Abstract
In this paper, an effective method for river-mouth improvement has been proposed on the basis of the results of experiments.
Regarding this method, reinforcement of the tractive force and disturbance of the flow and sand movement have been applied. The former is induced by the self-regulating gate system which has been proposed in a previous paper. The latter occurs due to the series bottom pile systems which are set up along the flow near the river mouth.
The gate system caused the river flow to dam up and the water discharged flows down naturally. The rapidly varied unsteady flow with the surge after the opening of the gate board has a large tractive force. Reinforcement of the tractive force occurs due to this flow. The series bottom pile system is made up of several sheet piles arranged in a straight line with proper separations and angles. Two series's of pile system are set up on the right and left hand sides of the main flow near the river mouth. Each sheet pile of the series pile system is arranged so as to converge water flow between the both pile systems and to diverge sediments outside of that region. The sand transported from the main flow region accumulates behind the both pile systems. An especially good water routing system can be obtained in this way.
The optimum arrangement of the piles is also discussed from the results of the movable bed experiments.
