Sediment Movement in Alluvial Rivers - River Dynamics and Integrated River Management - page 299

Fig. 5.37 (a) Flood discharge ( Q ), sediment concentration ( S ), stage and average and deepest bed elevation of the
channel at the Longmen station during a hyperconcentrated flood from August 1 to 4, 1970; (b) Flood discharge,
sediment concentration, average and deepest bed elevations, and the additional surface slope Ƹ J ) at the Chaoyi
station on the North Luohe River during a hyperconcentrated flood from August. 6 to 9, 1977
Fig. 5.38 Bed erosion process during a hyperconcentrated flood at the Huayuankou station in the lower Yellow
River in August 1992 (where E is elevation, B is the channel width, Q is the flow discharge, and S is the sediment
concentration)
Figure 5.39 shows the stage-discharge relation of hyperconcentrated floods at the Huayuankou station
on the lower Yellow River. The stage was high in the rising limb of the floods and reduced by more than
1m in the falling limb of the flood for the same discharge, because the channel bed was scoured down by
several meters during the hyperconcentrated floods. Figure 5.40 shows the stage-discharge relation of a
recent hyperconcentrated flood in 2004 at the Aishan station on the lower Yellow River. The highest
sediment concentration and the crest discharge of the hyperconcentrated flood flowing into the
Xiaolangdi Reservoir were 542 kg/m 3 and 2,960 m 3 /s and the released concentration and discharge from
the reservoir were 346 kg/m 3 and 2,690 m 3 /s. The flood consisted of two waves, the first one occurred
from August. 22 - 25 and the second one from August. 25 - 31, with the crest discharge and maximum