Images: Wunderground + SAT24 (Click on images for larger view.)
Flash flooding occurs when precipitation falls rapidly on saturated soil. The runoff collects in gullies and streams and, as they join to form larger volumes, often forms a fast flowing front of water and debris.
MSBWX recommends that people get out of the area of a flash flood. Many people tend to underestimate the dangers of flash floods. What makes flash floods most dangerous is their sudden nature and fast moving water. A vehicle provides little to no protection against being swept away. It may make people overconfident and less likely to avoid the flash flood. More than three quarter of the fatalities attributed to flash floods in South Africa are people swept away in vehicles when trying to cross flooded rivers, bridges, ravines and roads. As little as 500cm of water is enough to carry away motor- and LDV vehicles. TURN AROUND DON'T DROWN!!
On the other hand floods can also occur in rivers, when flow exceeds the capacity of the river channel, particularly at bends or meanders. Floods often cause damage to homes and businesses if they are placed in natural flood plains of rivers. While flood damage can be virtually eliminated by moving away from rivers and other bodies of water, since time out of mind, people have lived and worked by the water to seek sustenance and capitalize on the gains of cheap and easy travel and commerce by being near water. That humans continue to inhabit areas threatened by flood damage is evidence that the perceived value of living near the water exceeds the cost of repeated periodic flooding.
Some floods develop slowly, while others such as flash floods, can develop in just a few minutes and without visible signs of rain. Additionally, floods can be local, impacting a neighbourhood or community, or very large, affecting entire river basins.
Some things to be aware of:
- be aware of any signs of heavy rain
- if you see or hear rapid rising water get to high ground
- do not attempt to cross the flowing water
- evacuate quickly and move to higher ground
- Know your location when you are driving. If you needed rescue, would you be able to direct emergency crews to your location? Be alert.
- Never drive through a flooded road or bridge. Back up and try a different route. In many cases, it takes far less than a few centimeters of water to incapacitate a vehicle. It may stall, leaving you stranded, and depending on the level of water, you may not be able to open a vehicle door. Do not underestimate the power of moving water.
- Stay on high ground. If your car is trapped, get out if you can safety do so and move to higher ground. If you're driving through a hilly area or place that is subject to flooding along a stream and hear a flash flood warning, go to high ground. Never try to outrun a flash flood.
- Watch for flooding at bridges and dips in the road. Never drive where water is over bridges or roads. The bridges or the road could suddenly be washed out. If you're driving at night, be especially careful because visibility is limited. If you should drive into water, don't try to drive out of it. Get out of the car and safely return to higher ground. Remember that rocks, tree limbs and other debris can be caught in moving water and can be dangerous if you are forced to walk, wade or swim through flood waters
- If you have to walk or wade through flood water, use a stick to poke the ground in front of you with each step. It can help you determine water levels, the bottom surface and the safest possible way to get to higher ground.
Remember that flash floods can come without warning, and sometimes without weather. Be alert and heed all warnings and recommendations from officials.
Keep safe!!
Johan Terblanche
Founder: MSBWX, SAWDOS, SAWDIS
Mossel Bay
7 January 2014
