A Methodology to Assess the Morphological Change of a Multilevel Beach Cusp System and their Hydrodynamics: Case Study of Long Strand, Ireland

Nuyts, S.; Murphy, J.; Li, Z., and Hickey, K., 2020. A methodology to assess the morphological change of a multilevel beach cusp system and their hydrodynamics: Case study of Long Strand, Ireland. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 593-598. Coconut Creek (Florida), ISSN 0749-0208. Characterising the behaviour of highly dynamic and small-scale coastal features is challenging, for lack of a non-intrusive and cost-effective survey methodology that can map coastal features with high spatial and temporal resolution. Unmanned Aerial Vehicles (UAV) are already widely used in coastal research but to date, they have primarily been used as an auxiliary approach for traditional survey methods (e.g. beach profiles). In this study, a methodology is proposed to fully capture the dynamic behaviour of a multilevel beach cusp system. The aim of the research is to establish a method that links the morphological change of these rhythmic coastal features with detailed information of the hydrodynamics in the study area. This is achieved with a UAV system in combination with MIKE 21 Spectral Waves FM Model. Long Strand, Co. Cork in Ireland is used as a case study to evaluate the proposed methodology. Results show that the proposed approach allows to accurately determine beach cusp parameters (i.e. spacing, amplitude, elevation, and depth) and link their high spatial topographical data with the hydrodynamic forces at any given location. Using this survey method in future, coastal research will allow for a better understanding of complex dynamic coastal features and their behaviour over time.