今天推介一个新的BCL北京城市实验室项目“中国城市体系的重新定义”
该项目涵盖《Functional Urban Area Delineations of Cities on the Chinese Mainland Using Massive Didi Ride-hailing Records》、《Delineating the Regional Economic Geography of China by the Approach of Community Detection》等研究内容,以供大家学习与交流。
此外,这一方面的多个项目的研究工作正在继续,考虑到内容没有发表,后续时机成熟时继续补充推送。
PS:以上为【北京城市实验室 Redefining Chinese City System 单元】分享内容,具体内容可进入网站查看。
《使用大量的滴滴乘车记录区分中国大陆城市的功能性城市区域》
Functional Urban Area Delineations of Cities on the Chinese Mainland Using Massive Didi Ride-hailing Records
一个城市的行政边界“不足”或“越界”相关的问题已成为全球性现象。一个城市的行政边界不能有效地代表其劳动力和经济活动的实际规模和影响。尽管许多现有案例研究已经对单个城市的功能性城市区域进行了调查,但尚未研究如何在大型城市或整个国家规模有关的地理空间中划定城市区域的问题。这项研究提出了一种基于乘车大数据的FUA识别方法。在这项研究中,从世界上最大的汽车叫车在线平台(滴滴出行)收集了超过4,300万张匿名的2016年汽车叫车记录。然后提出了一种核心外围方法,该方法使用全国范围的细粒度旅行来了解中国大陆的功能性城市地区。这项研究调查了所有39,007个乡镇中的4,456个,以期为定义中国大陆城市功能区提供一种新方法。此外,通过比较功能性城市区域及其行政范围来确定四种类型的城市,并使用23个中国城市群进行进一步评估。在全球范围内,随着Didi,Grab,Lyft和Uber等基于互联网的乘车服务的迅速使用,本研究为更大范围地描述功能性城市区域提供了实用的基准。
PS:以上为【北京城市实验室 Redefining Chinese City System 单元】分享内容,具体内容可进入网站下载查看。
《用社区发现方法描绘中国的地理区域经济》
With the obvious regionalization trend in the new period of urbanization in China, the scientific delineation of functional regions (FRs) at different scales has become a heated topic recently. Since the 20th century, western academia has formed a basic idea of metropolitan areas’ (MAs) delineation based on population density and commuting rate, for which the subjectivity of threshold setting is difficult to overcome. In this study, community detection algorithms from the field of network science are employed, namely the Louvain algorithm with adjustable resolutions and Combo with high-precision output, respectively. We take the nationwide car-hailing data set as an example to explore a bottom-up method for delineating regional economic geography at different scales based on the interconnection strength between nodes. It was found that most of the prefecture-level cities in China have a dominant commuting region and two or three secondary commuting sub-regions, while regional central cities have extended their commuting hinterlands over jurisdictional boundaries, which is not common due to the larger initial administrative divisions and the comprehensive development niveau of cities. The feasibility and limitation of community detection partitioning algorithms in the application of regional science are verified. It is supposed to be widely used in regional delimitation supported by big data. Both of the two algorithms show a shortage of ignorance of spatial proximity. It is necessary to explore new algorithms that can adjust both accuracy and spatial distance as parameters.
《是否所有城市都具有相似的城市形态?重新定义具有普遍兴趣点的城市,并使用中国城市和街区级别的指标对其进行评估》
Urban forms reflect spatial structures of cities, which have been consciously and dramatically changing in China. Fast urbanisation may lead to similar urban forms due to similar habits and strategies of city planning. However, whether urban forms in China are identical or significantly different has not been empirically investigated. In this paper, urban forms are investigated based on two spatial units: city and block. The boundaries of natural cities in terms of the density of human settlements and activities are delineated with the concept of ‘redefined city’ using points of interests (POIs), and blocks are determined by road networks. Urban forms are characterised by city-block two-level spatial morphologies. Further, redefined cities are classified into four hierarchies to examine the effects of different city development stages on urban forms. The spatial morphology is explained by urbanisation variables to understand the effects. Results show that the urban forms are spatially clustered from the perspective of city-block two-level morphologies. Urban forms tend to be similar within the same hierarchies, but significantly varied among different hierarchies, which is closely related to the development stages. Additionally, the spatial dimensional indicators of urbanisation could explain 41% of the spatial morphology of redefined cities.
《中国城市实体地域识别:社区尺度的探索》
Identifying Spatial Cities in China at the Community Scale
Scientifically identifying cities in the spatial dimension is a basis for objectively understanding urbanization, improving urban and rural statistics and formulating urban and rural planning strategies. In this article, using communities as basic administrative units and the data of urban built-up areas, a straightforward method to identify physical urban area has been established. We used this method to identity the physical urban area in Chinese whole territory and redefined Chinese city system. According to our studies, there are total 1,227 cities in China from the perspective of physical urban area covering 60,535km2 and this city amount is 86.2% higher than the amount of Chinese administrative cities which is 659. There are 126 Chinese administrative cities did not contain any cities from the physical urban area perspective, including 19 prefecture level cities, such as Sanming, Nanping, Chongzuo, Lincang, Yan’an, Yulin, Ya’an, Karamay, Donghai and 107 county level cities, such as Sansha and Alar, Dunhuang, Tongren, Wugang, Zhangshu, Jianyang and Wuyishan. There are 10 administrative cites contain at least 5 cities from the physical urban area perspective, which can be suggested to be divided into several smaller cities for management. They are Chongqing (16 cities), Beijing (12 cities), Suzhou (9 cities), Changzhou (7 cities), Shanghai (7 cities), Tianjin(6 cities), Wuhan (6 cities), Zaozhuang (6 cities), Shantou (6cities) and Foshan (6 cities). Our study is expected to provide supports for urban and rural planning and construction department and ministry of civil affairs to adjust urban administrative boundaries.
We have already shared the derived spatial cities of China in 2015 in the Data Released channel (see Data "38 Spatial cities of China in 2015").
《使用新数据重新定义中国城市系统空间实体维度》
Modern Chinese cities are defined from the administrative view and classified into several administrative categories, which makes it inconsistent between Chinese cities and their counterparts in western countries. Without easy access to fine-scale data, researchers have to rely heavily on statistical and aggregated indicators available in officially released yearbooks, to understand Chinese city system. Not to mention the data quality of yearbooks, it is problematic that a large number of towns or downtown areas of counties are not addressed in yearbooks. To address this issue, we have redefined the Chinese city system, using percolation theory in the light of newly emerging big/open data. In this paper, we propose our alternative definition of a city with road/street junctions, and present the methodology for extracting city system for the whole country with national wide road junctions. A city is defined as “a spatial cluster with a minimum of 100 road/street junctions within a 300 m distance threshold”. Totally we identify 4,629 redefined cities with a total urban area of 64,144 km2 for the whole China. We observe total city number increases from 2,273 in 2009 to 4,629 in 2014. We find that expanded urban area during 2009 and 2014, comparing with urban areas in 2009 are associated with 73.3% road junction density, 25.3% POI density and 5.5% online comment density. In addition, we benchmark our results with the conventional Chinese city system by using yearbooks.
《使用开放数据了解自然城市的不均衡城市扩张》
The last several decades have witnessed a rapid yet uneven urban expansion in developing countries. The existing studies rely heavily on official statistical yearbooks and remote sensing images. However, the former data sources have been criticized due to its non-objectivity and low quality, while the latter is labor and cost consuming in most cases. Recent efforts made by fractal analyses provide alternatives to scrutinize the corresponding “natural urban area”. In our proposed framework, the dynamics of internal urban contexts is reflected in a quasi-real-time manner using emerging new data and the expansion is a fractal concept instead of an absolute one based on the conventional Euclidean method. We then evaluate the magnitude and pattern of natural cities and their expansion in size and space. It turns out that the spatial expansion rate of official cities (OCs) in our study area China has been largely underestimated when compared with the results of natural cities (NCs). The perspective of NCs also provides a novel way to understanding the quality of uneven urban expansion. We detail our analysis for the 23 urban agglomerations in China, especially paying more attention to the three most dominating urban agglomerations of China: Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD) and Pearl River Delta (PRD). The findings from the OC method are not consistent with the NC method. The distinctions may arise from the definition of a city, and the bottom-up NC method contributes to our comprehensive understanding of uneven urban expansion.
《使用公交线路和人口密度定义中国城区功能》
欢迎大家点击文末的“阅读原文”或复制搜索此链接:https://www..com/projects-1/31-redefining-chinese-city-system/,关注北京城市实验室 Redefining Chinese City System 单元深入探索。
更多内容,请点击微信下方菜单即可查询。
请搜索微信号“”关注。
Email:@gmail.com
Emaillist: BCL@freelist.org
新浪微博:
微信号:
网址: http://www..com
责任编辑:孟庆祥