Mechanism of sediment transport by flood and longitudinal peak discharge amplifications in the Yellow River
Abstract
As the general principle of river bed evolution during the fluvial process, the channel is formed by river flows, while the movement of river flows is contained by channels. When the hyperconcentrated flood propagates along the wandering reach of the Yellow River, the peak discharge of the flood can increase along the reach. Due to the recurrence of this phenomenon, attentions have been drawn from various stakeholders, since the amplifications of flood peak can jeopardize flood control works. By analyzing the field observed data, we present our research findings of “scour during rising” and “deposit during falling” of a flood event, as well as the sediment transport mechanism with constant discharge. The bedform affects the characteristics of sediment transport and the resistance force. When the bedform is in the dynamic equilibrium state, sediment transport characteristics can be described as “the more sediment input, the more sediment output”. When the shear stress created by flow acting on bed is increasing, scour is observed on the channel bed. On the contrary, when shear stress is decreasing, deposition is observed. When the shear stress remains the same, sediment transport is in the equilibrium state. After the operation of Xiaolangdi Reservoir, due to coarsen of the bed material, the bedform resistance increased. When the flow condition changes and the bed roughness decreased abruptly, the increasing flow velocity can result in the reduction of channel storage volume. This is the main reason for the longitudinal amplifications of peak discharge in the wandering reach of the Yellow River.
- Publication:
-
IOP Conference Series: Earth and Environmental Science
- Pub Date:
- October 2019
- DOI:
- 10.1088/1755-1315/351/1/012036
- Bibcode:
- 2019E&ES..351a2036Q