Research On The Grading And Zoning Of Landforms In The Eastern Qinling Mountains

Geomorphological regionalization is a scientific way to the analysis of geomorphological features,reflecting the similarity and difference of landform features in different regions,and it is helpful to understand geomorphological features and the law of geomorphological development.In the case of global change and the growing influence of human activities,geomorphological features are changing continuously.As a based natural geographic element,the change of geomorphological features has extensive and profound influences on the natural environment and even the social and economic development.Consequently,it is of great value to develop geomorphological regionalization research work.The research area is located the east of Qinling Mountains,involving Shaanxi,Henan and Hubei Provinces,between the second and third step of Three Gradient Terrains of Chinese landform,resulting in the complexity of geomorphological features.Influenced by monsoon climate deeply,the phenomenon of human activities on social production and economic development is more obvious than other regions in Qinling Mountains.Consequently,it is also more sensitive for geographic elements to global change and changes caused by human activities,especially geomorphological element.For further understanding of geomorphological features and spatial differentiation of Eastern Qinling Mountains,making a supplement and improvement for geomorphological researches of Eastern Qinling Mountains,and providing scientific reference for the research and programming of other natural resources in Eastern Qinling Mountains and even the whole Qinling Mountains,it is necessary to carry out the research work of geomorphological regionalization on Eastern Qinling Mountains.In order to obtain the information of geomorphological features of Eastern Qinling Mountains,providing fundamental data for geomorphological regionalization,based on the DEM(Digital Elevation Model)data,supported by ArcGIS 10.4 software,terrain factors were extracted.In the course of extraction,the primary task was to obtain the optimal statistical unit of the Eastern Qinling Mountains,which could be calculated by using a suitable change point method.On the basis of extraction of terrain factors,the geomorphological types were classified.For fusing information of terrain factors as much as possible,and reducing the workload of the classification of geomorphological types,the extracted terrain factors were in need of a series of siftings,and these selected factors would be the constitution of the best terrain factor combination,used as the foundation of the classification of geomorphological types.Then,combining the classification of geomorphological types with the research methodologies of other nationwide or regional geomorphological regionalization work,geomorphological regionalization of Eastern Qinling Mountains was completed.The following conclusions are drawn:(1)Selecting the mean change point method to calculate the optimal statistical unit of Eastern Qinling Mountains.The result showed that 17×17 mesh size(0.173 km2)was the optimal statistical unit of extraction of parts of macro terrain factors,such as the relief amplitude.The extraction of terrain factors was composed of micro terrain factors and macro factors.Micro terrain factors included slope,aspect,vertical curvature,horizontal curvature,illumination of relief shading based on DEM.Macro terrain factors included elevation,relief amplitude,surface cutting depth,surface roughness,coefficient of variation in elevation.(2)On the basis of summarizing domestic and foreign index of the classification of geomorphological types,selecting elevation,relief amplitude as the indices of primary geomorphological type.By a series of siftings for other terrain factors,due to the abilities of carrying a large amount of geomorphological information and reducing the repetitive rates of geomorphological information,slope,total cumulative curvature(the product of vertical curvature and horizontal curvature),surface cutting depth,coefficient of variation in elevation,calculated by Sheffield entropy method,were determined to be the best terrain factor combination for the secondary geomorphological type classification.(3)By selecting elevation,relief amplitude as the indices of primary geomorphological types,geomorphological type classification of Eastern Qinling Mountains was divided into 10 kinds of geomorphological types,such as low altitude plain,low altitude terrace,etc.According to the best terrain factor combination,which included slope,total cumulative curvature,surface cutting depth,coefficient of elevation variation,by given weights for the 4 factors respectively with AHP(Analytic Hierarchy Process),establishing a multi-factor layer and making an spatial overlay with primary geomorphological type layer,the region of Eastern Qinling Mountains were divided into 20 kinds of secondary geomorphological types,such as low altitude flat plain,low altitude flat terrace,etc.(4)On the basis of classification of geomorphological type,according to geomorphological regionalization methodologies,such as regional spatial differentiation principle,choosing regionalization plan as "geomorphological region,geomorphological subregion,geomorphological plot",selecting Danfeng-Shangnan fault zone as main reference,and making contrasts with geomorphological features,the first geomorphological zone was established.Then,on the basis of the first geomorphological zone,combining with the primary geomorphological types,the second geomorphological zone was established.On the basis of the second geomorphological zone,combining with the secondary geomorphological types,the third geomorphological zone was established.Lastly,Eastern Qinling Mountains landform was divided into 2 geomorphological regions,6 geomorphological subregions,and 14 geomorphological plots.