against a wall of moving water.
Coastal Flooding
This type of flooding is caused by the unusual combination of high tides and winds which make them even higher. Flood warnings will usually include information concerning this possibility and evacuation is the best action.
Flood Aftermath
As flood waters recede, then leave a scene of destruction, devastation and chaos. This will include all kinds of debris including, unfortunately, the bodies of flood victims. With the expected decay, combined with water pollution, comes the risk of disease and therefore, extra precautions are required.
Burn all animal corpses – do not risk eating them – and boil all water before using. Some crops may still be available after the floodwaters recede and birds that have escaped the flood will be safe and good to eat.