Flood Disaster Risk Assessment Of Shennongjia

Flood disaster is one of the severest natural disasters in our country,and the damage it costs is enormous.According to the statistics,the annual direct economic losses caused by floods in China have reached 253.9 billion yuan per year,accounting for 0.45%of the total GDP since 2010.The average annual impact population is 113.7 million,more than 8%of the total population.There is also a number of 954 annual death toll due to the floods disasters.Meanwhile,secondary disasters caused by floods also cause billions of yuan of direct losses each year.Currently,the study of flood research in China is mainly aimed at urban areas,and the ones for the villages and towns in the mountainous area,where the economy is relatively backward but still has about 600 million people to live,are still inadequate.Shennongjia forest region is a regional representative of the villages and towns which are severely affected by floods in China.This paper focuses on the research and demonstration of key technologies of integrated disaster prevention and mitigation in villages and towns,a program supported by national science and technology department.It studies the influencing factors of flood disasters and secondary disasters in Shennongjia area,and evaluates the flood risk in this forest regin.These studies are of scientific and practical significance for the development planning and disaster prevention and control of villages and towns in mountain areas.The main content of this paper is as follows:This paper systematically introduces the basic theory and method of flood risk assessment,and constructs the flood risk assessment system of mountain villages and towns.Based on the causes of the damage and the formation mechanism of the flood disaster,a system of two major parts including the natural environment risk and the disaster carrying capacity are formed,which has more than 20 indexes.With the combination of scenario simulation,flood intensity,damage situation and other factors are embodied by flood danger area along the river surface.What’s more,the sensitivity of the objects bearing disaster strikes is quantified.In this paper,a comprehensive evaluation model based on cloud model,entropy and GIS technology is constructed.In the aspect of weight calculation,the initial weights are obtained by fitting the interval value and the most probable value of the experts’ scores by the backward cloud generator,and then the weights are corrected by combining the amount of information reflected by the entropy.By the stage of model evaluation,the index data are computed by using the cloud model and the piecewise function,so as to obtain the continuous evaluation level expression.After that,using GIS to build Shennongjia flood system database,the research unit is refined,and the data is processed and expressed in both spatial distribution and value scale.By comparing the opinions of engineering experts and scholars,this paper analyzes the natural environment,population,characteristics and distribution of disaster bearing objects,disaster bearing capacity and other aspects of Shennongjia.Based on the calculation of the model,the analysis results of 5 kind of flood intensities with a precision of 10 meters multiplied by 10 meters are included:comprehensive risk of floods in Shennongjia,risks in the important areas,rainfall horizontal distribution,dangerous degrees distribution of natural environment,the distribution of disaster bearing objects’ vulnerable value in the important areas,the ability of basic and flood disaster corresponding capacity in different places,and so on.Besides,property losses at various flood intensities are simulated.Subsequently,there a series of maps correspondingly provided for reference of the development planning and the construction of disaster prevention and mitigation measures.