This blog post should have been started a while ago – for the moment I did, the ferocious rain seems to have died down.

Nevertheless we now know that December 2015 was the wettest month on record, not that this is any consolation for much of northern England and Scotland. Now is the period for offering proposals to make sure ‘it does not happen again’, not that this is really possible but we should try.
soil roots 392x272What has been interesting as I read these is the lack of joined-up thinking in the solutions. Many articles looked for someone to blame. The farmers were in the firing line for not managing their land in a way that soaks up the rain and for not planting trees. The latest is that they might be paid for storing water upstream. Others question the priorities at the top and the Environment Agency felt that they had to state that people were more important than wildlife. Hopefully what follows will show that protecting one and enhancing the other can be on the same side of the coin.

Many commentators, such as George Monbiot, Matt Ridley and the BBC magazine, are right and have been saying for some time that flood protection work needs to start at the top of the catchment so that the water arrives in centres of population less quickly. However, everyone, not just farmers, has a part to play. Here I set out three broad areas of natural flood management that can contribute to reducing the peak flows that we have seen cause so much damage in the past few weeks.

First, adjusting the land management at the top of the catchment so that the rain that falls soaks into the soil rather than run off the surface. Planting and managing trees can be helpful here, but only in the right place and with a plan for future management. Species rich unimproved grassland and herb-rich grass lays that are sensitively managed are just as valuable in holding water back in the soil as woodland.

Research team examining soil structure

The answer lies under our feet. Soil with high levels of organic matters and a variety of root systems enables water to seep deep into the ground. Where there is compaction or long-term poor species variability, often the case on improved pastures, then the likelihood of run off increases. However farmers are increasingly turing towards min or zero-tillage minimising soil disturbance and maximizing the benefits of deep rooted plants such as radishes in cover crops or chicory in grass swards. The benefits are better soil health which makes soil more resilient to weather extremes and increases productivity. Much has been made of the work at Pontbren, where trees are said to outperform grassland in attenuating rainfall, but the comparison was only made with plots of improved pasture. Note that there has only been talk of planting, not managing what we already have. It would be foolish and detrimental to wildlife and people to plant trees on unimproved pastures in the uplands. The partnership approach to the re-wetting programmes in the uplands sets a good example of shared problem solving.

Second, once the water has gathered into small water bodies and streams there is a need to slow the flow so that the water does not gain the momentum that can be so destructive. This is best undertaken high up in the catchment above centres of population through the introduction of small and frequent structures into the stream, even in those which do not run all year round. As it collects together, water will want to flow downhill by the quickest route and in this pattern gains speed and material. The aim is to continually block and change the path the water takes, thus slowing it down.

In one of smaller river valleys in Stroud over 80 structures have been introduced to do this and the early signs are that in this winter, while other streams appear to be running strong and full, those with the natural flood management features are calmer and slower. This is part of the Stroud Natural Flood Management initiative. A short film detailing this can be watched on Vimeo.

 

Map detailing the location of the Stroud Valleys project
Map detailing the location of the Stroud Valleys project
Examples and impact of the natural barriers used in the project
Examples and impact of the natural barriers used in the project

Finally, in centres of population there is a place for the community to ensure that rain water does not over-stretch the drains and water infrastructure. This might be in the form of rain water gardens, green walls and roofs and other features that absorb rain water and ‘slow the flow’. The huge growth in the paving over and sealing of front gardens, often for parking, increases the swift run off of water. Communities are often ideally suited to highlighting issues of blocked culverts or other obstructions that can cause localised flooding – but often lack the knowledge of who to inform.

In combination across a catchment these factors would increase the overall level of flood protection by slowing the flow of water and reducing the overall peak flows. They are not enough on their own but alongside flood defences would make catchments more resilient to the sort of weather we have recently experienced. What is clear to me is that flood protection and catchment management need to be more closely integrated. Flood protection has largely been the exclusive domain of engineers and it is now clear that we need to think more deeply than merely increasing the height of the flood defences. Apologies if this seems obvious but judging by some of the articles, it has only just become apparent to some. The mechanisms are in place as each catchment has a catchment partnership made up of a range of non-engineer stakeholders and the regional flood committees containing mostly engineers.

This would protect more people and reduce the frequency in which flooding impacts on their lives and businesses. Interestingly all of this would also benefit wildlife – the two go together and we should look to work with nature rather than see is as something separate. Something David Cameron seems to overlook in his ‘epiphany’ with two water voles.

Chris Short, CCRI.

Co-lead for Centre for the Study of Floods and Communities.

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