Research on the Asymmetry of Cross-Sectional Shape and Water and Sediment Distribution in Wandering Channel

Abstract

The construction of a river regulation project has changed the cross-sectional shape of a river and significantly impacted the evolution of the river regime. In this paper, an asymmetry index was proposed to characterize the changes in the shape of the river cross-section and the distribution of water and sediment factors. According to the transverse distribution formula of the river section and water and sediment factors, the asymmetry of the cross-sectional shape as well as water and sediment factors along with the transverse distribution in the wandering reach of the lower Yellow River before and after the construction project was calculated, respectively. The results showed that the cross-sectional shape of the river channel before and after the building was asymmetric, and the cross-sectional shape of the river channel after the construction was more asymmetric than that of the free development channel without engineering constraints; at the same time, under the action of a limited control boundary, the asymmetry of cross-section flow velocity and sediment concentration and other water and sediment factors along the transverse distribution were more prominent, the flow velocity and sediment concentration along the transverse distribution increased, the river flow was more concentrated, and the sediment transport capacity of the channel improved significantly under a large flow (5000 m3/s). This study revealed the positive effect of river regulation projects on the river regime evolution of the wandering river and provided new ideas for the study of river regime evolution.