Demonstrating the Benefits of Natural Flood Management

More natural means of managing flooding are desirable and should be brought foward by the Government in a new White Paper on water. So commented Anne McIntosh MP, Chair of the Environment, Food and Rural Affairs (EFRA) Select Commmittee and of the All Party Group on Flood Protection, at a parliamentary event attended by the BES Policy Team yesterday evening. The well-attended meeting was organised by Oliver Pescott, the most recent BES-funded Fellow at the Parliamentary Office of Science and Technology (POST), to launch the POSTnote he authored on ‘Natural Flood Management’.

Natural flood management (NFM) is defined in the POSTnote as ‘the alteration, restoration or use of landscape features’. One of the four speakers, Dr Paul Quinn, Newcastle University, made it clear that NFM is not about taking a system back to a natural state but working with and engineering natural processes. Dr Quinn presented work in which he had been involved within the town of Belford, in which residents have faced six major flooding events within the course of seven years. During extreme events, huge amounts of rainfall can be observed running off farmland; this can be tackled effectively, Dr Quinn suggested, by ‘catchment systems engineering’, which seeks to ‘slow, store and filter’ water. Farm tracks, specially engineered to store water behind them; dams which ‘leak’ slowly to control water flow; and the use of woody debris (‘beaver dams’) to perform a similar function can all help to attenuate run-off.

Dr Wendy Kenyon, James Hutton Institute, highlighted the importance of working with land-managers if those wishing to control flooding wished to work with natural processes as stated. Dr Kenyon’s team have conducted a number of semi-structured interviews with farmers, revealing that first and foremost, farmers are concerned with the viability of their businesses. Dr Quinn had presented results showing that 10 – 20 storage ponds could make a significant difference to the peak water flow; Dr Kenyon argued that the presence of this number of ponds on agricultural land could begin to have a significant effect on the farmer’s bottom line and so the viability of this proposal would need to be considered carefully.

It is important to ensure too that farmers are able to access funding to support their efforts to implement NFM. Fifty eight percent of farmers questioned by Dr Kenyon said that they would be encouraged to introduce NFM measures if there was more funding available to do so and if it could be applied for easily. This is significant as under the Common Agricultural Policy, money is already available to support NFM but, according to Dr Kenyon, farmers have not been accessing this as a source of funds. We need, Dr Kenyon suggested, to work with farmers to find out why.

The issue of the scale at which experiments are undertaken and from which conclusions can be drawn is a highly significant one. It became clear through the presentations that there is a great deal of uncertainty concerning the robustness of conclusions which can be drawn about flood attenuation at the catchment-scale through NFM, based on small-scale experiments. Dr Neil McIntrye, Imperial College London, suggested that although strategic tree-planting can have an affect on ameliorating flooding at a local scale, this beneficial effect is likely to be marginal at regional to larger scales. The true benefits of such interventions are only likely to become apparent, Dr McIntyre suggested, once further research has been undertaken to understand catchment-scale interactions.

The case was therefore made for greater investment in field experiments and better modelling to understand the benefits of NFM. Anne McIntosh MP questioned why the science had not yet revealed these benefits, to which the scientists responded that the high cost of studying natural processes over time and the uncertainty created by extrapolating the results from one study site to another, where geomorphology and hydrology may be very different, constrain the ability to draw robust conclusions. Dr Quinn suggested that scientists would do best to measure at an appropriate scale and then build confidence in extrapolating conclusions, for example through better models.

Funding the necessary experiments and modelling approaches, alongside funding NFM interventions will be a challenge. Anne McIntosh suggested that there was little appetite in Government to pass the cost of NFM projects, including efforts to monitor the efficacy of these projects, onto the consumer through higher water bills. Ms McIntosh, and others, suggested that Payments for Ecosystem Services could be one mechanism of paying for NFM, although here the beneficiaries (presumably the consumers) would still need to pay for the NFM interventions implemented by land-managers (the providers of the ecosystem service of flood alleviation).

There should be scope to deliver NFM alongside other services as part of a framework of multi-functional land-use. Speakers did not touch on this to a great extent and it would have been interesting to have heard more from this perspective. Dr Quinn mentioned that buffer strips planted at the sides of agricultural land can slow the flow of run-off, indicating both a biodiversity and a NFM benefit. Dr Quinn also mentioned the need for multiple stakeholders to come together (eg as in Belford), including ecologists, land-managers and residents, to discuss and agree a shared vision for a catchment. South West Water is investing a great deal of money in NFM measures but for water quality reasons (eg reducing sediment load in the watercourse), with consequent benefits for river ecology. However, overall there was little discussion of the ecological benefits, or disbenefits, of NFM approaches.

In opening the meeting, Anne McIntosh informed attendees that in a meeting of the Liaison Committee (involving all Chairs of Parliamentary Select Committees), members had extracted from the Prime Minister an undertaking that a Water Bill would be published early in the next Parliamentary session. The BES will watch with interest to see whether NFM is incorporated into the Bill when drafted.

Applications for the next BES Fellowship at POST are now open and close on Thursday 5th April. If you are in the second or third year of your PhD in ecology at a UK institution, consider applying. Find out more from the BES website.