Landslips in the Brecon Beacons National Park can significantly affect raw water quality, sometimes turning reservoirs “red”. As part of the Dŵr Cymru Welsh Water WaterSource approach to Catchment Management, the Catchment Team and stakeholder partners have taken an innovative approach combining collaborative working, new science and a nature-based solution to investigate, understand and address this issue.
The success of this new way of working has been recognised by the Institute of Water Annual Innovation Awards; with the approach winning the Welsh Area Innovation of the Year 2016/17 and Runner-Up Innovation of the Year 2016/17 at the National Finals.
An emerging risk
The Brecon Beacons National Park is an area which provides almost half of the drinking water Welsh Water supplies every day to its customers, this includes the majority of Cardiff and Swansea.
Heavy rainfall events in the Brecon Beacons can often generate landslips and the mobilisation of fine sediments, turning reservoirs downstream “red” in what have become termed “red events” (the distinctive red soils of the area are a feature of the underlying Old Red Sandstone).
These sudden increases in suspended sediment load can pose a considerable treatment challenge for the receiving water treatment works. The “red events” can also have a wider significant impact on biodiversity, local communities and tourism.
Finding the root cause
To initiate a collaborative approach to understand and address this issue, Welsh Water’s Catchment Team organised and hosted the first stakeholder meeting to focus on this in 2010. The event brought together more than 40 stakeholders and experts. It was clear that the root cause of why landslips were occurring in this location were not well understood and there was little agreement on how the land could be managed to reduce the potential of future landslips so the stakeholders agreed to form a partnership; working together to take an evidence based approach to understanding the problem and to inform future management decisions.
To support the agreed evidence based approach, Welsh Water funded a PhD with Aberystwyth University, which commenced in 2011. Following an extensive sub-catchment study, the outcomes of the PhD confirmed that a combination of long periods of dry weather immediately followed by heavy rainfall events as well as a lack of deep rooted stabilising vegetation were the main triggers of the landslips that cause the “red events”.
Piloting nature-based solutions
As part of the PhD research a hazard risk map identifying locations at high risk of future slope failure was produced. It was also identified that a change to deep rooted vegetation could help stabilise soil and slopes, reducing the risk of future slope failure.
The partnership were keen to trial a nature-based solution to increase the ecological resilience to landslips by re-introducing local, native species of willow and alder trees to areas at high risk of slope failure; the deep roots would help bind the soil and increase its stability, thereby reducing slope failure potential and increasing environmental value. Biodiversity, improved soil protection and enrichment; reduced runoff rates and carbon capture would also be greatly enhanced by the tree planting.
Planting in this catchment is challenging for a number of reasons including that the trial area is on common land and so there are constraints on fencing (no fencing is allowed!) and tree protection on the common, the whips had to be planted without any form of protection! Despite these challenges, a total of 10,000 trees are being planted, the Willow whips are harvested locally at a site just under three miles away from the trial area. Early results have been extremely promising – even following a very dry period and no protection from livestock, 42% of trees are establishing well with a further 38% still in the ground but slower to establish and just 20% have been damaged by livestock. Monitoring will continue and learning from the trial sites will inform the approach taken to the next quota of whips due to be planted in Autumn 2017 and Spring 2018.
Collaboration has been at the heart of our work; partnership working and successful communication with an evidence-based approach has been key to the project’s success and securing agreement amongst stakeholders. This project has increased morale and created a new culture where open and honest conversations can be held and will leave a legacy of a Partnership open to new ways of working.
Identifying spatially where there is a high probability of future landslips within drinking water catchments has provided an opportunity to mitigate the risk to water quality through the use of a nature based solution. Looking further ahead, this approach will improve the landscape resilience to future challenges such as climate change and the evidence and learning will be used to inform the development of the Brecon Beacons Mega Catchment landscape scale approach.
The project would not have been possible without the participation and support of a number of individuals and organisations. Our thanks go to Dr Joanna Clint (née Matthews) & Professor Paul Brewer, Aberystwyth University; Bayden Rees, local Farmer; Brecon Beacons Grazing Association; National Trust; Brecon Beacons National Park Authority; Coed Cymru; Natural Resources Wales and Welsh Government.
PROJECT LEGACY: Brecon Beacons mega catchment approach
In May 2017 Welsh Water launched the Welsh Water 2050 consultation, in which Catchment Management is recognised as the “first line of defence”. If catchment management can deliver raw water quality that is expected, manageable and consistent, it can help build resilience into the water supply system, reducing chemical and energy usage as well as the need for future capital investment, as well as delivering a whole host of multiple benefits for the environment and local communities.
Traditionally, topography has been used to define the boundaries for catchment management. In the Brecon Beacons drinking water catchments are geographically located next to each other and form a “Mega Catchment” at the landscape scale. So many of the things that can influence water quality don’t recognise topographical catchment boundaries (e.g. sheep grazing common land, wildfires); recognition of this has caused Welsh Water to rethink the future approach to catchment management.
The Brecon Beacons is not only a “Mega Catchment” for water, it is also a “Mega Catchment” for biodiversity, agriculture, forestry, people and tourism amongst other things. In order for any management approach to work it needs to work for all stakeholders.
Going forward Welsh Water continue to work closely with partners, communities, land managers and users to co-create a vision for the Brecon Beacons that delivers social and environmental enhancements in this iconic landscape so that it remains prosperous and resilient for years to come. Working successfully at the pilot scale has produced evidence which will enable Welsh Water to upscale this approach to landslip management in the Brecon Beacons and more widely as part of our WaterSource approach to Catchment Management.
Insert Image: Impact of a “red event” on the Cantref Reservoir
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