Measurement Of Urban System Structure Supported By Multi-source Big Data

The urban system structure is the spatial presentation of the cooperative and restrictive relationship among towns based on their own characteristics and connectivity,including hierarchical scale structure,regional spatial structure,and functional type structure.Measuring the urban system structure is not only a requirement for National Territorial Development Plan,but also the entry point for urban research in the era of big data.Based on the measurement results,the rational planning of the urban system structure is conducive to maximizing regional benefits and realizing the healthy operation of urbanization.However,there is currently no measurement framework of the urban system structure that is applicable to multiple scales at the same time.Based on multi-source big data such as mobile phone signaling,enterprise big data,POI,AOI,etc.,this paper calculates the contact frequency of units,constructs the spatial database of industrial enterprises and scenic spots,counts the number of visitors to transportation hubs,identifies commercial functional areas,and analyzes the nuclear density of science and education places.Subsequently,this paper proposes a measurement framework of urban system structure which is suitable for multi-level scales.The framework can be separated into three parts:(1)From the perspective of flow space,the urban centrality index is calculated and the urban hierarchical scale structure is measured by coupling volume and direction of connections;(2)From the perspective of flow space,the regional spatial structure of towns is measured systematically and sufficiently which integrates the analysis of the distribution,connection and combination of towns;(3)According to the scale of the study area,the corresponding applicable function type identification methods are applied.Specifically,the scale at district and county level uses the Nelson method,which based on the number of employees in each Industrial classification for national economic activities;while the township-level scale proposes the identification framework of urban function type structure.This paper uses the urban system structure measurement framework to measure the urban system structure of the Ningbo City,and finds that: the hierarchical scale of Ningbo presents a "pyramid" structure of "1+4+13+70";the regional space presents the spatial pattern of "One main-core,Four sub-core,Five axes and Four districts";the functional type manifest the cores plays a number of functions,and the industrialization level of the towns in the north wing of Ningbo is better than that in the south wing,but its tourism development level or potential is inferior to that in the south wing of Ningbo.Finally,according to the measurement results of Ningbo’s urban system structure,the implementation of Ningbo urban overall planning is evaluated,and then suggestions for optimizing the spatial pattern of the city are put forward.The case study of Ningbo City verifies the applicability and scientifically of the measurement framework of urban system structure.The case shows that using the urban system structure measurement framework can quantitatively analyze the development status of towns and even regional area,and provide suggestions for coordinating urban space and urban development planning.