Optimising NFM in headwater catchments to protect downstream communities

Lead Research Organisation: University of Manchester
Department Name: Environment, Education and Development

Abstract

Natural flood risk management (NFM) describes methods of modifying hillslope and catchment runoff through the modification of landscapes to restore natural hydrological behaviour which limits downstream flood risk. This proposal is for a focussed study of NFM benefits associated with wider ecosystem restoration work which is under way across the uplands of the UK. Headwaters comprise 60-80% of the length of most river systems and high slopes and high rainfall mean that they are important areas of hillslope runoff production. Across the UK there are communities which are prone to flash flooding from steep upland catchments. These headwater catchments are relatively small catchments and are areas where extensive upland restoration is occurring and so they are locations where positive impacts of NFM measures are likely to be observed. Vulnerable communities in headwaters are often small and dispersed with land values that rarely justify hard engineering flood defences through standard cost-benefit approaches. If relatively low cost upland restoration approaches can mitigate risk to communities such as this then it will be possible to provide some protection to communities where funding precludes hard engineering approaches.
This project will work with project partners Moors for the Future and Greater Manchester, Merseyside and Cheshire Environment Agency who have existing funded NFM work in the southern Pennines to undertake a series of field experiments. These will assess the potential impact of various forms of gully blocking, restoration of Sphagnum cover on moorlands, and establishment of upland woodlands on hillslope runoff production and channel flow. It will also assess the longer term evolution of woodland and gully blocking approaches through the study of mature woodland and well established gully blocked systems. This is an important consideration since investment in NFM works requires confidence in the long term impact of the restoration on runoff and knowledge of any ongoing maintenance costs for the interventions.

Installation of NFM schemes to mitigate flood risk requires careful planning and prediction of potential impacts. This project will develop conceptually sophisticated but computationally simple models which can run multiple scenarios in order to assess the catchment wide impacts on runoff of NFM measures implemented to a variety of designs and in a variety of spatial configurations.
The model will be developed (with input from project partner CH2M and input from potential users such as EA) and validated using data from the Glossop Brook catchment in Derbyshire which has a history of major flash flooding impacting households in the town of Glossop. The modelling approach will then be used to assess possible NFM interventions in the upland catchments draining to 21 communities at risk on the eastern edge of Greater Manchester. In each of these catchments we will model the optimum configuration of upland restoration measures for NFM benefit.

The project will also work with partners (Environment Agency, Natural Resources Wales, Scottish Environmental Protection Agency, International Union the Conservation for Nature) to identify existing headwater flow records across the UK which relate to areas of significant upland restoration. At these sites we will model expected impacts and interrogate the available flow data for evidence of these effects on runoff.

The project will work with its range of project partners which span England, Wales and Scotland and which comprise regulators, land managers and industry to develop guidelines to optimise future implementation of NFM measures in headwater catchments across upland Britain.

Planned Impact

Increasing frequency of floods with devastating impact on communities has meant that there is widespread interest in approaches to mitigating the impacts of heavy rainfall on downstream settlements. The efficacy of natural flood risk management (NFM) is therefore a pressing area of concern for a wide range of stakeholders including those charged with flood defence and policy (e.g. Environment Agency, Scottish Environmental Protection Agency, Natural Resources Wales and local councils), land managers, environmental consultancies, and communities at risk.
Successful completion of this project will provide a major advance in the understanding of the impact of upland landscape restoration (such as woodland planting and peatland restoration) on downstream flood risk. The project will also develop models to allow optimisation of NFM benefits at the planning stage of restoration works. The project will develop open source modelling approaches which will allow rapid assessment of multiple scenarios of NFM implementation for headwater catchments. These models, developed with input from project partners CH2M and the EA, will be freely available. They will be designed to support and supplement existing industry standard approaches, and could become a part of the standard toolkit for rapid assessment of projects by regulators and consultants. These advances will be of direct use to policy makers in terms of planning new flood defence works, and assessing the catchment scale impact of NFM measures in headwater catchments.
The project will develop guidelines for the optimum implementation of NFM works. We will work with project partners to co-produce these guidelines, and disseminate these to the widest possible range of stakeholders on completion of the project. The guidelines will cover both the design of NFM features and the spatial planning of these approaches. These planning principles will support land managers in the development of upland restoration schemes which will maximise NFM benefits alongside other ecosystem service benefits.
Quantification and prediction of NFM benefits will allow implementation of flood protection schemes based on NFM approaches in areas where hard engineering approaches are too costly, and will also provide the basis for assessing mixed schemes where NFM benefits are able to minimise the degree of hard engineering required for a given protection level. Therefore, there is potential for the implementation of low cost headwater NFM measures that will allow a greater degree of flood protection within limited budgets.
Ultimately, the aim of this work is to positively impact communities at risk of headwater flooding. Demonstration and quantification of NFM benefits associated with upland land restoration may allow the implementation of meaningful flood defence in communities where largescale hard engineering solutions will not be supported. This would empower communities to take local action to protect their homes. The project will produce a travelling exhibition of project findings which will be displayed in local settings to communicate the project's work to communities at risk.
 
Description The project has completed pre-intervention monitoring of runoff from erosion gullies on peat moorland on circa 20 sites in the peak District to the east of Manchester. The study of a large number of sites has demonstrated that despite considerable natural variability the degree of change in runoff behaviour in response to moorland restoration seen in a previous study by the team is beyond the range of variability seen at the sites in this study. This validates the conclusions of the previous work and allows us to hypothesise that the restoration measures which are about to be installed at the study sites will generate measurable change in runoff behaviour and so potentially contribute to downstream flood resilience.
Exploitation Route Too early to say, need the result of the intervention study that is under way.
Sectors Environment

 
Description EFRA Peatland Select Committee
Geographic Reach National 
Policy Influence Type Gave evidence to a government review
 
Description Responded to Environment Agency FCRM national strategy consultation
Geographic Reach Europe 
Policy Influence Type Participation in a national consultation
 
Description Written evidence to the Environment, Food and Rural Affairs Committee's State of peatland in England inquiry. Evidence submitted by Dr Emma Shuttleworth on behalf of the Environmental Processes Research Group, The University of Manchester
Geographic Reach National 
Policy Influence Type Gave evidence to a government review
URL https://www.parliament.uk/business/committees/committees-a-z/commons-select/environment-food-and-rur...
 
Description Towards a microbial process-based understanding of the resilience of UK peatland systems
Amount £45,439 (GBP)
Funding ID NE/S016724/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 02/2019 
End 01/2020
 
Description Environment Agency 
Organisation Environment Agency
Country United Kingdom 
Sector Public 
PI Contribution Protect team are working with EA to monitor impact of EA funded NFM work
Collaborator Contribution EA are providing advice, access to data and field support for hydrometry, as well as attending regular project meetings.
Impact None to date
Start Year 2018
 
Description Moors for the Future 
Organisation Moors for the Future Partnership (MFF)
Country United Kingdom 
Sector Public 
PI Contribution The team are working closely with Moors for the Future on selecting sites for field experiments which Moors fo the future will undertake restoration on. The team are providing expertise to Moors on experimental design and data analysis for this project and other work. The team are working with Moors to jointly publish data from this and previous projects
Collaborator Contribution Moors are playing a major role in planning field experiment locations and managing relations with landowners.
Impact 2019 Alderson, D.M, Evans, M.G., Shuttleworth, E., Pilkington, M., Spencer, T., Walker, J., and Allott, T.E.H. Trajectories of ecosystem change in restored blanket peatlands, Science of The Total Environment, 665: 785-796 2018 Shuttleworth, E., Evans, M.G., Pilkington, M., Milledge, D. Walker, J. & Allott, T.E.H. (2018) Blanket peat restoration delays flows from hillslopes and reduces peak discharge. Journal of Hydrology X
 
Description National Trust 
Organisation National Trust
Country United Kingdom 
Sector Charity/Non Profit 
PI Contribution Working with the National Trust who are landowners for some of our experimental sites.
Collaborator Contribution Permissions, discussions of sites, feedback at the steering group on gully blocking prctive
Impact None yet beyond those reported for the grant as a whole
Start Year 2017
 
Description Downpour game engagement with Cumbria wildlife trust 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact Emma Shuttleworth demonstrated the Downpour game flood engagement activity to Cumbria Wildlife Trust and discussed production of a bespoke version for their needs (ongoing)
Year(s) Of Engagement Activity 2020
 
Description EA NFM roadshow 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact Presentatiuonof 'Mind the gap' to the Environment Agency NFM roadshow
Year(s) Of Engagement Activity 2019
 
Description NFM article Geography Review 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Schools
Results and Impact Article on peatland restoration and NFM by Martin Evans (PI) published in Geography Review magazine which reaches thousands of 6th form geography students across the UK and internationally. (GR 33(2) November 19
Year(s) Of Engagement Activity 2019
 
Description Radio interviews on 5 live and LBC radio 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact 9/11/19 Radio interview with PI (5 live breakfast and LBC radio) about the project in the aftermath of severe flooding in the first week of November 2019
Year(s) Of Engagement Activity 2019