Experiment Study Of Wave Propagation And Deformation On The Sloping Sandy Bed

Increased sediment transport led to changes in seabed under action of waves. Theseabed of sandbar would affect the wave propagation and deformation. Coupling andbed form of wave propagation and the bed surface morphology evolution are verysignificant for the evolution and transformation of shallow continental shelf of theincident wave is perpendicular to the coast.In order to study interactions between the wave deformation and the evolution ofbed form, the experiment is carried out in a wave flume with a1:20sloping sandyseabed by prototype sand that is median size of0.47mm. A wide range ofmeasurements from the regular wave runs are reported, including time series of waveheights, changes of bed profile，and the definition of the wave height variation rate K₁and the ratio of sandbar high and sandbar long K₂. Through the analysis of K₁and K₂changes, the relationship could be obtained between the wave deformation and the bedevolution. Finally, the preliminary conclusion sandbar movement mechanism is got.The experimental results show that because of the influence of waves by ashallow on slope, so the wave height increases, wave peak is variable pointedly andwave trough is variable plainly. Because of sand bed resistance effect, the averagewave height decreases before the wave breaking point, and the maximum averagewave height move in the direction of the shoreward. The rate of change of relativewave height with sandbar height and sandbar width is proportional ratio. Breakingzone sand suspended sediment concentration at the top of sand bar is closely relatedwith water depth and bottom bed surface. When sand bar is formed and move, therewill be large suspended sediment concentration. Bar back and forth movement isperiodic, the time of the cycle is random, sand dam slope movement direction bothonshore and offshore direction. Sand bar scale tends to stable after multiple waves,and the bottom bed has both sedimentation and erosion in each group of waves atbreaking zone. The time average sediment transport rate tends to zero after multiplewaves, and the net sediment transport of breaking zone on slope turn to zero underlong time waves. Wave breaking down and upper formation reflux flow is the mainreason of suspended sediment concentration and sand dam offshore and onshoremovement.