Home » General » Take Heed of Flash Flood Warnings

Flash flooding happens every year in Zimbabwe and everyone is aware of this. Most of our rainfall is concentrated into just a third of the year, from late November to late March, and quite a lot of this seasonally concentrated rainfall comes in the form of heavy storms with occasional cyclones in the Mozambican channel intensifying these, or even every few years coming inland.

In our towns and cities, the effects of the general seasonally and storm-induced flooding can be worse. Runoff is swift from the roofs, roads, carparks and paved areas of the typical urban setting and a lot of thought has been put into the required engineering to move this water swiftly off the roads and yards into drains which all empty into the old stream and river beds.

Even these have throughout the city been artificially deepened to ensure that run-off is swiftly removed down the five rivers that actually take Harare’s runoff out of the city.

But this means that the streams and rivers criss-crossing Harare are likely to rise very rapidly within an hour of heavy rains starting to fall. And despite all the talk about wetlands the urban environment has so modified runoff that even if half the city was a wetland they would do almost nothing to stop flood problems.

To put the problem into perspective, Harare receives over a year about 40 percent more rain than the British capital of London, but with the biggest difference being that Harare’s rain falls mostly over four to five months while London’s rain is fairly evenly spread over the year. And yet even London has floods.

In rural areas the problems can be less severe, but people who live in some parts of the country, mainly flattish lands, can be flooded out when storms are heavy and rivers will rise fast at times and water levels can remain high for days, or even weeks.

Most rural communities are aware of flood risks in their area. Sometimes communities have made a decision to build on land that they know will be flooded occasionally simply because it is more convenient than building on land a long walk from fields and pastures. But then they must take heed of warnings and move before the floods come.

But for most Zimbabweans the dangers come from the rising streams and rivers. People, instead of staying put on one bank or going to the next bridge, take chances and try to ford a stream or cross a flooded bridge. Flowing water exerts very powerful forces and people and cars are swept away. The aice is simple: do not take chances.

Modern forecasting can give adequate warning about major storms and even cyclones.

Modern communications ensure that even the most remote communities can be told of the likelihood of a flood in their area in time. Many agencies, including the police, warn pedestrians and motorists every year not to take chances when they need to cross a fast flowing stream or river.

What is now needed is for people to take heed of these warnings. Then flooding is simply inconvenient, rather than life-threatening. Water brings life it does not have to bring death.

Source : The Herald