Techniques for Sediment Discharge Measurement in Laboratories

Abstract

New measurement techniques for sediment discharge have been devised, employing both direct and indirect methods. In the direct method, two devices were made. The first one had a fixed inclined 0.3mm mesh screen, pump and baskets driven by a belt. Because of the choke of the sieve etc., the applicability of this system was limited in the range of Q<20 l/s, Q, =0.2-1.0kg/min and d= 0.4-2.0mm. The second device consisted of a trommel and a tipping bucket hung to a load cell. This device has been found to work well for sand and small gravel up to a flow rate of 40 l/s. In the indirect method, the author tested the idea of utilizing a microphone confined in a pipe. Using this method, the sound generated by the collision of the gravel particles was clearly detected. When the pipe is set on the bed surface, the statistical property of the collision depends on the flow condition. However, when the pipe is attached to a board which is set at an appropriate height at a step-down such as the downstream end of a flume, it no longer strongly depends on the flow condition. In that conformation, however, it is apt to be broken by the impact of gravel.