This paper presents the observed morphological evolution of a multilevel beach cusp system in Long Strand, Co. Cork, Ireland. The surveys were carried out with an Unmanned Aerial Vehicle (UAV) system between March and September 2019. From this site, three levels of beach cusps on the beachface (i.e., lower beach level, mid beach level and upper beach level), and critical cusp parameters are reported, including cusp spacing, cusp elevation, cusp depth, and cusp amplitude. Thus far, such an extensive dataset has not previously been reported in the literature from a single site. The evolution of the different cusp parameters is then linked with the hydrodynamics in the study area, and new prediction theories are proposed for the different cusp parameters. The Lower beach level cusps (1 < z < 2.5 m Irish Transverse Mercator (ITM)) changed with every tide and appeared when surf-similarity parameter-ξ₀ < 1.55. These cusps had a mean cusp spacing of λ_mean = 11.09 m, which are closely linked with the predictions of the self-organisation theory (p < 0.05). In contrast, the Mid beach level cusps (2.5 < z < 3.5 m ITM) are less dynamic compared to the Lower beach level cusps and can persist between spring tidal cycles. They had a mean cusp spacing of λ_mean = 18.17 m. The Upper beach level cusps (approximately z = 6 m ITM) are above astronomical tide levels and have a mean cusp spacing of λ_mean = 40.26 m. They did not change significantly over the survey period due to a lack of major storm events. These findings give a better understanding of the evolution of different cusp parameters for a multilevel beach cusp system and can be used to formulate a global theory regarding their change over time.

This research presents a study on the morphodynamic evolution of the Rossbeigh coastal barrier and its dune system, located in Dingle Bay, County Kerry, Ireland. The study examines the evolution of the system over a 19-year period (2001–2019) through remote sensing, geographic information system (GIS) analysis, and field-based surveys. This research provides an ideal opportunity to examine a natural erosion event, referred to as cannibalization on a coastal barrier and its dune system. Since the beginning of this century, significant erosion has been visible on the coastal barrier, with the erosion eventually leading to a breaching event in the winter of 2008/2009. Over the study period, analysis has shown that the vegetated dunes decreased by more than 60 percent, the width of the breached area reached a maximum width of over 1 km and a change in orientation and appearance on the coastal barrier has been quantified. The analysis identifies a growing drift-aligned zone, contrasted with a reduction in the stable swash-aligned zone. Significantly, the point between these zones (i.e., the hinge point) has been shown to have moved by more than 1 km also. The migration of this hinge point and cannibalization of the dunes are illustrated. Finally, the potential mechanism for beach healing is identified, utilizing the rich datasets collected during the study, thus providing an insight into the long-term behavior of a dynamic coastal barrier system undergoing naturally driven cannibalization.

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.