We have theoretically and experimentally investigated the effects of vegetation on the flow resistanceand the bed-load transport. The results are summarized as follows;
It is assumed that the flow resistance is composed of the drag force acting on vegetation and the shear stress interacting between the flow and the bed surface of mobile grains. Furthermore, adopting Eq. (2) for the vegetal retardance and Eq. (9) for the law of resistance in mobile beds respectively, the flow resistance in vegetated channels is given by Eq. (11). For the sake of simplicity, we introduce the coefficient Cdε which contains several influences of the drag coefficient Cd, the coefficient β, the vegetal flexibility, etc., then Eq. (11) is expressed by Eq. (15) . And Eq. (16) corresponds to the resistance law of channels filled with tufts of plants. On the other hand, we obtain the bed-load transport expression (Eq. (37) ) by means of the brief tractive force model (Eq. (22)-(31) ), and its applicability is experimentally confirmed. In this expression, Eq. (33) for the effective tractive force τ
*e, Eq. (34) for the critical tractive force τ
*c respectively should be adopted.
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