O' Connor, M., Cooper, J. A. G., and Jackson, D. W. T., 2007. Morphological behaviour of headland-embayment and inlet-associated beaches, northwest Ireland. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 626 – 630. Gold Coast, Australia, ISSN 0749.0208

Both static and dynamic environmental conditions contribute to the behaviour of coastal sedimentary systems. Sand beaches on the bedrock-framed northwest coast of Ireland exist in two distinct planform settings that offer the opportunity to examine their varying behaviour. Beaches in this region are either located in coastal re-entrants between rocky headlands and backed by vegetated sand dunes or adjacent to the inlets of large sandy estuaries that are themselves located in bedrock valleys. They all have a finite sediment volume due to the deeply embayed coastal morphology and lack of contemporary sediment input. The behaviour of these types of systems over the past 170 years is recorded in historical maps, air photographs and morphological measurements. Preliminary results show that the beaches of inlet-associated systems involve complex exchanges between beach, dunes and tidal delta while headland-embayment beaches cycle sediment between beach and dunes. The inlet-associated beaches are typically more dynamic than the headland-associated beaches, although both are subject to the same range of wave forcing. Inlet-associated beaches appear to show cyclicity in their behaviour that alternates between rapid erosion and accretion at horizontal scales of decametres and timescales of decades. Headland-embayment beaches show relative stability or slow progressive erosion. High magnitude storms, long term patterns of ‘storminess’ and morphological feedback all offer potential explanations for the behaviour identified.