Our Lower Wye Green Infrastructure work is currently focussing on the Unclassified County Roads (UCRs) around Tintern and Whitebrook communities. These beautiful, historic lanes are facing pressures that are resulting in their degradation, so much so in some cases that they are no longer useable by many people. These lanes are vital in linking rural communities and are a key part of the historic fabric of the AONB. Working in partnership with Monmouthshire County Council Highways and the MonLife Green Infrastructure and Public Rights of Way (PRoW) teams, we are piloting nature-based solutions to reduce the run-off and erosion of the less degraded routes, and agreeing the next steps for the severely degraded routes.
Latest news – Slowing the Flow in Chapel Hill Road, Tintern
This Easter 2021 we installed our first pilot Natural Flood Management (NFM) scheme in Chapel Hill Road Unclassified County Road (UCR) in Tintern. This pilot scheme is the first of its kind in any of the UCR’s in the lower Wye Valley, so we will be keeping a close eye on it over the next 12 months. Unusually, we’re actually looking forward to the next storm so we can assess how the lane performs under high flow conditions!
It will take a little time for the ground work to settle and bed down, but the changes to this long-neglected UCR are very positive. We’re receiving some great feedback and we’re delighted with how natural the scheme looks. Still very much a characterful, unpaved road, the surface is now much less uneven, rutted and boulder-strewn. There are fewer steep sections and ‘drop-offs’. This makes for much easier and more enjoyable walking and riding. These improvements will enable more people to enjoy this route, although we do appreciate those who relished the technical challenges previously posed may be a little disappointed by the modifications.
The cross-drains and log water-bars have been embedded into the road’s surface and backfilled to ensure stability. A number are already working away, diverting spring flows promptly into the adjacent Limekiln Brook. This means those long, wet sections have gone and the lane is generally much drier underfoot. A new channel cut in the mid-upper bedrock section will help to divert overland flow and retain water within the brook channel rather than it cascading down the whole width of the rock slab and lane as it previously did.
This is a Natural Flood Management pilot scheme, with the emphasis on ‘natural’ and ‘pilot’. With landowner agreement, the already felled logs came from the next door woodland, so we couldn’t have found a more cost-effective, natural, robust material. As a pilot or trial project, we’ll be monitoring the logs for 12 months to confirm their effectiveness in slowing the flow and testing their resilience. If they prove successful we could look at rolling this out in other UCRs in the area, subject to funding of course. If not, we’ll be back to the drawing board.
NFM is a concept that is being increasingly adopted UK-wide. It has been trialled for a number of years now in various catchments and is proving effective in helping to lower local flood risk. It is also something that individual landowners and small organisations can implement themselves, without resorting to expensive and intrusive hard engineering. You can download a useful NFM handbook here. Also, one project held up as an exemplar of NFM work is the Stroud Rural Sustainable Drainage Project. Their latest YouTube video is here: Natural Flood Management on the River Twyver
For this we need to look at the bigger picture. To be really effective, NFM interventions need to be little and often [the cumulative effect of sub-optimal structures], holding back and slowing the flow of as much water as possible. And they must be considered on a catchment scale. So these 19 cross-drains will not solve flooding issues on their own, but when complemented by other work with landowners in the catchment above Chapel Hill Road (installing natural leaky dams and leaky ditch barriers, strategic tree planting, hedge planting and fencing, farm yard Sustainable Drainage measures) this little and often approach can amount to a significant amount of water being slowed as it flows down through the catchment during storms.
It is still early days in our NFM work in this catchment, but every small scheme installed helps to slow that flow and reduces the flood risk a fraction.
Chapel Hill Road is an Unclassified County Road (UCR) and these user-groups are legally entitled to use this road. The Wye Valley AONB Management Plan recognises that legal use of UCRs facilitates appreciation of some of the Special Qualities of AONB and provides access for disabled and less-abled people into the countryside. Fingers are regularly pointed at motorised off-road vehicles as the culprits for degrading the UCRs, but this is akin to blaming cars for causing potholes on our A-roads. Water is the problem here and to make the road more resilient for all user groups, the solution is to install appropriate drainage to better manage the water.
This project has long been in the making. Essentially, Monmouthshire County Council (MCC) as the Highways Authority responsible for the UCR, had 3 options: 1) do nothing and let the surface degradation and associated issues continue, 2) install an engineered highway drainage scheme (concrete, large plastic culvert pipes etc.) or 3) adopt a Natural Flood Management approach working with adjacent landowners and installing low-key NFM installations to reduce the flow and monitor the effectiveness. Unsurprisingly options 1 & 2 were not viable for MCC. In 2017 MCC’s Flood Risk Manager commenced proposals on option 3, liaising with adjacent landowners.
In 2018 the Wye Valley AONB was successful in securing funding from Natural Resources Wales (NRW) for a pilot project to investigate NFM and Green Infrastructure (GI) initiatives. This looked at 4 sub catchments of the lower Wye. The Limekiln brook catchment and the Chapel Hill Road UCR were identified as one of the areas to target this pilot work. The consultancy WS Atkins was commissioned to recommend a suite of NFM interventions around the wider sub-catchment and, for Chapel Hill Road, a series of cross-drains were recommended. We funded some modest NFM installations on farmland in the upper catchment and then secured further funding to deliver the Chapel Hill Road scheme. The cross-drains scheme was designed and installed under the overview of a land drainage consultant.
This scheme was funded by the Welsh Government through the Sustainable Landscapes, Sustainable Places grant. It was coordinated by the Wye Valley AONB Unit and supported by MCC’s Highways and MonLife Departments.
With climate change increasing heavy rain events, the Wye Valley AONB team will continue to seek project funding for NFM, to help our local communities and landscape adapt and become more resilient. So do watch this space!
The matter of highway potholes lies outside the Wye Valley AONB’s remit, plus the funding that the AONB secures for projects such as this is not eligible to be spent on potholes.
If you have any more questions please do get in touch with Nickie at firstname.lastname@example.org