ImageRecent winter storms brought serious flooding to the UK – from mid-December onward through the beginning of January the rains seemed endless, and pictures of flooded fields and houses commonplace. Add to these the ferocious storms that swept away chunks of the seafront at Aberystwyth and various other locations on the west coast, and it begins to look as if climate change predictions are coming true – as David Cameron said at the time.

Residents of the Somerset Levels, which were badly hit by flooding after similar floods in 2012, have put forward different explanations. They point to the fact that in their area rainfall was not significantly in excess of the annual average, yet houses that previously had not flooded in over 80 years had been flooded twice in just two years. Some, in other blogs, have blamed the Environment Agency for not  dredging the rivers Parrett and Tone – the EA’s own computer modelling, according to the Western Morning News, has showed that dredging would have increased the rivers’ carrying capacity from its current 60% to 90%, significantly reducing (the EA’s words) the flood severity.

There are other obvious, well-rehearsed culprits in flood events, key among which is upstream development. Here, large areas of previously permeable land have been converted into impermeable surfaces, off which rainfall runs into watercourses quickly and in far greater volumes than before, creating sharper and higher flood peaks. 

Development in flood plains has long been identified as a risky practice, but one that has been allowed regardless of the obvious issues. So what is the truth? Who is to blame? Is the Environment Agency, as some have suggested, keen to see the Levels returned to their original marshland state? On the east coast the EA’s philosophy of ‘managed retreat’ has seen sea defences dismantled so that land can flood, reducing (where this is possible) the impact of flooding from this source. The EA is also an advocate of restoring flood plains to their original use where possible. This would indeed reduce the impact of flooding by allowing waters to spill onto permeable land and percolate naturally into the ground, rather than be channelled swiftly downstream to flood some other location. 

In its defence, the Environment Agency points to the environmental impact of river dredging, something that was not considered as an issue of any significance when it was regularly undertaken. Since the engineering-led solutions of the 1960s and 70s (‘dredge, channel and hope it goes somewhere else’ might be an apt description) much more importance has been assigned to environmental impact – what happens to the invertebrates in the rivers, the plants they feed on, and the fish that feed on them – the whole complex food web that dredging disrupts? And of course, dredging is a solution that simply pushes the problem downstream rather than solving it, possibly creating flooding for another area in the process. The EA by definition has to consider environmental impacts, although the residents of Muchelney might well, with feeling, suggest that their needs are somewhat more important than those of a few river creatures and their downstream neighbours. 

Identifying the key causes of the flooding is an important part of finding the solution. There are advanced computer modelling programmes that can do exactly that, factoring in the upstream rainfall, the impact of storm water discharges from all identified sources, permeable and impermeable surfaces and other structures that either speed or impede the flow of water. Such models can provide deep insight into flood events – one of the country’s leading water research bodies, HR Wallingford, modelled the Boscastle flooding, a fascinating exercise that proved the local terrain, a series of almost stationary storm events over the river basin and the cumulative effects of detritus blocking key water access points, worked together to create an extreme event.

For the Levels, it is likely that a combination of factors again played a part. The area is a natural floodplain, so upstream influences are almost inevitably going to have a major effect. These would include upstream flood defences to protect major towns (an investigation would look at whether new defences had been added that might have exacerbated the flood risk), and of course development, as well as whether a dredging regime of some sort would have made the situation better.

Resolving the flooding will have to take account of the highly-engineered nature of the area – like the Fens, the Levels have been reclaimed from their natural state and a ‘natural’ solution is therefore not possible. However, any solutions will have to be flexible, sustainable and smart. One good starting point would be upstream attenuation through SUDS – sustainable urban development systems. 

SUDS means introducing retention ponds, grassed areas that can be  used to collect rainwater during storms, swales to guide storm waters to such features and permeable paving, which would allow rainfall to soak through car parks and pavements rather than run off into drains.  If these systems were widely adopted upstream, they would undoubtedly help.

Farmers could be encouraged to plant trees, which are a valuable means of absorbing water – EU funding tends to provide financial incentives to reduce, rather than increase, the number of trees on agricultural land, and this needs to be addressed. The EA’s reduced funding and manpower (it is losing 1700 staff) could be a real obstacle in the search for solutions – local flood schemes, which are within the EA’s remit, could help, as might planned use of those floodplains that can flood harmlessly. 

People may also have to work to make their own homes more flood resilient, and plan for flooding – those who live on flood plains would be wise to take as many precautions as they can regardless of other improvements. Devices to block air bricks are available, as are ‘dagger boards’ to protect doors – these are used in Venice, one of the most flood-prone cities in the world. People have built bunds to protect their properties. 

The culprit, when it comes to flooding, should not be identified as global warming – it is not yet possible to attribute single events to that source, and  it is a concept too easily used as a way of dismissing problems rather than solving them. It is, rather, an inheritance of various short-sighted actions in the past that have come back to haunt low-lying areas.

There are ways to reduce the likelihood of flooding, but they will take concerted efforts from various sources starting with homeowners and including upstream town councils, the Environment Agency and national government. In order to make change happen, there will need to be commitment to do so from the very top. The whole subject is discussed in much detail in the Pitt report on the 2007 floods, which is still available on the internet – the BBC has key points at http://news.bbc.co.uk/1/hi/uk/7472813.stm. The current Water Bill going through parliament is supposed to address some of the issues, such as flood insurance. More information about the regulations (and there are many) can be obtained at https://www.gov.uk/government/policies/reducing-the-threats-of-flooding-and-coastal-change

It’s not that nothing is being done, it is more that there is so much to do. Bearing that in mind, people living on flood plains should do as much as they can to protect themselves, because a complete solution is impossible.

 

 

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