BLOG: SCORE Water challenge – Working with Natural Processes to alleviate flooding
Bradford District in the North of England is characterised by steep sided valleys and includes the Rivers Aire and Wharfe. It is situated in the middle catchment of these rivers with urban areas in the district and further downstream impacted by river and surface water flooding. One approach to reduce this flood risk is Working with Natural Processes (WwNP) which involves implementing measures that help to protect and restore the natural functions of catchments, floodplains and rivers.
By Kirsty Breaks-Holdsworth PhD, Flood Risk Officer Bradford Council
The Cow and Calf Rocks on Ilkley Moor
WwNP takes many different forms from gully blocking in moorland areas, to tree planting and fenced buffer strips on river banks in lowland areas to slow down the flow of water. Measures can have additional benefits in terms of habitat, ecological improvements and restoration of valuable peatland. WwNP is particularly suitable for the Bradford District as it is approximately 70% green space and includes part of the South Pennines moorland, a designated Special Area of Conservation (SAC).
Funding was secured for pilot WwNP projects on Harden Moor (River Aire) and Ilkley Moor (River Wharfe). Harden Moor as part of Phase 2 of the Leeds City Council Flood Alleviation Scheme and Backstone Beck was funded by Defra (Department for Environment, Food & Rural Affairs) as part of a national pilot. Both sites are owned by Bradford Council and managed by the Countryside and Rights of Way (CRoW) Team. The projects were led by Council’s Drainage Team and designed to use earth bunds, gully blocking in the form of stone leaky barriers, sphagnum moss planting, timber leaky structures, footpath turn-bys to redirect flow and tree planting.
Timber leaky barrier in action
Stone leaky barriers on Ilkley Moor Timber leaky barriers on Backstone Beck
JBA Consulting was commissioned by the Environment Agency to carry out a WwNP modelling study on four catchments within Yorkshire to determine how potential measures can help to effectively reduce flood risk and methods were chosen based on this modelling and site walkovers by staff from different partner organisations.
Due to the difficulty of accessing the sites, a horse was used to pull timber for leaky structures on Harden Moor and a helicopter was required to move stone and timber onto Ilkley Moor – very contrasting mechanisms of delivery!
Horse delivering timber Stone being delivered by helicopter
The projects involved collaborative working with a number of partners including the Environment Agency (EA), Leeds FAS2 NFM team, Moors for the Future (MFTF), the EU Interreg North Sea Region Smart Cities and Open Data Reuse (SCORE) project, Friends of Ilkley Moor (FoIM), Yorkshire integrated Catchment Solutions Programme (iCASP), White Rose Forest (WRF), Dales Land Net and local volunteers.
In order to determine if WwNP is effective the measures put in place need to be monitored and again, this can be done in a variety of different ways from monitoring flow rates on watercourses with data loggers and depth gauges to visual observations. We wanted to install as many different measures as possible on the Backstone Beck project and it is our partners that have made that possible. The delay in implementation of physical works due to the Covid pandemic also resulted in us gathering more baseline data (18 months) than originally anticipated!
The SCORE project part-funded the installation of flow monitors with real time telemetry at three locations on Backstone Beck and funded fixed point photography posts. These allow changes in the ground cover and conditions to be visually monitored over time. Members of the public are encouraged to take and upload photographs using QR codes at these fixed locations whilst they are out walking and enjoying the moorland scenery.
Dales Land Net installed LoRaWAN enabled soil moisture monitors in the upper Backstone Beck catchment to see if the ground stores more water over time (an additional benefit of that could be reduced fire risk on the open moor). MFTF installed pressure loggers near the larger leaky structures and time lapse photography to enable us to see how the structures respond in storm conditions.
Bradford Council ‘tipping bucket’ rain gauge on Ilkley Moor
Fixed post photography installation on Ilkley Moor Water flow monitoring on Backstone Beck
The Council has provided funding to ensure that a further 18 months of data will be captured now the measures are in place. The SCORE project and other partners are publishing all data on the project as open so that it can be made of use to others with interest in the work. The baseline flow data captured is already being utilised by iCASP in a project to assess the effectiveness of the recently implemented measures by building a catchment and river model. It will build on previous iCASP WwNP projects such as Hardcastle Crags in Calderdale, but with the advantage of access to a significant quantity of monitoring data at the site. Backstone Beck is an ideal WwNP test case of integrating multiple stakeholder issues in one model and will draw together separate pieces of iCASP WwNP project work and staff experience in one project.
There are many flood risk management authorities, asset owners and local authorities invested in the outcomes of the WwNP but none have responsibility for the whole catchment. An aim is to provide partners with a better holistic understanding of how changes will impact on the surface water in the catchment. Partners will be encouraged to co-develop and co-fund a mutually beneficial open model that transcends individual interests. It will help assess what proposed changes to drainage arrangements within the catchment might mean for the Beck, for example, helping to explore a potential diversion of Ilkely Tarn outflows from the combined sewer.
