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.
At times when we experience floods, such as those currently devastating people’s homes and businesses in parts of Yorkshire, Derbyshire and Nottinghamshire, it is very common to see people attempting to distill the problem down to a single cause. In complex hydrological systems there is no sense in taking this simplistic approach; rather the whole catchment needs to be considered and we need to think about how we make entire catchments more resilient to extreme events. This is one reason for the ’i‘ in the NERC-funded Yorkshire Integrated Catchment Solutions Programme (iCASP). We work on the understanding that what happens in one area of the catchment affects other parts of the catchment because it is a whole system.
Our work looks at how processes integrate across the entire catchment and while finding solutions to environmental problems we also seek ways to address multiple problems at once, thereby delivering value for money. It isn’t just physical elements of catchment management, there’s a human element too: we work closely with partners and stakeholders on all projects to build relationships and trust and to support organisations to work together in confidence to maximise beneficial outcomes.
Flood Forecasting, and Drought & Flood Risk Mitigation are two of our six workstreams that determine the work we fund. We draw upon the research of several universities in the region including the University of Leeds, University of Sheffield and the University of York to address problems that organisations across Yorkshire are seeking to tackle. This ranges from trying to improve the ability of local councils to respond to weather forecasts by improving the advice provided in a forecast, or implementing measures that slow the flow of water across the landscape so it takes longer to move into the rivers and doesn’t contribute to sudden peak flows.
Restoring the peatland in the upper reaches of a catchment means that rainfall there takes longer to move through and into rivers downstream. Our Peatland Restoration project has developed guidance for practitioners and managers to help their decision-making as to the best restoration techniques to return the system to its normal functionality of water storage and slowing downstream flow. An added benefit of this kind of restoration is that functioning peatland acts as a sink/store locking up carbon that might otherwise be driving climate change.
Natural Flood Management: modelling, mapping and monitoring
Several of our other projects are on the same theme as this: using natural processes to slow and store water moving through the landscape to avoid the mass flows and peaks that cause problems. There are many Natural Flood Management (NFM) pilot projects throughout Yorkshire funded by government. Our iCASP projects are supporting these by working with partner organisations to develop modelling, mapping and monitoring capability.
We use computer models to understand which parts of a catchment contribute greater quantities of water into a watercourse than other parts, and to understand the role that landscape features – both natural and human-made – may play in this process either slowing or storing water. Our modelling expertise is currently being used in our Calderdale NFM project to understand how three tributaries contribute to water flows further downstream.
Combining rainfall data and high resolution terrain data, combined with the knowledge gained from site visits means we can create ‘Opportunity Maps’ that allow an identification of what the current landscape management means for flood risk and what might be done in future.
Once developed, Opportunity Maps allow us to identify locations where NFM interventions such as tree planting, aerating soil, buffer strips or leaky dams may best be sited for maximum effect. In the case of our Don Catchment project, we work with the land managers to identify which interventions could be installed by volunteers, what interventions would be best and where our mapping allows us to identify the additional impacts these interventions may play. Many NFM interventions can serve multiple purposes; they may not only slow down the flow of water across the landscape, but they might also improve water quality or provide valuable habitat for wildlife, contributing to improved biodiversity and species richness in an area.
“We feel very privileged to have benefited from our involvement in iCASP, as it has given us access to expertise that has resulted in opportunity maps that are guiding our decision-making in relation to our Hidden Heritage Secret Stream (HHSS) project. These maps identify locations in the landscape where we can have the most impact, and they have also helped highlight the types and locations of NFM interventions that not only slow the flow of runoff, but also reduce diffuse pollution and increase ecological connectivity across the landscape. Our team is using the maps to identify sites for investigation on the ground, and they have been very useful when engaging with our partners and landowners.”Ed Shaw, Director Don Catchment Rivers Trust
Monitoring the impact and effectiveness of NFM interventions is critical; both to being able to identify what impact is delivered, but also in being able to make the case for funding such measures and for their ongoing maintenance. A key aim of another of our Natural Flood Management projects is to improve the monitoring capability of those using NFM so they are able to carry out rigorous monitoring to contribute to the evidence base for this kind of flood risk intervention.
In our Payment for Outcomes project we are working with the National Trust to build NFM measures into their payment for outcomes trial. Farmers on some of the Trust’s tenanted farms will receive payment for the environmental outcomes they achieve, and this work will eventually inform Defra’s new Environmental Land Management Scheme and show how NFM can be integrated within this.
To maximise all the benefits of this work, we’ve developed a Natural Flood Management Community of Practice (CoP) to bring together people working on NFM to share skills, experience and best practice, build capacity and discuss challenges and opportunities. The CoP meetings draw upon the expertise we are deploying in the NFM projects we work on and also brings together people from across the region – and increasingly from beyond it too – to understand how best to manage their areas of land in the most appropriate ways for our future climate.
Slowing the flow of water through a catchment, and the measures put in place to do this are just one aspect of the measures we are working on. As demonstrated in the last week, at times rainfall is extreme and even if there are lots of interventions in place upstream, the sheer quantity of water is overwhelming, so we also work on improving flood forecasting. Our Enhanced Surface Water Flood Forecasts project worked with a range of partners to trial new forecasting software to assess whether it helped flood risk managers and emergency responders in the decision-making processes they go through in a flood event.
“In response to Defra’s Surface Water Management Action Plan, the Environment Agency and Met Office are scoping a new capability for sharing with responders very short range and rapid update forecasting (“nowcasting”) for the type of rainfall that causes surface water flooding. The Enhanced Surface Water Flood Forecasts project final report, including feedback from the incident response workshop, has provided valuable information and user response insight for the discovery phase of this project and we expect that continued engagement with the iCASP team will continue to be beneficial for understanding user needs and exploring piloting opportunities.”Graeme Boyce, Project Executive, Flood Forecasting Centre
Our Living With Water Catchment Telemetry Integration project, which the Living with Water Partnership are undertaking in Hull, will bring together remote monitoring data of water flows carried out by several organisations with decision-making software to create a tool that will help deliver operational preparedness for events such as those we have seen in the last week and identify optimal locations for future monitoring. Combining such data collected by these organisations has not been done at this scale before; this way of joint working will be extremely powerful in making higher levels of knowledge available to decision makers and first responders about actions to take and deployment of flood defences.
Our newest project – Bridging the knowledge gap to boost SME resilience – starting later this month will be working on ways to build the resilience of the SME sector. Here in Yorkshire, much of the private sector is made up of SMEs who can be very vulnerable to flooding and the knock–on effects to the regional economy of a flood event can be significant and far-reaching. The project will work with local authorities and the insurance sector to develop a robust methodology for assessing the direct and indirect costs of floods on the SME sector so they are able to tailor their flood assessments and responses appropriately. By providing detailed information on the effectiveness of resilience measures and risk reduction activities, flood risk can be properly priced and managed by SMEs and appropriate support can be given to SMEs to make them more resilient and able to reduce their risks. Local Authorities will be better able to carry out future flood assessments, lobby for additional funds to better prepare for future flooding and, in the event of a flood, prioritise their response in a consistent and timely manner.
iCASP is also working with City of York Council on the Yorkshire Future Flood Resilience Pathfinder project to understand the current level of Property Flood Resilience (PFR) measures in place across Yorkshire, and what can be improved.
This just a snapshot of some of the work we are undertaking to produce solutions to water challenges across Yorkshire, the UK and globally. Our work extends right across catchments, from high and remote peatlands where some of the water that floods peoples’ homes begins its journey, to the streets where we live and the monitoring and forecasting that takes place to try to improve the way we respond, the advice given and the deployment of measures to reduce flood risk.
“Over time, we are increasing the number and diversifying the types of flood management techniques that will reduce peak flows downstream providing new tools to support farmers, villages, towns and cities susceptible to floods.”Joe Holden, Director, iCASP
The environment is a complex system and we need to work at many different levels to tackle integrated problems. With climate change increasing the likelihood of extreme weather events, it is clear that we need to continue to invest in ways to address resilience and to use a wide range of solutions across the landscape to tackle flooding, rather than think about each component of the system in isolation.
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.
This article by Prof. Joe Holden was originally published in the IUCN Peatland Programme newsletter July 2019
1. Holden, 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 (2013).
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: 10.1029/2007WR006052 (2008).
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: 10.1002/hyp.10408 (2015).
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 (2017).
12. Brown, L. E. et al. Sediment deposits from eroding peatlands alter headwater river invertebrate biodiversity. Global Change Biology 25, 602-619 (2019).
Until 15 January 2020, iCASP will be carrying out a survey to better understand people’s views on measures to avoid flooding, in particular, Natural Flood Management (NFM).
We invite anybody who is interested or involved in NFM to take part and share your views. We want to hear about, and better understand, how you feel about NFM. You may have been a volunteer installing NFM interventions, or own land where NFM measures have been installed, you may have walked past some when out and about, or you may not have encountered them at all – whatever your experience, we would like to hear what you think about them.
Over the last few years there have been a wide range of NFM measures implemented across the UK. Here in Yorkshire we have several pilot schemes being trialled and monitored to build up our understanding of the processes, benefits and considerations when installing these kinds of flood measures.
Understanding how people perceive NFM, their levels of knowledge of different interventions and their views on NFM allows us to ensure this is considered when designing future schemes so that they are more acceptable and the benefits are more clearly articulated.
The survey should take no more than 15 minutes to complete and your answers will be stored completely anonymously in line with GDPR requirements. Click here to access and complete our NFM survey.
Links to articles about some NFM schemes in the region:
On 28 October, Dr Alison Dunn, lead academic on iCASP’s Invasive Non Native Species (INNS) project gave a keynote presentation at the International Conference on Aquatic Invasive Species about the growing problem of invasives, and the work she is doing to address this.
Because of the growing threat that some invasive species pose to our natural environment, and even in some cases to human health, there’s a real need to stop or dramatically slow their spread. One example of a particularly nasty invasive species is Giant Hogweed , a plant that can cause severe burns on human skin resulting for some people in long-term skin sensitivity problems; the current cost to UK local authorities of tackling this particular plant species is over £365,000 a year. It is this growing problem and cost of dealing with invasive species that is the driver for much of Dr Dunn’s work.
Her iCASP project is breaking new ground by working with local authorities to improve their biosecurity policies and procedures, and embedding this into their routine activities to slow the spread of invasive species. The project draws upon learning from another of her projects working with several organisations in the heart of the Yorkshire Dales to ensure that learning, resources, and successful ways of improving biosecurity are shared.
Local organisations and authorities are not the only people whose awareness and actions Dr Dunn is seeking to change; she gave evidence to the House of Commons Environmental Audit Committee’s inquiry into Invasive Species earlier this year stressing the importance of improved and robust biosecurity:
“Check Clean Dry and Be Plant Wise are flagship campaigns by DEFRA and we have found that where people are aware of those campaigns, their biosecurity behaviour does change, but awareness is not very high”
The report of the inquiry was published last week and biosecurity features strongly in the recommendations from the Committee to the Government. We now need to wait for the government’s response and whether changes are made to policy and legislation longer term.
The INNS iCASP project runs for another year and seeks to develop guidance and biosecurity protocols that will be embedded within local authorities across the Yorkshire region and will ultimately be made available to be used by organisations worldwide to help slow the spread of INNS.
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.
This October is the 3rd anniversary of the Calderdale Flood Action Plan (FAP) . You can find out more about who is involved with delivering the plan, the various pieces of work being undertaken and get an idea of the costs and the benefits of work already carried out through infographics produced to highlight key actions and work so far
iCASP academics have 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.
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.
Additional links that may be of interest:
With much of the map of England lit up with flood warnings and alerts this morning, this serves as a timely reminder about the importance of ongoing work into flood forecasting.
The recent iCASP project on Enhanced Surface Water Flood Forecasts (ESWFF) set out to try to enhance the forecasts that are issued to help decision making in the run up to, and during, a flood event. A wide range of people utilise these flood forecasts including the emergency services, flood planners in local authorities, water utilities and the Environment Agency.
The culmination of iCASP’s ESWFF project was a mock incident response workshop in April that used data from a previous flood incident to see if enhanced forecasts would lead to different decision making. Involving many different flood responders in the workshop gave useful insight into the value placed on different kinds of information, how decision makers use different pieces of information and how the information could be further improved for clarity and ease of use.
Several recommendations came out of the project, including how to better support local authorities in their responses to surface water flooding, and further development and testing of user-centric surface water forecast information.
The executive summary, final report and a flyer about the project can all be freely downloaded:
Executive Summary (of final report)
Flyer about the project