Quantitative Research On The Spatial Network Model Of Urbanization Development Evaluation Based On Spatial Constraints

Urbanization is an inevitable trend of human social politics and economic development,and it is also the mainstream of the development of the world today.From the perspective of regional form,urbanization can be regarded as a process of regional advancement in which rural construction land is gradually transformed into urban construction land.The spatial network model theory and methods can be used to abstract geographic entities such as urban-rural construction land as network nodes.By constructing a spatial network model and studying network characteristics,the relationship between the urban-rural construction land spatial pattern and the urbanization process can be explored.The spatial network model has unique advantages in studying the evolution and evaluation of urbanization.However,there are still some basic theoretical and technical problems that have not yet been resolved,which seriously hinders the application of it.In order to further expand the depth and breadth of the application of spatial network models in urbanization development evaluation and urban geography,this paper conducts research on the determination of search distance parameters of spatial network models based on spatial constraints,the theoretical and technical issues of spatial constraints in consideration of the actual geographical environment,and the experimental problems of the application of the spatial network model of urbanization development evaluation based on spatial constraints,taking the Hangjiahu Plain as the research area and urban-rural construction land as the research object.The research results have important theoretical and application value in urban geography and other disciplines.The main work of this paper is as follows:(1)Determining the optimal search distance parameter based on space constraints.This paper draws on the research ideas of Kernel Density Estimation(KDE)theory and methods,introduces the four most widely used and optimal bandwidth calculation methods in KDE,and combines the geometric characteristics of urban-rural construction land and their spatial distribution patterns to expand the search distance calculation formula.By comparing and evaluating the scientificity and rationality of the spatial network models constructed with different search distances,a method for determining the optimal search distance of the spatial network model of urban-rural construction land based on spatial constraints is creatively proposed.Finally,the rationality and applicability of the method are verified on the spatial scale and the time scale.(2)Determining constraint algorithm of spatial network model based on traffic accessibility.This paper uses the traffic network data to construct the traffic network topology dataset required for reachability analysis.And using the OD cost matrix analysis tool to calculate the traffic accessibility evaluation results based on the minimum time cost between construction sites.On this basis,a spatial network model constraint algorithm based on traffic accessibility is proposed.And the spatial network model that is initially constructed is constrained based on the actual traffic environment.By comparing the changes of network model evaluation indexes before and after space constraints,the characteristics of the changes and the feasibility and effectiveness of the model algorithm are studied.(3)Application research on the spatial network model of urbanization development evaluation based on spatial constraints.In order to explore the spatial evolution law of the rapid urbanization of the Hangjiahu Plain from 2005 to 2015,this paper constructs a spatial network model for evaluating urbanization development based on spatial constraints,and quantitatively compare the evaluation indicators such as the area and number of construction land,the Degree Centrality and Local Significace of nodes,and the Mean Local Significance of edges,taking the data of the Hangjiahu Plain in 2005 and 2015 as the research object.The conclusions of the paper are as follows:(1)An effective method for determining the optimal search distance of a spatial network model: Calculating the preliminary search distance based on the spatial distribution pattern of elements and their density centers.Based on this,the index k of the kNN algorithm is adjusted to obtain the corresponding order closest to the preliminary result and its optimal search distance.(2)The application experiments of the spatial network model constraint algorithm show that: The accessibility analysis based on the actual traffic environment has a good spatial constraint effect on the spatial network model of urbanization development assessment.The network model evaluation indicators show that the overall change is small before and after the spatial constraints,and the regional changes are obvious and scattered.It not only ensures that the evaluation indicators are basically consistent before and after the constraints,but also can restrict and modify the local areas based on the realistic traffic restrictions.(3)The spatial network model of urbanization development evaluation based on spatial constraints has good effects and unique advantages in the development research and evaluation of urban-rural construction land.The urbanization development of the Hangjiahu Plain from 2005 to 2015 has achieved remarkable results.The number and area of urban-rural construction land has increased rapidly,the scope of construction land has continued to expand.The spatial connection between construction sites is gradually strengthened,playing an increasingly important role in the coordinated development of urbanization.The proportion of land use in urban areas has increased rapidly,while the proportion in rural areas has decreased significantly.The urbanization level of the Hangjiahu Plain has increased significantly,and urbanization has continued to intensify.The Hangjiahu Plain is in the process of intense urbanization development.