INCREASING numbers of people in Europe are being killed by flash floods like the one that left about 100 holidaymakers dead yesterday at a campsite in the Spanish Pyrenees.
Although so called freak storms, particularly heavy localised thunderstorms, have always been part of the weather pattern the destruction they cause nowadays is greater.
This is mainly due to the way that man has changed the landscape. To gain more land, planners put rivers in channels too narrow to accommodate floods. Houses are built on flood plains and in mountains natural vegetation has been cut down. Forests and alpine meadows used to soak up the rain like a sponge and slow down the flood. New roads and tracks provide rapid run off and can increase flows off the land 200 per cent.
Soil erosion on disturbed mountainsides, particularly during two day intense rainstorms like the fatal one 860 metres (2,800 ft) up in the Pyrenees, causes a series of dams in streams and ditches. When one mini dam bursts a chain reaction can set in, causing extraordinary devastation in a few minutes. Thousands of tonnes of mud and rock can come cascading down mountainsides crushing cars and houses.
Italy, southern France and Spain have been particularly prone to such floods in the last two or three years. In north east Italy yesterday, rescue workers said they had evacuated nearly 100 people after a landslide filled dozens of homes with mud and stones. The slide followed torrential rain on Wednesday night in the Italian Alps near the ski resort of Cortina D'Ampezzo.
Eleven people were killed in the Tuscany region of Italy in June when ferocious storms caused mudslides and rivers burst their banks. Bridges and cars were swept aside and houses submerged.
In Spain last August 11 people were killed in the central town of Yebra after a sudden storm.
More than six inches of rain in 24 hours caused flash floods in southern France which killed four people in January. Three of the dead were from one family - a brother and sister, aged 10 and 12 and their mother drowned when their caravan was swept away.
In November 1994 32 people were killed in northeast Italy and southern France when storms swept through the region causing a series of landslides and river bridges to be swept away.
Britain also has regions where such a danger exists after storms. The village of Polperro in Cornwall is prone to flash flooding and uses a warning system. If a large amount of water is detected higher in the river it sets off a siren in the village. Polperro suffered a flash flood a year and a half ago when the narrow river channel through the village could not cope with the quantity of water.
Although there is no evidence that any of the recent floods in Europe have anything to do with climate change, the increasing intensity of rainstorms in Europe is one of the predictions of the Intergovernmental Panel on Climate Change which reported in June. It says that when rain comes it will fall in shorter bursts in much larger amounts bringing dangers of sudden floods.