As part of the Natural Flood Management (NFM) work being undertaken on the Calderdale Flood Action Plan, which iCASP’s Calderdale NFM project is contributing to, three sub-catchments in Calderdale are being modelled to improve understanding of how the current land management impacts upon flooding.
On 14 November, Tom Willis held a workshop to explore the modelling work he has been undertaking. Tom has been using SD-TOPMODEL which helps identify which areas of the 3 sub-catchments contribute most to flooding in the lower valley. Knowing which parts of a catchment contribute most to peak flows makes it easier to assess the impact of locating an NFM measure in one place rather than another, and allows prioritisation of those measures that will have the greatest benefits.
Having seen how the model works, workshop participants could apply their knowledge and insight of the catchment into devising different scenarios for the next on-the-ground stage of the project. They then live-tested them during the session to see their impact upon peak flood levels
The next steps in this project will be the creation of a
handbook to assist landowners and managers in targeting the most appropriate
NFM measures across the catchment.
In 2008 Joe Holden and colleagues published research that showed how water running over Sphagnum on blanket peatlands moved much more slowly (often ten times slower) than water running through sedges or bare peat. This spawned a new body of research which has shown how revegetation of peat, particularly if it is possible to get a dense Sphagnum cover, can slow the flow of water during storm events to reduce the flood peak downstream. The research indicates priority areas in the landscape for dense surface revegetation that will generally maximise flood benefits. Given that research has also recently shown sediment release from bare peat strongly influences peatland stream ecosystems this gives added impetus to revegetating peatlands and enhancing Sphagnum cover to achieve maximum downstream benefits for river habitats and flood risk.
Unlike most soil types where movement of water through the
soil attenuates the rate of water loss into rivers, research has shown that
water movement in blanket peatlands tends to be dominated by flow very close to
the surface or at the surface1. This means large volumes of
water move over short periods of time, associated with rainfall or snowmelt,
producing very high flow peaks in blanket peatland rivers compared to the flows
that occur during dry weather2, 3. The condition of the
peatland surface may therefore be crucial in determining the downstream flood
peak during storms.
Over a decade ago research was published that showed how water running over Sphagnum on blanket peatlands moved much more slowly than water running through sedges or bare peat4. This spawned a new body of research which tried to establish whether such effects made any difference to riverflow. This work, which included both empirical field demonstrations5, 6 and modelling experiments7-9, has now shown that revegetation of peat, particularly if a dense Sphagnum cover can be achieved, can slow the flow of water during storm events reducing the flood peak downstream. These effects hold (and can be proportionally greater) even for the very largest storm events10. The research indicates priority areas for the densest revegetation in the landscape to maximise flood benefits. These areas include strips of peatland several metres wide that run either side of streams, ditches and other watercourses, and areas of peatland covering other gently sloping parts of the catchment.
Research has also recently shown that sediment release from bare peat strongly influences peatland stream ecosystems11, 12 affecting both their biodiversity and functioning. This shows that we need to do all we can to disconnect sediment sources from the peatland streams. The most effective way to do so is to support revegetation of peatlands, especially near any watercourses. Thus, targeted restoration work that aims to achieve an end-point with a dense Sphagnum understorey will deliver maximum downstream benefits for river habitats and flood risk, while simultaneously adding resilience to the peatland ecosystems in the face of climate change, drought and wildfire.
J. & Burt, T. P. Runoff production in blanket peat covered catchments.
Water Resources Research 39, 1191, doi:10.1029/2003WR002067 (2003).
2. Acreman, M. & Holden, J. How
wetlands affect floods. Wetlands 33, 773-786, doi: 10.1007/s13157-013-0473-2
3. Price, J. S. Blanket Bog in Newfoundland
2. Hydrological Processes. Journal of Hydrology 135, 103-119 (1992).
4. Holden, J. et al. Factors affecting
overland flow velocity in peatlands. Water Resources Research 44, W06415, doi:
5. Grayson, R., Holden, J. & Rose, R.
Long-term change in storm hydrographs in response to peatland vegetation
change. Journal of Hydrology 389, 336-343 (2010).
6. Shuttleworth, E. L. et al. Restoration
of blanket peat moorland delays stormflow from hillslopes and reduces peak
discharge. Journal of Hydrology X 2, 100006 (2019).
7. Gao, J., Holden, J. & Kirkby, M. J.
A distributed TOPMODEL for modelling impacts of land-cover change on river flow
in upland peatland catchments. Hydrological Processes 29, 2867-2879, doi:
8. Gao, J., Holden, J. & Kirkby, M. J.
The impact of land-cover change on flood peaks in peatland basins. Water
Resources Research 52, 3477-3492 (2016).
9. Lane, S. N. & Milledge, D. G.
Impacts of upland open drains upon runoff generation: a numerical assessment of
catchment-scale impacts. Hydrological Processes 27, 1701-1726 (2012).
10. Gao, J., Kirkby, M. & Holden, J. The
effect of interactions between rainfall patterns and land-cover change on flood
peaks in upland peatlands. Journal of Hydrology 567, 549-559 (2018).
11. Aspray, K. L., Holden, J., Ledger, M. E.,
Mainstone, C. & Brown, L. E. Organic sediment pulses impact rivers across
multiple levels of ecological organisation. Ecohydrology doi: 10.1002/eco.1855
12. Brown, L. E. et al. Sediment deposits
from eroding peatlands alter headwater river invertebrate biodiversity. Global
Change Biology 25, 602-619 (2019).
iCASP is working on a project to integrate Natural Flood Management (NFM) into the National Trust’s ‘Payment for Outcomes’ trial. The Trust are undertaking the trial on some of their tenanted farms working with the Yorkshire Dales National Park Authority and Yorkshire Dales Rivers Trust. Their work will help to inform Defra’s new Environmental Land Management Schemes (ELMS). It seeks to pay for farmers for the environmental outcomes they achieve on land they farm.
The iCASP project is focused on identifying opportunities for NFM measures and discussing with farmers how NFM could fit into a payment scheme that would make business sense for them. These valuable insights will help inform future payment schemes which focus on payment for outcomes.
iCASP produced maps of each farm showing the parcels of land tenanted from the National Trust. The land parcels were overlaid on to maps, produced from SCIMAP. These maps show areas of risk related to diffuse pollution (e.g., fine grained sediment) and the connectivity of overland flow of water to the main channel network – together, these maps show which areas of land could benefit from further management. This allows us to generate ‘opportunity maps’ that indicate where NFM interventions might best be sited; for example installation of a leaky dam in a particular location might work well to slow peak flows of water or buffer strips to help reduce sediment (soil) being washed away.
Ground-truthing of the map outputs is crucial to understand the farm in more detail to ensure NFM opportunities are placed in the correct locations. For example, smaller flow pathways that connect sediment and water to the main channels, may not have been picked up during the modelling due to the resolution of data used. Speaking to the land owner is vital at this point to understand how the land is currently used and managed and where there are current issues (e.g., waterlogged soil). This is another layer of information that can be used to ground-truth the modelling output and also verify the locations of potential NFM interventions.
We have recently visited five farms taking part in the trial to do this ground-truthing. This has meant we’ve been able to annotate all the maps to verify the modelling output. This has allowed us to come up with a better understanding of which NFM interventions could be used and their locations on the farms.
The next step in this process will be to meet with all the farmers and other organisations involved in the project to share the knowledge gained by the process and produce final maps of the suggested interventions. Meeting with the farmers will also provide valuable feedback on the opinions of NFM, which interventions the farmers would be willing to install on their land and how these efforts might be incorporated into a payment scheme that pays the farmer for the environmental benefits they produce by installing NFM. iCASP will feed the key points of these discussions to DEFRA to inform the development of ELMS as well as share this useful insight with other projects looking at payment for outcomes (e.g. the Horizon 2020 CONSOLE project iCASP is part of). The National Trust will use the insights evaluate how NFM could be incorporated into their Payment for Outcomes trial.
iCASP academics been involved with work in Calderdale that aims to reduce the flow of water through the catchment using Natural Flood Management (NFM) measures. The iCASP project has been using a rain-fall run-off model, SD-TOPMODEL, to help with identifying which areas of 3 sub-catchments of the Upper Calder River contribute most to peak flows. Understanding which parts of a catchment are contributing most to flooding in the lower valley make it easier to assess the impact of locating an NFM measure in one place rather than another and allow prioritisation of those measures that will have greatest benefits.
The model produces maps like the one below that shows the speed at which water is flowing and uses rainfall data from nearby weather stations and high resolution terrain data. This modelling is combined with on-the-ground visits and meetings with landowners, land managers and flood risk managers to get the fullest picture of what is going on across the landscape when it rains.
The modelling and site visits improve understanding of what contributions existing landscape features already make; for example hedges and walls can help slow the flow of water across the land and by acting as a temporary store help reduce the peak flows of water. These aspects can then be included to further improve the representation of these features in the model. The modelling and site visits also allow experts to identify where in the landscape new NFM features can be located to further slow and store water.
At a meeting in November the modelling results will be presented to all the partners working on flood measures in Calderdale. From these results a handbook will be created to assist land owners in targeting appropriate NFM interventions, and to further understand how the whole catchment responds during flood events.
Last week iCASP facilitated a meeting with the National Trust and Water@Leeds to identify future opportunities for collaborative working.
The National Trust (NT) are one of the largest land owners in the UK, and around 40% of land in the UK drains into a watercourse which runs through a NT property. The Trust recognises it has a responsibility to restore environments to healthy, beautiful and well-functioning status as well as ensuring their ongoing management methods and practices maintain that status. They’re not just seeking to help store carbon, reduce flooding and restore soil health, but do this whilst also ensuring the land they own remains beneficial to wildlife and people.
Collaborating with Water@Leeds will enable the Trust to feed into the latest research and development activities which in turn could increase the implementation of evidence-based management decisions across their properties. Collaborating with the Trust provides opportunities for researchers to trial innovative new activities in real world settings and access a wealth of information from those who live on and manage the land. iCASP can help to facilitate this collaboration by identifying the priorities of the National Trust and translating Water@Leeds research to help answer key questions to the challenges faced.
The meeting considered several ways of working together; from PhD studentships to research grants and fellowships. Possible collaborations were identified across a range of topics including water quality, habitat management and biodiversity enhancement, natural flood management and carbon management. These themes cut across a variety of catchments where both the Trust and University of Leeds researchers work.
The National Trust are already project partners on the iCASP Payment for Outcomes project that is seeking to include natural flood management (NFM) in the Trust’s Payment for Outcomes trial. In turn the Trust’s trial can help inform Defra’s new Environmental Land Management Scheme (ELMS) and how a range of different measures to improve environmental outcomes can be included and paid for. The iCASP project focuses on several of the Trust’s tenanted farms and aims to identify which NFM interventions are most suited to the farms and surrounding land, and pay farmers and land managers for the work they undertake to achieve these improvements.
We hope to build on the partnership working already underway and facilitate more collaboration in the future to benefit the beautiful places owned and managed by the Trust for the benefit of us all.
On the iCASP office wall, amongst lists of current and developing projects, year planners and maps there is a brightly coloured poster about getting research in to parliament. As iCASP is all about achieving impact from existing environmental science we do a range of activities to ensure iCASP’s work gets into parliament. Below is a summary of some of this activity
A new webpage on the iCASP website details some of our responses to various consultations and inquiries. These vary from the local to the national level and they draw on science right across the iCASP remit. And it isn’t just written evidence. Recently Alison Dunn, who leads our Invasive Non Native Species project, was invited to attend and give oral evidence to the Environmental Audit Committee as part of their Invasive Species inquiry
Environmental Audit Committee oral evidence session as part of the Invasive Species inquiry
Written and oral evidence to inquiries and consultation isn’t the only way that iCASP and the people that work on iCASP projects get research in to parliament.
Another way of getting our work in front of MP’s and their researchers is talking to them directly. Joe Holden Director of iCASP, was recently asked to meet with Alex Sobel MP and brief him on iCASP and the projects we are funding. iCASP has also met with MPs Rishi Sunak and Julian Sturdy out in the Yorkshire Dales to tell them about iCASP.
Every year we invite an MP to give a key note talk at our annual Confluence event, and then plan the agenda to time their arrival to coincide with a break allowing them to talk to a range of people working across different iCASP projects. The Yorkshire catchment that iCASP covers is large so there are a lot of MP’s constituencies meaning the MPs we engage with will have different priorities depending upon constituency location. Many are involved with different select committees, have Ministerial roles or are in the shadow cabinet, or are involved with different APPGs based upon their personal interests. We had Angela Smith MP attend Confluence in 2018 and Alex Sobel joined us this year. This allowed us to engage with them as constituency MPs and also as members of the Environment, Food and Rural Affairs and Environmental Audit Committees respectively.
The work of researchers working on iCASP projects gets used in many different ways, one recent example is the report from ONS looking at the natural capital of UK peatlands which drew on the work of several iCASP researchers. Researchers can also act as external reviewers of articles, reports and papers having an input that way. iCASP director Joe Holden was an external reviewer for the recent POSTnote on Wildfires.
This is just a snapshot of some of the activities we’ve been involved with to get research into parliament; it demonstrates the diversity of opportunities available and demonstrates the need for researchers to continually engage with parliament at different levels to ensure their understanding and knowledge is based on the most up to date science available. We have a busy Autumn of consultation responses planned, but it’s worth the effort knowing that this will be influencing policy making and future policies that affect the catchment and all who live here.
This week has seen the 12th anniversary of the 2007 floods which impacted across swathes of the UK and affected villages, towns and cities across Yorkshire. It is timely to look at some of the measures put in place since then to alleviate flooding in the future. Natural flood management (NFM) has had some coverage in the media recently with both the BBC and ITV reporting stories that cover activities iCASP projects are supporting.
Countryfile recently visited Hardcastle Crags near to Hebden Bridge to find out more about leaky dams and how they will help tackle flooding in the future. The NFM work in Hardcastle is as a direct result of the 2015 Boxing Day floods. iCASP has been working with the Environment Agency, JBA and the Yorkshire Dales Rivers Trust, amongst others, on monitoring and measuring the range of benefits of NFM measures such as the leaky dams seen in the programme. The main focus of iCASP’s work has been developing approaches to measure whether or not the dams work to deliver flood alleviation. A future focus of the work will be to help quantify the additional benefits of these types of interventions – such as more varied habitat for wildlife, improved water quality and enhanced well-being for visitors to the area – which will be vital for making the business case for future natural flood management measures. Find out more about the Hardcastle Crags leaky dams from Countryfile
Natural flood management encompasses a range of different measures, not just leaky dams. An ITV news report on tree planting in Hebden Bridge mentioned how this work will draw upon the expertise of iCASP later in the year to understand the impact of trees already planted. iCASP will be working on the project to help identify how features, such as trees and hedges, can absorb heavy rainfall and contribute to alleviating flooding, as well as investigating how different soil types and land covers also contribute to flooding. Decisions on where trees and hedges should be planted in the future, for optimal benefit, will be informed by a rainfall-runoff model developed at the University of Leeds. Read the ITV report
These NFM activities rely upon a range of different partners getting involved. A diagram showing the range of different partner organisations, drawing from the voluntary, charitable, private, public and regulatory sectors, has been developed to give a flavour of the interactions in these activities in the Calderdale area. View the interactive diagram
A group of farmers are at the heart of an iCASP project which will be supporting the trial of a new national scheme for paying land managers to deliver benefits such as healthy soil or an increase in bees and other pollinators. The National Trust and Yorkshire Dales National Park Authority are running a ‘Payment for Outcomes’ trial with a group of tenant farmers in the Yorkshire Dales which will help to test the feasibility of Defra’s new Environmental Land Management Scheme (ELMS).