Coastal process study to support new defences at Criccieth West Beach

Helping determine the preferred option for sea wall protection

Cricceth’s West Beach in Gwynedd, northwest Wales, is subject to coastal erosion and potential failure of the existing coastal defence structures. There has been a trend of declining beach levels causing an increased level of exposure and risk to the current defences.

Cyngor Gwynedd Council and engineering consultancy YGC recorded a trend of lowering beach levels which could result in failure of the sea wall. Without significant capital investment to refurbish and maintain the sea wall, the frontage will be at risk due to flooding and erosion over the next 100 years.

YCG commissioned ABPmer to support the development of a Strategic Outline Business Case for coastal works at the beach. We completed a coastal process study supported by numerical modelling to determine the preferred option for protecting the existing sea wall.

To complete the sediment transport study, discern the local sediment transport processes, and so understand how to retain beach levels, we completed:

• A literature review and data collation

• Historic trend analysis of beach levels

• Spectral wave modelling of Cardigan Bay to determine how waves are transformed inshore as they are refracted by the shallow bathymetry off the beach

• Hydrodynamic modelling using ABPmer’s SEASTATES tide and surge model to derive the regional and local flow regime, to understand whether residual tidal currents influence the sediment transport regime

• A calculation of potential sediment transport rates and beach alignments

• Identification and appraisal of options to manage beach levels and protect the sea wall

The study provided supporting evidence for YGC to submit a Strategic Outline Business Case to Welsh Government for funding to protect the sea wall. 

ABPmer is a recognised authority in numerical modelling and metocean criteria, and is regularly called upon to provide technical input to engineering design that satisfies both consenting requirements and international standards. Discover how your project can benefit from our design support services.