Xinjiang arid area is characterized by low rainfall, strong evaporation capacity, sparse vegetation, intensive tectonic movement, and fragile ecological environment ; the rainfall-type debris flow in the arid area are obviously different from the same type debris flow in humid and subhumid area of China with conditions of rainfall excitation, watershed morphology, motion and deposition processes, material composition, active period and disaster mechanism. Investigations and analyses of characteristics of rainfall-type debris flow in the arid area will reveal the rule of the occurrence and development and explore the evolution trends, to establish reasonable disaster reduction measures. Qiaoquli gully located in Kashgar is a typical arid area rainfall debris flow gully. The 50-year frequency outbreak of debris flow in 2005 destroyed chinapakistan highway . Further investigation to this debris flow gully will contribute to our understanding of this kind of debris flow disaster characteristics and mechanism.

Sediment deposition caused by debris flows and floods is an important process controlling the evolution and regression of lake, and even a pervasive environmental problem. Qiong Lake is regards as a “bright phearl of the altiplano” in the Yunnan Plateau, and because debris flows construct a vital links between mountain slope and Qiong Lake, so the debris flows drove by rainfall will control the evolution rule of rift lakes. Based on the data of lake shorelines of Qiong Lake, it was found that the shoreline was push forward by 665 m since 1998. In addition, in the recent 30 years, turbidity current deposits have generated underwater levee and other landscapes in the deep water area of Qiong River. This paper has analyzed the matter migration process induced by debris flows, and presented the regime change pattern of debris flow along river channel and corresponding mechanical mechanism, mainly revealed the submarine transportation and deposition pattern of debris flow. The above studies provide a helpful way of comprehending the formation mechanism of turbidity flow induced by debris flow, and the transportation pattern. Based on severe sediment deposition catastrophes in this kind of rift lakes from debris flows and floods, disaster mitigation must be planned and appropriate engineering countermeasures put in place as soon as possible.

Sediment deposition caused by debris flows is an important process controlling the evolution and regression of lake, and even a pervasive environmental problem. The frequent debris flows construct a vital links between mountain slope and Qiong Lake transporting lots of sediment into lake, and further making the lake depth and lake area shallower and smaller constantly. In the paper, we select the Guanba River in the northeast of Qiong Lake as a case studying the effect of debris flows on Lake depositon and the characteristics of typical debris flow, and document the sediment deposition in the Guanba River estuary. The control factors contributing to debris flow initiation indicate that the debris flows are drove by rainfall, earthquake and human activities together, and the occurrence frequency of debris flows in the study area will continue to increase.

In these years the southern part of Tianchi Lake has been occupied by deposited sediments which were carried by debris flows. As a result, the lake is shrunk and the sight of the lake is ruined. In the paper, on the basics of field work, we first combine both of the geographical maps 1971 and 2003 to make sure the landscape difference; secondly we estimate the average thickness of earth eroded by debris flow; thirdly we estimate the volume of the soil on the fan. In the 32 years between 1971 and 2003 the deposit fan has gone forward for 216m, and the deposits reaches at 1.85 million m³, of which 49％ come from upstream and 51％ comes from the old fan. The frequent debris flow occurrence is due to both natural conditions and over grazing.