Meteorological Office sees gloomy future for flood prospects

A weather expert from the Meteorological Office’s Hadley Centre revealed that new methods of forecasting UK weather patterns show an even more flood-filled future than was previously estimated. There are also grave problems for locating new developments which will have to be constructed in the next few years, delegates heard at the 21 March conference Sustainability – Development and Flood Risk in London, organised by the Chartered Institution of Water and Environmental Management (CIWEM).

Using preliminary studies of regional climate models, Dr Richard Jones, Manager of Regional Predictions at the Hadley Centre, said that new methods for predicting UK weather patterns have foreseen at least a doubling of “extreme precipitation”, the heaviest 10% of precipitation events, within this century. By observing patterns from 1961 to 1995, Jones said that the mean of extreme precipitation events has already increased by 60%. Although the models are by no means complete, Jones said, the new methods have a highly increased resolution allowing forecasters to predict regional variations more accurately. For example, detailed examinations of the river catchments of Lewes, York and Shrewsbury, the three towns most affected by flooding in 2000, showed a much higher predicted occurrence of one and seven -day extreme precipitation events in years to come, as well as substantially reduced return periods between events.

By 2080, Jones said, there will be significantly more rain during the winter in South West England and across Wales, and significantly less in North West Scotland, while all other areas will experience more winter rain but not to such a dramatic extent. During the summer, the south and east of England will become significantly drier, whilst the rest of the UK will be wetter. By 2080-2100, UK winter temperatures will have increased by 3-4.5 °C and summer temperatures by 2.5-4 °C, Jones said.

These predictions do not bode well for current UK development plans, which will already need to involve building on floodplains, flood defence and development experts from the Environment Agency and the DETR said, despite the Deputy Prime Minister’s recent promise to limit building in flood risk areas (see related story). There has already been a steady increase over the last five years in the number of planning applications for development in floodplains, delegates were told. In 2000, 223,000 planning applications for houses were submitted, of which some 9% are in floodplains. If this trend were extrapolated to the 3.8 million houses proposed by 2021, 342,000 additional houses would be built in flood risk areas. “This does not add up to a sustainable community,” commented Peter Bye, Chairman of the Anglian Region’s Flood Defence Committee.

Besides this, there is evidence that development within floodplain areas attracts further development, and an even greater dependence on flood defences, delegates heard and the updated Planning Policy Guidance Note 25 will not solve the problems of flooding, David Brook from the DETR’s Planning Directorate said. Firstly, it only covers new development, and secondly flood risk may still be outweighed by other factors in favour of development, he said. “How do we provide the houses which we are obliged to do, once we remove the possibility of building in the greenbelt?” asked Jean Venables, from the Thames Region’s Flood Defence Committee . “Therefore we are only left with flood plains.”

Lewes’ Director of Planning and Environmental Services, Lindsay Frost, said that there were serious tensions between national and regional policy on sustainable development. In Lewes, 3900 new homes are required by 2006, but with only a limited number of brownfield sites, and severe restrictions on flood risk building, outlying greenfield sites may be forced to bear the brunt of new development. “This is a situation not unique to Lewes, but occurring up and down the country,” Venables commented .