RESULTS AND DISCUSSION

4.1 Sediment budget

4.1.1 Channel erosion and deposition

The sediments in the LYR are mainly received from the middle reaches, and long-term deposition in the lower reaches has raised the riverbed above the surrounding ground, which is called a “suspended river”. The LYR generally accumulated deposits prior to 2000, with a cumulative deposition of 83×108 m3 between 1950 and 2000. Since the operation of the XLD reservoir began in 2000, the LYR has changed gradually from a sedimentation pattern to an erosion pattern due to the large quantities of sediment trapped by the dam, with a decrease in the cumulative deposition volume, as shown in Figure 5.