Large-scale physical experimental study on the evolution of 3D bedform by irregular waves

A large-scale physical experiment was conducted to analyze the morphological seabed evolution in a large-wave flume at the Tianjin Research Institute for Water and Transport Engineering. The morphologies of the bedforms, ranging from two to three dimensions, were analyzed as wave mobility (represented by psi(w)) increased. The sand-ripple morphology underwent four stages: straight, staggered, lunate and flat. Furthermore, the three-dimensional (3D) features and flat patterns were enhanced with increasing psi(w). The seabed ripple was processed using a wavelet transform and filter method to eliminate the effects of noise and dunes. The ripple wavelength followed the gamma and lognormal distributions for irregular waves, whereas the distribution of ripple height transitioned from normal to exponential with increasing psi(w). Furthermore, to predict the ripple-geometry statistics more accurately, a modified predictor was developed based on the acquired large-scale experimental data. The findings of this study can aid the development of innovative methods for evaluating bedform morphologies and statistical parameters.