Design criteria for Outline Business Cases

wave and coastal process studies for the economic justification of new coastal defences around the Welsh coast

Understanding risk is the critical component in flood and coastal erosion risk management (FCERM). Working with Arup, we have completed numerous wave and coastal process studies providing the necessary design criteria required for the economic justification of new coastal defences (Outline Business Cases) around the Welsh coast. Locations include Penrhyn Bay on the north coast, Barmouth on the east coast and Porthcawl and Swansea Bay on the south coast of Wales.

For these studies we have been building local wave models with detailed bathymetry and LiDAR to provide a timeseries of wave and water levels applicable to the nearshore zone. These local models are driven with nearly 40 years of wave and water level conditions generated from our robustly calibrated and validated SEASTATES wave and water level hindcast models. From these timeseries, wave and water level pairings are derived using joint probability assessment and transformed through 1D shoreline models, using representative cross shore profiles, for use in the overtopping analysis.

The rate of overtopping is a result of both extreme wave/water level and the topography of the foreshore and it is critical to understand how these change in space and time. Extremes analysis are supported by coastal process assessments which use literature reviews, bathymetric analysis and Expert Geomorphological Assessment to produce a conceptual understanding of sediment transport. Where appropriate, our analysis is supported by modelling cross shore response and beach stability, and appraisal of scheme options.

For many of these locations we have supported Arup with detailed design, providing additional detail on extreme wave conditions, scheme modelling and producing beach management plans.