EFFECTS OF SAND-COVERING TO GRAVEL BEDS WITH LOW-FLOW CHANNEL ON GRAVEL MOBILIZATION AND CHANNEL EVOLUTION

Abstract

 Gravel beds formation in rivers downstream of dams may cause several issues such as a bed degradation and a channel immobilization. Many works have been conducted in order to make restoration of such rivers. On the ohter hand, when fine sediment (i.e., sand) is present in streambeds composed of gravels, the gravel can be more easily removed as compared with gravel beds without fine sediment. This phenomenon may indicate that the sediment augmentation to gravel beds using fine sediment is a viable alternative to mobilizing coarse surface layers. In this study, we investigated the effects of sand-covering to gravel beds with low-flow channel on gravel mobilization and channel evolution. The temporal variations in low-flow channel were examined by means of flume experiments. And the effects of sand-covering thickness on the channel width and depth was discusssed.