Case studies
River Bewl Restoration Project

River Bewl Restoration Project

River Bewl, Lamberhurst November 2016 - February 2018 Southern Water

FiveRivers worked in partnership with CMDP and Atkins on behalf of Southern Water to carry out a range of river restoration techniques to improve the ecological condition of the River Bewl through the National Trust estate at Scotney Castle.

We carried out significant daylighting as well as in channel improvements over 3km of river. Low ground pressure machinery and ground protection measures were critical to protect the existing SSSI grasslands. Our team worked with partners to re-use site materials, creating large wetland / hibernacula features at minimal additional cost.

Project requirements

Tasks

Extensive tree coppicing, cut back of ground vegetation and scrub clearance along the riverbank to open up the channel and create a mosaic of habitat.
Creation of low-level earth berms with brushwood base and gravel berms to narrow channel, accelerate flows and accentuate variation in planform.
Placing riffles and glides to provide shallower, faster-flowing sections to favour target ecological communities and locally entrain fine sediment to improve quality of spawning gravels for salmonids.
Floodplain excavation to increase habitat complexity through the provision of marginal backwater. Furthermore, pools provide a refuge for aquatic fauna during low-flow events.
Addition of large wood that serve as attachment sites and food sources for aquatic macro-invertebrates.
Generation of a hibernaculum with stacks of logs pilled up that gives a safe place to shelter through the cold of winter for reptiles and amphibians.
Re-profiling of the eroded bank to encourage in-channel and marginal vegetation.
Removal of a damaged fence to replace it with a new fencing.

Our approach

Key remarks

Site won woody debris was used for in-channel features to reduce the number of construction vehicles required and minimize the impact of the scheme on the local road network during construction.
Due to the amount of work the project was segregated into three phases.
The vegetation community located within the SSSI was translocated to preserve this scarce habitat.

Project outcomes

Effects

Restored 3 km of the River Bewl by re-grading the damaged banks, increase light penetration to support aquatic plants and install in-channel features to slow flows and create habitat variations.
Provided deep, still waters through the excavated pools which are excellent resting areas for fish and a nursery habitat for juvenile fish. Furthermore, backwaters enhance water quality by facilitating the deposition of fine sediments during low-flow events.
Large wood features can reinforce retention of organic matter that in turns improve nutrient processing and provide cover for fish.
Creation of a diverse riparian environment through the plantation of native species.