Research On Identification And Definition Of Beibu Gulf Urban Agglomeration Based On Multi-sourced Data

With the acceleration of urbanization,the urban agglomeration has become the main spatial component of new-type urbanization.Precisely defining the boundaries of urban agglomeration can find out the current problems,so as to better plan and guide the development of urban agglomeration and promote the integration of urban and rural areas.So far,the identification and definition of urban agglomeration boundaries is still one of the key issues in the related studies of urban agglomeration,but the use of research methods and data sources is still under exploration.In 2017,the country approved the “Development Plan for the Beibu Gulf City Group”.The newly planned Beibu Gulf City Group spans three provinces and autonomous regions of Guangxi,Guangdong,and Hainan,with a total of 15 cities and counties.Because academic urban agglomeration and administrative urban agglomeration are inconsistent,this study intends to adopt multiple types of data and methods to classify and comprehensively define Beibu Gulf Urban Agglomeration.While expanding the definition of urban agglomeration,the accuracy of the definition is improved,and the status quo and development of urban agglomeration are identified.Finally,the countermeasures and recommendations are proposed.The study is based on the urban spatial interaction theory and the plane statistics principle of geometric points.Taking Beibu Gulf City Group as an example,this paper obtained 2016 economic and social data within the administrative boundaries of the 46 districts and counties,and the population migration and nighttime lighting data for 2017.Using the fracture point model,network analysis and kernel density analysis,the three types of data were processed,and the identification results of Beibu Gulf Urban Agglomeration under the three types of data are obtained.After comparing the advantages and disadvantages of the above identification results,the study selected the population migration big data and nighttime lighting data to comprehensively define the boundaries of Beibu Gulf Urban Agglomeration.By comparing the results of the comprehensive definition with the planning scope of Beibu Gulf City Group in overlay analysis,the differences between the two are summed up,which proposes countermeasures and suggestions for the integration process of Beibu Gulf Urban Agglomeration.The main conclusions are as follows:(1)Identification of urban agglomeration based on economic and social data: The use of economic data to measure the level of urban comprehensive strength,and the identification of urban agglomeration based on the fracture point model,to arrive at 3 metropolitan areas,altogether 23 districts and counties,and the recognition results are much smaller than the planning range.It can be seen that based on the identification of urban agglomeration under the economic and social data and fracture point model,they are more dependent on the development level of the core urban area.However,the comprehensive strength of the Nanning municipal district,Haikou municipal district,and Zhanjiang municipal districts are relatively low,but not enough to radiate the entire research area.Or form an overlapping area of radiation,making the formation of an urban agglomeration.(2)Identification of urban agglomeration based on population migration big data: Identification of urban agglomeration based on urban contact intensity and urban network structure.The identification results are 2 urban agglomerations and 1 metropolitan area,a total of 44 districts and counties,covering almost the planning area.The identification results based on population migration data are obviously too large.Among them,there is an overestimation in the scope of the urban agglomeration determined by the strength of the first contact intensity,and it is reasonable to use the 10% threshold method to identify the urban agglomeration.(3)Urban agglomeration identification based on nighttime lighting data: Urban agglomeration is identified from the three aspects of total lighting,light intensity,and lighting concentration.The recognition result is 1 urban agglomeration,a total of 24 districts and counties.This result is much smaller than the planning scope.It is a continuous area that is continuously connected with the districts and municipal districts and their surrounding districts and counties.With the use of the kernel density method,urban agglomeration is more spatially clustered and have better spatial continuity.(4)Advantages and disadvantages of the three groups of identification results: Among the above three types of data and their identification methods,the identification methods based on economic and social data have the disadvantages of difficult data acquisition and low recognition accuracy;although the identification results based on population migration data are overestimated,the influence of geographical factors and administrative division factors are considered;the recognition results based on nighttime lighting data have the advantages of good spatial continuity and high spatial concentration,but it cannot exclude the influence of geographical factors.Therefore,the latter two can be combined and used in the comprehensive definition of urban agglomeration boundaries.(5)Comprehensive Definition of Urban Agglomeration and Suggestions for Countermeasures: The result of the comprehensive definition of the boundary of Beibu Gulf Urban Agglomeration is 2 urban agglomerations and 1 metropolitan area,which are urban agglomeration centered on the jurisdiction of Nanning City,urban agglomeration centered on Zhanjiang City and the metropolitan area centered on Haikou City,a total of 24 districts and counties.The defined results are far smaller than the planned area,and the degree of development of urban agglomeration is relatively low.This can be achieved by improving the core city's radiation capacity and actively fostering coastal cities,strengthening transport infrastructure,establishing a collaborative development mechanism for urban agglomeration,and promoting the integration process so that cities within the planned scope can form an urban agglomeration.