Figure 10 Typical cross-sectional
profiles of the LYR at (a) Weicheng section and (b) Yangxiaozhai
section.
During the period 1986-1999, the river channel seriously shrank and
deposited sediment; the width of the main channel was obviously reduced
with decreases ranging from 300 to 2000 m, and the capacity of flood
discharge also decreased (Shen et al., 2000).
During
the operation of the XLD reservoir and the implementation of the WSRS,
low-sediment concentration flows were released from the reservoir, which
continuously scoured the riverbed and gradually widened and deepened the
main channel. The width of the main channel increased by 2600 m at the
WC section and 780 m at the YXZ section from 2000 to 2017.
We measured the changes in the widths of the main channel and the
floodplains during 2000-2017, as shown in Figure 11. Width changes in
the main channel vary greatly from HYK to GC; taking the DBT section as
the boundary, the widths of the main channel from HYK to DBT are between
400-2300 m, and the widths of the main channel are concentrated the
range from 500-1000 m in the DBT - GC reach. Width changes in the
floodplain can be divided into three parts: i) the width of the HYK - WC
reach increases gradually downstream, ii) the width of the WC - DBT
reach is relatively stable and shows little change along the river, and
iii) the width of the DBT - GC reach decreases gradually along the
river.