How floods could affect your home

HUNDREDS of thousands of homes facing a potential flooding crisis in the South-East have been identified using a state-of-the-art digital map.

After the disastrous flash flood in Cornwall, experts used computer simulations of rain and flood levels to pinpoint where big increases in rainfall would hit hardest.

The map - the most detailed ever of flood-prone areas in the region - is meant to help homeowners and insurance companies decide how much flood protection is needed, and could be invaluable in assessing the effects global warming could have on the capital.

Users can zoom in on individual houses to see exactly how they will be affected.

Government figures have shown that property worth more than £220bn in England and Wales, including up to 750,000 homes in the South-East, are in flood-prone areas. And as plans for 120,000 new homes in the Thames Gateway area are finalised, experts say the new map is long overdue. John Hollis, home insurance manager at More Th>n, Royal & Sun Alliance's insurance subsidiary, said the map shows the full extent of the problem for the first time.

He said: 'Previously we have only looked at the risk for large areas, like SW11 for example. Now we can pinpoint individual full postcodes... and we are insuring a lot more people we previously might not have. We are also working on expanding our system to include details of the risks of storm damage.'

Claims for storm and flood damage rose to more than £6bn between 1998 and last year - double the previous five-year period - and are set to triple by 2050, according to the Association of British Insurers (ABI).

Mr Hollis said: 'We are seeing a lot more torrential summer downpours and the risk of flash floods is very high at the moment.

'London's flood defences, including the Thames Barrier, were designed to be effective until 2050, but there is a lot of debate over their effectiveness now.'

However, More Th>n's map will soon be eclipsed by a three-dimensional map of Britain, to be released by Norwich Union later in the year. It will take into account every detail of individual houses and streets, using airborne radars and complex cameras.

The most damaging floods of recent years were in the winter of 2000. The ABI estimated the cost to insurers at £1bn, for which policyholders are still paying through higher premiums.

While prolonged rain worries insurers, flash floods leading to storm surges are causing increasing concern.

Professor Mae Cassar, a flooding expert at University College London, said: 'We would need a very high tide and severe storms with a lot of heavy rain for the Thames to burst its banks. But I think climatologists agree it is not out of the question.'