Study Of Cartographic Generalization On Landslide Hazard In Zhejiang Province Based On Fuzzy Inference System

Landslide is a natural disaster phenomenon in which the soil(or rock mass)slides down in a large area under the influence of rainwater immersion,earthquake or other factors.Landslide hazard are highly destructive and extremely harmful,bringing billions of dollars losses to countries around the world every year.The topography of Zhejiang Province is complex,the landform and geological lithology are diverse,and the fault structure is widely distributed,which provides geological conditions for the occurrence of landslide hazard.At the same time,Zhejiang Province belongs to the subtropical monsoon region,with abundant rainfall and frequent extreme rainstorms,providing hydrological and climatic conditions for landslide hazard.Due to its complex geographical features and climate background,Zhejiang Province has became a area with frequent landslide hazard in China.With the rapid development of Zhejiang and new countryside construction,the land resources that can be developed are gradually reduced,and human activities are continuously advancing to the hilly areas.At the same time,typhoon activities have gradually increased in recent years,and the threat of landslides caused by extreme weather such as heavy rains is gradually increased.The cartographic generalization of landslide hazard risk map can not only visually display the distribution law of landslide hazard in Zhejiang Province,but also excavate information such as high-risk areas of landslide hazard in Zhejiang.Therefore,cartographic generalization of landslide hazard risk map in Zhejiang Province can provide scientific decision-making basis for landslide hazard risk management and prevention.Based on ArcGIS,MATLAB and other software platforms and Mamdani-type fuzzy inference system,this paper conducts a study of cartographic generalization on point features of the landslide hazard risk in Zhejiang Province.The paper analyzed the characteristics and distribution of landslide hazard in the study area,and the spatial distribution layer of landslide is superimposed with the factors of disaster environment and hazard factor.The influence of each factor on the development and distribution of landslide is analyzed by using the statistical method of classification and the CF coefficient of certainty coefficient.According to the characteristics of landslide hazard in Zhejiang Province,five layers including terrain slope,landform type,multi-year average precipitation,annual rainstorm days and landslide disaster degree were selected as the mapping constraints.The Mamdani-type fuzzy inference system is constructed on the MATLAB software platform.The landslide hazard data from 1995 to 2015 is taken as the research object,and the fuzzy reasoning of risk level value is carried out for the landslide point.Then,basing on the landslide hazard risk map obtained by fuzzy reasoning results to establish cartographic generalization grades,this study conduct cartographic generalization of different scales on the ArcGIS software platform.The main conclusions of this paper are as follows:(1)Temporal and spatial distribution law of landslide hazards in the study area:(a)The distribution characteristics of landslide hazards points in Zhejiang Province,mainly characterized by a small number of points concentrates in the north and west,large number of points sparsely distributed in the central part,and large number of points concentrated in the southeast.(b)The landslide hazard in Zhejiang Province mainly occurred from June to August,with the most concentrated in August,which is closely related to the precipitation distribution.In addition to the cold weather and other factors in February,the number of landslide disasters is small.Landslides in different months have appeared to varying degrees.(2)Based on the fractal and fractal dimension method,the distribution law of landslide hazard was studied.The results show that the spatial distribution dimensional value Ds of landslide hazard in Zhejiang is 1.1142,and the correlation coefficient(R)between the fractal scale and the distribution of disaster points is 0.9483,which pass the significance test.It shows that the spatial distribution of landslide hazard in Zhejiang has significant fractal characteristics.(3)After the comprehensive analysis of the distribution relationship between landslide hazard and various influencing factors,the main distribution characteristics of landslide hazard in Zhejiang are: The area where the terrain slope ranges from 8° to 30°,the landform type is low undulation hills and medium undulation hills,the annual precipitation reaches 1000 mm or more and the annual rainstorm days ranges from 3 to 7 days.(4)Cartographic generalization results of landslide hazard map reveals that there are four high-risk areas in Zhejiang:(a)Anji County in northern Zhejiang;(b)Jiangshan City and Changshan County in western Zhejiang;(c)Dongyang City in central Zhejiang;(d)Jingning Yi Autonomous County,Qingyuan County,Cangnan County,Yueqing City,Lucheng District and Luhai District,Pingyang County,Ruian City,Taishun County,Wencheng County And Yongjia County.And 50%~60% of landslide hazard are mainly concentrated in the mountainous areas along the southeast coast of Zhejiang.The results show that the cartographic generalization method of landslide hazard risk map basing on fuzzy inference system can effectively and intuitively reflect the high-risk area of landslide hazard,and the actual geographical law in Zhejiang Province.