Flood managementWhat tropical countries can teach the U.K. about flood management

Published 20 November 2009

Climate change has caused a change in the patterns of rainfall in the United Kingdom: rather than a procession of predictable showers, a new type of rain emerged — localized storms, dropping a lot of water in one place over a short period of time; villages and towns were overwhelmed; tropical countries have had a long experience with the type of rainfall

It rains in Britain in the summer; persistently and, until relatively recent years, predictably. The summer weather systems would see periods of good weather interspersed with weather fronts sweeping from Cornwall up toward the north-east coast, trailing curtains of rain.

Stuart Nathan writes that this changed, unexpectedly and catastrophically, in June and July 2007. Rather than a procession of showers, a new type of rain emerged — localized storms, dropping a lot of water in one place over a short period of time. Villages and towns were overwhelmed.

In Boscastle, a river burst its banks and swept cars down the steep valley into the heart of the village, where they formed a dam and allowed water to inundate the town and harbor. Tewkesbury’s historic abbey was surrounded by floodwater on a newly-formed island. The civil and military emergency services estimate that the rescue efforts were the biggest ever launched in peacetime.

It has become obvious that the water management infrastructure in many areas was inadequate to manage this type of rainfall. Urban planning engineers are now starting to turn to other countries for advice; countries where localized heavy rainfall is more common. Odd though it may seem, the chilly, damp United Kingdom is looking to the tropics. “We are looking to take lessons from wherever we can,” said Scott Steedman, vice-president of the Royal Academy of Engineering.

Wales, with its particularly soggy reputation, is looking closely at all options. “We’re well aware that we were lucky in 2007,” said Roger Falconer, professor of water management at Cardiff University. “If the weather systems had been a little to the west, we would have borne the full brunt.”

Currently, urban flood management in most towns is limited to the Victorian infrastructure of drains feeding into the pipes under the streets. “Almost every major city in the UK is facing similar problems,” added Falconer.

Other countries employ many techniques to control floodwaters, some of which may be more applicable to the United Kingdom than others. The best method, Falconer said, is “to create room for the water.” This involves planning areas of parkland in the zone where flooding is likely to occur, and diverting water into these when appropriate. This technique was used in Cardiff around the new Millennium Stadium.

Asian cities tend to have large open drain channels at the roadside, with further drainage down the middle; a technique