Calderdale catchment modelling workshop

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.

iCASP’s Tom Willis explaining how SD-TOPMODEL is being used to map three sub-catchments in Calderdale

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.

SD TOPMODEL output showing the baseline modelling for the Jumble Hole catchment

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.

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.

Natural Flood Management; have your say

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.

Examples of different NFM interventions Image credits (L-R): Richard Grayson, Richard Grayson, Jenny Armstrong, Mark Trigg, Susan Ballard

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:

Tree planting project trialled to tackle floods

Natural flood management for Yorkshire Dales communities

Pickering leaky dams flood prevention scheme ‘a success’

Major natural flood management project underway in Yorkshire

 

Modelling to support optimal location of flood measures

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

Infographic about Natural Flood Management work as part of the Calderdale Flood Action Plan (from https://eyeoncalderdale.com/fap-3rd-anniversary)

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.

SD-TOPMODEL output showing the baseline modelling for the Jumble Hole catchment

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.

Natural flood management in the media

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

Images of leaky dams and volunteers by Slow The Flow Calderdale

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

Prioritising Natural Flood Management interventions in Calderdale

Photo Courtesy: Slow the Flow

A rainfall-runoff model developed at the University of Leeds is the latest weapon in Calderdale’s efforts to prevent future flooding in the valley. SD-TOPMODEL is currently the only tool able to model the flow of water from hillslopes to the river at a sufficient spatial scale to allow Natural Flood Management (NFM) interventions and land management to be represented accurately for the characteristics of the Calderdale catchment.

An iCASP project using SD-TOPMODEL and starting in November 2018 will contribute to the Calderdale Flood Action Plan by helping to prioritise the siting of future NFM schemes.

Read morePrioritising Natural Flood Management interventions in Calderdale

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