Salix worked on the River Nairn in an award winning project to renaturalise the river, allowing it to meander again and restoring river processes.
The River Nairn at Aberader Estate had a long history of straightening, dredging and artificial embankments.
The channel had been straightened and constrained between embankments, becoming ‘perched’ above its floodplain due to aggradation of its bed.
The river corridor lacked the physical features and associated habitats that would naturally occur, mainly through the lack of morphological variability but also limited tree cover and large wood material in the active channel.
The perched channel was cut off from the surrounding floodplain. As a result, the water body was classified at less than good ecological status under EU Water Framework Directive (WFD) classifications.
Cbec were appointed to undertake the detailed design with Salix appointed as the Principle Contractor to deliver this innovative process led restoration project.
The river was opened up, the embankments were removed and the river was allowed to meander again, allowing space for the river to deposit and re-establish the natural processes. River restoration like this is a low carbon solution that will provide resilience in the face of increased flooding.
Our solutions are always based on re-establishing the natural river process and we used a process based design, we ran a sediment transport model to ensure the design was appropriate given the amount of bed load in the river.
We realigned part of the river and added large amounts of woody structure, which hugely benefited the process of the river.
Large woody deposits are an excellent low carbon, natural solution which provide the potential for a high biodiversity response, and alongside the slowing of the river this is what we saw with increased numbers of fish fry and a general improvement in the ecology in and around the river.
Our aim was to create a better chance for the establishment of lateral channel variability by allowing the natural development of alluvial sediment bars and erosion of banks where the river’s meanders naturally established themselves.
The large wood features help to “kick start” natural processes and dynamic channel changes
Since the work was completed the river has evolved rapidly, two large online wetlands have been created.
Removing the physical constraints that had contained the channel for so long has allowed the new channel to evolve rapidly, creating far mor diverse physical habitats within the river corridor, whilst re-connecting the river back to its floodplain.
The river’s fish numbers have been significantly improved along with other wildlife and the drainage of the agricultural land has been greatly improved without a cost to wildlife.
The results have exceeded expectations from the client and all the stakeholders involved in this scheme.
Our nature based solutions naturally ensure resilience in the face of climate change, allowing nature the space to adapt in our changing planet.
We have worked with Salix on a number of projects throughout East Anglia over the last 6 years, and we have always found them to be highly professional and competent. We have used their services as suppliers of quality wetland plants, with a traceable provenance, and as contractors to both supply and plant the wetland plants. In addition we have always relied on the technical advice and knowledge of David Holland, in particular, to help answer queries from our clients regarding wetland planting schemes we have been involved in, this is an added value part of their service, for which we are grateful.UPM Tilhill
We used HydraCX for the first time on a Network Rail project in Chipping Campden. We wanted to establish vegetation growth as quickly as possible on a slope with poor ground conditions without the need for importing topsoil due to possession time constraints. HydraCX provided an excellent growing medium for rapid germination.Carillion Rail
We invited Salix to re-landscape the watercourse through a design and build project. The works to the watercourse were completed within two weeks of starting on site and, despite a number of prolonged heavy rain events both during and after the works, the pre-established coir rolls and pallets all began putting on new growth within a matter of days providing the watercourse with instant channel vegetation and protection to the toe of the banks. The VMax reinforcement used to stabilise the slopes has also prevented any erosion to the sandy soil beneath and has allowed the rapid establishment of grass which wouldn’t have otherwise been possible.South Ribble Council
HydraCX gave an immediate impression the embankment was grassed, making it more visually pleasing to our travelling customers. The rapidity of grass growth was exceptional and it added additional strength to the slope surface.Network Rail
Excellent overall performance – very approachable and offered a good sustainable solutions to rectify a significant erosion scour to the river foreshore without comprising the existing flood defence. Carried out work to agreed timescale and budget. Certainly would value their future input.Environment Agency, Leeds
Your staff are always friendly, knowledgeable and helpful and we have always been pleased with the service and the quality of the wetland plants and planting services. Technical knowledge on erosion control is also excellent. Keep up the good work!Living Water Ecosystems Ltd
Atkins has worked with Salix on a number of projects, collaborating on design concept, trialling and implementation. We have found their experience valuable in delivering cost effective and environmentally functional solutions.Atkins