EXPERIMENTAL STUDY ON HYDRAULIC CHARACTERISTICS AND FLOOD WAVE PROPAGATION PHENOMENA IN A CHANNEL WITH SUDDEN WIDENING AND NARROWING AREA

Abstract

 Although channel width change longitudinally in river, detailed studies of hydraulic characteristics in areas where the river width changes, such as concave areas, have not focused on the longitudinal effects as fundamental research. In this study, experiments have been conducted to investigate the basic changes in the water surface profile and flow characteristics on the condition that steady and unsteady water supply in flume with and without widening area. As a result, it was possible to show the flow and sediment deposition trends peculiar to the widening area under steady flow, as well as the flood propagation characteristics under non-steady flow. In particular, under the condition that the widening area is more wide, the effect of the rise in water level in the upstream of narrow section is widely propagated upstream. In addition, it was shown that the flood wave propagated downstream before the water level rose sufficiently and also reduced the peak water level downstream although the short rise time of the flood wave delayed the rise of the water level within the widening area.