Salix to begin work on tidal erosion project along the River Thames this summer

June 11, 2021

Salix, an RSK group company, has been awarded a contract to restore saltmarsh habitats and prevent further erosion at West Thurrock lagoon and marshes, near Stoneness in Essex. The reserve, which has site of special scientific interest (SSSI) designation by Natural England, is currently designated as “unfavourable – declining” and the number of wintering birds is below the threshold. The saltmarsh and mudflat are vulnerable to the effects of coastal erosion from the River Thames due to coastal squeeze.

The saltmarsh habitats along the River Thames have decreased significantly with urbanisation, so much so that only 2% of the intertidal extent of the river has natural banks. The 3.6-hectare site near Stoneness lighthouse is a valuable habitat for birds and other wildlife. Vegetation is present at the top of the riverbank, creating the SSSI habitat, but the present susceptibility to the impacts of erosion has reduced this area significantly.

The team at Salix will work to protect 600 m of eroding saltmarsh fringe and will aim to create an additional two acres of new saltmarsh. Engineers will use brushwood polders to provide erosion protection and to improve the habitat for local wildlife populations. cbec eco-engineering, a Salix company, will undertake a bathymetric survey and find hard and soft levels. The information collected from these surveys will inform the final detailed design of the polders. The use of brushwood will stabilise the mudflat by creating a buffer to the wave action while accreting with sediment. As a result, this will improve vegetation establishment, providing sustainable and long-term erosion protection and restoration of the habitat area.

Salix has extensive experience working on numerous intertidal and estuarine projects, having co-authored the first edition of the Estuary Edges Handbook. Saltmarsh habitat restoration is of significant importance given the rate of degradation. Restoration can provide numerous benefits for biodiversity, erosion control and carbon sequestration.

More information about Salix and its specialist services can be found here.