The formation mechanisms

movement processes

and dynamic characteristics of debris flow in the Western Sichuan Plateau

a high altitude and cold climate area

are unique because of the effects of landform

geological structure

ormation lithology and climate conditions. The areas of water convergence

provenance and accumulation of debris flows in the Sitongda Valley

Ganzi County

Sichuan Province are investigated by field investigation

mapping and sieving test to determine their formation mechanisms and dynamic characteristics. Results indicate that: (1) There are a big difference in elevation of basin terrain and a high ratio of channel slope

which provides terrain conditions for formatting debris flow. (2) Because drainage area of debris flows is wide

short-term rainstorm in plateau climate is able to provide adequate water supply. (3) Rivers develop in more than 3 000 m altitude areas

located in a climate change belt within cold temperate

subfrigid and frigid zones. Rock mass is fractured and soil structure is loose

caused by the climate condition of strong sunshine and large difference temperature that makes rock contrast weathering strong

as well as the influence of Xianshuihe fault zone. The fractured rock mass and loss soil structure provide rich source for the formation of debris flow.