Bathymetric evolution of sand bed forms under partially standing waves

Abstract

Experiments were conducted in a large wave flume where the interaction between water waves and a movable sand bed were investigated. Monochromatic and poly- chromatic waves of specified amplitudes and period were generated under cases of weak (R=0.2) and/or strong (R=0.9) reflections. Experiments included one of two mean grain sand sizes (0.2mm and O.mm) to examine the effects of different sediment transport modes (bed load and suspended load), on the over all evolution of the sand bed. Throughout the experiments, conductivity probes measured the surface wave envelope, charged-coupled device (CCD) cameras recorded small scale (ripple) formations and migrations, while a digital camera was employed to capture large scale variations (bars) and ripples over the entire sand bed. A final experiment was conducted using a mixture of the two uniform grain size to observe sediment sorting within the sand bed. Numerous sieve analysis and measurements of the active sorting sand depth were performed on sediment samples from various positions along the flume to quantitatively study the phenomena of sediment sorting.