抄録
A giant debris flow occurred in Zhouqu County, Gannan Tibetan Autonomous Prefecture, Gunsu
Province, in the evening of 7 August 2010, causing 1765 deaths and missing, with enormous property
losses. It ruined 4321 houses and caused 22,667 homeless. The stricken area at Sanyanyu debris flow
was 50.0 hm2
including 3 hm2 urban area and 47 hm2
farmland. A dammed lake 2 km in length was
formed in Bailongjiang River by the debris flow deposit with 8~10 m high, which blocked the river. The
main urban area of Zhouqu city was inundated for one month. This tragic catastrophe raises a topic that
how a giant debris flow develops from a relatively small original one in source area and what
methodology can be used to identify whether a building is in danger or not. In order to understand this
issue, a detailed field survey had been carried out in catchments of Sanyanyu and Loujiayu. The field
survey revealed that flood in upstream eroded the debris barriers and unconsolidated soil bed in channel
and developed into debris flow. The laboratory physical experiments indicated that the major
mechanism of giant natural debris flows formation is scale amplification caused by cascading landslide
dam failures. Another process of scale amplification is that debris flow schleps sediment from erodible
channel bed. At last, a numerical technique will be developed to simulate danger area and momentum of
debris flow. Based on the results of dynamic simulation, a method of hazard assessment will be
established for identifying dangerous area. Hope this methodology can serve for urban management in
mountainous villages and townships.
