Field observation and modeling of wave set-up on a macrotidal beach: the Malipo Experiment

Abstract

Korea Research Ocean & Development Institute (KORDI: now renamed the Korea Institute of Ocean Science & Technology, KIOST) conducted a field observation experiment (the Malipo Experiment) using a variety of wave gages and current meters simultaneously at the Malipo Beach, South Korea, from December 2009 to March 2010 in order to understand the coastal processes in a macrotidal environment. The Malipo Beach has a typical macrotidal beach environment characterized by a very gentle beach slope of 1/50 and strong tidal currents corresponding to the extreme tidal range of 7 m. As a part of this program, we observed the intertidal-zone wave set-up using a wave-rider buoy moored at 20 m water depth and seven pressure-type wave gages perpendicularly aligned to the shore at the intertidal zone for 17 days beginning from December 17th, 2009 in order to understand wave breaking and set-up characteristics in the macrotidal environment. Based on the observation data analysis, the relationship between the wave set-up and wave height at offshore (H-s,H-0) is eta= 0.11H(s,0) showing that influence of alongshore tidal currents on the wave set-up was negligible. It was analyzed that, however, wave set-up might be influenced by shore-normal currents. The wave set-up at the study site was smaller than previous researches. It might result from its low breaking index and the wave characteristics of short wave period and wide-spreading directional spectra at the study site. Results of model simulation by combining a wave model with a circulation model showed that simulated wave set-up heights were generally lower than the measurements.