Trees: The Solution to Flooding?

By Sean on Jan 30 2014 | 0 Comments

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Photo by Bob Bowyer

In a month where various parts of the UK have seen some of the worst flooding for decades the media has been saturated with requests for an improvement in flood defences for those areas of the country most affected.

The barriers and barricades that communities are crying out for may present a final obstacle to floodwaters which are rushing toward populated urban areas, but they do not address the initial issues. The way we adapt and treat our riverbeds and countryside has a direct effect upon their ability to deal with rainwater. Should we now be looking at cheaper; more natural prevention?

Government policy over the past decade has largely been in the widening and dredging of riverbeds to allow for more water to be carried; many now, though, are suggesting other alternatives. Former Environment Secretary Lord Rooker recently stated that planting more trees could help prevent such harsh and sudden flooding in vulnerable areas. ‘Rewilding’, as it sometimes called, is the process of returning domesticated land, like grazing pastures and farmland, back to a more natural state, which evidence claims, can help prevent flooding.

 

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Photo © Copyright wfmillar

Schemes that encourage ‘rewilding’ though have implications upon the land owners and farmers who are being encouraged to implement them. The organisation CPRE (Campaign to Protect Rural England) has called for more money to be spent on ‘green farming schemes’ using a higher percentage of the grants given to farmers as part of the CAP (Common Agricultural Policy). In the news this week though, a Welsh Minister was criticised for diverting money away from the Direct Payments given to Farmers as part of the policy, and towards Rural Development projects, projects that could, in theory, include the re-forestation of areas. The criticism is that in reducing a source of income for these farmers he is reducing their competitiveness on the market.

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Photo by Mick Garratt

If planting trees and rewilding areas is to become a viable way of future flood prevention, how does it work, and how can it be achieved? We talk to a Professor in Physical Geography and representatives of the National Farmers Union and Woodland trust, two of the organisations involved in the issue to find out more:

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Q: Do trees prevent flooding?

A:“"This is a long researched and debated question, and the answer is not a simple yes or no. It would better to outline the potential impacts of vegetation on a river catchment:

• Forest canopies can reduce ‘ground raindrop impact’ meaning less sediment erodes from the river bank into the river. This in turn affects the ability of the river to hold more water.

• Trees can modify soil conditions allowing more water to be absorbed in to the soil and not through the channel networks of rivers.

• Roots can bind soil creating channel stability reducing the risk of a river’s banks bursting. Too much artificial vegetation however can prevent a channel from naturally adjusting and in turn impact the generation of floods."

Q: Where should they be planted?

A: “"Trees are typically found in a riparian corridor- i.e. a stretch of ground running parallel to the river channel. Trees are also planted far away from river corridor, as river flows and the potential generation of floods are not just about the channel alone, but the entire hydrological catchment area contributing to the supply of water and sediment."


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Q: How important is it that more trees are planted in the countryside? Does it have an effect on flooding?

A:“Trees are vital for a variety of reasons, not least their ability to soak up water and lessen the effects of flooding. They provide excellent source of natural shelter and shade for crops and livestock. You can read more about the scheme we have been involved with at Pont Bren here."

Q: Where should the funding for rewilding come from? Should farmers and landowners be doing more to help promote ‘green farming schemes’?

A:"It’s difficult to see how rewilding could work without the consent or cooperation of landowners and managers and progress in this area is most likely to come from landowners collaborating and looking to use some of the existing funding streams more creatively. This approach has clearly worked at Pont Bren. A good example of what could happen if landowners and land managers work together on a larger scale is perhaps illustrated by the work of United Utilities in the SCaMP project."


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Q: How important are the CAP grants given to farmers? How would a deduction affect them?

A: “The CAP grants are a critical source of funding for farmers. They are not only of financial benefit to farmers but help ensure that food and goods they supply can be sold at an affordable price for consumers, a deduction on the Direct Payments, given to farmers as part of the scheme, would put a strain on industry."

Q:If a deduction from the direct payments to farmers would not work, where should the money come from? And what else should be done to prevent flooding?

A:"To suggest that for example, an increase in funding for rewilding projects around the Somerset Levels would have prevented this year’s flooding is ill-advised. Slowing the flow upstream can help reduce flooding, but without works like dredging downstream to maintain the capacity and conveyance of our lowland rivers, we are just pouring water into a bath with the plughole blocked. We need to see a rebalancing of the amount spent on flood risk management, away from simply building higher embankments and walls around urban areas built within the floodplain, and instead reinvested in maintaining our rivers and existing infrastructure.”

 

It is now clear that rewilding to reduce the risk of flooding is not as simple as it first seems. It is, as we can see from our contributors, not only an environmental issue but embroiled in a political debate about funding. There is no guarantee that it works and there are in fact potential risks to the process. Despite this, it should be considered as a realistic and progressive alternative, especially as other means do not appear to be working.

So, as academics and representatives from both the farming and conservation communities now discuss the potential benefits and limitations of the process, so should we.

What do you think? Let us know in the comments section below!

 


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