Understanding disaster risk: flash floods

by Sunday News Online | Sunday, Mar 4, 2018 | 237 views

THE ability to prepare for disasters comes after full knowledge of the hazard and the risks has been acquired. Knowledge and awareness of prevailing hazards for certain times of the day, months and seasons must be maintained at all times. The rainy season is usually characterised by flooding, thunderstorms and lightning.

The Sendai Framework of action which is acting as a guideline in all disaster risk reduction activities from 2015-2030 has “understanding disaster risk” as its first priority. Policies and practices for disaster risk management should be based on an understanding of disaster risk in all its dimensions of vulnerability, capacity, exposure of persons and assets, hazard characteristics and the environment. Such knowledge can be leveraged for the purpose of pre-disaster risk assessment, for prevention and mitigation and for the development and implementation of appropriate preparedness and effective response to disasters.

Disaster risk refers to the likelihood of loss of life, injury, destruction and or damage due to the occurrence of a disaster. Flash floods can be defined as a sudden and destructive rush of water down a narrow gully or over a sloping surface, caused by heavy rainfall. Flash floods are a result of different factors as environments differ from place to place.

In most urban settlements despite intense precipitation, flash floods are mainly a result of poor drainage systems. This can be likened to Harare CBD where most drains are now blocked due to the increase in disposal of solid waste in the storm drains hence interrupting the normal flow of water whenever it rains. The risks associated with such floods in the urban settlements include, collapse of structures, sweeping away of vehicles, contamination of water sources and even road traffic accidents due to slippery roads and bad vision.

One can cross a river while its levels are normal and when they return they cannot manage to cross through as the immediate intense rains would have filled the water source to its above maximum levels. Such are the risks associated with flash floods. They can make bridges be submerged in water thus making movement or transportation almost impossible. The obvious result of persistence in crossing a flooded river is drowning which might eventually cause loss of life if urgent assistance is not provided.

A flash flood warning is issued when a flash flood is imminent or is already occurring. You should:

- Move to higher ground immediately or stay on higher ground.
- Keep your TV or radio on and evacuate if necessary
- Keep your cellphones switched on, in case service providers sends warning messages and so as to contact emergency providers.

If you’re at home:
- Bring in outdoor furniture and move indoor furniture to a higher floor if possible.
- Unplug all electrical appliances.
- Turn off your gas and electricity at the main valve (if instructed) to help prevent fires and explosions.
- Climb to the highest place you can.

If you’re driving:
- Move to higher ground immediately and avoid stopping near streams, rivers, or creeks
- Never drive through flood water as advised by the Traffic Safety Council of Zimbabwe, even if it looks shallow. It may be deeper than it looks and just 2 feet of water can sweep your car away.

Impacts of flash floods
- loss of human and animal life
- damage to property and infrastructure
- destruction of crops
- deterioration of health conditions owing to water-borne diseases

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