Flood Prevention
Brute Force and Sandbags? If wild weather becomes the norm we`ll need smarter ways to deal with it.
Seven years ago it was people living along the Mississippi who saw floods sweeping through their homes. Earlier this year it was Mozambique, then the European Alps and Vietnam. Now it`s Britain`s turn to see normally placid rivers in full spate, reclaiming their natural flood plains from the high streets, car parks and backyards. But what is the cause?
The weather is always unruly. Most weeks, by sheer chance, some kind of weather record is broken somewhere, and now it`s Britain1s turn. But there may be more to it than chance. Copies of a report from the UN`s Intergovernmental Panel on Climate Change, confirms that during the past century `there has been an increase in heavy and extreme precipitation events in the mid and high latitudes of the northern hemisphere`.
This pattern could have many causes. One is that we are finally beginning to see the effects of man-made climate change. The world is demonstrably getting warmer, and many climate models predict that warming will make winters in the northern Europe wetter. We can`t say that global warming has `caused` a particular downpour in Britain or the Alps, Vietnam or Mozambique. Weather is too random for that. But global warming may well be shifting the probability that extreme weather will occur. And probability is crucial in our practical response to climate change.
In England and Wales, the Environment Agency designs barriers to cope with the severest floods expected in a hundred years. This year`s events will force it to recalculate the odds, just as earlier floods are forcing recalculations elsewhere.
One lesson everyone should have learned is that massive engineering works aren`t necessarily the answer. The US spent $7 billion over 60 years trying to contain the Mississippi, but that didn`t stop the floods of 1993. In Britain, the Environment Agency has been warning for years that towns and villages have made themselves increasingly vulnerable to heavy rain. The water meadows and ploughed fields, lakes and bogs that once soaked up storm waters are losing their capacity to do so. The risk of flooding rises every time a farmer plants a field that was formerly left bare over the winter, or a developer concrete a patch of green for a superstore. Or indeed, when flood defences are raised somewhere upstream. Flood defences that cut rivers off from their flood plains just shift the danger elsewhere. The US are busy tearing down levees on the Mississippi and giving the river back some of its flood plain. The Germans and the Dutch plan the same on the Rhine.
Rivers need space. If that means changing the way land is farmed or stopping certain kinds of development, so be it. It is too late to halt global warming in its tracks. To deal with the increasing unpredictable and extreme rainfall it will likely bring, we have to work with nature rather than try to defeat it.
If you wish advice on a flood prevention scheme for your property please contact David direct.
