Thursday, 31 July 2014
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Last week's poll: flood mitigation

Large areas of the UK are subject to flood warnings. What would be the most cost-effective ways for engineering to reduce the risk of flooding?

It’s been a slightly less soggy week in much of the UK, but the ground is still saturated and 536 readers replied to our poll on how engineering could contribute to lessening flood risk. A clear majority of respondents, 53 per cent, agreed that the best way was imply to not build developments in areas which are at risk of flooding.


The next largest, 21 per cent, favoured earthworks and plantings designed to disperse floodwaters before they reached any buildings. A slightly more ‘engineered’ version of this, soakaway zones to absorb water run-off from roofs and pavements, attracted the support of 14 per cent; while the smallest group, 12 per cent, opted for storm drains and tanks separated from the general sewer system to handle rainwater.

Our upcoming feature on the proposals for a Thames Tideway Tunnel to supplement the capital’s sewer system will address several of these points. Please let us know your view on flood engineering below.

Readers' comments (8)

  • I'm often annoyed by the poor and/or misleading options shown theengineers polls.

    In this case, soakaway zones and earthworks should not be considered as competing options for solving the problem, but complementary. Both can be used alongside either other, or chosen on a case-by-case basis.

    Additionally dedicated storm drains and tanks are not necessarily a competing idea either, they are a solution which may be the only economical choice when considering areas which are already built-up and need retrospective flood prevention measures.

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  • In many parts of the uk rivers are no longer dredged properly. Whilst river widths are unchanged the river depths have been reduced. Typically in Bedfordshire these depths are around 20-25% less today than they were 30 years ago.

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  • I am surprised by the proportion of people who think the solution is 'simply' not to build in flood risk areas. How does this help deal with developments already built in those areas?

    As Dave C says, these polls often imply a choice between solutions which are not mutually exclusive but can provide a superior answer when judiciously mixed.

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  • There was a brilliant article in the Guardian on this topic which really to me sums up the whole situation. I realise that George Monbiot for many of your readers is not perhaps seen as the ideal man in this area, for many reasons, but in this case I believe he has the right answer. I can see no point in regurgitating his views so I just recommend the article. The only part that he cannot and does not answer is that of the people with houses already in flood zones.

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  • Why not build houses on stilts as they do in other countries. This not only keeps the buildings out of anticipated flood levels, but maximises the surface soak-away area.

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  • I am surprised on the simplistic responses on this subject. The only real solution to this problem is carefully planning, execution and management of public infrastructures. This includes building reservoirs in rivers, canalizing rivers with oversized capacity and managing reservoir levels based on weather forecasts. This is how torrential rain is managed in the Mediterranean countries where this problem was far worse than what it can ever be in the UK. It's surprising to me that this was not planned 50-70 years ago in the UK so now it is more difficult and expensive to solve.

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  • I suggest that implementing controls on where building takes place is not strictly an Engineering Solution but pure common sense.
    As much of the flood water is run off from higher ground the engineering solution should also address modification of large areas which are currently impermeable such as drives and car parks so that water can be absorbed rather than simply run off to lower ground.

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  • Flood mitigation is not my specialist field, so this may be a crazy idea, but :- Why don't we build a tidal lagoon generation station across the mouth of the estuary of the river Parret, the tidal fall in the Severn estuary is very high. Most of the year it would generate green electricity, but in times of flood risk, the lagoon could be kept at low tide level.In combination with dredging this would speed up the river and help drain the Somerset flats. This could be a privately funded project, with compensation being paid if generation has to stop.

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