Study On Geological Hazard Risk Assessment In The Central Region Of Himalayan Mountains By The Method Of GIS

China is one of the countries with serious geological disasters in the world.Geological disasters have the characteristics of large frequency of occurrence, widegeographic distribution and large loss. In recent years, the theories and methods ofgeological hazard risk assessment have a large improvement and progress. Theresearch achievement not only provides a scientific basis for the prevention ofgeological disasters but also play a significant role in disaster alleviation. Therefore, itis essential to study geological hazard risk zonation in order to protect the people’slives and properties and reduce the losses caused by disasters.In this paper, the Central Himalayan Mountains which includes six counties ischosen as the research object. Based on the data got by field survey and laboratorycollection, integrated analysis of the distribution characteristics of geological disasters,formation conditions and induced factors, we did the geological hazard riskassessment in the area by using Analytic Hierarchy Process and BP neural network.The main contents of this paper are as follows:According to the field investigation and the analysis, this paper summarizesnatural environment and the characteristics of geological environment includingmeteorology and hydrology, soil and vegetation, topography, formation lithologyand human activities, ect. The research area is located in the southwest of TibetanPlateau, among the Brahmaputra, Himalayan Mountains and Laguigangri Mountains.There are rolling mountains with complex terrain, large vertical variation, andcomplex geological structure, which cause a wide range of structural types. Therainfall time is concentrated and uneven distribution. Surface water is primarilycomplemented by snowmelt water and precipitation.Through analysis of distribution law, formation conditions and induced factors, itcan be seen that the basic factors of affecting the disasters are topography, formation lithology, geological structure and groundwater. The induced factors are rainfall factor,new tectonic movement, earthquake and human activities.In the process of research, we extracts important and controlling factors toestablish the geological hazard evaluation index system, and select basic factor andinduced factor as the first class index, and further refine to the second and the thirdindex. Basic factors include elevation, slope, exposure, type of rock formation,distance of tectonic effects and land-use types, and the induced factors includeearthquake, rainfall and human activities. After determining the index system, we dospatial analysis for each evaluation factor.In the paper, we select Analytic Hierarchy Process and BP neural network forrisk assessment. When it uses AHP method, the weigh caculation is very importantwhich is related to rationality and correctness of the results, and further to caculate thegeological hazard index.According to the results of the analysis, the study area isdivided into five zones, which are called higher risk zone, high-risk zone, danger zone,low-danger zone and no danger zone. When it uses BP neural network method, do thenetwork training to make sure the stability of the model, and then use the neuralnetwork prediction module to inverse the weigh of each evaluation factor. Also, thestudy area is divided into five levels. At last, it makes the geological hazard zoningmap with the aid of GIS.It makes a comparison to the two results and analyzes the reasons which cause thedifferences. The result of AHP method is difficulty objective and impartial because ofjudgment matrix are scoring by the experts’ experience with some human interference.The neural network method requires the training sample representative, independentand multiple. Training test needs a greater number of samples in order to ensure itsstability and accuracy. Finally, according to the actual situation of the study area, itmakes some suggestions for the geological disaster prevention measures.