Understanding uneven urban expansion with natural cities using open data

Abstract

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 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, either. 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 in the study area.

Simulating Uneven Urban Spatial Expansion under Various Land Protection Strategies: Case Study on Southern Jiangsu Urban Agglomeration

“…Up to now, related research has been carried out at the international [2,16], national [17], and regional scales [18,19]. Developing countries have been of particular concern as most USE and population growth have happened there in recent decades [20]; Asia and Africa alone are estimated to dominate the future growth of the global urban population between 2014 and 2050 [21].…”

“…Gottmann and McGee provided valuable information regarding the spatial pattern and structure of urban expansion at the regional scale [24,25]. The following researchers explore uneven phenomena with various methodologies and datasets [17], spatial patterns and structures [26], dynamic urban systems [27,28], and influencing factors and mechanisms [11,29]; while some have centered their research on topics about land use regulation policies [11]. Most scholars focus on historical processes and current states, while few attempt to predict or simulate future possibilities related to uneven land development.…”

FracL: A Tool for Characterizing the Fractality of Landscape Gradients from a New Perspective

“…In practical computation, the value of ht-index is affected by how one confirms an observation of "far more small things than large ones" or, more precisely, by the threshold percentage of "small things" therein. Scholars have used different threshold percentages of small things, such as 33% [44], 40% [45], and 50% [46,47], but it is important to note that a comparison between two ht-indexes is meaningful only if they are computed based on the same threshold.…”

Differentiation of Demographic Dynamics as a Result of Unevenness in Socio-Economic Development of China

“…Urbanization. By assessment of China's urbanization scale, scientists draw conclusions on the considerable and ever-growing inequality of the country's regions in terms of production, public investments, infrastructural development, standard of living, and thus the natural population growth and population gain from migration [6][7][8][9][10]. The seriousness of urbanization-induced demographic and socio-economic transforms occurring in China is reflected in the following quotes: "The China Dream is an Urban Dream" [11], "High-tech development in the USA and China's urbanization would be two key factors affecting the process of human society development in the 21st century" [6].…”