Debris Flows and Landslides - River Dynamics and Integrated River Management - page 247

Fig. 4.72 Debris flow-guiding channels on a debris flow gully in the Xiaojiang River basin
(a)
(b)
Fig. 4.73 (a) Debris flow control dam cascade on the Houshan Ravine of Heishui County, Yunnan Province, China
(after Kang, 1996); (b) Comb frame dam on a debris flow gully in Taiwan, China (See color figure at the end of this topic)
Debris flows carry a lot of sediment and fill the reservoirs very quickly. Bed load particles roll or jump
over the dam crest and cause abrasion. Figure 4.74(a) shows a check dam on the Diaoga River in the
Xiaojiang River basin, which was constructed 30 years ago. The dam has been cut into a groove one
meter wide and 4.5-m deep by the bed load movement. The rate of abrasion of the dam was as high as
0.15 m/yr. Moreover, the flow over the spillway is energetic and causes local scour of the dam base,