Evaluation Of Debris Flow In Zongsheng County Of Yunnan Province

The types of geological disaster of Yongsheng are many and the distribution scope of disasters is wide. The disasters are controlled by many factors, such as space, formation lithology, geological structure, human engineering activity and so on. Yongsheng is located in the Chenghai fault and along the Jinsha River, with diverse topography and extremely fragile ecological environment. Geological disaster like debris flow, landslide and unstable slope is high in frequency, widespread in distribution, large in destructive action, is the main disasters to restricting Yongsheng’s economic and social development, resulting in loss of life and property. Debris flow occured frequently is the main geological disaster in YongSheng, and most of the debris flow pass the village endangering the lives and property of the villagers, as well as public life and property safety. In order to realize the formation mechanism of debris flow and provide a scientific basis for the prevention and control of debris flow, the assessment of the geological hazards of debris flow in Yongsheng was made.This thesis relies on the presided over by the Yunnan Provincial Bureau of geological surve’s Project of "Detailed Investigation of Geological Hazards in Yongsheng " of "Detailed Investigation of Geological Hazards in Yunnan province in 2013". Selected eight assessments by field investigation and summarized previous experience:landform, elevation, slope, gully density, soil type, maximum rainfall in one day, basin population density, vegetation coverage rate. Using ArcGIS to analyze the disaster mechanism; and using RoughSet theory to analyze the sensitivity of the evaluation factors; according to the results of sensitive analysis worked out sensitive factor weight based on RoughSet theory and fuzzy analytic hierarchy process (FAHP), respectively, Yong Sheng county debris flow disaster prone area evaluation. Comparison of the two methods to determine the weights of the results and the advantages and disadvantages of two. Finally, the method of rough set theory and analytic hierarchy process is used to get the weight, and worked out the final result of the partition of debris flow hazard assessment.The paper divide the debris flow in YongSheng Country into three types. Such as low easy-happening area, mid easy-happening area, easy-happening area and highly easy-happening area. The respective of them are 12027km2,20362km2,10002km2, and 7273km2. The density of disaster points are 0.0015798,0.0019644,0.0061988,0.0114121.The physiognomy is rifted basin, and river terrace in the highly easy-happening area. The terrain mostly is low but it is steep along the river. The soil is very thick in the area. Human activities greatly influence the development of the terrain. Daily rain fall is heavy in YongSheng Country. The physiognomy is rifted basin. The altitude and gradient is low. The exposed rocks are clayey. There are lots of rivers and ravines in the area. The terrain is middle-mountain that is relatively flat. Exposed rocks are hard. The gradient is flat and vegetation is good. Human activities less influence the development of area because of the hard rock and the good vegetation. So the disaster do not relatively develop.