Morphodynamic Evolution and Adaptability of Nourished Beaches

Beach nourishment has been widely used for coastal protection in China. However, few beaches have been monitored after nourishment, and the evolution of nourished beaches has not yet been elucidated. This paper presents a study of two nourished beaches, both of which are in low-wave-energy environments but have different tidal ranges: Huizhan Beach, with a large tidal range, and Meiliwan Beach, with a small tidal range. To gain a better understanding of the evolution of these nourished beaches, beach profile surveys were carried out repeatedly over 4 and 2 years after nourishment, respectively. The nourished beach evolutions were analyzed in terms of profile morphology, foreshore slope, dry beach width, and remaining sand volume. From the results obtained, it can be seen that Huizhan Beach profiles demonstrated major changes during the initial adjustment, followed by a stable state, while Meiliwan Beach profiles demonstrated major changes both during the initial adjustment and after a storm. Moreover, Huizhan Beach presented a rapid volume loss during initial adjustment, which was related to both the steeper foreshore slope and longshore spreading. For the analysis of profile equilibration, Huizhan Beach profiles changed rapidly and achieved equilibrium in several months, while Meiliwan Beach changed in stages and approached final equilibrium after the first postnourishment storm. The different mechanisms of profile equilibration at the two beaches were closely related to the tidal ranges of the sites. On the basis of the observed evolution, two types of profile evolution patterns of nourished beaches with different tidal ranges were proposed.