A cross-wavelet study of alongshore nonuniform nearshore sandbar behavior

Nearshore sandbars, ridges of sand fringing coasts in water depths less than 10 m, often show alongshore variability, known as rips and crescentic sandbars. Using a data set collected at the Gold Coast (Australia) we analyze the sequential development of alongshore variability in a double sandbar system using continuous wavelet and cross-wavelet transforms. Our results show that just emerging inner-and outer-bar variability develop independently from each other at a range of wave lengths. However, in time the inner-bar variability becomes slaved to the outer-bar variability. These results have important implications how to approach the modelling of the generation and subsequent evolution of alongshore sandbar variability.