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Assessing sustainability of urbanization by a coordinated development index for an Urbanization-Resources-Environment complex system: A case study of Jing-Jin-Ji region, China
Ecological Indicators 96 (2019) 383–391
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Original Articles
Assessing sustainability of urbanization by a coordinated development index for an Urbanization-Resources-Environment complex system: A case study of Jing-Jin-Ji region, China
T
⁎
Xuegang Cuia,b, Chuanglin Fanga, , Haimeng Liua, Xiaofei Liua a b
Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China
A R T I C LE I N FO
A B S T R A C T
Keywords: Urbanization-Resources-Environment complex system Coordinated development index Sustainable urbanization Jing-Jin-Ji region
China’s rapid urbanization has produced a number of resources and environmental problems, making it necessary to provide a scientific basis for the promotion of sustainable urbanization. This study integrates systems theory with complexity science to create an Urbanization-Resources-Environment complex system (URE) to assess the sustainability of urbanization, beginning by conjoining a theory of urbanization and ecological environment coupling. We developed a comprehensive coordinated development index for URE (URECDI) to represent the internal connectivity and influence between the urbanization, resources and environmental subsystems, and also indicate the sustainability of urbanization. This study analyzed trends observed in URE for 13 cities in the Jing-Jin-Ji region (JJJ) of China, using statistical data collected from 2005 to 2015. The main results are: (1) urbanization efficiency, resource utilization efficiency and environmental quality are the largest influences on the indices, which indicates that they are key factors in the behavior of URE; (2) coordination between subsystems of URE within JJJ was not good, but showed an increasing trend during 2005–2015; and (3) URECDI indicated significant differences between 13 cities, which suggests that we can increase coordination within URE by implementing a zoning strategy, and adjusting policies and investment to favor low-coordinated cities. The coordinated development index can reveal the overall characteristics of URE and ensure regionally sustainable urbanization.
1. Introduction In recent times, urbanization has developed globally at an unprecedented rate. In the last 50 years, the global urban population has grown by nearly 20%. By 2008 over 50% of the global population lived in urban areas; in 2016, the extent of global urbanization reached 54.3% (World Bank Group, 2017). Urbanization is one of the most significant human activities to affect Earth. It is a process that concentrates populations in towns, cities, and metropolitan areas and alters land use with the urban landscape (Angel, 2012). Urbanization includes a complex geographical relationship between humans and the land surface as well as associated economic and social activities (Pitman, 2005; Friedmann, 2006; Fragkias et al., 2017). Urbanization drives global economic growth, affects global and regional resources, and changes the natural environment on many scales. It fundamentally changes the ecology of a region (Tratalos et al., 2007; Grimm et al.,
2008; Liu et al., 2011). Urban expansion alters land use and land cover, affects ecosystem biodiversity, modifies watershed hydrology, and changes biogeochemical cycles through waste discharge (Pataki et al., 2011; Kong et al., 2012; Lin et al., 2015; Schneider et al., 2015; Kalantari et al., 2017). After reform and opening-up in China, there have been benefits from rapid economic development, and urbanization has increased significantly (Bai et al., 2014; Yin et al., 2014). From 1978 to 2015, the proportion of China’s population that lived in cities increased from 17.9% to 56.1%, with an average annual growth rate of 1.03%, which is much higher than in the rest of the world over the same period (National Bureau of Statistics, 2006–2016a). However, China’s rapid urbanization has also caused a series of resource-related and environmental problems, including loss of arable land, water and energy shortages, habitat fragmentation, increased carbon emissions, and particulate matter pollution (Wang et al., 2013; Li, 2015; Xu et al.,
⁎ Corresponding author at: Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, China. E-mail addresses: [email protected] (X. Cui), [email protected] (C. Fang), [email protected] (H. Liu), [email protected] (X. Liu).
https://doi.org/10.1016/j.ecolind.2018.09.009 Received 3 April 2018; Received in revised form 4 August 2018; Accepted 6 September 2018 1470-160X/ © 2018 Elsevier Ltd. All rights reserved.
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2015; Li et al., 2016; Liu et al., 2016; Wang and Liu, 2017). Air and water pollution are intense, and other environmental contaminants abound in China’s major cities and urban areas (Fang et al., 2010; Wang et al., 2017). For example, monitoring data indicate the severity of PM2.5 pollution in China’s urban agglomerations (Fang et al., 2016c). Many scholars are interested in the relationship between urbanization and the natural environment because of the effects of rapid urbanization in China. The natural environment and the built urban environment form a complex system with multiple feedback loops. They are coupled in a nonlinear relationship which can be represented by an inverted U-shaped or an S-shaped curve (Wang et al., 2014; Fang et al., 2016b; Zhao et al., 2016; He et al., 2017). Within systems theory and complexity science, a system is defined as complex when its constituent elements cannot explain the overall characteristics of the system due to their nonlinear links (Gallagher and Appenzeller, 1999; Bailey, 2001; Espinosa and Walker, 2011). A complex system has many characteristics, including numerous components, rich and complex interactions between them, openness, and being dynamic rather than in equilibrium (Cilliers and Spurrett, 1999). There is an urban–environment nexus that includes the use of both natural and built resources and which can be thought of as an Urbanization-Resources-Environment (URE) complex system which is an open, complex, and dynamic system, and which has a formal structure and a certain functionality (Xie et al., 2016). Within URE, urbanization (U), resource (R) and environmental (E) subsystems are individually complex systems that interact nonlinearly, and the nature and activity of their interconnections determine the development of the URE complex system. If one or more of the interconnected subsystems act abnormally, then the overall coherence and operation of URE will also be abnormal (Kelly et al., 2007). The urbanization and environmental coupling (UEC) model treats urbanization, resources, and the environment as independent systems with complex interactive forcing relationships. However, from a complex systems perspective, the three systems are inseparable and thus form a larger system, URE, the coherence and internal state of which indicates the sustainability of urbanization (Holland, 1996; Fang and Wang, 2013). URE, in contrast to UEC, emphasizes the integrity, structure, and overall evolution of the subsystem couplings. URE is an integrated dynamic system with a complex structure which is always evolving from low-level disorder to high-level order (Li et al., 2010). Sustainable development theory holds that the state of coordination between subsystems can provide a criterion for judging whether the system tends towards high-level order, which is an indicator of sustainable development (Lélé, 1991; Jordan et al., 2010; Wang and Zhou, 2016). Rapid urbanization in China has forcibly affected the environment, while environmental change has, in turn, affected sustainable urbanization, especially in major cities and urban agglomerations which determine economic development and future urbanization (Fang et al., 2016a). It is necessary to analyze and understand the interactions between the urbanization, resources, and environmental subsystems of URE to realize sustainable urbanization. Suitable management measures should be implemented without delay. This paper attempts to deepen the understanding of the overall process of connectedness between urbanization, resources and environment and to find the direction of sustainable urbanization by outlining a complex system theory of Urbanization-ResourcesEnvironment (URE). This research has two goals: to develop an index that accurately represents the overall effect of the three subsystems on the sustainability of urbanization; and to present a case study of 13 cities in Jing-Jin-Ji region to demonstrate the use and effectiveness of the index. First, starting with the established urbanization and environmental coupling (UEC) theory, we develop a coordinated development index for URE (URECDI) to analyze the degree of interaction between U, R, and E subsystems and provide an indicator of the sustainability of urbanization. Second, we use URECDI to analyze the
Fig. 1. Location and extent of JJJ.
sustainability of urbanization for 13 cities in Jing-Jin-Ji region (JJJ) during 2005–2015. The remainder of this paper is organized as follows. Section 2 describes the study area, data screening, and the methodology used to establish a value for URECDI. Section 3 discusses the models developed in Section 2, analyzes the results obtained for 13 cities in JJJ, and assesses the efficacy of URECDI. Section 4 sets out the main conclusions derived from the study. 2. Materials and methods 2.1. Study area Jing-Jin-Ji region (JJJ) includes Beijing, Tianjin, and Hebei, which includes Shijiazhuang, Tangshan, Qinhuangdao, Handan, Xingtai, Baoding, Zhangjiakou, Chengde, Cangzhou, Langfang, and Hengshui (Fig. 1), all having different development characteristics. JJJ is one of the three largest urban agglomerations in China (the others are Yangtze River Delta and Pearl River Delta). It covers 217,156 km2, 1.9% of China’s territory, and in 2015 it had a population of 111.42 million and GDP of 1,129 billion dollars. JJJ is rapidly urbanizing; the urban population of the region increased from 30.3% in 1990 to 62.7% in 2015, an average annual growth rate of 1.3%. Table 1 shows the economic indicators and urbanization rates for JJJ in 2015. The rapid development underlying Table 1 is likely to put pressure on both resources and the environment. JJJ has become an area of serious water shortage, air pollution, water pollution, and conflict between economic development and environmental sustainability because of rapid urbanization and economic development (National Development and Reform Commission, 2015). Sustainable urbanization in JJJ faces enormous challenges. 2.2. Data pre-processing The data used in this paper were mainly obtained from China Statistical Yearbook (2006–2016) (National Bureau of Statistics, 2006–2016b), China Statistical Yearbook on Environment (2006–2016) (National Bureau of Statistics and Ministry of Environmental Preservation, 2006–2016), China City Statistical Yearbook (2006–2016) (National Bureau of Statistics, 2006–2016a), China Urban 384
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Table 1 Indicators of economy and urbanization in JJJ region, 2015. City
GDPa (billion $)
GDP per capital ($)
GDP growth rate in 2014 (%)
Percentage of urban population
Beijing Tianjin Shijiazhuang Tangshan Qinhuangdao Handan Xingtai Baoding Zhangjiakou Chengde Cangzhou Langfang Hengshui
369.51 265.53 87.35 97.99 20.08 50.50 28.33 52.99 21.89 21.82 53.31 39.72 19.59
17,024 17,165 8162 12,561 6533 5354 3884 4587 4951 6180 7163 8704 4416
6.9 9 7.5 5 6.9 6.8 6 6 5.8 6.8 7 7.5 7.6
86.5 82.6 58.3 58.3 54.1 51.4 47.7 46.7 52.2 46.8 48.6 55 46.6
Source: Beijing Municipal Bureau of Statistics, 2006–2016; Tianjin Municipal Bureau of Statistics, 2006–2016; The People’s Government of Hebei Province, 2006–2016. a Denotes gross domestic product. Fig. 2. Interaction between subsystems of URE.
Construction Statistical Yearbook (2006–2016) (Ministry of Housing and Urban-Rural Development, 2006–2016), Beijing Statistical Yearbook (2006–2016) (Beijing Municipal Bureau of Statistics, 2006–2016), Tianjin Statistical Yearbook (2006–2016) (Tianjin Municipal Bureau of Statistics, 2006–2016) and Hebei Economic Yearbook (2006–2016) (The People’s Government of Hebei Province, 2006–2016). To eliminate differences in dimension, magnitude, and sign between indicators xj, we normalized the data (Li et al., 2012):
For positive data: Xij =
For negative data: Xij =
The probabilityPij of the indicator x j in year i : Pij =
Information entropy Ej for the index j: Ej = −
Weight Wj for the index j: Wj = (1)
∑ (Pij × ln Pij)
(4)
i=1
(5)
Dj m
∑ j = 1 Dj
(6)
where n is the number of years, and m is the number of indicators. Finally, we calculated the composite index Si for each subsystem in year i using Eq. (7):
x jmax −x ij x jmax −x j min
(3)
n
Entropy redundancy Dj for the index j: Dj = 1−Ej
x ij−x j min x jmax −x j min
1 ln n
Xij n
∑i = 1 Xij
(2)
m
where xij represents the value of a variable, x, indexed by j, in year i; xjmax and xjmin are the respective maximum and minimum values of indicator xj over all years. The values of all indicators xj were normalized into [0, 1].
Composite index Si for each subsystems in year i; Si =
∑ Wi × Xij (7)
j=1
2.3.2. URE coordinated development index Coordination reflects the degree of coherence between all subsystems, as well as the extent to which the system tends to be ordered (Mamat et al., 2013). In order to calculate the coordination of URE, we developed the URE coordinated development index (URECDI), which is based on the coordination degree model for China National Sustainable Communities (Wu et al., 2017). URECDI can be used to assess sustainable urbanization in most regions since the interactions between urbanization, resources, and environment occur everywhere that urbanization occurs. The above index will comprehensively reflect the comprehensive level of sustainable urbanization. To obtain URECDI, we first calculate the coordination degree between pairs of subsystems as follows:
2.3. Methods 2.3.1. Index system for evaluation of URE Fig. 2 shows the stucture of URE and its internal interaction. We developed a comprehensive indexing system in order to evaluate URE and its component subsystems. The topmost composite index for URE, URECDI, is derived from three composite (second level) indexes, one for each of the three major component subsystems of URE, U, R and E. The composite index for U is derived from two weighted indexes for second level indicators (urbanization level and urbanization efficiency) which are in turn derived from ten primary indicators. The composite index for R is derived from two weighted indexes for second level indicators (resources per capita and resources utilization efficiency) which are in turn derived from six primary indicators. The composite index for E is derived from two weighted indexes for second level indicators (environmental quality and environmental governance) which are in turn derived from six primary indicators. Table 2 shows the composition of the indexes in detail. We used the entropy method to determine the indicator weightings in order to avoid any effects due to subjectively determining weights (Chen et al., 2013b). Information entropy is a mathematical concept; it reflects the disorder of the system and varies by index. We determined the weight of each primary indicator as follows:
Coordination degree between U and R in year i: CURi = 1−
|SUi−SRi| max(SUi, SRi ) (8)
Coordination degree between U and E in year i: CUEi = 1−
|SUi−SEi| max(SUi, SEi ) (9)
Coordination degree between R and E in year i: CREi
|SRi−SEi| = 1− max(SRi, SEi ) (10)
where SUi, SRi and SEi respectively represent the composite indexes of 385
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Table 2 Indicators used to evaluate the composite contributions of urbanization, resources and environmental subsystems in URE. The composite indexing of URE Subsystem
Second level indicator
Indicator weight
Urbanization subsystem (U)
Urbanization level
0.29
Urbanization efficiency
0.71
Resources per capita
0.59
Resources utilization efficiency
0.41
Environmental quality
0.55
Environmental governance
0.45
Resources subsystem (R)
Environmental subsystem (E)
a
a
Primary indicator
Indicator weighta
Percentage of urban population Percentage of urban construction land Percentage of the secondary and tertiary industry GDP per capita (Yuan) GDP per unit land area (104 Yuan/km2) Number of college students per 10,000 people Number of doctors per 10,000 people Parks and green areas per capita (m2) Road areas per capita (m2) Income ratio of urban to rural residents
0.104 0.082 0.107 0.099 0.091 0.100 0.078 0.111 0.112 0.116
Water resources per capita (m3) Arable land areas per capita (ha) Grassland areas per capita(ha) Woodland areas per capita (ha) Water consumption per unit of GDP (m3/104 Yuan) Energy consumption per unit of GDP (ton of SCE/104 Yuan)
0.176 0.187 0.124 0.107 0.203 0.204
Discharged volume of SO2 per unit of GDP (t/104 Yuan) Discharged of waste water per unit of GDP (t/104 Yuan) Percentage of vegetation with green areas Percentage of environmental pollution control investment Sewage treatment plants per 10,000 people Garbage disposal plants per 10,000 people
0.185 0.183 0.181 0.164 0.146 0.142
Using the entropy method (EM).
impact on the urbanization subsystem, U. Altogether, these three indicators explain 33.9% of the total change in the subsystem. These findings suggest that, over the past ten years, population and land use change were not good indicators of the level of urbanization in JJJ. Thus the Chinese government should not pay too much attention to the degree of urbanization (Chen et al., 2013a). Urbanization has been largely uncontrolled, but we should pay more attention to the efficiency and quality of urbanization, especially focusing on income inequality, public infrastructure facilities, and creating a livable environment.
the individual subsystems U, R and E in year i. We calculate the coordination degree of the combined system URE by:
Coordination degree of URE in year i: Ci = average (CURi, CUEi, CREi ) (11) The coordinated development index of URE, as well as reflecting the coordination degrees between different subsystems, also takes into account the composite indexes of each subsystem:
Coordinated development index of URE in year i : CDIi =
Ci × average (SUi, SRi, SEi )
(12)
3.1.2. Resources subsystem Table 2 shows that energy consumption per unit of GDP (0.204) and water consumption per unit of GDP (0.203) are the two primary level indicators that had the most influence on the resources subsystem, R. Altogether, these two indicators explain 40.7% of the total change in the subsystem. These findings suggest that, in comparison with resources per capita, the efficient utilization of resources better indicates the overall level of the resources subsystem in JJJ. Resources are scarce in JJJ and the availability of water resources is low (Li et al., 2017). The region needs to use water, energy, and other resources more efficiently, for example by using water and energy saving technology.
CDIi takes a value in the range [0, 1]. The higher the value of CDIi, the more coherence there will be between subsystems of URE. We can classify URECDI as shown in Table 3 (Chen and Wang, 2010). 3. Results and discussion 3.1. Comprehensive level of urbanization, resources and environmental subsystems The effects of individual indexes on the composite index for each subsystem are analyzed to identify implications for future policy in JJJ.
3.1.3. Environmental subsystem Table 2 shows that discharged volume of SO2 per unit of GDP (0.185) and discharged wastewater per unit of GDP (0.183) are the two primary level indicators that had the most influence on the environmental subsystem, E. Altogether, these two indicators explain 36.8% of the total change in the subsystem. These findings suggest that pollution control is more effective than environmental regulation in improving the overall quality of the environment in JJJ, which shows that the Treatment after Pollution approach may not be effective in China (Sun et al., 2010), especially in JJJ. Thus the government should pay more attention to upgrading industrial and environmental technology to ensure a better environment. Sections 3.1.1–3.1.3, the above analyses show that efficient urbanization, effective resource utilization, and improved environmental quality contribute more to the urbanization, resources and environmental subsystems than the other factors that were identified. The
3.1.1. Urbanization subsystem Table 2 shows that income ratio of urban to rural residents (0.116), road areas per capita (0.112), and parks and green areas per capita (0.111) are the three primary level indicators that had the greatest Table 3 Five types of coordinated development index for URE. Coordinated development index (CDI) range
Coordination types
0.00–0.20 0.21–0.40 0.41–0.60 0.61–0.80 0.81–1.00
No coordination (NC) Little coordination (LC) Basic coordination (BC) Good coordination (GC) Excellent coordination (EC)
Source: Wu et al. (2017). 386
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Fig. 3. Trends in the urbanization subsystem.
3.1.6. Environmental subsystem There was an increasing but fluctuating trend in the environmental subsystem during 2005–2015, as shown in Fig. 5. Changes are mainly due to improvements in environmental quality, as indicated by volume of SO2 discharged per unit of GDP and volume of wastewater discharged per unit of GDP. Changes are also due to improved waste management, as indicated by the number of sewage treatment plants per 10,000 people and the number of garbage disposal plants per 10,000 people. However, investment in environmental pollution control is low as a proportion of total investment, which limits the effects of environmental control. The gap between Beijing and Tianjin and other cities began to shrink after 2014 as a result of the integration of environmental protection measures in JJJ (National Development and Reform Commission, 2015).
effectiveness of subsystems will be significantly improved by controlling the main influencing factors. Sections 3.1.4 through 3.1.6 discuss the results of using the URECDI calculations to identify the composite trends in each subsystem treated as a whole.
3.1.4. Urbanization subsystem There was an increasing trend in the urbanization subsystem during 2005–2015, as shown in Fig. 3. Urbanization is increasing in JJJ due to rapid growth in population and economy, as indicated by GDP per capita and GDP per unit land area. However, income (in)equality, as indicated by the income ratio of urban to rural residents, and public infrastructure facilities, as indicated by road area per capita, have not been given enough attention. Urbanization in Beijing and Tianjin is far greater than in the other cities in Hebei, shown by the significant gap between them.
3.2. Coordinated development index of URE The coordinated development index, CDI, represents the behavior of the composite complex system URE. It indicates the sustainability of urbanization within the region. Table 3 categorized the degree of coherence between the subsystems of URE according to the values of CDI and described them as coordination types. Table 4 shows the annual classifications of cities by coordination type within in JJJ during 2005–2015. The coordination types of URE in JJJ have two characteristics. First, URECDI is not high and all cities fall into one of the three categories LC, BC and GC. Most cities are BC, followed by GC; a few cities were LC
3.1.5. Resources subsystem There was an increasing trend in the resources subsystem during 2005–2015, as shown in Fig. 4. The increase is mainly due to a significant decline in water and energy consumption per unit of GDP. Resource usage per capita (indicated by water resources per capita and arable land area per capita) decreased significantly, indicating great pressure on resource usage. Zhangjiakou and Chengde, with abundant resources per capita, show far greater resource usage than other cities.
Fig. 4. Trends in the resources subsystem. 387
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Fig. 5. Trends in the environmental subsystem.
3.2.1. Beijing Fig. 6 shows that for Beijing both URECDI and coordination degrees between all subsystems are stable and at a high level for the period 2005–2015. Beijing is the capital of China and has received enough investment to improve the quality of urbanization, the efficient use of resources, and environmental quality. During the period many polluters have been closed and relocated. However, some indicators constrain CUR and CRE, such as low resource usage per capita (e.g., water resources per capita or arable land areas per capita). The capacity to provide resources in Beijing is at risk of being overloaded due to excessive population growth. This problem could be alleviated by relocating some of the population or improving the efficiency of resource utilization.
early in the period. Due to excessive urbanization beyond the supply capacity of resources and the carrying capacity of the environment, there is some incoherence in URE that constrains sustainable urbanization. Second, URECDI showed an increasing trend in most cities during 2005–2015. JJJ is one of China’s most important urban agglomerations and the Chinese government has invested heavily in the region, particularly as it hosted the 2008 Olympic Games. As a result, urban construction, efficient resource utilization, and effective pollution control have all increased, which improved the coordination types of URE. The cities in JJJ can also be described as high-coordinated (e.g., Beijing, Tianjin, and Qinhuangdao; developed (e.g., Chengde and Baoding); and low-coordinated (e.g., Xingtai and Zhangjiakou). To further understand the coordinated development process represented by URE, we examine Beijing, Chengde, and Xingtai as representative cities of each of the three groups.
3.2.2. Chengde Fig. 7 shows that both URECDI and the coordinating degrees CUR
Table 4 The coordination types of URE in JJJ, 2005–2015. Year
2005
2006
2007
2008
2009
2010
Beijing Tianjin
2012
2013
2014
2015
GC BC
GC
Shijiazhuang
BC
Tangshan
BC
GC
BC
Qinhuangdao Handan
BC
GC
GC BC
Xingtai
GC
LC
BC
BC
Baoding
BC
Zhangjiakou Chengde
2011
GC
LC
BC
LC
BC
Cangzhou Langfang
GC BC
Hengshui
No coordination (NC)
GC
BC
GC BC
Little coordination (LC)
Low level
Basic coordination (BC)
Good coordination (GC)
High level
The coordination types of URE
388
Excellent coordination (EC)
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Fig. 6. URECDI and coordination degrees in Beijing.
Fig. 8. URECDI and coordination degrees in Xingtai.
neglecting development in favor of coordination. This differs from the orthodoxy of urbanization and environmental coupling, which emphasizes the promotion of sustainable urbanization by ensuring and maintaining coordination between all systems (Wang et al., 2014). It can be seen that high quality coordination can be obtained only on the basis of the full development of each subsystem, rather than by simply pursuing coordination as an end in itself, which is inconsistent with urbanization and environmental coupling theory. Sustainable urbanization is not intended to excessively restrict urbanization, but to sustainably maintain coordination between urbanization, resources and environment. The large gap in URECDI that separates Beijing and Tianjin from other cities indicates that we should adjust policy and investment to be more favorable to low-coordinated cities, and so better balance development through a zoning strategy. An increase in URECDI for JJJ will indicate that this has happened. Overall, URECDI is an indicator that allows us to assess the sustainability of urbanization, and to identify any necessary corrective countermeasures. Fig. 7. URECDI and coordination degrees in Chengde.
4. Conclusions
and CRE for Chengde showed increasing trends during 2005–2015, due mainly to the benefits from the resources subsystem R. Chengde receives some national and local investment, which is used to improve resource usage and reduce environmental impacts. CUE showed a decreasing trend, which was caused by the low composite index for the urbanization subsystem U. Chengde is an underdeveloped city and while the resources and environmental subsystems have improved the urbanization subsystem is ignored. Given its current status, Chengde should increase its urbanization efforts.
Unconstrained urbanization can cause serious resource and environmental problems, so the promotion of sustainable urbanization is an important goal. A major step towards achieving this goal is to identify what drives sustainable urbanization, and find the main factors that influence it. From the starting point of urbanization and environmental coupling, this study uses complexity science to define a complex Urbanization-Resources-Environment system (URE), in which the component subsystems interact nonlinearly. Unlike purely economic or sociological approaches, our approach assesses sustainable urbanization using systems theory coupled with complexity science. We think that sustainable urbanization requires the coordinated development of urbanization, resources and environment, and that the three subsystems form a unified system through complex behavioral associations. We developed comprehensive indexes, which can be used to evaluate the urbanization, resources and environmental subsystems in order to assess the behavior of this complex system. We also developed a coordinated development index for URE (URECDI) which indicates the sustainability of urbanization. Using 13 cities of the Jing-Jin-Ji region in China as examples, we illustrated how the comprehensive indexes and CDI can show the degree of coordination and coherence of URE. We learned the main factors that influence URE by using the entropy method to obtain the index weights and we are, thus able to promote sustainable urbanization. We found that urbanization efficiency, resource utilization efficiency and environmental quality had the greatest influence on the indexes, which indicates that they are the principal factors that influence URE, and so significantly influence the
3.2.3. Xingtai Fig. 8 shows that, although it improves, URECDI for Xingtai was low during 2005–2015. However, the coordination degrees between all subsystems are high, although they fluctuate significantly. The main reason for low URECDI is that the composite indexes of all three subsystems are low. Therefore, to increase CDI for Xingtai, we need to comprehensively improve the levels of the urbanization, resources and environmental subsystems. Understanding URECDI is essential for sustainable urbanization in JJJ because the region will lead China’s future urbanization. It is necessary to monitor URECDI for this region to ensure the sustainability of the urbanization, resources, and environmental subsystems. Analysis of three representative cities showed that the composite subsystem has a significant effect on URECDI, especially for low-coordinated cities. It is necessary to ensure the suitable development of all subsystems to achieve sustainable urbanization. This means there is a need to balance subsystem coherence with subsystem development, rather than 389
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process of urbanization. The preceding conclusions show that improving the efficiency and quality of the subsystems is effective in promoting sustainable urbanization. At a composite level, the subsystems showed an increasing trend during 2005–2015, but regional differences exist. The urbanization subsystems for Beijing and Tianjin and the resource subsystems for Zhangjiakou and Chengde had significantly higher indexes than for other cities. Benefits from integrated environmental protection that occurred 2014 reduced the gap between environment subsystem indexes for Beijing and Tianjin and those for other cities. Thus implementing a zoning strategy must also be considered as a way to improve sustainable urbanization. Beijing and Tianjin need to further improve the resources and environmental subsystems, Zhangjiakou and Chengde need to upgrade the urbanization subsystem, and the other cities need to make efforts to improve the three subsystems. Analysis of CDI showed that subsystem coordination within URE for JJJ varies, and fell into three types: little coordination, basic coordination and good coordination. URECDI for JJJ showed an increasing trend during the period 2005–2015. We classified 13 cities as high-coordinated, developed, and low-coordinated based on their coordination type and selected Beijing, Chengde, and Xingtai as representative cities of each type to analyze in detail. Through this analysis, we found that the best way to increase CDI is to increase each of the composite indexes of the urbanization, resources and environmental subsystems, and to adjust policy and investment to favor low-coordinated cities. This is different from standard urbanization and environmental coupling theory, which emphasizes the coordination of different elements of urbanization rather than their individual effects. Our work on the URECDI indicates that URE will achieve excellent coordination only if the three subsystems are fully developed. The differences between subsystems that are outlined in the paper impact sustainable urbanization strategies. It is not necessary to constrain the development of URE subsystems (especially urbanization) simply to ensure coordination between the different subsystems. Rather, and more importantly, we should comprehensively improve URE subsystems which will result in improved coordination between them. We adopted the ideas of complex system theory to create a model that uses comprehensive indexes to provide a coordinated development index. We used that index as a measure of internal subsystem interaction in URE and as an indicator of the degree of sustainable urbanization in JJJ. Sustainable urbanization is significantly affected by the interactions of urbanization, resources and environment, which occur globally. Since the assessment method is based on a combination of systems theory and complexity science, rather than being derived from regional experiences, our approach will be effective in other regions, in China and beyond. Sustainable urbanization within JJJ, and within other areas of China, will benefit if coordination within URE is improved by individually improving urbanization practices, resource usage, and the environment.
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Ecological Indicators journal homepage: www.elsevier.com/locate/ecolind
Original Articles
Assessing sustainability of urbanization by a coordinated development index for an Urbanization-Resources-Environment complex system: A case study of Jing-Jin-Ji region, China
T
⁎
Xuegang Cuia,b, Chuanglin Fanga, , Haimeng Liua, Xiaofei Liua a b
Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China
A R T I C LE I N FO
A B S T R A C T
Keywords: Urbanization-Resources-Environment complex system Coordinated development index Sustainable urbanization Jing-Jin-Ji region
China’s rapid urbanization has produced a number of resources and environmental problems, making it necessary to provide a scientific basis for the promotion of sustainable urbanization. This study integrates systems theory with complexity science to create an Urbanization-Resources-Environment complex system (URE) to assess the sustainability of urbanization, beginning by conjoining a theory of urbanization and ecological environment coupling. We developed a comprehensive coordinated development index for URE (URECDI) to represent the internal connectivity and influence between the urbanization, resources and environmental subsystems, and also indicate the sustainability of urbanization. This study analyzed trends observed in URE for 13 cities in the Jing-Jin-Ji region (JJJ) of China, using statistical data collected from 2005 to 2015. The main results are: (1) urbanization efficiency, resource utilization efficiency and environmental quality are the largest influences on the indices, which indicates that they are key factors in the behavior of URE; (2) coordination between subsystems of URE within JJJ was not good, but showed an increasing trend during 2005–2015; and (3) URECDI indicated significant differences between 13 cities, which suggests that we can increase coordination within URE by implementing a zoning strategy, and adjusting policies and investment to favor low-coordinated cities. The coordinated development index can reveal the overall characteristics of URE and ensure regionally sustainable urbanization.
1. Introduction In recent times, urbanization has developed globally at an unprecedented rate. In the last 50 years, the global urban population has grown by nearly 20%. By 2008 over 50% of the global population lived in urban areas; in 2016, the extent of global urbanization reached 54.3% (World Bank Group, 2017). Urbanization is one of the most significant human activities to affect Earth. It is a process that concentrates populations in towns, cities, and metropolitan areas and alters land use with the urban landscape (Angel, 2012). Urbanization includes a complex geographical relationship between humans and the land surface as well as associated economic and social activities (Pitman, 2005; Friedmann, 2006; Fragkias et al., 2017). Urbanization drives global economic growth, affects global and regional resources, and changes the natural environment on many scales. It fundamentally changes the ecology of a region (Tratalos et al., 2007; Grimm et al.,
2008; Liu et al., 2011). Urban expansion alters land use and land cover, affects ecosystem biodiversity, modifies watershed hydrology, and changes biogeochemical cycles through waste discharge (Pataki et al., 2011; Kong et al., 2012; Lin et al., 2015; Schneider et al., 2015; Kalantari et al., 2017). After reform and opening-up in China, there have been benefits from rapid economic development, and urbanization has increased significantly (Bai et al., 2014; Yin et al., 2014). From 1978 to 2015, the proportion of China’s population that lived in cities increased from 17.9% to 56.1%, with an average annual growth rate of 1.03%, which is much higher than in the rest of the world over the same period (National Bureau of Statistics, 2006–2016a). However, China’s rapid urbanization has also caused a series of resource-related and environmental problems, including loss of arable land, water and energy shortages, habitat fragmentation, increased carbon emissions, and particulate matter pollution (Wang et al., 2013; Li, 2015; Xu et al.,
⁎ Corresponding author at: Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, China. E-mail addresses: [email protected] (X. Cui), [email protected] (C. Fang), [email protected] (H. Liu), [email protected] (X. Liu).
https://doi.org/10.1016/j.ecolind.2018.09.009 Received 3 April 2018; Received in revised form 4 August 2018; Accepted 6 September 2018 1470-160X/ © 2018 Elsevier Ltd. All rights reserved.
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2015; Li et al., 2016; Liu et al., 2016; Wang and Liu, 2017). Air and water pollution are intense, and other environmental contaminants abound in China’s major cities and urban areas (Fang et al., 2010; Wang et al., 2017). For example, monitoring data indicate the severity of PM2.5 pollution in China’s urban agglomerations (Fang et al., 2016c). Many scholars are interested in the relationship between urbanization and the natural environment because of the effects of rapid urbanization in China. The natural environment and the built urban environment form a complex system with multiple feedback loops. They are coupled in a nonlinear relationship which can be represented by an inverted U-shaped or an S-shaped curve (Wang et al., 2014; Fang et al., 2016b; Zhao et al., 2016; He et al., 2017). Within systems theory and complexity science, a system is defined as complex when its constituent elements cannot explain the overall characteristics of the system due to their nonlinear links (Gallagher and Appenzeller, 1999; Bailey, 2001; Espinosa and Walker, 2011). A complex system has many characteristics, including numerous components, rich and complex interactions between them, openness, and being dynamic rather than in equilibrium (Cilliers and Spurrett, 1999). There is an urban–environment nexus that includes the use of both natural and built resources and which can be thought of as an Urbanization-Resources-Environment (URE) complex system which is an open, complex, and dynamic system, and which has a formal structure and a certain functionality (Xie et al., 2016). Within URE, urbanization (U), resource (R) and environmental (E) subsystems are individually complex systems that interact nonlinearly, and the nature and activity of their interconnections determine the development of the URE complex system. If one or more of the interconnected subsystems act abnormally, then the overall coherence and operation of URE will also be abnormal (Kelly et al., 2007). The urbanization and environmental coupling (UEC) model treats urbanization, resources, and the environment as independent systems with complex interactive forcing relationships. However, from a complex systems perspective, the three systems are inseparable and thus form a larger system, URE, the coherence and internal state of which indicates the sustainability of urbanization (Holland, 1996; Fang and Wang, 2013). URE, in contrast to UEC, emphasizes the integrity, structure, and overall evolution of the subsystem couplings. URE is an integrated dynamic system with a complex structure which is always evolving from low-level disorder to high-level order (Li et al., 2010). Sustainable development theory holds that the state of coordination between subsystems can provide a criterion for judging whether the system tends towards high-level order, which is an indicator of sustainable development (Lélé, 1991; Jordan et al., 2010; Wang and Zhou, 2016). Rapid urbanization in China has forcibly affected the environment, while environmental change has, in turn, affected sustainable urbanization, especially in major cities and urban agglomerations which determine economic development and future urbanization (Fang et al., 2016a). It is necessary to analyze and understand the interactions between the urbanization, resources, and environmental subsystems of URE to realize sustainable urbanization. Suitable management measures should be implemented without delay. This paper attempts to deepen the understanding of the overall process of connectedness between urbanization, resources and environment and to find the direction of sustainable urbanization by outlining a complex system theory of Urbanization-ResourcesEnvironment (URE). This research has two goals: to develop an index that accurately represents the overall effect of the three subsystems on the sustainability of urbanization; and to present a case study of 13 cities in Jing-Jin-Ji region to demonstrate the use and effectiveness of the index. First, starting with the established urbanization and environmental coupling (UEC) theory, we develop a coordinated development index for URE (URECDI) to analyze the degree of interaction between U, R, and E subsystems and provide an indicator of the sustainability of urbanization. Second, we use URECDI to analyze the
Fig. 1. Location and extent of JJJ.
sustainability of urbanization for 13 cities in Jing-Jin-Ji region (JJJ) during 2005–2015. The remainder of this paper is organized as follows. Section 2 describes the study area, data screening, and the methodology used to establish a value for URECDI. Section 3 discusses the models developed in Section 2, analyzes the results obtained for 13 cities in JJJ, and assesses the efficacy of URECDI. Section 4 sets out the main conclusions derived from the study. 2. Materials and methods 2.1. Study area Jing-Jin-Ji region (JJJ) includes Beijing, Tianjin, and Hebei, which includes Shijiazhuang, Tangshan, Qinhuangdao, Handan, Xingtai, Baoding, Zhangjiakou, Chengde, Cangzhou, Langfang, and Hengshui (Fig. 1), all having different development characteristics. JJJ is one of the three largest urban agglomerations in China (the others are Yangtze River Delta and Pearl River Delta). It covers 217,156 km2, 1.9% of China’s territory, and in 2015 it had a population of 111.42 million and GDP of 1,129 billion dollars. JJJ is rapidly urbanizing; the urban population of the region increased from 30.3% in 1990 to 62.7% in 2015, an average annual growth rate of 1.3%. Table 1 shows the economic indicators and urbanization rates for JJJ in 2015. The rapid development underlying Table 1 is likely to put pressure on both resources and the environment. JJJ has become an area of serious water shortage, air pollution, water pollution, and conflict between economic development and environmental sustainability because of rapid urbanization and economic development (National Development and Reform Commission, 2015). Sustainable urbanization in JJJ faces enormous challenges. 2.2. Data pre-processing The data used in this paper were mainly obtained from China Statistical Yearbook (2006–2016) (National Bureau of Statistics, 2006–2016b), China Statistical Yearbook on Environment (2006–2016) (National Bureau of Statistics and Ministry of Environmental Preservation, 2006–2016), China City Statistical Yearbook (2006–2016) (National Bureau of Statistics, 2006–2016a), China Urban 384
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Table 1 Indicators of economy and urbanization in JJJ region, 2015. City
GDPa (billion $)
GDP per capital ($)
GDP growth rate in 2014 (%)
Percentage of urban population
Beijing Tianjin Shijiazhuang Tangshan Qinhuangdao Handan Xingtai Baoding Zhangjiakou Chengde Cangzhou Langfang Hengshui
369.51 265.53 87.35 97.99 20.08 50.50 28.33 52.99 21.89 21.82 53.31 39.72 19.59
17,024 17,165 8162 12,561 6533 5354 3884 4587 4951 6180 7163 8704 4416
6.9 9 7.5 5 6.9 6.8 6 6 5.8 6.8 7 7.5 7.6
86.5 82.6 58.3 58.3 54.1 51.4 47.7 46.7 52.2 46.8 48.6 55 46.6
Source: Beijing Municipal Bureau of Statistics, 2006–2016; Tianjin Municipal Bureau of Statistics, 2006–2016; The People’s Government of Hebei Province, 2006–2016. a Denotes gross domestic product. Fig. 2. Interaction between subsystems of URE.
Construction Statistical Yearbook (2006–2016) (Ministry of Housing and Urban-Rural Development, 2006–2016), Beijing Statistical Yearbook (2006–2016) (Beijing Municipal Bureau of Statistics, 2006–2016), Tianjin Statistical Yearbook (2006–2016) (Tianjin Municipal Bureau of Statistics, 2006–2016) and Hebei Economic Yearbook (2006–2016) (The People’s Government of Hebei Province, 2006–2016). To eliminate differences in dimension, magnitude, and sign between indicators xj, we normalized the data (Li et al., 2012):
For positive data: Xij =
For negative data: Xij =
The probabilityPij of the indicator x j in year i : Pij =
Information entropy Ej for the index j: Ej = −
Weight Wj for the index j: Wj = (1)
∑ (Pij × ln Pij)
(4)
i=1
(5)
Dj m
∑ j = 1 Dj
(6)
where n is the number of years, and m is the number of indicators. Finally, we calculated the composite index Si for each subsystem in year i using Eq. (7):
x jmax −x ij x jmax −x j min
(3)
n
Entropy redundancy Dj for the index j: Dj = 1−Ej
x ij−x j min x jmax −x j min
1 ln n
Xij n
∑i = 1 Xij
(2)
m
where xij represents the value of a variable, x, indexed by j, in year i; xjmax and xjmin are the respective maximum and minimum values of indicator xj over all years. The values of all indicators xj were normalized into [0, 1].
Composite index Si for each subsystems in year i; Si =
∑ Wi × Xij (7)
j=1
2.3.2. URE coordinated development index Coordination reflects the degree of coherence between all subsystems, as well as the extent to which the system tends to be ordered (Mamat et al., 2013). In order to calculate the coordination of URE, we developed the URE coordinated development index (URECDI), which is based on the coordination degree model for China National Sustainable Communities (Wu et al., 2017). URECDI can be used to assess sustainable urbanization in most regions since the interactions between urbanization, resources, and environment occur everywhere that urbanization occurs. The above index will comprehensively reflect the comprehensive level of sustainable urbanization. To obtain URECDI, we first calculate the coordination degree between pairs of subsystems as follows:
2.3. Methods 2.3.1. Index system for evaluation of URE Fig. 2 shows the stucture of URE and its internal interaction. We developed a comprehensive indexing system in order to evaluate URE and its component subsystems. The topmost composite index for URE, URECDI, is derived from three composite (second level) indexes, one for each of the three major component subsystems of URE, U, R and E. The composite index for U is derived from two weighted indexes for second level indicators (urbanization level and urbanization efficiency) which are in turn derived from ten primary indicators. The composite index for R is derived from two weighted indexes for second level indicators (resources per capita and resources utilization efficiency) which are in turn derived from six primary indicators. The composite index for E is derived from two weighted indexes for second level indicators (environmental quality and environmental governance) which are in turn derived from six primary indicators. Table 2 shows the composition of the indexes in detail. We used the entropy method to determine the indicator weightings in order to avoid any effects due to subjectively determining weights (Chen et al., 2013b). Information entropy is a mathematical concept; it reflects the disorder of the system and varies by index. We determined the weight of each primary indicator as follows:
Coordination degree between U and R in year i: CURi = 1−
|SUi−SRi| max(SUi, SRi ) (8)
Coordination degree between U and E in year i: CUEi = 1−
|SUi−SEi| max(SUi, SEi ) (9)
Coordination degree between R and E in year i: CREi
|SRi−SEi| = 1− max(SRi, SEi ) (10)
where SUi, SRi and SEi respectively represent the composite indexes of 385
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Table 2 Indicators used to evaluate the composite contributions of urbanization, resources and environmental subsystems in URE. The composite indexing of URE Subsystem
Second level indicator
Indicator weight
Urbanization subsystem (U)
Urbanization level
0.29
Urbanization efficiency
0.71
Resources per capita
0.59
Resources utilization efficiency
0.41
Environmental quality
0.55
Environmental governance
0.45
Resources subsystem (R)
Environmental subsystem (E)
a
a
Primary indicator
Indicator weighta
Percentage of urban population Percentage of urban construction land Percentage of the secondary and tertiary industry GDP per capita (Yuan) GDP per unit land area (104 Yuan/km2) Number of college students per 10,000 people Number of doctors per 10,000 people Parks and green areas per capita (m2) Road areas per capita (m2) Income ratio of urban to rural residents
0.104 0.082 0.107 0.099 0.091 0.100 0.078 0.111 0.112 0.116
Water resources per capita (m3) Arable land areas per capita (ha) Grassland areas per capita(ha) Woodland areas per capita (ha) Water consumption per unit of GDP (m3/104 Yuan) Energy consumption per unit of GDP (ton of SCE/104 Yuan)
0.176 0.187 0.124 0.107 0.203 0.204
Discharged volume of SO2 per unit of GDP (t/104 Yuan) Discharged of waste water per unit of GDP (t/104 Yuan) Percentage of vegetation with green areas Percentage of environmental pollution control investment Sewage treatment plants per 10,000 people Garbage disposal plants per 10,000 people
0.185 0.183 0.181 0.164 0.146 0.142
Using the entropy method (EM).
impact on the urbanization subsystem, U. Altogether, these three indicators explain 33.9% of the total change in the subsystem. These findings suggest that, over the past ten years, population and land use change were not good indicators of the level of urbanization in JJJ. Thus the Chinese government should not pay too much attention to the degree of urbanization (Chen et al., 2013a). Urbanization has been largely uncontrolled, but we should pay more attention to the efficiency and quality of urbanization, especially focusing on income inequality, public infrastructure facilities, and creating a livable environment.
the individual subsystems U, R and E in year i. We calculate the coordination degree of the combined system URE by:
Coordination degree of URE in year i: Ci = average (CURi, CUEi, CREi ) (11) The coordinated development index of URE, as well as reflecting the coordination degrees between different subsystems, also takes into account the composite indexes of each subsystem:
Coordinated development index of URE in year i : CDIi =
Ci × average (SUi, SRi, SEi )
(12)
3.1.2. Resources subsystem Table 2 shows that energy consumption per unit of GDP (0.204) and water consumption per unit of GDP (0.203) are the two primary level indicators that had the most influence on the resources subsystem, R. Altogether, these two indicators explain 40.7% of the total change in the subsystem. These findings suggest that, in comparison with resources per capita, the efficient utilization of resources better indicates the overall level of the resources subsystem in JJJ. Resources are scarce in JJJ and the availability of water resources is low (Li et al., 2017). The region needs to use water, energy, and other resources more efficiently, for example by using water and energy saving technology.
CDIi takes a value in the range [0, 1]. The higher the value of CDIi, the more coherence there will be between subsystems of URE. We can classify URECDI as shown in Table 3 (Chen and Wang, 2010). 3. Results and discussion 3.1. Comprehensive level of urbanization, resources and environmental subsystems The effects of individual indexes on the composite index for each subsystem are analyzed to identify implications for future policy in JJJ.
3.1.3. Environmental subsystem Table 2 shows that discharged volume of SO2 per unit of GDP (0.185) and discharged wastewater per unit of GDP (0.183) are the two primary level indicators that had the most influence on the environmental subsystem, E. Altogether, these two indicators explain 36.8% of the total change in the subsystem. These findings suggest that pollution control is more effective than environmental regulation in improving the overall quality of the environment in JJJ, which shows that the Treatment after Pollution approach may not be effective in China (Sun et al., 2010), especially in JJJ. Thus the government should pay more attention to upgrading industrial and environmental technology to ensure a better environment. Sections 3.1.1–3.1.3, the above analyses show that efficient urbanization, effective resource utilization, and improved environmental quality contribute more to the urbanization, resources and environmental subsystems than the other factors that were identified. The
3.1.1. Urbanization subsystem Table 2 shows that income ratio of urban to rural residents (0.116), road areas per capita (0.112), and parks and green areas per capita (0.111) are the three primary level indicators that had the greatest Table 3 Five types of coordinated development index for URE. Coordinated development index (CDI) range
Coordination types
0.00–0.20 0.21–0.40 0.41–0.60 0.61–0.80 0.81–1.00
No coordination (NC) Little coordination (LC) Basic coordination (BC) Good coordination (GC) Excellent coordination (EC)
Source: Wu et al. (2017). 386
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Fig. 3. Trends in the urbanization subsystem.
3.1.6. Environmental subsystem There was an increasing but fluctuating trend in the environmental subsystem during 2005–2015, as shown in Fig. 5. Changes are mainly due to improvements in environmental quality, as indicated by volume of SO2 discharged per unit of GDP and volume of wastewater discharged per unit of GDP. Changes are also due to improved waste management, as indicated by the number of sewage treatment plants per 10,000 people and the number of garbage disposal plants per 10,000 people. However, investment in environmental pollution control is low as a proportion of total investment, which limits the effects of environmental control. The gap between Beijing and Tianjin and other cities began to shrink after 2014 as a result of the integration of environmental protection measures in JJJ (National Development and Reform Commission, 2015).
effectiveness of subsystems will be significantly improved by controlling the main influencing factors. Sections 3.1.4 through 3.1.6 discuss the results of using the URECDI calculations to identify the composite trends in each subsystem treated as a whole.
3.1.4. Urbanization subsystem There was an increasing trend in the urbanization subsystem during 2005–2015, as shown in Fig. 3. Urbanization is increasing in JJJ due to rapid growth in population and economy, as indicated by GDP per capita and GDP per unit land area. However, income (in)equality, as indicated by the income ratio of urban to rural residents, and public infrastructure facilities, as indicated by road area per capita, have not been given enough attention. Urbanization in Beijing and Tianjin is far greater than in the other cities in Hebei, shown by the significant gap between them.
3.2. Coordinated development index of URE The coordinated development index, CDI, represents the behavior of the composite complex system URE. It indicates the sustainability of urbanization within the region. Table 3 categorized the degree of coherence between the subsystems of URE according to the values of CDI and described them as coordination types. Table 4 shows the annual classifications of cities by coordination type within in JJJ during 2005–2015. The coordination types of URE in JJJ have two characteristics. First, URECDI is not high and all cities fall into one of the three categories LC, BC and GC. Most cities are BC, followed by GC; a few cities were LC
3.1.5. Resources subsystem There was an increasing trend in the resources subsystem during 2005–2015, as shown in Fig. 4. The increase is mainly due to a significant decline in water and energy consumption per unit of GDP. Resource usage per capita (indicated by water resources per capita and arable land area per capita) decreased significantly, indicating great pressure on resource usage. Zhangjiakou and Chengde, with abundant resources per capita, show far greater resource usage than other cities.
Fig. 4. Trends in the resources subsystem. 387
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Fig. 5. Trends in the environmental subsystem.
3.2.1. Beijing Fig. 6 shows that for Beijing both URECDI and coordination degrees between all subsystems are stable and at a high level for the period 2005–2015. Beijing is the capital of China and has received enough investment to improve the quality of urbanization, the efficient use of resources, and environmental quality. During the period many polluters have been closed and relocated. However, some indicators constrain CUR and CRE, such as low resource usage per capita (e.g., water resources per capita or arable land areas per capita). The capacity to provide resources in Beijing is at risk of being overloaded due to excessive population growth. This problem could be alleviated by relocating some of the population or improving the efficiency of resource utilization.
early in the period. Due to excessive urbanization beyond the supply capacity of resources and the carrying capacity of the environment, there is some incoherence in URE that constrains sustainable urbanization. Second, URECDI showed an increasing trend in most cities during 2005–2015. JJJ is one of China’s most important urban agglomerations and the Chinese government has invested heavily in the region, particularly as it hosted the 2008 Olympic Games. As a result, urban construction, efficient resource utilization, and effective pollution control have all increased, which improved the coordination types of URE. The cities in JJJ can also be described as high-coordinated (e.g., Beijing, Tianjin, and Qinhuangdao; developed (e.g., Chengde and Baoding); and low-coordinated (e.g., Xingtai and Zhangjiakou). To further understand the coordinated development process represented by URE, we examine Beijing, Chengde, and Xingtai as representative cities of each of the three groups.
3.2.2. Chengde Fig. 7 shows that both URECDI and the coordinating degrees CUR
Table 4 The coordination types of URE in JJJ, 2005–2015. Year
2005
2006
2007
2008
2009
2010
Beijing Tianjin
2012
2013
2014
2015
GC BC
GC
Shijiazhuang
BC
Tangshan
BC
GC
BC
Qinhuangdao Handan
BC
GC
GC BC
Xingtai
GC
LC
BC
BC
Baoding
BC
Zhangjiakou Chengde
2011
GC
LC
BC
LC
BC
Cangzhou Langfang
GC BC
Hengshui
No coordination (NC)
GC
BC
GC BC
Little coordination (LC)
Low level
Basic coordination (BC)
Good coordination (GC)
High level
The coordination types of URE
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Excellent coordination (EC)
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Fig. 6. URECDI and coordination degrees in Beijing.
Fig. 8. URECDI and coordination degrees in Xingtai.
neglecting development in favor of coordination. This differs from the orthodoxy of urbanization and environmental coupling, which emphasizes the promotion of sustainable urbanization by ensuring and maintaining coordination between all systems (Wang et al., 2014). It can be seen that high quality coordination can be obtained only on the basis of the full development of each subsystem, rather than by simply pursuing coordination as an end in itself, which is inconsistent with urbanization and environmental coupling theory. Sustainable urbanization is not intended to excessively restrict urbanization, but to sustainably maintain coordination between urbanization, resources and environment. The large gap in URECDI that separates Beijing and Tianjin from other cities indicates that we should adjust policy and investment to be more favorable to low-coordinated cities, and so better balance development through a zoning strategy. An increase in URECDI for JJJ will indicate that this has happened. Overall, URECDI is an indicator that allows us to assess the sustainability of urbanization, and to identify any necessary corrective countermeasures. Fig. 7. URECDI and coordination degrees in Chengde.
4. Conclusions
and CRE for Chengde showed increasing trends during 2005–2015, due mainly to the benefits from the resources subsystem R. Chengde receives some national and local investment, which is used to improve resource usage and reduce environmental impacts. CUE showed a decreasing trend, which was caused by the low composite index for the urbanization subsystem U. Chengde is an underdeveloped city and while the resources and environmental subsystems have improved the urbanization subsystem is ignored. Given its current status, Chengde should increase its urbanization efforts.
Unconstrained urbanization can cause serious resource and environmental problems, so the promotion of sustainable urbanization is an important goal. A major step towards achieving this goal is to identify what drives sustainable urbanization, and find the main factors that influence it. From the starting point of urbanization and environmental coupling, this study uses complexity science to define a complex Urbanization-Resources-Environment system (URE), in which the component subsystems interact nonlinearly. Unlike purely economic or sociological approaches, our approach assesses sustainable urbanization using systems theory coupled with complexity science. We think that sustainable urbanization requires the coordinated development of urbanization, resources and environment, and that the three subsystems form a unified system through complex behavioral associations. We developed comprehensive indexes, which can be used to evaluate the urbanization, resources and environmental subsystems in order to assess the behavior of this complex system. We also developed a coordinated development index for URE (URECDI) which indicates the sustainability of urbanization. Using 13 cities of the Jing-Jin-Ji region in China as examples, we illustrated how the comprehensive indexes and CDI can show the degree of coordination and coherence of URE. We learned the main factors that influence URE by using the entropy method to obtain the index weights and we are, thus able to promote sustainable urbanization. We found that urbanization efficiency, resource utilization efficiency and environmental quality had the greatest influence on the indexes, which indicates that they are the principal factors that influence URE, and so significantly influence the
3.2.3. Xingtai Fig. 8 shows that, although it improves, URECDI for Xingtai was low during 2005–2015. However, the coordination degrees between all subsystems are high, although they fluctuate significantly. The main reason for low URECDI is that the composite indexes of all three subsystems are low. Therefore, to increase CDI for Xingtai, we need to comprehensively improve the levels of the urbanization, resources and environmental subsystems. Understanding URECDI is essential for sustainable urbanization in JJJ because the region will lead China’s future urbanization. It is necessary to monitor URECDI for this region to ensure the sustainability of the urbanization, resources, and environmental subsystems. Analysis of three representative cities showed that the composite subsystem has a significant effect on URECDI, especially for low-coordinated cities. It is necessary to ensure the suitable development of all subsystems to achieve sustainable urbanization. This means there is a need to balance subsystem coherence with subsystem development, rather than 389
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process of urbanization. The preceding conclusions show that improving the efficiency and quality of the subsystems is effective in promoting sustainable urbanization. At a composite level, the subsystems showed an increasing trend during 2005–2015, but regional differences exist. The urbanization subsystems for Beijing and Tianjin and the resource subsystems for Zhangjiakou and Chengde had significantly higher indexes than for other cities. Benefits from integrated environmental protection that occurred 2014 reduced the gap between environment subsystem indexes for Beijing and Tianjin and those for other cities. Thus implementing a zoning strategy must also be considered as a way to improve sustainable urbanization. Beijing and Tianjin need to further improve the resources and environmental subsystems, Zhangjiakou and Chengde need to upgrade the urbanization subsystem, and the other cities need to make efforts to improve the three subsystems. Analysis of CDI showed that subsystem coordination within URE for JJJ varies, and fell into three types: little coordination, basic coordination and good coordination. URECDI for JJJ showed an increasing trend during the period 2005–2015. We classified 13 cities as high-coordinated, developed, and low-coordinated based on their coordination type and selected Beijing, Chengde, and Xingtai as representative cities of each type to analyze in detail. Through this analysis, we found that the best way to increase CDI is to increase each of the composite indexes of the urbanization, resources and environmental subsystems, and to adjust policy and investment to favor low-coordinated cities. This is different from standard urbanization and environmental coupling theory, which emphasizes the coordination of different elements of urbanization rather than their individual effects. Our work on the URECDI indicates that URE will achieve excellent coordination only if the three subsystems are fully developed. The differences between subsystems that are outlined in the paper impact sustainable urbanization strategies. It is not necessary to constrain the development of URE subsystems (especially urbanization) simply to ensure coordination between the different subsystems. Rather, and more importantly, we should comprehensively improve URE subsystems which will result in improved coordination between them. We adopted the ideas of complex system theory to create a model that uses comprehensive indexes to provide a coordinated development index. We used that index as a measure of internal subsystem interaction in URE and as an indicator of the degree of sustainable urbanization in JJJ. Sustainable urbanization is significantly affected by the interactions of urbanization, resources and environment, which occur globally. Since the assessment method is based on a combination of systems theory and complexity science, rather than being derived from regional experiences, our approach will be effective in other regions, in China and beyond. Sustainable urbanization within JJJ, and within other areas of China, will benefit if coordination within URE is improved by individually improving urbanization practices, resource usage, and the environment.
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