Author(s): Guangqian Wang; Junqiang Xia; Baosheng Wu
Keywords: Riverbank erosion; Erosion mechanisms; Erosion rates; Temporal and spatial variation; The Lower Yellow River
Abstract: Riverbank erosion, including lateral erosion and mass failure, is one of the fluvial processes in the Lower Yellow River. The loss of riparian farmland and the undermining of structures adjacent to the river make it an important economic factor. Failed bank material is a significant source of the sediment load transported in the reach. This paper investigated riverbank erosion mechanisms and rates in the Lower Yellow River, and results of the study indicated that bank erosion is mainly caused by the direct scouring in the Lower Yellow river’s braided reach, while in its meandering reach, bank erosion is caused by the rapid fall of the in-channel water stage following a high-flow event. Riverbank erosion is very prominent during nonflood seasons, but it is negligible during flood seasons. In this paper, a new method was proposed to calculate bank erosion rates using the existing hydrological data. Through analyzing the observed data at seven sites along the 786km-long Lower Yellow River, temporal and spatial variation characteristics of bank erosion mechanisms and rates were obtained, which revealed that the erosion rates in the braided reach are much greater than those in the meandering reach, and that the erosion rates before the construction of the Sanmenxia Dam were slightly greater than those after construction. For a given discharge, bank erosion rates decrease along the Lower Yellow River, and they are closely related to bank stability coefficients and channel geomorphological coefficients. In addition, this study proposed some empirical formulas for calculating the riverbank erosion rates at different sites.