Abstract
A model experimeut by means of simplified channel bed (Fig.l)was carried out in order to study for the mechanism of the movement and accumulation of gravel on a stream bed. The results of a preliminary experiment were very complicated against our expectation, and so the observation of the process of this experiment led us into the introduction of an idea of critical discharge. We experimented to study for the relation between slope and critical discharge. The results were as Fig.2
