Laboratory Measurements of Sediment Flux and Bed Level Evolution in the Swash Zone

A detailed laboratory study of swash zone sediment transport under dam-break waves on a fine sandy slope was carried out. A newly developed sediment transport measurement system was applied for simultaneous measurement of sediment concentration and transport velocity with a vertical resolution of 0.53 mm based on particle image velocimetry (PIV) and a light extinction method, respectively. Concentration data were combined with velocity data to produce sediment flux and were used to investigate the characteristics of sediment transport in the swash zone under dam-break waves. It was found that sand particles followed the flow well in the experiment. Phase difference between the maximum velocity and maximum concentration in the initial uprush was obvious. The maximum concentration varied significantly between different elevations. The onshore flux was much larger than the offshore flux, and the flux near the bed was much larger than that at the higher elevations. The net transport was offshore close to the ...