Flood Defense and Water/Sediment Management—With Particular Reference to The Yellow River - River Dynamics and Integrated River Management - page 377

more unstable. The flood discharge capacity of the channel was thence reduced and the flood stage at the
same discharge was substantially enhanced (Wang and Li, 2003).

Variation of Tongguan's Elevation (water-surface elevation at Tongguan for a flow of 1,000 m 3 /s) Fig. 6.45

Fig. 6.46 Aggradation of the lower Weihe River measured at cross-sections WY-2 (21km from Tongguan) and WY-7
(59km from Tongguan) from 1960 to 2001

Simon (1989, 1996) studied channel response in disturbed alluvial channels and found that the
changes imposed on a fluvial system tend to be absorbed by the system through several stages of channel
adjustment and following exponential decay equations. The response of the Weihe River to the
Sanmenxia Dam closure is more complex because the raised Tongguan's elevation is not stable and the
effect has transmitted from the confluence to Xianyang Station (180 km upstream from Tongguan.
Erosion and sedimentation caused by the ascending and descending of Tongguan's Elevation propagated
upstream in retrogressive waves. Figure 6.47a-c shows the distribution of the deposition rate per unit
river length in the periods 1960-1969, 1969-1973, and 1973-1980, respectively, in which the horizontal