The Influence of a Finite Control Boundary on the Morphological Evolution of Wandering Channels

Abstract

Although it is a consensus in academic circles that regulation works will change a channel’s shape, the quantitative relationship between the finite control boundary and the channel’s shape parameters is still unclear. In this study, a flume model test was carried out, and the evolution of channel’s shape under different engineering densities was qualitatively analyzed. Based on the construction of river regulation works and measured hydrological data of the wandering channel in the lower Yellow River from 1960 to 2014, the channel shape parameters (bending coefficient, swing range of the main streamline and river facies coefficient) of the wandering channel in different periods were calculated, and the variation in the channel shape parameters with the density of regulation works in different periods was analyzed. The results showed that the river regime cannot be effectively controlled with less dense regulation works; in this case, the regulation works have little impact on the channel’s morphology. With an increase in the density of regulation works, the evolution of channel morphology was obviously different. Specifically, the river bending coefficient increased as a whole from 1.14 in 1949–1960 to 1.32 in 2011–2014, indicating that the regulation works have had an obvious restraining and improving effect on the river’s morphology. The swing range of the main stream obviously decreased, with an average value of about 500 m; the river facies coefficient decreased dramatically from 20~88 before 1960 to 15 in 2014, and the channel morphology has developed with a tendency to be narrow and deep. The research showed that a finite control boundary can significantly improve the channel’s shape, limit the wandering characteristics of the river reach to a certain extent, stabilize the main stream and control the river’s regime.