Lateral Variations in Suspended Sediment Concentration over Dunes

A series of laboratory flume experiments were conducted to characterize lateral variations of suspended sediment over dunes. Forty experimental runs were made using flow depths of 0.328 and 0.127?m in a 1.2-m-wide channel. The Froude number was 0.47 and the median diameter of the bed material was 0.52?mm. Point samples of suspended sediment and depth-integrated values calculated using acoustic backscatter data were collected simultaneously at two lateral positions at spacings of 0.41, 0.20, 0.10, and 0.05?m. Root mean square differences between the paired samples increased from 30 to 94% and from 20 to 45% of the mean concentration for point samples and depth-integrated samples, respectively, as the lateral spacing between samples was increased. Lateral variations in the concentration of suspended sediment should be considered when designing sediment sampling strategies over dune beds.