ABSTRACT
This study conducts a flume experiment to explore the hydraulic and sediment control function in the narrow-section of a river. The laboratory experiment is expected to show how a river’s narrow section retains and drainages sediment when there is a large scale flood event. A narrow-section scale model was set up for the flume experiments, with parameters including contraction ratio, contraction length, and sediment supply concentration. The data analysis in sediment deposition processes upstream of river narrow section, sediment reduction rate, and sediment trapping rate allows to understand the role of a river’s narrow section in regulating the amount of sediment. The results show that (1) the contraction ratio is more effective in sediment control than any other parameter; (2) under large sediment supply cases, the sediment trapping efficiency increases with the contraction ratio; (3) dimensionless sediment concentration decreases with the contraction ratio. Moreover, under different sediment supply cases, high-intensity and short-duration sediment supply improves the sediment trapping efficiency. The results confirm that the river narrow section of a river has the capacity to trap sediment and reduce sediment discharge when a large scale flood event occurs.
