Integrated River Management - River Dynamics and Integrated River Management - page 745

Xiaojiang River from the river's right side. The measured stream power per width for the two streams
were almost equal ( p = 9.2 kg/ms for Chaqing Gully and p = 10.16 kg/ms for Hunshui Gully) and the
sediments in the two rivers were from debris flow deposits. The sediments in the two streams had very
similar size distributions, in which the median diameter in the Hunshui Gully was slightly larger, as
shown in Fig. 11.31. Nevertheless, the rates of bed load transport in the two streams were extremely
different. A step-pool system developed in the Chaqing Gully and the value of S P was 0.155. The energy
consumed by the step-pool system was quite high and the flow had no energy to carry bed load.
Therefore, the rate of bed load transport was very low ( g b = 0.0001 kg/ms). Conversely, in Hunshui Gully
where there was no step-pool system the measured value of S p was small with a value of only 0.04. The
flow energy was consumed mainly through bed load motion and the measured rate of bed load transport
was g b = 18.9 kg/ms, which was about 2x10 5 times higher than the value in the Chaqing Gully.

(a) (b)
Fig. 11.30 Comparison of Chaqing Gully (a) and Hunshui Gully (b) (Chaqing Gully: p = 9.20 kg/ms, S p = 0.155, g b =
0.0001 kg/ms; Hunshui: p = 10.16 kg/ms, S p = 0.04, g b = 18.9 kg/ms) (See color figure at the end of this topic)

Fig. 11.31 Size distributions of bed sediment in the Chaqing and Hunshui gullies

A similar story occurred in the Awangxiaohe and Dabaini ravines. The measured stream power for the
two streams was almost equal ( p = 2.6 kg/ms for the Awangxiaohe Ravine and p = 2.5 kg/ms for the
Dabaini Ravine). The sediment in both ravines was from debris flow deposits. A step-pool system had