Seasonal changes of sandbar behavior in Nanwan Beach, South China

Frequent leveling data of beach profiles is collected from Nanwan Beach, which is characterized by a large seasonal variation in wave climate. Variability of the bar crest position obtained from the data of measured profiles is examined to quantify seasonal changes of the sandbar by empirical orthogonal function (EOF) analysis. The first eigenfunction showed that a rhythmic bar is a common feature of the beach all year round. The second eigenfunction effectively indicated that the two-dimensional variability of the bar behavior is of seasonal changes. The cross-shore bar movement ranged -30-40 and -2-60 m in summer and in winter, respectively. The next two eigenfunctions represented three-dimensional components of the bar behavior with a range of -21-21 and -30-21 m in summer and in winter, respectively.