城市人口的收缩由来已久,德国政府资助项目(Shrinking Cities)已经证实,全球范围内人口超过100万的450个城市地区,总体上失去了其城市人口的十分之一。德国学者近几年进行了开创性的探讨(发表在Environment and Planning
A/B上),以居住人口作为评价指标已成为共识。总体上,国际上发生城市收缩的原因,主要在于,(1)全球化背景下从制造业到服务业的经济转型,以及由此造成的劳动力结构性失业和产业资本外流;(2)其他影响因素还包括郊区化、战争、自然或人为灾害、老龄化或低生育率,以及东欧国家社会主义制度的瓦解等。
Many cities across particular areas in Europe and North America have a dwindling population, emerging vacant spaces, and the underuse of existing urban infrastructure (Haase et al., 2014). As one
of the more prosperous urbanized countries in the world, China has witnessed an unprecedented active stage of urban expansion (see the Beijing City Lab Ranking 8 for details, http://www.beijingcitylab.com/ranking/), which also attracted extensive attention from
academics (Deng et al., 2010).
Our previous study on mushing Jiedaos (the basic administrative unit of a city proper) indicates that urbanization in China often involves a significant political dimension. Largely rural
settlements (eg, Zhen) could be accorded with the city status (eg, Jiedao) overnight by administrative power, which further accelerates the urban process (Wu et al., 2015).
Meanwhile, some large cities and inshore developed cities in East China have attracted huge numbers of migrants from rural areas and small cities during the last ten years. Vacant villages have
been widely reported in the context of China (Long et al., 2012), while we observe a shrinking phenomenon at township and city levels.
For all the townships in mainland China, we estimated their population (residents not Hukou) based on the Population Censuses of China in 2000 and 2010, respectively. We found that 19,882 among
all 39,007 townships were losing their population during 2000-2010, and the total area was 3.24 million km2, which covered almost about one third territories of China (Figure 1). Those
shrinking townships are distributed in both rural and urban areas. Among them are 1,147 urban townships with a total area of 47,420 km2 in 367 cities.
Besides shrinking townships observed, we further identify 180 shrinking cities in China including one provincial capital city Urumqi, 40 prefectural-level cities and 139 county-level cities
(Figure 1). In addition, we use a cartogram to reveal population density in 2010 at the prefectural level, based on which shrinking prefectures are mapped (Figure 2).
More work is needed to understand these shrinking localities, the reasons behind the population falls, and possible policy tools. Both decision makers and city planners are accustomed to the
urban growth and population increasing in China. We hope that these featured graphics will inform them of our findings. In addition, we have established the Chinese shrinking city research
network (http://www.beijingcitylab.com/projects-1/15-shrinking-cities/) for exploring this important issue via proposing necessary
planning rules for shrinking cities.
Decreased population density at the township and city levels
Analysis on Variation of Quality of Street Space in Shrinking Cities Based on Dynamic Street View Pictures Recognition: A Case of Qiqihar
As the focus of urban planning in China converts from incremental planning to stock-based planning, researches concerning shrinking cities become increasingly important. Street being one of the
basic elements of cities, the changes of spatial quality of it are essential to the evaluation of the changes of shrinking cities. This study uses street views from the Tencent Maps to evaluate
the changes of quality of street space in the central districts of Qiqihar from 2013 to 2015. The research reveals that the quality of street space of Qiqihar is getting better while the rapid
change of commercial real estate under residential buildings suggests a decline in economy. Based on this finding, the“Population-Economy-Space Decline Lagging Phenomenon”is proposed to
illustrate the change mode of population, economy and spatial quality during the shrinking process of cities.
Shrinking Cities in China: The Other Facet of Urbanization
We have published a Springer book entitled "Shrinking Cities in China: The Other Facet of Urbanization". More information is available online at Springer (https://www.springer.com/us/book/9789811326455).
This book offers an essential introduction to the phenomenon of shrinking cities in China, highlighting several case studies, qualitative and quantitative methods, and planning responses. As an
emerging topic in urbanizing China, cities experiencing population loss have begun attracting increasing attention. All chapters of the book were contributed by leading researchers on the subject
in China. Richly illustrated with photographs for a better visual understanding of the topic, the book will benefit a broad readership, ranging from researchers and students of urban planning,
urban geography, urban economics, urban sociology and urban design, to practitioners in the areas of urban planning and design.
Identifying Shrinking Cities with NPP-VIIRS Nightlight Data in China
Although there has been a rapid urbanization in China since the 1980s, the simultaneous urban shrinkage phenomenon has existed for a long time. The study of shrinking cities
is particularly important for China as the current urban development has changed from physical expansion to built-up area improvement. After redefining what constitutes a
city (what we term a natural city), we compared the adjusted nightlight intensity of National Polar-orbiting Partnership Visible Infrared Imaging Radiometer Suite
(NPP-VIIRS) data between 2013 and 2016 to accurately identify shrinking cities throughout China. The results indicate that there are 2,862 redefined natural cities
in China and that the total area reaches 53,275 km2, about 0.5% of the national territory. Based on this, we identified 798 shrinking cities with a total area of 13,839
km . After analyzing the relative position of shrinking cities and internal shrinking pixels in the geometric space, the morphological characteristics of shrinking cities were
systematically classified into six patterns. The majority of shrinking cities belong to scatter shrinkage, central shrinkage, and local shrinkage; only 5% are complete shrinkage;
the rest are unilateral shrinkage and peripheral shrinkage. In addition, six shrinkage causes were quantitatively classified and summarized by referring to multiple-source urban
data and municipal yearbooks. To enrich the methodological system for urban shrinkage, the research provides a reminder of the need to consider the other side of urbanization
(i.e., dissolution of social networks) and proposes appropriate strategies and policies to address shrinkage issues.
Shrinking cities on the globe: Evidence from LandScan 2000–2019
Shrinking cities have spread across the globe in recent decades, characterizing signifificant population loss, economic decline, and decay in spatial quality. To maintain global economic
prosperity in the context of urban shrinkage and support decision making in the direction, it is necessary to accurately identify shrinking cities on a global scale. We utilize
redefifined natural city boundaries and the LandScan dataset to identify and map shrinking cities experiencing population loss on the globe. As a result, we have identifified 5004
shrinking cities worldwide, with a total area of 126,930 km2 during 2000–2019. The ratio of which in number and in area is 27% and 22%, respectively. The shrinking cities are
clustered and mainly located in Europe, Eastern Asia, and northeastern United States. There are 41 countries with more than 20 shrinking cities on the globe. The number of shrinking
cities in China reached 679, which is the most. Among the 41 countries, the median value of the natural cities’ shrinking ratios of Iraq, Iran, Austria, South Africa, Russia,
Georgia, and Belarus is >50%, indicating that the urban population loss in these countries is relatively serious. Our fifindings can be used to inform decision makers and
urban planners to adjust the “growth-oriented” planning paradigm and adopt precise strategies, to form a healthier urban development.
Classification of shrinking cities in China using Baidu big data
In the context of rapid urbanization, shrinking cities cannot be ignored. The classification of shrinking cities according to the patterns of urban population changes is the key to
reveal the "hollow" and changing characteristics of the population. Researchers classified the shrinking cities in Western developed countries as "perforated", "doughnut"
and "peripheral" types. However, there is a lack of evidence showing the types of shrinking cities in China. This paper takes the redefined physical cities in China (excluding Hong
Kong, Macao and Taiwan) as the study area, and employs Baidu Huiyan's 200 m × 200 m grid cell permanent population data from November 2016 to November 2018 to identify different types
of shrinking cities in the country. Our results show that 1506 physical cities have experienced a population reduction between 2016 and 2018, accounting for 49.8% of the total number
of physical cities (3022). Furthermore, in order to accurately identify the types of shrinking cities, 126 densely populated and severely shrinking cities during the study period were
selected as the research samples, mainly located to north of the Qinling Mountains and Huaihe River of China. Our analysis shows that the shrinking types of the sample cities can be
classified into five categories: "perforated", "complete", "local", "doughnut", and "peripheral". The number of cities with perforated shrinkage is the largest, which numbered 47 (37.3%
of the sample cities), most of which are found in Heilongjiang Province, Inner Mongolia Autonomous Region and Gansu Province. Complete shrinkage ranks the second, including 33 cities,
which accounts for 26.2% of the samples, and mainly distributed in Gansu and Shaanxi provinces. The numbers of shrinking cities with local, doughnut and peripheral types are 25, 18 and
3, respectively. These cities are mainly distributed in Heilongjiang and Inner Mongolia. This is because the governments paid more attention to the development speed over quality during
the first half of China's urbanization process, and adopted a growth- oriented urban planning strategy. Traditional industries declined due to resource depletion or economic
transformation, and the transfer of industries under active government adjustment, all of which contribute to the
emergence of perforated shrinkage. This study could provide scientific evidence for micro management of urban development, optimization of land use pattern, improvement of
urban livability, and conduct of urban planning and design in the context of urban shrinkage.
Shrinking cities in China: Evidence from the latest two population censuses 2010–2020
As the world’s largest developing country, most Chinese cities are experiencing both population shrinkage and spatial expansion in the context of rapid urbanisation. To address the negative
impacts of urban shrinkage in a targeted manner, it is necessary to accurately identify shrinking cities in China. In this study, we utilise the sixth and latest seventh population
census data to identify and map shrinking cities in China that are experiencing population loss between 2010 and 2020. As a result, we identified 1507 shrinking districts and counties
(52% of all 2896 districts and counties in China), with a total area of 4.4 million km2, covering almost 46% of China’s territory. In addition, we further found that from 2010 to 2020, there
are 266 shrinking cities in China, an increase of 86 (12%) compared with 2000–2010. This indicates that the situation of shrinking cities in China has become more critical. From the
perspective of spatial distribution, Chinese shrinking cities are clustered, mainly in the northeast and central regions.We also plot the proportion of shrinkage in a deformed form to
reveal which prefecture-level cities are losing population from 2010 to 2020. Our findings provide policymakers and urban planners with a reference and warning that measures should be
taken to adjust the growth-oriented planning paradigm to reverse the negative impact of population loss on urban development.
Satellite monitoring of shrinking cities on the globe and containment solutions
Shrinking cities are often neglected in the context of global urbanization, the tip of the iceberg that was driven by underlying complex sets of causes. Therefore, it is urgent and
crucial to investigate the invisible aspects of global urbanization propelling specific challenges to attain Sustainable Development Goal 11 (SDG 11) related to sustainable cities and
communities. Here, we identify shrinking cities in 1992–2000, 2000–2012, and 2013–2018 and predict them in 2018–2050, using nighttime light images and redefifined natural city boundaries. The
proportion of shrinking cities increased from 9% to 16 and 25%. Looking ahead, there will be 7,166 predicted shrinking cities in 2050, accounting for 37% of all cities. In
this context, synergistic efforts like regreening vacant lands and constructing
compact cities would help achieve SDG 11 in consideration of the new urban shrinking landscape with multisource data like CO2 emissions and points of interests (POIs).
Future shrinking cities on the globe: A projection map for 2020–2100 based on global gridded population dataset
Shrinking cities have become increasingly prevalent worldwide due to various factors, which pose serious challenges to affected areas in terms of population decline, economic decline, and spatial
deterioration. While existing research studies have focused on identifying shrinking cities, there is a need for global projections to mitigate uncertainties in their growth trajectories.
Spatially explicit population grids offer a new approach to identifying potentially shrinking cities with suffificient spatial resolution. By utilizing a global gridded population dataset from
2020 to 2100 under the SSP2 (Middle of the Road) scenario, we produce a global projection map for future shrinking cities. Among the total 19,024 natural cities, 9682 cities (50.9%) will face
population decline and 1751 cities (9.2%) may lose more than half population by 2100. Cities in East Asia and East Europe may face serious population decline.
Global gridded population dataset in 2020 and 2100 under SSP2 can be open accessed at
Characteristics of "resident population in physical urban area" in
identifying shrinking cities: An examination based on
literature review and multi-source data
In the context of China reaching its population peak and moving into a new stage of urbanization, the study of shrinking cities has increasingly captured the attention of the
academic community. This paper undertakes a thorough systematic review of the literature and empirical studies, focusing particularly on the methodologies used for identifying shrinking
cities in China. One key method discussed is from the study which utilized "resident population in physical urban area" data to identify shrinking cities. To enhance the precision of
this methodology, our study conducted extensive geocoding of all village- level administrative units across China. Using urban-rural classification codes, we approximated the boundaries
of "urban areas" as referred to "resident population in physical urban area" data. This allowed for a more nuanced comparison of these theoretically derived boundaries with those
observed through remote sensing technologies and actual boundaries of natural cities. This comparison sheds light on the specific characteristics of defining urban areas solely based on
this data. Further exploring the implications of these findings, our research utilized multi- source population data to identify the number and proportion of shrinking cities in China
between 2010 and 2020. The study uncovered some insights: Firstly, the urban- rural classification codes used in population statistics tend to merge numerous natural cities into a
single urban unit. This aggregation makes it challenging to analyze population changes within individual natural cities. Secondly, the "resident population in physical urban area" data
is not suitable to accurately reflect the population dynamics in nearly a thousand county- level small and medium-sized towns, which are crucial to understanding the broader
urbanization trends. Due to these characteristics, the estimations of shrinking city numbers and proportions as defined by this data require further discussion. By applying the
boundaries of 2444 natural cities in China and integrating multiple data sources like WorldPop and LandScan, our research found that the proportion of shrinking cities lies between
26.7% and 31.3%. This study underscores the importance of utilizing a diverse array of data sources and analytical methods to more accurately identify and understand the phenomenon of
urban shrinkage in China. Such a comprehensive approach helps mitigate the uncertainties that single data sources may introduce, providing a more robust framework for policymakers and
urban planners addressing the challenges of urban decline.