Debris Flows and Landslides - River Dynamics and Integrated River Management - page 222

(a) (b)
(c) (d)
Fig. 4.33 (a) Normal bed load-laden flow at low slope and low discharge; (b) Initiation of a head with rolling
particles; (c) High concentration of particles in the head; (d)Debris flow head rolls down like a bulldozer (after Wang
et al., 2005)
In two-phase debris flows, the solid particles always collide with each other during motion. Collision and
abrasion make the particles round and smooth. Figure 4.34 shows stones with a round shape and smooth
surface from the two-phase debris flow deposit in the Diaoga Ravine, a tributary of the Xiaojiang River
in Yunnan Province of China. Local people use these stone spheres for decoration in front of their houses.
Fig. 4.34 Spherical stones with smooth surface from the two-phase debris flow deposit in the Diaoga Ravine, a
tributary of the Xiaojiang River in Yunnan Province of China