Cho, Y.J. and Park, S.H., 2023. Deformation of wave slope distribution due to the presence of infra-gravity waves and its effect on shoreline motion. In: Lee, J.L.; Lee, H.; Min, B.I.; Chang, J.-I.; Cho, G.T.; Yoon, J.-S., and Lee, J. (eds.), Multidisciplinary Approaches to Coastal and Marine Management. Journal of Coastal Research, Special Issue No. 116, pp. 613-617. Charlotte (North Carolina), ISSN 0749-0208.

Infra-gravity waves, which underlie swells in a mild sea, play a crucial role in the beach restoration process. They have distinct features that set them apart from other water waves. When sub-harmonic wave-wave interactions evoke infra-gravity waves in a wavefield, they leave behind a characteristic imprint in the form of a probability plateau shaped slope distribution. This study proposes the hypothesis that wave slope can provide the most comprehensive insights of random wavefield, particularly when random waves undergo alterations via resonant wave-wave interactions, and that the probability plateau shaped by infra-gravity waves is closely linked to shoreline motion. The hypothesis was tested using in-situ wave data collected at three locations on the east coast of Korea and a year-long shoreline survey data at Mang-Bang from April 26, 2017 to April 20, 2018. The results showed that during shoreline advancement, a probability plateau was present in the wave slope distribution, while during the retreat period, the plateau could not be found. Thus, the hypothesis was partially confirmed.