- 10th November 2021
- Posted by: Miranda Pont
- Category: Projects
Location: North Wales Client: Natural Resources Wales
The River Alyn flows through North Wales and discharges into the River Dee north of Wrexham. Like many UK rivers it has a long history of industry and land-use related changes, which have impacted present-day hydromorphological and ecological conditions. Physical modification of the channels to supply industry, and severe water losses via mining-exacerbated limestone fissures have led to a complex hydrological regime and widespread system pressures. These pressures impact hydromorphic process, form and ecological function and are causing many of the water bodies within the catchment to fail under the Water Framework Directive.
Our Catchment and River Restoration Team were asked to investigate the feasibility of several high-level river restoration opportunities, developed as part of the Rive Alyn Restoration Plan which we produced for Natural Resources Wales (NRW) in 2019.
The opportunities included:
- restoring flow sinuosity and channel heterogeneity
- re-meandering straightened channel reaches or introducing large woody material
- techniques that focused on restoring river continuity and ecological functioning of river corridors (e.g. weir removal, reconnection to floodplains, improved riparian planting and buffer zone creation).
For this study four reaches were taken forward and their feasibility assessed to determine the options and their ability to deliver necessary hydromorphic and ecological improvements under the Water Framework Directive (WFD). We used a multi-disciplinary approach to the project to ensure a wide range of needs were considered and to identify key constraints to help steer the proposals.
The project developed river restoration opportunities to both concept and outline design stages. We created concept proposals to restore natural processes and reduce the effects of system pressures that limit ecological habitat potential and interaction between the river channel and its riparian zone and floodplain. We also prepared an outline design for the removal of a large weir, to pave the way for morphological and ecological rehabilitation of the river reach.
The River Alyn benefits from an active community who are passionate about improving the condition and health of the river. This project has involved these key members throughout the process alongside Natural Resources Wales; the next step will be to engage with a wider network of stakeholders to develop the proposals further.