There is currently a tendency for the UK to look towards the Netherlands for models of how to deal with flood risk. This is a sensible option if considering seasonal flooding of low lying or coastal areas. But a meeting held at the Academy today studied the case for looking further afield to areas of the world that routinely deal with tropical downpours, because the nature of the flooding risk in the UK is changing, with rain-triggered flash flooding becoming more common.
“Catastrophic flooding events are now more often caused by summer storms than by relentlessly rising rivers during wet winters,” said Dr Scott Steedman FREng. “Summer downpours, such as those at Boscastle, Morpeth, Tewkesbury and Crewkerne, are set to become more common as forecasts of more extreme weather events accompany predictions of climate change.”
Dealing with tropical downpours has been a routine matter for generations of Malaysians. Dato’ Ir. Husaini Sulaiman, Director General of the Department of Irrigation and Drainage at Malaysia’s Ministry of Natural Resources and Environment, told the Academy how the drainage systems have been upgraded and improved in cities across the country. Kuala Lumpur, centred on the confluence of two rivers, experiences major flooding on a regular basis and the latest innovation is the recently opened SMART motorway tunnel that can double as a storm drain during monsoon rains – see Ingenia magazine’s article at www.ingenia.org.uk/ingenia/issues/issue30/Darby.pdf
Coping with the rapid fall and dispersal of a summer downpour is more complicated than making sure the current drainage system is working properly or upgrading it. New thinking in terms of design and short-term storage of run-off is required along with specific measures that can be used as the normal drainage system becomes overwhelmed, because relying on foulwater drains can result in foulwater overflowing the system as has been seen in London on a number of occasions, resulting in severe pollution of the River Thames.
The risk of flash flooding is particularly acute in Wales, and Peter Jones of the Welsh Assembly Government told the meeting that they are moving from responding to flooding events to active management of the risk. Professor Roger Falconer FREng, Halcrow Professor of Water Management at Cardiff University, used the Boscastle flooding to show how simple engineering solutions could reduce the level of flooding. Fencing off rivers in risk areas, for example, would help to stop cars being washed into the flowing water and compounding the problem.
Michael Norton MBE, Managing Director Water and Power at Halcrow, spoke of the company’s work around the world in managing flood risk and designing sustainable urban drainage systems. These schemes centre on making room for flood water and storing it temporarily until it can be released more slowly into the drainage system.
Notes for editors
Founded in 1976, The Royal Academy of Engineering promotes the engineering and technological welfare of the country. Our fellowship – comprising the UK’s most eminent engineers – provides the leadership and expertise for our activities, which focus on the relationships between engineering, technology, and the quality of life. As a national academy, we provide independent and impartial advice to Government; work to secure the next generation of engineers; and provide a voice for Britain’s engineering community.
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