Regional Debris Flow Formation Characters And Fatalness Regionalization On Moxi River Basin

Moxi river located in the southwestern of China,where is a concentrative glacial debris flow area. The debris flow represents some characters related to moraine, Intensity of tectonic movement and climate environment. Based on the former research, this thesis according to the item of chengdu institute of geology and mineral resources,study the geological environmental conditions, formation process, sources conditions and endangerment of the drainage area’s debris flow. The following are the main contents and innovations of this paper:(1) Formation background:From the aspects of the new tectonism, rock type, topography, climatic types and human engineering economic activity, this thesis analyses the geological background conditions, explains that the drainage area with sufficient conditions for occurring superlarge debris flow.(2) Debris flow type:Based on a general survey in49debris flow ravines, which are large in scale(ravine length>4km) or with direct harmful, this thesis researches the debris flows’ types according to the water resources, material source type, geomorphological position, outbreak frequency and the substances composition. This work can provide basement for prevention of debris flow.(3) Material source control:After surveying the types and characteristics of the area’s incompact material source distribution, this thesis estimate the total amount of incompact material source and reserves of strong activity material sourcesource,and also research the providing ways of incompact material source.All of this study can provide direction and positon for material source prevention of debris flow.(4) Evolution trends:Based on the research of debris flow-prone level, evolution stages, and three formation conditions, such as source material, water hydrodynamic conditions, terrain conditions, combined with the rainfall amount history in that day and earlier days, and the statistical analysis of debris flow occurrence frequency this thesis’s studies showed that the formation conditions of debris flow area has not changed, and the large debris flow occurrence periodic is about10-15years, so the large debris flow threat is still exists.(5) Debris flow hazard:Acorrding to the survey of history disaster circumstantiality, the thesis identified the hazard form, losses and risk of the area’s debris flow. In the end, the debris flow hazard zone has been divided, the whole basin is divided into eight most dangerous areas and a danger zone, and then summariz the debris flow hazard areas distribution and main Hazardous objects.