Tackling flooding; whole catchment approaches

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 functionality

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.

Images of Sphagnum in peatland

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.

Images from the Natural Flood Management Community of Practice meeting in June 2019

Improved forecasting

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.

Building resilience

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.

Sphagnum is a key ingredient of natural flood management

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).

Getting research in to Parliament

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.

3 tweets showing direct engagement with MPs: Joe Holden meeting with Alex Sobel,  and Angela Smith speaking at Confluence 2018  and Alex Sobel at Confluence 2019 having both mingled with attendees in the morning break

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.

Networking is another way that our researchers can get iCASP research in to parliament. This might be as simple as attending an event organised for parliamentarians such as the recent IUCN Peatlands meeting in the houses of parliament.

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.

And finally, in these days of social media its very easy to get information in front of MPs directly by just responding to their questions, for example Holly Lynch MP recently asked the government about future plans for managing peatland responsibly, we were able to point her in the direction of our optimal peatland restoration work.

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.

Making the case for peatland restoration

A new digital publication to help peatland restoration projects make a strong case for investment has been produced by the Yorkshire Integrated Catchment Solutions Programme (iCASP).

A ‘User Guide for Valuing the Benefits of Peatland Restoration’ explains very simply how different methods can be used to evaluate benefits such as flood risk reduction, carbon storage, water quality improvements and recreational amenity.

Read moreMaking the case for peatland restoration

Maximising pay-back from peat restoration

Efforts to restore Yorkshire’s vast peat bogs will soon be getting a welcome boost, thanks to a new project being developed by the Yorkshire Integrated Catchment Solutions Programme (iCASP).

The Yorkshire Peat Partnership and Moors for the Future Partnership will be working with the Universities of Leeds, Manchester and Durham to develop tools that people can use when they consider how to get the most value from restoring a bog even as the climate changes.

The project team will develop a user-friendly and updated version of a modelling tool called DigiBog. They will also create a ‘menu of methods’ for valuing the benefits of peatland restoration. This will help restoration practitioners plan their programmes to generate maximum social benefit.


Read moreMaximising pay-back from peat restoration

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