Shoreface morphodynamics of a high-energy, steep and geologically constrained shoreline segment in Northern Ireland

The shoreface, a complex and poorly understood part of the coastal zone, plays a critical role in sediment transport processes between the beach and the inner shelf. This two-year study examined the surface and subsurface architecture and the process-response mechanisms of a high-energy, steep and geologically constrained shoreface segment (1–20 m depth) in Northern Ireland. Fourteen sequential bathymetric surveys, covering an area of ~ 2 km2, were compared and analysed in order to investigate seabed changes and their relationship to wave and wind forcing. Results reveal that the shoreface is highly dynamic and complex. An examination of high-energy conditions and lower-than-average energy conditions revealed significant periods of both accretion and erosion. These complex morphodynamic responses are attributed mainly to a combination of antecedent (pre-survey) morphology, differences in wind forcing and coastal surges. A comparison of seabed changes over 2 yr reveals net shoreface accretion, which is attributed to inner-shelf to shoreface sediment transport. Over the same period, the adjacent West Strand beach showed moderate erosion. The study provides information on the morphodynamics of a steep, high-energy embayment shoreface, a coastal environment which has received little previous attention.