PROFILE AND FLUCTUATION OF WATER SURFACE OF THE MEANDERING COMPOUND CHANNEL FLOW WITH STEEP GRADIENT BED

Abstract

We might make a channel into a compound channel, as an effective way for the flood control and environmental reasons. Recently, even the river of steep gradient the river is often reconstructed into a compound channel. However, we have not enough knowledge how much safety we can secure, and what standard of cross section is easy for maintenance of a steep gradient river.In this research, we have conducted experiments using meandering compound channel with different gradients. Especially, we investigated longitudinal and transverse profiles and fluctuations of water surface, depending on gradient of the channel. In case of steep gradient, we found that it is possible difficult to maintain the main channel unchanged, because of remarkable flow exchange between the main channel and floodplain, high velocity appeared near the bank, and large fluctuation of water surface.