]> 2026-04-09T05:10:54+00:00 Case study:River Cleddau 500 en River Cleddau case study Approved New bioengineering elements in order to stabilize slope banks Bank reprofiling Salix River & Wetland Services Limited Natural Resources Wales Great Britain Environment Agency Wales No No Yes false Before 1.jpg After 1.jpg Bank re-profiling.jpg Marginal habitat creation.jpg Bank section before works 2004 (courtesy of Salix Water & Wetland Services Ltd) Bank section after works 2005 (courtesy of Salix Water & Wetland Services Ltd) Bank re-profiling (courtesy of Salix Water & Wetland Services Ltd) Marginal habitat creation (courtesy of Salix Water & Wetland Services Ltd) No 51.822357339934,-4.9751329421997 Richard Salix River & Wetland Services Limited Edwards Fencing New bioengineering elements in order to stabilize slope banks, Bank reprofiling,,Fencing, ,Fencing,,, 4922 Natural Resources Wales, Bank section after works 2005 (courtesy of Salix Water & Wetland Services Ltd) 2004-07-31Z 2453217.5 After_1.jpg Complete The River Cleddau in South West Wales is a mobile gravel bed river of moderate to high energy and an important spawning tributary for migratory fish. The project undertaken in 2004 aimed to demonstrate the effectiveness of soft engineering techniques in managing extensive erosion problems, whilst still encouraging natural river processes to continue. The demonstration reach in particular had a history of instability and planform adjustment. An initial geomorphological survey and detailed design plan were carried out by Salix for the Environment Agency Wales and Pembrokeshire Rivers Trust. The initial survey concluded that overgrazing and poaching were accelerating erosion in the demonstration reach. Hard engineering techniques, such as blockstone revetments, have been traditionally used in higher energy river systems to control bank erosion. However, the use of such techniques removes any scope for marginal vegetation to establish, thus lowering the ecological value of the river. It can also deflect energy to other areas of the bed or bank, maintaining the overall erosion problem. As part of a three-year project, entitled “Fishing Wales” the Environment Agency Wales were keen to demonstrate that softer bioengineering methods could be used to control the extensive erosion, whilst maintaining geomorphological processes, and enhancing the physical habitat of the river. The aim of the demonstration was to show that bioengineering techniques can be used as an alternative to blockstone in mobile gravel bed rivers to control erosion, whilst restoring physical habitat to degraded channels, thus helping to ensure the sustainability of fish stocks in Wales. A range of bioengineering techniques were used based on the local reach scale erosion process, water depth and stream power. In areas with low stream power these included bank grading and toe protection using live willow bundles (faggots/fascines), whilst in areas with greater erosive energy whole upturned tree roots with 2 metres of trunk still attached were installed to act as physical revetments and also deflect flow away from eroding banks (40 tree roots used in total). All the trees used were grey willow (Salix cinerea) or crack willow (Salix fragilis) and have since grown to provide excellent habitat and cover. In addition the entire reach was fenced in order to keep livestock off the banks. Living plant material was obtained from the Cleddau catchments. The project has been successful in demonstrating soft bio-engineering methods. The Pembrokeshire Rivers Trust and Salix report that 80-90% of planted material has survived, with a mix of other vegetation also colonising the site. Salix have since identified some issues with Himalayan balsam competing with native planting, but this has been acknowledged as a catchment wide problem (see evidence in photos). The River Restoration Centre would like to thank Salix River & Wetland Services Ltd for providing the content and photographs for this case study. River Cleddau river cleddau No 500 South West Wales Western Wales Fencing W. Cleddau - Anghof conf to Cartlett Brook conf w. cleddau - anghof conf to cartlett brook conf River Cleddau, Haverfordwest river cleddau, haverfordwest 100 - 1000 km² 175 100 - 200 m W. Cleddau - Anghof conf to Cartlett Brook conf GB110061031340 Fisheries Habitat and biodiversity 29 10 - 50 k€ GB110061031340 W. Cleddau - Anghof conf to Cartlett Brook conf 2004-07-01Z 2453187.5 2013-01-02T13:54:45Z 2456295.0796875 2019-01-02T16:02:45Z 2458486.1685764 River Cleddau 500 1 plainlist 5 [[Category:Case study]] [[Project title::!River Cleddau]] [[Subcatchment title::W. Cleddau - Anghof conf to Cartlett Brook conf]] River Cleddau# QUERYa7a3320998088f89632057bd2caa4ac4