Figure 9 Variations in the riverbed slope (a) and changes in thalweg migration from HYK to GC (b).

4.2.1 Changes in the cross-sectional form

Changes in both the discharge and the sediment load not only affect the channel longitudinal profile but also have a strong influence on the evolution of the cross-sectional form. The cross-sectional form of the braided reach in the LYR shows high complexity. Figure 10 shows a set of typical cross-sectional geometries, represented by the sections at Weicheng (WC) and Yangxiaozhai (YXZ) in different years. Among them, WL is a representative section of the suspended river in the HYK-DBT reach, and YXZ is a typical section of the secondary suspended river in the DBT-GC reach.