Wye Valley National Landscape commissioned CBEC to identify feasible remediation options for approximately 1.4 km of footpath alongside the River Wye, immediately south of Monmouth, which is currently eroding or at risk of future erosion. The affected sections form part of the Wye Valley Walk, a nationally important long-distance trail valued by both local communities and visitors. The route provides public access to the distinctive landscape, cultural heritage, and biodiversity of the Wye Valley.
Erosion pressures within the project area are understood to be influenced, in part, by fluvial processes associated with the River Wye (Afon Gwy). CBEC’s options appraisals approach employed a process-based assessment framework, incorporating nature-based solutions (NBS) where appropriate, to develop sustainable and resilient remediation options that aligned with the physical process regime of the River Wye and the functional requirements of the Wye Valley Walk.
CBEC undertook an options appraisal process to determine the most appropriate remediation measures to be implemented within the project area. The options appraisal was underpinned by a comprehensive desk-based review and a high level geomorphic walkover to establish a clear picture of the current condition of the riverbank and path alignment, identify the key processes contributing to ongoing erosion, and highlight any constraints or considerations that may influence feasible remediation options at this specific site.
A targeted field survey determined that the main cause of erosion was arising from a steep, near-vertical bank profile composed predominantly of friable sands and silts with very low clay content. As the popular footpath was unpaved, frequent footfall combined with periods of heavy rain had resulted in boggy conditions that further destabilised the bank face, resulting in mass failure across the bank face – despite the toe of the bank being relatively stable.
A full feasibility assessment of potential remediation options was presented to the client with the benefits, disadvantages and primary risks with suggested mitigation measures. Options ranged from ‘DO nothing’ and ‘Set path back to valley top’ through a series of crib wall structures through to construction of a raised walkway, depending on the nature of the pressures in that section. The preferred option suggested was to install a crib wall structure to stabilise the bank and support the path along with selective tree crown thinning, coppicing and complete removal of trees deemed to be at risk of collapse into the river. Other options recommended elsewhere included resurfacing the sections with compacted gravel, proactive tree management, installing fencing along the bank top to prevent access and setting back and widening of the footpath away from the top of bank.
