Emergy-based Urban Ecosystem Health Assessment for
Typical Cities along the Belt and Road
S H Chen
1
, C Ma
2
, M R Su
2
，
*
, Y Z Tan
1
, Y F Liu
1
and F X Meng
2
1
School of Environment and Civil Engineering, Dongguan University of Technology,
Dongguan 523808. China.
2
Research Center for Eco-Environmental Engineering, Dongguan University of
Technology, Dongguan 523808. China.
Abstract. In order to promote construction of a green Belt and Road, it is necessary to
evaluate the status of Chinese cities along the Belt and Road, amongst which urban ecosystem
health is a useful indicator. Based on re-understanding of urban ecosystem health, we first
proposed a new assessment framework composed of structure, function, process, and system.
Subsequently, we applied the systems-oriented tool-emergy analysis-to simulate the urban
ecosystem and establish the concrete assessment indicators of urban ecosystem health
associated with the framework. Finally, we calculated the comprehensive urban ecosystem
health index and compared the health status of 14 typical cities using the set pair analysis.
The results indicated relatively high levels of urban ecosystem health in the cities of Kunming
and Xi’an in 2015. Levels of urban ecosystem health in Shenzhen, Shanghai, Zhengzhou, and
Beijing were relatively low, while these levels were moderate in other cities. We also
proposed suggestions of improving urban health states according to the results of limiting
factor analysis for different cities.
1. Introduction
The Silk Road Economic Belt and the 21st Century Maritime Silk Road (hereinafter referred to in
combination as the “Belt and Road” Initiative) were proposed by the Chinese government as
strategies for effectively aligning changes in its domestic and international situations. In the new era
of globalization, this long-term strategy will have significant and far-reaching impacts for both China
and other countries. A basic principle of the “Belt and Road” Initiative is green development, which
requires enabling eco-environmental protection to serve, support and guarantee the Belt and Road
construction towards environment-friendly routes [1]. As the key node and executive unit of green
development, the healthy development of cities is essential for the construction of the Belt and Road
[2]. It is necessary to first evaluate the health states of cities along the Belt and Road, especially when
considering the fact that there is still a lack of ecological assessment for cities although a number of
studies related to the “Belt and Road” have been conducted from aspects of economics, international
issues, and ethnic issues [3].
In this study, we conducted a systematic assessment of the health status of representative urban
ecosystems located along the Belt and Road routes, by combining emergy analysis, a useful method
562
Chen, S., Ma, C., Su, M., Tan, Y., Liu, Y. and Meng, F.
Emergy-based Urban Ecosystem Health Assessment for Typical Cities along the Belt and Road.
In Proceedings of the International Workshop on Environmental Management, Science and Engineering (IWEMSE 2018), pages 562-567
ISBN: 978-989-758-344-5
Copyright © 2018 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved

of systems ecology, with set pair analysis, a method of uncertainty analysis. In doing so, we
identified limiting factors and proposed regulatory suggestions that could provide a scientific basis
for the advancement of the Belt and Road initiative.
2. Urban ecosystem health assessment methods
2.1. Feature of urban ecosystem health
There is not a well-acknowledged concept of urban ecosystem health due to the complexity of urban
ecosystem. Based on our re-understanding of urban ecosystem health and its existent concepts [4],
we identified the following four interactive features of a healthy urban ecosystem: (1) rational
structure which emphasizes the diversity of components and balance amongst them, (2) optimal
function which emphasizes both the urban ecosystem’s ability of maintaining its own structure and
providing services for human beings, (3) smooth process which emphasizes the efficiency of
interaction between urban ecosystems and their external environment, and (4) sustainable system
which emphasizes the ability of supporting urban development in the future.
2.2. Emergy-based urban ecosystem health indices
In order to comprehensively measure the above-proposed four interactive features of urban
ecosystems, we applied a useful systems-oriented method, named as emergy analysis, for urban
ecosystem health assessment in this paper. With the merit of quantifying different sorts of energy and
materials in a common unit, emergy analysis connects different subsystems and factors together
through various flows among them and also provides a unified analysis platform for different urban
ecosystems [5-6]. It enables the systematic evaluation of different features of urban ecosystems and
scientific comparison of ecosystem health among different cities.
According to their specific meanings, 17 emergy-based indices were selected to reflect the health
status of urban ecosystems from the four aspects of structure, function, process, and system. The
concrete structure of these indices and their expressions are given in Table 1. More details of the
indices can be found in the related references [7-8].
Table 1. The emergy-based index system.
Number
Item
Expression
Weight
Structure
0.25
1
Non-renewable resource emergy ratio
N/U
0.2
2
Renewable resource emergy ratio
R/U
0.2
3
Purchased emergy ratio
(F+G+P
2
I
3
)/U
0.2
4
Electricity in energy consumption ratio
ELE/EC
0.1
5
Emergy diversity index




 




0.3
Function
0.25
6
Power emergy usage ratio
ELE/U
0.2
7
Emergy dollar ratio
U/GDP
0.2
8
Emergy yield ratio
(N+R+R
1
+F)/(F+R
1
)
0.2
9
Emergy self-support ratio
(R+N)/U
0.2
10
Emergy per area
U/Area
0.1
11
Emergy per person
U/POP
0.1
Process
0.25
12
Emergy exchange ratio
(F+G+P
2
I
3
)/P
1
E
0.25
13
Environment load ratio
(F+N)/(R+R
1
)
0.25
14
Emergy waste ratio
W/R
0.25
15
Emergy input and self-emergy ratio
(F+G+ P
2
I
3
)/(R+N)
0.25
System
0.25
16
Emergy sustainable indices
EYR/ELR
0.4
17
Emergy index for sustainable development
EYR*EER/(ELR+EWI)
0.6
Emergy-based Urban Ecosystem Health Assessment for Typical Cities along the Belt and Road
563

2.3. Mathematical model
Considering the intrinsic uncertainty of urban ecosystem health, we applied a useful uncertainty
method, set pair analysis, to process the emergy-based index data and relatively evaluate the health
status of different cities. It enables maintenance and integration of various information embodied in
the assessed cities and multi-layer analysis of urban ecosystem health characteristics, contributed by
its respect of uncertainty information.
The detailed calculation based on set pair analysis can be found in the literature [9-10]. Briefly
speaking, in the space of comparison [U, V] of the assessed city s
k
(the set composed of the
emergy-based indices data), we combined the weight of each index in Table 1 (obtained based on
analytic hierarchy process [11] and the Delphi method) to calculate the average identity degree
(marked as a
k
) and the average contrary degree (marked as c
k
). Finally, we calculated the relative
proximity degree of s
k
and U (marked as r
k
), which determines the ranking of the assessed city s
k
in
relation to urban ecosystem health status. A higher value of r
k
indicates a higher level of urban
ecosystem health.



n
r
krrk
awa
1
(1)



n
r
krrk
cwc
1
(2)
kk
k
k
ca
a
r


(3)
2.4. Study area
Considering the representativeness of typical cities and the availability and limitations of urban data,
we finally selected 14 typical cities located along the Belt and Road routes, including Guangzhou,
Shenzhen, Shanghai, Qingdao, Fuzhou, Urumqi, Changchun, Kunming, Beijing, Zhengzhou, Wuhan,
Chongqing, Hefei, and Xi’an.
3. Results and discussion
3.1. Urban ecosystem health states in 2015
As Figure 1 shows, Kunming and Xi’an evidenced relatively high levels of ecosystem health in 2015,
whereas the urban ecosystem health of Shenzhen, Shanghai, Zhengzhou, and Beijing were relatively
low. The health of other investigated cities remained at a medium level. To conduct a more detailed
and comprehensive diagnosis of the health status of each city’s ecosystem and to identify limiting
factors, set pair analysis was performed on the four ecosystem health subindices relating to structure,
function, process, and system. Levels of the structural sub-index of ecosystem health for Kunming,
Hefei, Shenzhen, and Fuzhou were higher than those of other cities, whereas these levels were
relatively low in Urumqi and Zhengzhou. Kunming, Urumqi, Hefei, and Xi’an evidenced a relatively
high health status relating to the functional sub-index, whereas Zhengzhou, Shanghai, and Beijing
evidenced a relatively poor health status. Levels of the process sub-index of urban ecosystem health
were relatively high for Chongqing, Hefei, Changchun, and Fuzhou, whereas these levels were
relatively low for Shenzhen, Shanghai, and Zhengzhou. Finally, a trend of polarization was found for
the system sub-index of urban ecosystem health. Whereas levels of this sub-index were relatively
high for Kunming, Changchun, Wuhan, Chongqing, and Xi’an, they were relatively low for
Shenzhen, Shanghai, Zhengzhou, and Beijing.
IWEMSE 2018 - International Workshop on Environmental Management, Science and Engineering
564

Figure 1. Urban ecosystem health index and health subindices relating to structure, function,
process, and system in 2015.
3.2. Concrete analysis of urban ecosystem health for Shenzhen
3.2.1. Multi-dimensional analysis of Shenzhen Ecosystem Health Subindices. To analyze the status of
Shenzhen’s ecosystem health in more detail and to identify key constraining factors, we performed a
multidimensional analysis of this city’s ecosystem health subindices (see Figure 2). Figure 1 shows
that Shenzhen's ecosystem health subindices relating to structure and function were at medium levels,
while those for process and system were at low levels. Therefore, attempts to, improve Shenzhen’s
ecosystem health should focus on the dimensions of process and system.
Figure 2. Multidimensional analysis of Shenzhen’s ecosystem health subindices.
Emergy-based Urban Ecosystem Health Assessment for Typical Cities along the Belt and Road
565

For the process dimension, the health status of Shenzhen’s urban ecosystem is relatively low,
indicating that Shenzhen's ecosystem is not able to communicate smoothly with its external and
internal subsystems. Moreover, the efficiency of this process is relatively low. Of the investigated
cities, the environmental load ratio, emergy input and self-emergy ratio of Shenzhen were much
higher than those of other cities, whereas its emergy exchange ratio was lower. The environment load
ratio reflects the pressure exerted by a developing system on the natural environment. Our findings
indicated that Shenzhen’s natural environment is under great pressure. Consequently, there is a need
to change the previous approach that prioritized economic benefits achieved through a reduction of
environmental benefits and to strengthen environmental protection and resource conservation. The
economic development of the urban system must demonstrate high levels of efficiency and
competitiveness. It must also entail free renewable resources and a rational mix of purchased
resources that are of high quality in terms of energy. A higher emergy input and self-emergy ratio
will reduce the competitiveness of the urban ecosystem. The emergy exchange ratio reflects the
benefits and losses of the system relating to foreign exchanges. In developed countries or regions of
the world, this ratio is generally greater than 1. However, Shenzhen’s emergy exchange ratio is 0.16,
which means that emergy wealth lost in foreign trade is higher than the emergy wealth that is
received. This indicates that the emergy wealth of the urban ecosystem is always flow ing out. For the
system dimension, the two index values for emergy sustainable indices and emergy index for
sustainable development were very low, indicating that Shenzhen’s overall system demonstrates a
low level of sustainable development of the ecological-economic system that has remained under the
shadow of economic prosperity as the key goal.
3.2.2. Suggestions aimed at enhancing Shenzhen’s urban ecosystem health. In light of the above
analysis focusing on Shenzhen’s urban ecosystem health, we offer the following suggestions for
improving the health of urban ecosystems in Shenzhen:
 The concept of green development should be established, which entails strengthening
environmental protection, pollution control, ecological construction, and supervision of
environmental protection. In addition, there is a need to improve the environmental
infrastructure, and relieve pressure on the city's natural environment.
 Trade import and export projects need to be adjusted. Exports of raw resource products
should be reduced, with export as much as possible to final products, input high-value
technology, culture, and education.
 Independent innovations should be prioritized, and sustained efforts should focus on
developing new energy sources along with energy-saving and environmental protection
approaches. Further, efforts should be made to develop other strategic emerging industries
and modern service industries and to improve the social and economic benefits exchanged
under unit environmental pressure. Such initiatives would contribute to optimizing the
system’s performance in relation to sustainable development.
4. Conclusions
In order to promote the construction of Belt and Road, it is necessary to understand the strength and
weakness of the Chinese cities along the Belt and Road, based on which reasonable planning can be
determined to guide the long-term construction. Aiming at the status quo that there is a lack of
comprehensive evaluation for cities along the Belt and Road, urban ecosystem health was selected as
the unified media to diagnose the situation of different cities in this paper. According to our
re-understanding of urban ecosystem health, we first proposed an original assessment framework of
Structure-Function-Process-System, and then introduced emergy analysis to establish concrete
indicators of urban ecosystem health assessment.
IWEMSE 2018 - International Workshop on Environmental Management, Science and Engineering
566

The results indicate that the health status of typical Chinese cities situated along the Belt and
Road routes is at a medium level in general. Of these cities, those evidencing high economic levels,
such as Shenzhen, performed poorly for the system dimension, indicating that the development of the
ecological-economic system of these cities, under the shadow of economic prosperity as the key goal,
demonstrated a low level of sustainability. More analysis was implemented for Shenzhen, and certain
suggestions was given to improve the health state.
Acknowledgments
This research was financially supported by the National Key R & D Program of China (No.
2016YFC0502800), the Consulting Project of Chinese Academy of Engineering (No. 2017-XY-23),
the National Natural Science Foundation of China (No.71673027), the Natural Science Foundation
for Distinguished Young Scholars of Guangdong Province (No.2017A030306032), GDUPS (2017),
and the Scientific Research Foundation for High-level Talents and Innovation Team in Dongguan
University of Technology (No. KCYKYQD2016001). We thank Radhika Johari from Liwen Bianji,
Edanz Editing China (www.liwenbianji.cn/ac), for editing the English text of a draft of this
manuscript.
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