Effect of Bed Forms on the Detachment of Benthic Algae by the Sediment Transportation

Abstract

A series of hydraulic experiments were conducted for quantitative evaluation on the detachment effect of benthic algae on uneven riverbeds caused by sediment loading. We focused on the shielding part created by the exposure height of gravel and the width between pieces of gravel. The experimental results showed that the shielding was affected by both the exposure height of gravel and the width between pieces of gravel, with the exposure height of gravel having the larger effect. In addition, it was suggested that the movement of the sediment was restricted by an uneven riverbed. In order to take into account the effect of the shielding, a shielding coefficient was introduced to examine the effective tractive force and effective amount of work. There was a positive correlation between effective tractive force and the effective amount of work with the detachment characteristic value. Thus, it is possible to estimate the detachment characteristic value in uneven riverbed using the effective tractive force and effective amount of work.