Risk Analysis And Zoning Of Mountain Flood Disasters Based On TRMM Satellite Rainfall Data

Mountain torrents occur frequently in hilly areas in China,which seriously threatens the lives and property of local people and restricts the sustainable development of local economy.Mountain flood risk zoning is a non-engineering measure for flood control and disaster reduction,which transforms passive disaster relief into active disaster avoidance.In this paper,the typical hilly area-ziyaun County as the research object.When collecting mountain torrent disaster data in the study area,the introduction of TRMM 3B42V7 satellite rainfall data makes up for the shortage due to the lack of rainfall stations.Based on the risk and vulnerability of mountain torrent disasters,the relationship between risk factors affecting mountain torrent disasters is analyzed from three perspectives:disaster-causing factors,disaster-pregnant environment and disaster-bearing bodies.The risk index system of mountain torrent disasters in the study area is constructed,and the risk analysis and regionalization of mountain torrent disasters in the study area are further carried out.The main research results are as follows:(1)According to the actual situation of flash flood disaster,this paper mainly considers the selection of impact indexes which are closely related to flash flood disaster from the angle of risk and vulnerability of flash flood disaster.The average monthly rainfall,maximum 24-hour-rainfall,maximum 3-day-rainfall,elevation,slope and river network density were selected as the risk factors,and the population density,GDP density,percentage of cultivated land and traffic network of the study area were selected as the vulnerability factors.The weight of risk index and vulnerability index is calculated by AHP respectively.The weight of rainfall index,0.633,is the largest among the risk factors,and the weight of population density in vulnerability analysis is 0.41,which reflects that rainfall is the direct motive force of flash flood disaster and the principle of people-oriented prevention and control.ch is suggesting that the rainfall is an important factor to induce flash flood disaster.(2)Analyzing the accuracy and adaptation of TRMM 3B42V7 satellite rainfall data in the study area,the results of correlation,relative deviation and mean square root error on the daily and monthly scale of the ground site are not enough to support the good development of this study,and the rainfall data of TRMM 3B42V7 satellite should be calibrated by GDA method.The correlation on the monthly scale is 0.994,0.998,and the mean square root error is 2.06 and 13.02 respectively,which indicates that the calibration TRMM 3B42V7 satellite rainfall data is strongly correlated with the ground site and the error is small,and can describe the rainfall spatial distribution in the study area well.(3)The risk factors of flash flood disaster in the study area were selected and analyzed in detail from two aspects of the risk and vulnerability of flash flood disaster.The risk analysis of flash flood disaster shows that the risk of flash flood disaster is higher in northeast than that in southwest of Ziyuan County.This paper analyzes the vulnerability of flash flood disaster,and shows that the vulnerability of flash flood disaster in the center of the region which including Guali Township,Ziyuan town and Liangshui township is large,and the spatial difference of vulnerability is smaller in other areas.(4)The risk map of mountain torrent disasters in the study area is superimposed by its risk distribution map and vulnerability distribution map,and then the risk level of the study area is divided into four levels:low risk,medium-low risk,medium-risk and high-risk by natural fracture method,and the risk distribution map of the study is obtained.Finally,according to the principle of risk zoning in disaster science,risk zoning is carried out in towns and villages as a unit,and the risk zoning map of the study area is obtained.