An Evaluation and Optimization of Green Development Strategy for the Nanjing-Hangzhou Eco-Economic Zone in China

Abstract

The Analytic Hierarchy Process and Entropy Weight Method were used to measure the green development level of nine major urban areas in the Yangtze River Delta and the Nanjing-Hangzhou Eco-economic Zone. The results demonstrated that firstly, the green development level of the Shanghai-Nanjing-Hangzhou metropolitan area shows increasingly sequential characteristics, with each city generally experiencing a “ladder” over time and displaying a hierarchy in its spatial distribution. Second, according to the green development subsystem evaluation, the Nanjing-Hangzhou Eco-economic zone is better than Shanghai-Nanjing and Shanghai-Hangzhou in terms of environmental loading and green governance, but it is weaker than both regarding economic performance, social welfare, and driving innovation. Therefore, this paper focuses on the general idea of green development and proposes optimization strategies and implementation recommendations for strengthening the green development of the Nanjing-Hangzhou Eco-economic Zone with respect to the currently weak areas of innovation, economic performance, and social welfare.

1. Introduction

Regional coordinated development is a balanced concept of development that encouraged the coordination of factors among regions, and achieves regional cooperation, sharing, and win-win results. This new development concept includes promoting the integrated development of national major regional strategies with urban agglomerations, establishing a new model whereby central cities lead the development of urban agglomerations. Urban agglomerations drive regional development and promote integrated and interactive development among different regions and sectors [1,2]. Early in 2010, the Chinese State Council approved the implementation of the Yangtze River Delta Regional Planning, proposed to vigorously build the Nanjing-Hangzhou Economic Belt. In 2018, the integrated development of the Yangtze River Delta became part of a national strategy. The continuously increasing national strategic orientation provided a steady stream of external power to construct the Nanjing-Hangzhou Economic Belt.

Nowadays, China is committed to green development which is an ecological concept of sustainable development that focuses on people’s livelihoods and ever-growing needs for a better life. It is widely recognized that green development is an effective way to address the relationship between economic development and environmental protection, to promote the harmonious co-existence of the economy and natural systems, and to transform the natural system from being in an ecological deficit to being in a surplus [3]. The green development of urban agglomerations is based on the actual carrying capacity of the natural resources and ecological environment. By optimizing the economic structure and transforming the mechanisms driving development, ecological civilization and economic development are equally emphasized, supplemented by powerful policy guarantees. This ensures a balance among regional resources, the environment, the population, and economic development, which builds a sustainable model that features common, coordinated, and equitable development [4,5]. The Nanjing-Hangzhou Economic Belt is in the economically developed Yangtze River Delta region. This zone is taking the lead in implementing important actions that reflect the practice of green development concepts and provides an advanced model for developing regional ecological and economic development [6]. To further develop this ecological civilization, theNanjing-Hangzhou Economic Belt should summarize the past experience and continuously improve the green development model, so as to accelerate the formation of the “Nanjing-Hangzhou Eco-economic Zone” and improve the functional quality of Nanjing-Hangzhou urban agglomerations.

Although many studies have focused on regional green development [7,8,9,10], most of them have qualitatively discussed the regional green development strategy and have not paid attention to the green development status of the Nanjing Hangzhou Eco-economic Zone, nor have they made a quantitative evaluation of the green development status of the Nanjing-Hangzhou Eco-economic Zone. To this end, this study optimizes the evaluation indicators of regional green development and uses these indicators to quantitatively evaluate the green development status of the cities in the Nanjing Hangzhou Eco-economic Zone. On this basis, this study systematically analyzes the mode, experience, and existing problems of green development in the Nanjing Hangzhou Eco-economic Zone, and puts forward strategic suggestions for further development.

2. Data and Methods

2.1. Overview of the Research Background and Data Sources

2.1.1. Overview of the Research Background

The Nanjing-Hangzhou Eco-economic Zone is located in the most economically developed area in China. It connects Shanghai in the east with the Anhui-Jiangsu Economic Zone and the middle and upper reaches of the Yangtze River Economic Zone in the west. The zone is an extension of the Yangtze River Economic Zone to the south and serves as the gateway for the Yangtze River Delta to the west. It is approximately 270 km long and extends through southwestern Jiangsu and northeastern Zhejiang, two regional central cities in Nanjing, with Hangzhou as group leader. Meanwhile, this zone connects 15 districts and counties across 6 cities including Nanjing City, Hangzhou City, Changzhou City (Liyang City, Jintan District), Zhenjiang City (Jurong City), Wuxi City (Yixing City), and Huzhou City (Figure 1).

As of 2019, the permanent resident population was about 23.68 million, accounting for about 1.71% of the country’s total population. The regional GDP was about 2641.181 billion yuan, accounting for about 3.57% of the national total. The Zone is endowed with excellent ecological resources, and many sources of rich cultural features. In total, six cities have achieved the title of being a “national famous historical and cultural city”, and the area includes the slow city culture of Gaochun, tea culture of Liyang, purple sand culture, and ceramic culture of the Changxing and Yixing area. The Anji and Guangde areas are known worldwide for their bamboo culture. Nanjing, Huzhou, and Zhenjiang are all pilot demonstration zones for national ecological progress, leading the country in at the regional level. The completion and opening of the Nanjing-Hangzhou high-speed railway further consolidated the development pattern of the Shanghai-Nanjing Hangzhou Golden Triangle. The Nanjing-Hangzhou “one-hour commuting circle” broke through the obstruction created by the north-south development of the Yangtze River Delta and strengthened the integration of the Nanjing-Hangzhou-Xuzhou area. This has created a new impetus for further developing the Nanjing-Hangzhou Eco-economic Zone and the Pan-Yangtze River Delta.

2.1.2. Data Sources

The data used in this paper include China’s administrative division data, social and economic statistical data, environmental index data, population migration data, and traffic and commuting data. The study uses data from 2018 about cities in the Yangtze River Delta. More specifically, the data of China’s administrative divisions came from the 1:1 million basic geographic databases provided by the National Geographic Information Resource Directory Service System. Social and economic statistical data were obtained from the China City Statistical Yearbook [11] and China Regional Statistical Yearbook [12] in 2018 also. Some missing data were found by querying statistical yearbooks of provinces and cities, and national economic and social development bulletins, or were processed using the interpolation method. Environment index data were drawn from China’s Environmental Statistics Yearbook [13] and were combined using the crawler to obtain real-time data about fine particles (PM2.5) and the air quality index (AQI) from the query platform. The time-sequenced evolutionary trends were determining using MySQL database cleaning, data sorting, and data summaries of the historical environmental data for major cities along the Nanjing-Hangzhou line. The same time period was used for each city section.

Population migration data were collected from the 2018 Spring Festival migration database within the Tencent location big data website. Population flow was spatially visualized for the Yangtze River Delta region using the XY-to-line tool of GIS. The Gephi social network analysis software was used to construct a hierarchical network illustrating the degree of connection between population nodes for prefecture-level cities in the Yangtze River Delta region. The “core-periphery” theory was used to clarify the spatial structure characteristics of population flow in the Yangtze River Delta region. The traffic commuting data were collected in a batch format through the map interface developed by Baidu. Based on the comprehensive traffic travel mode, we calculated the time needed to travel between the centroids of counties and cities along the Shanghai-Nanjing-Hangzhou line and visualized the OD connection using GIS.

2.2. Evaluation System Construction

As the frontier area for the integrated development of the Yangtze River Delta, the Nanjing-Hangzhou Eco-economic Zone has a developed economic base. As the “Ecological Green Edge” for the integrated development of the Yangtze River Delta, it also has rich ecological resources. This area makes the zone an ideal study area for constructing an indicator system of ecological priority and coordinated regional development; this type of system can then highlight the green and high-quality development processes in urban agglomerations in developed regions. This paper reflects an innovative and integrated approach, by systematically analyzing the relevant urban literature on the development axis of Nanjing and Hangzhou, and by establishing a green and high-quality development indicator system that conforms to the laws of urban development and that reflects the characteristics of the ecological economy of Nanjing and Hangzhou.

2.2.1. Construction of Green Development Indicator System

Using a series of green development evaluation programs issued by Jiangsu and Zhejiang provinces in recent years, this paper reviews the relevant research about green high-quality development indicators [2,7,8,14], combined with actual data for the Nanjing-Hangzhou Eco-economic Zone. The paper creates a green development evaluation indicator system for the zone, formed using a first-level index system of economic performance, social welfare, innovation, environmental load, and green management. An additional 21 secondary indicators covering industry, employment, ecology, people’s livelihoods, and science and technology (

Table 1. The Green High-quality Development System of the Nanjing-Hangzhou Eco-economic Zone.

Target Layer	Rule Layer	Specific Indicators and Codes		Unit	Index Attribute
The Green Development Indicators	Economic Performance B1	X1	Per capita GDP	ten thousand yuan	Positive
		X2	Proportion of tertiary production	%	Positive
		X3	Public financial revenue	hundred million yuan	Positive
		X4	Public financial expenditure	hundred million yuan	Positive
		X5	Labor force employment	%	Positive
		X6	Industrial output value above designated size	hundred million yuan	Positive
	Social Welfare B2	X7	Per capita disposable income of urban residents	yuan	Positive
		X8	Per capita social consumption retail sales	yuan	Positive
		X9	Books in public libraries per 100 people	piece	Positive
		X10	Number of beds per 10,000 people	piece	Positive
		X11	Green area per capita	M2	Positive
	Innovation drives B3	X12	Proportion of technology expenditure	%	Positive
		X13	Proportion of education expenditure	%	Positive
		X14	The number of college students per 10,000 people	people	Positive
	Environmentalload B4	X15	Industrial waste water discharge per unit of GDP	t	Negative
		X16	Sulfur dioxide emissions per unit of GDP	t	Negative
		X17	Industrial dust emissions per unit of GDP	t	Negative
	Green governance B5	X18	Industrial dust removal volume	t	Positive
		X19	Comprehensive utilization rate of industrial solid waste	%	Positive
		X20	Sewage treatment rate	%	Positive
		X21	Domestic waste treatment rate	%	Positive

Data source: The author combined relevant literature for collation and illustration.

).

The economic performance indicator (B1) is the basis for characterizing the development level of the Nanjing-Hangzhou Eco-economic Zone, including GDP per capita; income and expenditures for public finance; industrial output values above the area’s designated size; and other indexes reflecting the regional economic development level and the level of societal production. The employment situation is also considered, which reflects the degree of connection between the regional industrial structure and local economic development. In summary, this index reflects the quality of regional economic development. The social welfare index (B2) is an index reflecting the living quality and status of local residents, including disposable income, social consumption, and retail sales. These indicators directly reflect local public service capabilities and benefits supporting resident lives, including the per capita green area, public library collections, and the number of beds per 10,000 people. The driving innovation index (B3) is a reference for measuring the endogenous forces that sustain local efforts to promote green development. This index includes expenditures on science and technology, education, and the number of college students per 10,000 people. These indicators are important parameters for improving the productivity level of green development. The environmental load index (B4) is the index reflecting the local environmental carrying capacity and includes discharge indexes for wastewater, waste gas, dust, and other forms of waste. Green governance (B5) mainly refers to the local level of ecological conservation and environmental governance. It is measured using indicators such as garbage disposal rate, sewage treatment rate, and the degree of comprehensive waste utilization.

To test the scientific level of the index system, built based on six high quality requirements of urban space in Nanjing-Hangzhou, the big data analysis of green development indicators extended to urban and rural construction; reform and opening up; the ecological environment; people’s livelihood; and other variables. The goal was to comprehensively and systematically evaluate the green development of the Nanjing-Hangzhou Eco-economic Zone. In addition to data for Nanjing, Zhenjiang, Changzhou, Wuxi, Huzhou, and Hangzhou in the Nanjing-Hangzhou Eco-economic Zone, the research also included data for Suzhou, Shanghai, and Jiaxing in the Yangtze River Delta region. This provided an overall perspective on regional coordination and enabled a comparative study.

2.2.2. Brief Introduction of the Green Development Evaluation Method

Constructing an index system involves determining weights, and a weighted system often has the general characteristics of supporting multi-objective decision-making, having a hierarchy, and combining qualitative and quantitative methods. Scholars have conducted significant research identifying ways to determine weights and evaluation models. Weight determinations can be divided into subjective and objective categories. Subjective approaches include fuzzy evaluations, the Delphi method, the analytic hierarchy process [15], and other methods mostly based on expert decisions, field research, interviews, and other forms. Objective approaches include principal component analysis [16], mean square error [17], and information entropy weighting (IEW) [18,19]. Since these methods fully combine the objective attributes of an ecosystem and urban development, it is widely used to determine the weight of regional development indicators. The evaluation dimensions include linear weighting [20], TOPSIS [21], and other comprehensive evaluation methods. These include coupling evaluation [22], gray correlation analysis [23,24], linear regression [25], quadrant diagrams [26], and other sustainable evaluation models.

In general, past studies selecting index weights have mostly adopted a single method whereas few studies have combined multiple methods for selecting weights. Based on the characteristics of the Nanjing-Hangzhou Eco-economic Zone regional development level, and on subjective and objective empowerment complementarities, this paper applies the analytic hierarchy process and entropy weight method to build a green high-quality development index system for the Nanjing-Hangzhou Eco-economic Zone. The paper also incorporates index weights and applies a linear weighting method to comprehensively evaluate the regional development level.

The entropy weight method uses the degree of the discrete dispersion models of the fuzzy comprehensive evaluation matrix and each index. The greater the dispersion degree of the index (the greater the entropy gain), the greater the influence the index has on the comprehensive evaluation (the greater the weight). This method avoids the errors that subjective factors can create in determining weights. The entropy weight method is used to determine the weight of indicators to ensure the index parameters are not zero. As such, this paper adopts a standardized way to conduct the dimensionless processing for each index and shifts the index evaluation matrix of the index layer to the right by one unit. First, it removes the dimensions of the index, and applies the extreme value method to better reflect the role of the negative index. Next, the entropy weight method is applied to calculate the weight attributes of each item in different years and the indicators in different years are weighted to reflect the comprehensive level of green and high-quality development for each year. By taking the weight of the j-th index value of the i-th city in X_ij, the steps of the entropy weight method used to calculate the comprehensive development level are as follows:

$$\mathrm{Dimensionless} \mathrm{processing} \mathrm{of} \mathrm{indicators}: U_{ijk}=\frac{X_{ijk}-\min X_{ijk}}{\max X_{ijk}-\min X_{ijk}}$$

(1)

Calculate the weight of each index X_ij in the k-th year:

$$Y_{ijk}=\frac{U_{ijk}}{{\displaystyle {\sum }_{k=2012}^{2018}{U}_{ikj}}}(k=2012,2013,\dots ,2018)$$

(2)

Calculate the index entropy:

$$e_{ijk}=-M{\displaystyle {\sum }_{k=2012}^{2018}{Y}_{ijk}}In{Y}_{ijk}, \mathrm{and} M=\frac{1}{In9} (\mathrm{nine} \mathrm{cities} \mathrm{including} \mathrm{Shanghai}, \mathrm{Nanjing}, \mathrm{and} \mathrm{Hangzhou})$$

(3)

$$\mathrm{Calculate} \mathrm{entropy} \mathrm{redundancy} \mathrm{information}: d_{ijk}=1-e_{ijk}$$

(4)

$$\mathrm{Calculate} \mathrm{the} \mathrm{weight} \mathrm{of} \mathrm{indicators}: W_{ijk}=\frac{d_{ijk}}{{\displaystyle \sum d_{ijk}}}$$

(5)

Calculate the comprehensive level of green and high-quality development of each city

$$\mathrm{in} \mathrm{the} k-\mathrm{th} \mathrm{year}: Q_{ik}={\displaystyle {\sum }_{j=1}^n{W}_{ijk}}·U_{ijk}$$

(6)

3. Results and Evaluation

Stata15.0 econometric analysis software was used to calculate the weight of green and high-quality development indicators for each city for each year using the entropy method. Then, the weights of the different indicators from 2012 to 2018 were calculated. Formula (6) was then used to calculate the comprehensive green and high-quality development index of Shanghai-Nanjing-Hangzhou Golden Triangle urban agglomeration (

Table 2. The green and high-quality development index of Shanghai-Nanjing and Hangzhou-Golden Triangle urban agglomeration.

Year\ City	2012	2013	2014	2015	2016	2017	2018	Mean	Range
Nanjing	0.324	0.379	0.361	0.353	0.413	0.414	0.426	0.381	0.102
Zhenjiang	0.261	0.257	0.266	0.267	0.258	0.244	0.260	0.259	0.023
Changzhou	0.286	0.307	0.306	0.317	0.323	0.338	0.342	0.317	0.056
Wuxi	0.338	0.358	0.325	0.312	0.348	0.355	0.362	0.343	0.050
Huzhou	0.267	0.221	0.258	0.254	0.262	0.263	0.268	0.256	0.047
Hangzhou	0.421	0.422	0.418	0.414	0.449	0.458	0.512	0.442	0.098
Suzhou	0.368	0.427	0.453	0.453	0.482	0.445	0.476	0.443	0.114
Shanghai	0.737	0.771	0.748	0.773	0.788	0.801	0.832	0.779	0.095
Jiaxing	0.298	0.297	0.301	0.305	0.315	0.317	0.327	0.309	0.030

Data source: The author used the entropy weight method for calculation.

).

3.1. Comprehensive Evaluation of the Green Development of the Nanjing-Hangzhou Eco-Economic Zone

The visualization of the measurement results shows that the level of green and high-quality development of Shanghai-Nanjing-Hangzhou urban agglomeration increases each year (Figure 2a). From 2012 to 2018, the green and high-quality development index increased by 0.056, reflecting an annual increase of 0.008, with a clear growth rate. More specifically, the growth rates in 2012–2013 and 2015–2016 were relatively large, while the growth rates in 2013–2015 and 2016–2017 were flatter, which is a reflection of the stable development period after the national macroeconomic policy regulation and stimulus in the previous year. Since the founding of an era of predominant ecological civilization in 2012, 2015 was the first time that green development was put forward as one of the new national development concepts, alongside the comprehensive benefits of supply-side structural reform. The ensuing in-depth implementation of the green strategy, which became the policy source of green development, drove the overall development index of Shanghai, Nanjing, and Hangzhou. Indeed, they experienced an overall leap the next year which then developed into a stable state. It can thus be seen that macro policy is an important factor affecting green sustainable development. At the same time, the green development index of cities along the Nanjing-Hangzhou line experienced a “wave-like” growth phase, with a steady increase between 2012–2013, followed by a slight decline in 2013–2015, and then a rapid increase in 2015–2018 (Figure 2b). The overall level of development has improved but compared with the Shanghai-Nanjing-Hangzhou urban agglomeration as a whole, there remains room for improvement. This significantly highlights the traditional “weak edge” image of the Nanjing-Hangzhou line.

In addition, the features of the green and high-quality development of the Shanghai-Nanjing and Hangzhou urban agglomerations are significantly different, with the green and high-quality development level of each city representing a “step-like” and “hierarchical” distribution. From the perspective of extreme value distribution, the minimum value of Huzhou’s green and high-quality development index was 0.221 in 2013, and the maximum value of Shanghai’s green and high-quality development index was 0.832 in 2017. This reflects a range of 0.611, which is a significant gap equivalent to one and a half of Nanjing’s development level in one year.

Based on each city’s average green development index (Table 2), the quality of green development in the Shanghai-Nanjing-Hangzhou urban agglomeration can be divided into three echelons: Shanghai (0.779) ranked first in the green development of the Yangtze River Delta urban agglomeration, with performance surpassing the second-best city, Suzhou, by about 43.13% (0.443). This also fully reflects that Shanghai was one of the country’s first regions to open up and is in a leading position with respect to economic development and urban governance, environmental governance, ecological construction, driving innovation, and other aspects. At the same time, the “1 + 7” integrated development model of the Shanghai metropolitan area has further established its “benchmark” status in the Yangtze River Delta urban agglomeration. The primacy of 1.75 (0.779/0.443) indicates that the green and high-quality development of Shanghai, which is in the first echelon, needs to radiate further into the surrounding cities and drive the coordinated development of green and high-quality deeper into the region.

The second echelon of the urban agglomeration includes Suzhou, Hangzhou, and Nanjing, with city-level green development indices ranging between 0.381 and 0.443. Nanjing and Hangzhou are the provincial capitals of Jiangsu and Zhejiang provinces, respectively. They are also strong comprehensive central cities in the Yangtze River Delta region. As a city representing export-oriented economic development, Suzhou focuses on advancing local economic development by using foreign capital and improving the overall development strength of the city.

The third echelon of the urban agglomeration includes Wuxi, Changzhou, Jiaxing, Zhenjiang, Huzhou, and other cities, with city-level green development indices ranging between 0.256 and 0.343. These cities lie between the first two echelons of cities and enjoy the dividends brought about by the developed regional economy. In particular, the county’s economic development is extremely active, with the merging of ecological and cultural backgrounds and a relatively high level of economic and social development. However, it is also affected by the agglomeration effect of the regional “pacesetter” cities, making the comprehensive development level slightly lower than the first two echelons.

3.2. Time Series Dynamic Evolution of the Characteristics of Five Subsystems of Green Development in the Nanjing-Hangzhou Eco-Economic Zone

From an overall perspective of the Shanghai-Nanjing-Hangzhou urban agglomeration, with respect to the sub-system of green and high-quality development in this region four indicators are experiencing a steady rising trend; only social welfare is not. Of these, the innovation-driven item shows the most significant increase, with an overall increase of 0.2. Economic benefit has experienced the smallest increase. The development indexes of the five subsystems also show a differentiated distribution in different periods, driven by policy changes, development concepts, and industrial transformation and upgrades (

Table 3. Index of five sub-systems of Shanghai-Nanjing-Hangzhou urban agglomeration green and high-quality development.

Year	Economic Performance B1	Social Welfare B2	Innovation Drive B3	Environmental Load B4	Green Governance B5
2012	0.265	0.334	0.432	0.540	0.621
2013	0.268	0.368	0.451	0.581	0.639
2014	0.273	0.360	0.472	0.587	0.644
2015	0.274	0.353	0.512	0.588	0.660
2016	0.276	0.397	0.582	0.602	0.676
2017	0.279	0.410	0.594	0.623	0.684
2018	0.285	0.415	0.632	0.631	0.687

Data source: The author used the entropy weight method for calculation.

).

The five subsystems of green and high-quality development in the Shanghai-Nanjing-Hangzhou urban agglomeration all show a trend of overall steady improvement over the development time sequence. However, there are some spatial and temporal differences in the level of green and high-quality development among cities or urban belts (Figure 3). From the perspective of economic performance, the economic development level of the cities along the Shanghai-Jiaxing-Hangzhou line is the highest, with the index ranging between 0.439 and 0.452. The cities along the Shanghai-Nanjing line are second highest, with the index ranging from 0.338 to 0.447. The cities along the Nanjing-Hangzhou railway line are the lowest, with the index ranging between 0.165 and 0.177. This demonstrates that the economic performance of the cities along the Nanjing-Hangzhou railway line is low and also confirms the characteristics of the economic “weak side” with respect to the development axis of Nanjing-Hangzhou.

From the perspective of driving innovation drive, the cities along the Shanghai-Nanjing line have a low starting point (0.345), but then show sustained and rapid growth from 2012 to 2018. This indicates a continuous increase in investment in scientific research, innovation, and education along the Yangtze River. The starting point for the innovation index was highest among the Shanghai-Hangzhou cities (0.576), but the development momentum was slow and weak. The average error (0.363) associated with the starting point for the investment made in innovation-driven cities along the Nanjing-Hangzhou line suggests that the economic performance of the cities along the Nanjing-Hangzhou line affects the fiscal revenue of the region, indirectly reducing the investment in education and scientific research. The small local population base also leads to a low proportion of university students in the cities along the route. However, the average value (0.483) is higher than the average level (0.437) along the Shanghai-Nanjing line. This indicates that local governments along the Nanjing-Hangzhou Economic Belt are addressing the problem of “innovation-driven lag” and are gradually strengthening an innovation-driven development strategy, injecting new momentum into the green and high-quality development of the Nanjing-Hangzhou Ecological Economic Zone.

From the perspective of social welfare, the average level of Shanghai-Hangzhou cities along the line (0.522) is higher compared to Shanghai-Nanjing cities along the line (0.445) and Nanjing-Hangzhou cities along the line (0.310). This result is mainly influenced by economic factors. There is rapid economic development in Shanghai-Nanjing and Shanghai-Hangzhou cities along the line, with high resident income and high-quality infrastructure. This has led to a high living standard for the residents in the gold edge and silver edge(lucid waters and lush mountains are as valuable as gold and silver), while the social welfare index of the cities along the Nanjing-Hangzhou line is limited by the level of economic performance, and shows a relatively declining trend.

From the perspective of environmental load and green governance, these two indexes are both higher along the Nanjing-Hangzhou line compared to the Shanghai-Nanjing and Shanghai-Hangzhou lines. The interval between the two indicators is small, and they remain in a stable leading position over time. This shows that the cities along the Nanjing-Hangzhou line have placed pollution control and environmental governance in a similarly important position over time. It also shows that the region has excellent ecological environmental resources, a low development level, and a certain “late-comer” advantage. Cities along the Shanghai-Nanjing line intensified their environmental governance efforts in later years, but the effect is not significant. The economic growth path in these cities has not abandoned their path dependence of environmental pollution, and there remains a large gap with cities along the Nanjing-Hangzhou line.

In contrast, the cities along the line of Shanghai-Hangzhou focus on both environmental governance and reducing resource consumption. In particular, 2015 was a turning point when the environmental load index in these cities showed explosive growth, indicating effective implementation of the concept of green transformation and development. To integrate the analysis above, it was combined with an assessment of the 2016–2017 Ambient Air Quality Index (AQI). The AQI is a dimensionless index that measures the effect of comprehensive air treatment. The index comprehensively considers fine particulate matter (PM2.5), inhalable particulate matter (PM10), and pollution levels including sulfur dioxide (SO₂), nitrogen dioxide (NO₂), ozone (O₃), and carbon monoxide (CO). A lower AQI is associated with a better atmospheric environment. The AQI was used to evaluate the air pollution control effect in the Shanghai-Nanjing-Hangzhou urban agglomeration over three years (Figure 4).

The results show that the air environment in Shanghai, Nanjing, Hangzhou, Suzhou, Wuxi, and Changzhou improves over the three years (2016–2018), while the air environment in Zhenjiang, Huzhou and Jiaxing remains stable or slightly decreases. This is consistent with the general rule that cities with more developed economies experience environmental Kuznets Curves earlier. That is to say, in the face of environmental pollution, the government is often influenced by GDP competition, and tends to invest limited funds in economic construction. The government tends to be less enthusiastic about investing in environmental public goods that have slow investment results. This tends to lead to increases in environmental pollution from low to high levels. When economic development reaches a certain level, the further aggravation of environmental pollution strengthens people’s demands for better environmental governance. As a result, increasing attention is paid to ecological restoration and environmental protection, environmental pollution is gradually reduced from high to low levels, the degree of environmental pollution gradually slows, and environmental quality is gradually improved.

3.3. Spatial Mapping of Current Green Development Problems in the Nanjing-Hangzhou Eco-Economic Zone

Focusing on a regional perspective of the integrated development of the Yangtze River Delta, the evaluation indicators for the green development of the Nanjing-Hangzhou Ecological Economic Belt show that in terms of environmental load control and green governance, the basic indicators of the quality of green development support the definition of a “green edge” of the Yangtze River Delta. The ecological economic zone is significantly better than the “Golden Edge” and “Silver Edge” while functional development indexes, such as economic performance, social welfare, and driving innovation, are significantly behind the development axis of Shanghai-Nanjing and Shanghai-Hangzhou. This is precisely the problem associated with the green and high-quality development of the Nanjing-Hangzhou Ecological Economic Zone.

In the new era of ecological civilization, the Nanjing-Hangzhou Eco-economic Zone is expected to implement the concept of green and high-quality development. It needs to further highlight its advantages in green governance and environmental load control in the Yangtze River Delta urban agglomeration area and acknowledge shortcomings in the cities along the line. Combined with analyzing the urban spatial structure of the Nanjing-Hangzhou Eco-economic Zone, it is important to spatialize and visualize theoretical issues related to the development of related functions, including low economic performance, lagging innovation, and the weakening of social welfare. Promoting the green development of the Nanjing-Hangzhou Eco-economic Zone requires providing an objective basis for policy recommendations that maximize strengths and avoid and mitigate shortcomings and weaknesses.

3.3.1. Lagging Driving Innovation: “Strong Stem and Weak Branch” of Urban Structure

The ecological background along the Nanjing-Hangzhou Eco-economic Zone is well preserved and physically robust, with rich regional tourism resources and high ecological development potential. However, its green development driving innovation index lags behind the index for cities along the Shanghai-Nanjing and Shanghai-Hangzhou areas. This results in a low urban economic scale and per capita economic benefits, overall poor urban and rural construction quality, small urban built-up areas, and poor development efforts. This has resulted in the area representing a weakness in the West Wing of the Yangtze River Delta (Figure 5). This is inseparable from the urban spatial structure attributes of the Nanjing-Hangzhou Eco-economic Zone, which is characterized as having a “strong trunk and weak limbs”.

The radiation of the central city is limited, and there is a lack of central city guidance along the routes. Spatial barriers and lagging traffic development have led to a heavy reliance on the two major regional central cities of Nanjing and Hangzhou, hindering overall development along the Nanjing-Hangzhou Economic Zone. At the same time, it is difficult to provide a standard model for the development of cities along the routes because of the large differences in city scale, industrial structure, and functional orientation. In contrast, the steady development of the Suzhou-Wuxi-Changzhou metropolitan area on the Shanghai-Nanjing line has laid a solid foundation for the Shanghai-Nanjing urban continuous belt in terms of the industrial division of labour and transportation integration. There, Jiaxing City has gradually assumed a role as the regional center, which is driven by the effect of the integrated demonstration zone for green development in the Yangtze River Delta. Therefore, the Nanjing-Hangzhou Economic Zone needs to integrate regional network resources; cultivate new central cities and growth poles; and enhance the “waist” power of the Nanjing-Hangzhou Economic Zone.

The functional connection degree of cities along the route is weak. Nanjing has recently accelerated its integration with neighboring cities However, the inter-provincial coordination of powers between Nanjing and Hangzhou has relatively weak relationships between urban population and functions, compared to Shanghai-Nanjing and Shanghai-Hangzhou. Furthermore, an urbanization network spatial pattern has not yet emerged, leading to insufficient cooperation in the industrial division of labor in cities along the route. Population mobility brings about social exchanges and innovative resource sharing, which extends to information interconnection, industrial cooperation, ecological conservation, transportation, and other infrastructure co-construction between cities, thus constantly strengthening the connectivity between cities. However, based on the statistics of population mobility data of Tencent platform, it can be seen that the population mobility between cities along the Nanjing Hangzhou Economic Belt (Nanjing and Hangzhou, Hangzhou and Huzhou, Nanjing and Changzhou) is significantly less than that between cities along the Shanghai Nanjing Economic Belt (Shanghai and Suzhou, Suzhou and Wuxi) and between cities along the Shanghai Hangzhou Economic Belt (Hangzhou and Jiaxing, Hangzhou and Shaoxing), which also affects the coordinated development and green development of cities along the Nanjing Hangzhou Economic Belt. In terms of regional transportation, the transportation framework of the Nanjing-Hangzhou Eco-economic Zone, such as the Nanjing-Hangzhou Expressway and Nanjing-Hangzhou High-speed Railway, has formed but it is inadequate and unbalanced. There are ongoing problems including fragmentation between regions and different modes of transportation: east-west connections are the most common, north-south connections are weak, and an overall interconnection pattern needs to be established (Figure 6). In terms of eco-tourism, the tourism resources of the three provinces of Jiangsu, Zhejiang, and Anhui have not been integrated to create a characteristic tourism and sightseeing belt. As regional integration in the Yangtze River Delta has accelerated, the contradiction between the “strong side of ecological resources” and the “weak side of the urban economy” will also intensify (Zhan, 2017). This highlights the need to strengthen and cultivate the radiation of regional central cities and strengthen the linkage of cities along the route, to promote regional coordination and high-quality development.

3.3.2. Low Economic Performance: Industrial Structure Is “Heavy on Nanjing and Light on Hangzhou”

The comprehensive evaluation results of the green development of the Shanghai-Nanjing-Hangzhou urban agglomeration show that the three cities of Suzhou, Hangzhou, and Ningxia are in the second echelon of cities. Nanjing (0.374) lags behind Suzhou (0.438) and Hangzhou (0.432) with respect to the comprehensive evaluation index of the green development of these cities. The overall performance of Nanjing’s green development economy, innovation, and governance is lower compared to Suzhou and Hangzhou. From the perspective of the composition of economic performance indicators, the proportion of urban tertiary industries and labor employment are important factors impacting this indicator. This indicates that Nanjing’s urban industrial structure and employment structure are the internal factors impacting the economic performance of the city’s green development. The unbalanced industrial structure of the two regional central cities of Nanjing and Hangzhou is a structural problem and has lowered the overall development level of the economic belt.

With respect to the industrial structure, although Nanjing and Hangzhou have a complete range of industrial industries, Nanjing’s industrial structure has been traditionally biased towards the development of heavy industries. The chemical, petrochemical, automobile, and electronic information industries have served as Nanjing’s four pillar industries, and are important factors driving Nanjing’s long-term economic development. In the Jiangsu section of the Nanjing-Hangzhou Eco-economic Zone, there is a relatively large proportion of traditional industries, with a significant number of enterprises engaged in primary processing at the start of the industrial supply chain. These add less value economically. In contrast, Hangzhou focuses on the developing light industries, such as textiles and food. The Zhejiang section of the Nanjing-Hangzhou Economic Belt also faces the problem of having a relatively high proportion of low value-added industries (Figure 7).

With the continuous advancement of supply-side structural reforms, the urban industries of Nanjing and Hangzhou face specific difficulties in transforming to a service-oriented economy. For example, the traditional industrial structure has led to a low level of overall land use in Nanjing, and the average land output which measures the land benefit, has remained at a low level and has grown slowly for a long time. With respect to the internal structure of urban service industry, the proportion of the production-oriented service industry is low, and the proportion of cultural tourism in the service industry is high. This imbalance slows improvements in urban function and quality. However, Hangzhou has a better light industrial foundation and is transforming to service industries and choosing new industries at a faster pace, and with a higher level of quality. In particular, the Internet, digital economy, cloud computing, and other new economies have provided a new impetus for development in Hangzhou, leading to a significantly higher level of economic performance development compared to Nanjing. In 2016, Hangzhou added 676.8 billion yuan of value to the service industry. This accounted for 61.2% of the regional GDP, which is 2.8 percentage points higher than seen in Nanjing. The service industry contributed 80% to economic growth, which was 7.1 percentage points higher than Nanjing [27].

3.3.3. Weakening of Social Welfare: Urbanization Development Is “Attaching Importance to Quantity and Ignoring Quality”

Improving the level of social welfare is an external positive effect of urbanization development. High-quality urbanization affects the supply level of basic public services in urban and rural areas. On 25 December 2019, the Chinese central government state issued Opinions on the Reform of the System and Mechanism for Promoting the Social Mobility of Labor and Talents, emphasizing the need to promote the flow of urban and rural elements by reforming the household registration system. This supports policies that link the scale of urban land use, the implementation of central investment projects, and the number of rural people settled. This replaces the traditional urban administrative level, specified economic scale and growth rate, and other factors that configure urban development elements and guide the flow of industries. These policies symbolized the development of a new type of urbanization, which requires the development of all cities to include competitive industries and high-quality public services, to attract the inflow of populations for characteristic industries, and retain populations with high-quality public services. New urbanization changes urban competition from the original one-dimensional competition (city status) to diversified competition. In other words, it rests on industrial advantages and city status: retaining and attracting the population; developing the economy; feeding back and improving the quality of the public environment and public services; developing strategic emerging industries; and guiding urban development into a virtuous circle.

The Yangtze River Delta, especially the Shanghai-Nanjing-Hangzhou Golden Triangle, serves as an important intersection between the “Belt and Road Initiative” and the Yangtze River Economic Belt. Indeed, it is one of the regions with the best urbanization foundations in China. The regional urbanization levels in 2018 indicate that the urbanization rate of permanent residents has exceeded 70% in 7 cities. The urbanization rates of Shanghai and Nanjing have both exceeded 80%; the rates in Hangzhou, Wuxi, Suzhou, Changzhou, and Zhenjiang have ranged between 70% and 80%; and cities such as Huzhou and Jiaxing have rates exceeding 60% (

Table 4. Population and urbanization cross-section status of Shanghai-Nanjing-Hangzhou urban agglomeration in 2018.

City	Permanent Population in 2018 (10,000)	Increase or Decrease (10,000)	Registered Population in 2018 (10,000)	Net Population Inflow in 2018 (10,000)	Urban Population in 2017 (10,000)	Urbanization Rate in 2018
Shanghai	2423.78	5.45	1447.57	976.21	2418.33	87.60%
Nanjing	843.62	10.12	696.94	146.68	642.68	82.50%
Hangzhou	980.6	33.8	774.1	206.5	637.07	77.40%
Suzhou	1072.17	3.81	703.55	368.62	332.94	76.05%
Wuxi	657.45	2.15	497.21	160.24	254.77	76.28%
Changzhou	472.9	1.13	382.2	90.7	188.57	72.50%
Zhenjiang	319.64	1.01	270.78	48.86	89.17	71.20%
Jiaxing	472.6	7	360.44	112.16	94.28	66.00%
Huzhou	302.7	3.2	367.06	35.64	93.3	63.50%

Data source: The 2018 China city statistical yearbook.

). However, the level of social welfare in the Nanjing-Hangzhou Ecological Economic Zone has weakened overall, indicating that the inertia of the urbanization development of the urban development axis of “Quantity over quality“ has not changed. This indicates that urbanization development has not qualitatively improved the supply of basic public services of a social welfare nature.

4. Green Development-Oriented Spatial Optimization Strategy of the Nanjing-Hangzhou Ecological Economic Zone

Excellent ecology, compact distribution, efficient land use, convenient transportation systems, and effective facilities are the important ways to realize the green development of new urban space [9,28]. The green and high-quality development of the Nanjing-Hangzhou Eco-economic Zone should be based on scientific understanding of the current spatial pattern, combined with a national-level strategic demand orientation and related development trends. The basic conditions of the ecological elements of the Nanjing-Hangzhou Ecological Economic Zone should be leveraged to maximize the scientific and technological innovation advantages of the two core cities of Nanjing and Hangzhou, integrating the spatial ecological resources and innovative resources along the axis. Such continuous optimization of the regional division of laborcultivates and expands new drivers of green development to explore the path toward green and high-quality development in the Nanjing-Hangzhou region.

4.1. Optimize the Pattern of Regional Division of Labor and Strengthen the Radiating and Driving Role of Central Cities

The “point-axis system” is an effective spatial structural model for land development and regional development. The application core of the “point-axis system” theory is to conduct land development and regional economic development within the mode of economic belt [10]. The Nanjing-Hangzhou Ecological Economic Zone is driven by the agglomeration of central cities and has a high-quality green ecological base along the line. The social economy, land resources, transportation facilities, and ecological elements in the zone should be rationally organized using a “point-axis system” model to realize the organic integration of the regional economy, social elements, and regional infrastructure.

4.1.1. Improve the Functions of the Central City

The following recommendations will maximize opportunities for the integrated development of the Yangtze River Delta as part of a national strategy, and the implementation of an ecologically prioritized green development strategy for the Yangtze River Economic Zone. The goals are to improve the innovation and service functions of the two central cities of Nanjing and Hangzhou, facilitate improvements in the overall energy level of the urban development axis of Nanjing-Hangzhou, and drive the balanced development of the ecological green edge of the west wing of the Yangtze River Delta.

(1) Improve service functions (supporting public facilities). Optimizing urban functions and qualities in the new era is based on fine and flexible governance. Nanjing and Hangzhou have a foundation of strong urban public service facilities and strong urban environmental qualities. The future should focus on improving the innovative source capacity and new economic service functions, by activating and utilizing historical and cultural resources; renewing old city facilities; renovating old communities; implementing rain and sewage diversion; upgrading cultural and sports facilities; and renovating ecological parks. It is also important to improve the energy level and core competitiveness of the Nanjing-Hangzhou central cities to meet the requirements of regional governance modernization and to comprehensively improve governance capabilities in the new era. At the same time, the core functions of the non-metropolis areas, such as general manufacturing, should be distributed in an orderly way to form a competitive and influential city brand. This central city brand and management mode can then be exported to the cities along the routes, providing services and support for the high-quality development of the Nanjing-Hangzhou Ecological Economic Zone and encouraging participation in the competition and cooperation of the Yangtze River Delta regional integration.

(2) Enhance innovation function (scientific, educational, and cultural resources). The high-quality scientific, educational, and cultural resources of Nanjing and Hangzhou can be leveraged to attract and join cutting-edge innovative elements. Supporting the corresponding policies and measures would encourage enterprises to independently innovate, initiating and opening the innovative function of the Nanjing-Hangzhou Ecological Economic Zone from the source, and building an “innovation community” across Nanjing and Hangzhou. It is also important to actively connect with the G60 Science and Technology Innovation Corridor to drive the formation of innovative clusters in small and medium-sized cities along the route. With improved service functions, the two central cities can attract science and technology innovation talent, converging into a flexible mediating agglomeration that can aggregate innovation resources and industrial settlements, creating a “catalytic enzyme” and building an “innovative intermediary enzyme”. This involves establishing a comprehensive innovation service chain, starting with facilities and industrial services, and creating both a hard and soft catalyzing innovation environment, enhancing innovation as a center city function.

(3) Expand leisure functions (integrate tourism resources). This recommendation involves deeply promoting the integration and development of Nanjing’s rich historical and cultural heritage, and Hangzhou’s modern fashions. This would involve leading the fashion frontier, enhancing leisure tourism and other functions, and amplifying the pivotal role of Hangzhou and Nanjing as tourist destinations. Integrating the core tourism resources of the two cities would create a new international city with both sophisticated tastes and interests, and would connect tourism resources along the route to promote the organization and branding of international tourism boutique routes.

(4) Strengthen the hub function (transportation distribution). The integrated development strategy of the Yangtze River Delta first promoted the status of Nanjing, Hangzhou, and regional central cities as transportation hubs. However, in the era of high-speed rail, improving the function of Hefei’s high-speed rail hub has weakened Nanjing’s road network hub function in the Yangtze River Delta urban agglomeration. Hangzhou has a limited radius relative to Shanghai, and its small hinterland somewhat restricts enhancements to its transportation hub function. This highlights the need to strengthen the hub function of Nanjing-Hangzhou. First, the service level of the city’s integrated transportation network needs to be continuously improved by advancing the city’s importance. Second, traditional transportation facility networks need to be optimized and improved based on the flow of people and logistics. More attention needs to be paid to constructing an information infrastructure, and intelligent and networked hub platforms, guided by the new economy involving the Internet and logistics networks. It is also vital to strengthen the interconnection of information elements between the two cities; drive improvements and upgrades to green network facilities based on the flow of information elements in small and medium-sized cities along the route; and support the construction of a green new economic urban agglomeration in the west wing of the Yangtze River Delta.

4.1.2. Optimize Regional Division of Labor

Reasonable regional division of labor is the foundation for effective operations and sustainable regional development. Forming an integrated development pattern of the Yangtze River Delta cannot be separated from the long-term tacit cooperation and division of labor among cities. The high-quality development of the Nanjing-Hangzhou Ecological Economic Zone requires the integrated development of the regional environment. This involves addressing the competitive and cooperative relationships between leading cities, the Golden Edge, the Silver Edge, and different nodes within the region.

(1) Realign the cooperation-competition relationship between Nanjing, Hangzhou, and Shanghai. To implement an integrated development pattern in the Yangtze River Delta, it is important to focus on overall strategic planning, maximizing the leading role of Shanghai as the central city in the Yangtze River Delta region, and highlighting the driving role of the “pacesetter” to the community. Nanjing and Hangzhou should continue to consolidate their leading roles in metropolitan areas and urban agglomerations, strengthening their role in promoting metropolitan areas and urban agglomerations and cultivating new growth poles. This would enhance the overall competitiveness of the region and form a coordinated development pattern featuring the rational division of labor, complementary advantages, and distinctive features.

(2) Explore the role of Nanjing and Hangzhou at the “Golden Edge” and “Silver Edge”. Nanjing and Hangzhou are central cities in the Nanjing-Hangzhou ecological economic belt and play an important role in the Shanghai-Nanjing urban development axis and the Shanghai-Hangzhou urban development axis. The golden axis of Shanghai-Nanjing urban development is an important spatial factor in implementing the Yangtze River Economic Belt strategy. Nanjing is a node city where multiple strategies are intertwined and superimposed, making it an important hub for connecting the east and west. The Silver Axis of Shanghai-Hangzhou Urban Development is the leader of the G60 Science and Technology Innovation Corridor. Hangzhou needs to undertake the spillover of the functions of Shanghai Center, while strengthening its own functions by constructing the Greater Bay Area and driving the Science and Technology Innovation Corridor to participate in the cooperation of the Yangtze River Delta. Nanjing and Hangzhou form an ecological green edge at the center of the city and should participate in economic construction on the edge of gold and silver driven by innovation activities. It is important to create a center city function orientation and build prioritizing ecological development strategy based on the two cities’ abundant landscape resources and technology innovation ability in the area.

(3) Optimize the division of labor between Nanjing and Hangzhou and small and medium-sized cities along the routes. In the ecological economic zone, the two cities should play the role of “leading city”, creating reasonable competitive and cooperative relationships between the cities along the line. To help the central cities play a radiating and driving role, it is important to gather regional medical innovations and cultural resources, improve urban functions, and strengthen physical fitness. It is also important to excavate characteristic ecological resources, actively develop the county-level green economy, promote the industrial transformation of the development axis of Nanjing-Hangzhou towns through county-level green economic development, and enhance awareness of regional ecological civilization protection [29]. The cities along the line should concurrently develop, driven by their own characteristics. This includes creating a reasonable division of labor, and striving to achieve differentiated ecological product value. Cities also need to avoid the siphon effect of homogenized competition on small and medium-sized cities along the line and avoid weakening the social and economic value of the ecological economic zone.

4.2. Cultivate and Strengthen New Drivers of Growth, and Promote Industrial Orientation of Regional Green Economy

Relying on the existing industrial base and ecological resource advantages, Nanjing and Hangzhou should maximize the advantages of industrial development.. They should also engage cities along the industrial chain in the division of labor and build mutual connections and complementary supporting cooperative relationships to build a cascading green economic system and promote the overall competitiveness of the region.

4.2.1. Build a Hierarchical Green Economic System

The Green Economy is a new type of economic structure, growth mode, and social form that is based on the traditional industrial economy, but that has a goal of coordinating across economic growth, ecological protection, and social equity. The green economy represents the direction of economic development in an era of ecological civilization. It is a new economic model that protects the climate, meets environmental requirements, and helps improve economic efficiency, and promote development [30]. In terms of the construction of the green economic system of Nanjing-Hangzhou Ecological Economic Zone, it is necessary to actively develop green industries under the radiation of the central city, increase the green transformation of traditional industries, and focus attention on low pollution, low emissions, and low energy consumption to transform industry and upgrade the economy. Further, reasonable regional cooperation and division of labor is needed to create both dislocation development and characteristic development among regional cities, and to innovate the construction of a green economic ecological system.

(1) Improving the industrial distribution of the green economy. These actions should include integrating regional green ecological elements and resources, and. strengthening the green industrial and innovation functions of the central cities in the Nanjing-Hangzhou Ecological Economic Zone. Other actions include focusing on the distribution of the central cities’ industrial chain links, such as headquarters economy, R&D, and high-end manufacturing, and also vigorously developing the innovation economy, service economy, and green economy. This entails creating a green industry, globally competitive innovation highland. It is also important to guide the green industry, with intelligent manufacturing: new materials for small and medium-sized cities; support for small and medium-sized cities consistent with a plant economy; and a focus on developing modern agriculture, tourism, health, medicine, and the agricultural products processing industries. It is also important to construct ecologically-based innovation-focused center cities in small and medium-sized cities and to introduce a green economy industrial structure.

(2) Strengthening factor scheduling and rational allocation of resources. The core of developing a green economy is improving economic efficiencies [31]. Promoting the green development of the Nanjing and Hangzhou regional economy requires collecting the innovative elements of Nanjing and Hangzhou, tackling major innovation carriers, laying out and implementing a number of science and technology industry projects, and driving improvements in the green efficiency of the innovation axis of Nanjing and Hangzhou with the green efficiency of the “core point”. Integrating the Nanjing-Hangzhou Ecological Economic Zone’s ecological resources, science and technology, education resources, and transport resources, through mechanisms such as the formation of the Nanjing-Hangzhou ecological technical innovation zone, can interact with the G42 Industrial Innovation Belt and the G60 Science and Technology Innovation Corridor to promote the transformation and upgrading of the regional industrial structure. This is performed through innovative development methods, to jointly build the power engine of the “Yangtze River Delta Science and Innovation Circle”.

(3) Establishing a platform for industrial cooperation and development. The development of an “Enclave Economy” is an inevitable requirement for implementing Xi Jinping’s vision of an ecological civilization. It is also a realistic choice for innovating the cross-regional cooperation model and addressing the problem of unbalanced and insufficient city development along the Nanjing-Hangzhou Ecological Economic Zones. Efforts are needed to build the “Enclave Park” of the Nanjing-Hangzhou Economic Belt into a new economic gateway for gathering high-end high-tech industries. This highlights the need to explore and improve the development model of “Enclave Economy”; encourage the integration and development of Nanjing-Hangzhou science and technology innovation resource elements and the ecological resources of cities along the line; and jointly build “zone parks” and “parks in parks” with the industrial parks of cities along the line. This would help realize the function spillover and industrial transfer of the central city. At the same time, it is important to promote the central city’s financial and venture capital institutions, and state-owned platforms with capital as a link to strengthen the cooperation with the Yangtze River Delta region, Nanjing, and Hangzhou along the city. Finally, it is vital to create conditions that help establish industrial alliances, guide the industrial linkage development of cities along the line of Nanjing and Hangzhou, and help industry climb to the middle and high end of industrial structure.

4.2.2. Vigorously Develop Scientific and Technological Innovation Industries

(1) Enhance green innovation transformation and move industries to the medium-high end of the global value chain [32]. Based on resource advantages and complementary conditions, we should form differentiated divisions of labor and cooperation across the industrial chain, focusing on making breakthroughs in a number of key and core technologies. It is also important to build a number of advanced manufacturing industrial clusters and modern service industry clusters that lead the world in scale and level, and cultivate a number of landmark advanced manufacturing clusters. Further, a Nanjing and Hangzhou science and technology innovation industry cluster should be created to strengthen the development of the Internet+, cloud computing, big data, and other new economic industries in Nanjing and Hangzhou, while expanding the distribution of the cities along the line. For example, Nanjing focuses on the financial industry, smart grid, high-end equipment manufacturing, new energy vehicles, while Hangzhou focuses on the distribution of transmission software and information technology service industry, and financial industry.

(2) Maximize the important role of cultural and ecological resources as new economic carriers. It is vital to rely on the talent highland and innovation peak advantages of Nanjing and Hangzhou to encourage the development of R&D-intensive industries. For example, Nanjing focuses on cultural tourism, information technology, and technical environmental protection, while Hangzhou focuses on e-commerce, cultural and creative industries, and tourism.

4.2.3. Optimize the Distribution of Cultural and Creative Industries

(1) Improving the distribution of the health industry in the Yangtze River Delta can be achieved through different approaches. These include combining the ecological and cultural resources of Nanjing and Hangzhou; steadily promoting the leisure tourism industry and health industry along the route; developing the “health + culture” industry with health as the theme; creating a leisure and health destination; and constructing a leisure tourism industry and health industry system in the Nanjing-Hangzhou Ecological Economic Zone.

(2) One goal for the zone is to form a characteristic industrial economic belt, with culture as the carrier and ecology as the backdrop. This requires maximizing the use of beneficial resources, other than ecological resources, along the Nanjing-Hangzhou line; implementing policy support for the ecological and cultural industry; and promoting the integration and embedding of different cultural forms. Examples of these include the Liyang tea culture, Anji bamboo culture, Gaochun slow city culture, and Hangzhou business travel culture. This would integrate the different fields of economy, society, science and technology, and tourism in the Nanjing-Hangzhou Zone.

(3) It is vital to strengthen the integration of traditional culture and modern culture in cities along the Nanjing-Hangzhou line, and increase the added value of cultural products, such as ecological culture and intangible culture. This involves extending the development of cultural products to include design and precision processing and high value-added manufacturing; integrating traditional cultural industries with modern manufacturing, technology, tourism, and other service industries; and activating intangible cultural heritage.

4.2.4. Compact the Comprehensive Development of Characteristic Agricultural and Forestry Products

(1) Persist in promoting the transfer of economic ecology and ecological economy [33]. Under the regional pattern of the integrated development of the Yangtze River Delta, it is important to address the economic ecology process of the “Gold Edge” and “Silver Edge;” to maximize the potential of regional ecological resources. This involves the strengthening and activation of ecological asset reconstruction and functions; the promotion of the ecology of the process from production to consumption; and the realization of the coordinated advancement of ecological construction and economic development. It is also vital to emphasize the process of “green edge” ecological economics, maximize the advantages of ecological resources, promote the capitalization of ecological resources, and transform ecological advantages into economic advantages. This involves realizing the value of ecological products in the regions along the Nanjing-Hangzhou line, promoting the value and capitalization of ecological assets, and providing ecological services and consumption costs.

(2) Building a green industrial highland. The first element in this recommendation is actively expanding agricultural scientific research projects and combining the food processing industry, biotechnology industry, and other industries to create a well-known brand of characteristic agricultural products. The second element is to strengthen the deep processing of agricultural products, based on the high-added value, and further enhance the science, technology, and tourism support functions of agriculture, and thus integrate these functions with urban leisure tourism and agricultural tourism education. The third element is to promote the six industries; integrate primary, secondary, and tertiary industries; develop new forms of agriculture; and promote the integration of agriculture with Internet+, crowdfunding, and the leisure experience. The fourth element is to jointly support the circulation of agricultural products, promote the development of high-quality agriculture, jointly develop and uniformly promote high-quality tourism routes, and advance the elephant-focused “Colorful Nanjing-Hangzhou Line” tourism brand.

4.3. Explore New Urbanization Models and Build a New Pattern of Green Development

Social development focuses on the multi-level needs of people. A key contradiction in today’s society is a shift in people’s yearning for a better life but encountering unbalanced and inadequate regional development. The traditional development model of increasing the urbanization rate by absorbing the settlement of the rural population is unsustainable. However, the problem must be identified and addressed at the source, integrating regional characteristics and superior resources; cultivating and expanding core competitive industries; and relying on regional characteristics and core industries to attract the inflow of external population and factors. A good business environment is created by providing high-quality public service products and reasonable corporate policies, retaining both people and capital. Decays over time are restored with spatial advantages, guiding the transformation of the traditional urbanization model of “industry-urban-people” to a new urbanization model of “people-urban-industry” [34], and building a new pattern of green development in the Nanjing-Hangzhou Ecological Economic Zone.

4.3.1. Spatial Pattern of Population Aggregation Guided by New Ecological Economy

Combining the new economic model with the development of urbanization can lead to a new type of ecological economy based on ecological resources. Activities can include using scientific and technological resources to develop the Internet economy; using human resources to develop a creative industrial economy; and guiding different groups of people in the ecological zone to form a population-gathering method and spatial organization that “Gather at the point, Disperse with the area”. Nanjing and Hangzhou should pay attention to the refined design and management of urban space quality to create a suitable space carrier for the new industrial economy. Agglomerating innovative resources and elements can help advance the horizontal association between related enterprises and talents; transform the environment to be a more intensive innovation space; create differentiated spatial development methods and spatial agglomeration forms; and explore new urbanization models.

4.3.2. Co-Construction and Sharing of Regional Infrastructure to Promote Urbanization

Rationally combining and operating regional infrastructure and encouraging facility co-construction and sharing are important ways to develop new urbanization [35]. Associated initiatives include accelerating improvements in the regional comprehensive transportation network construction of the Nanjing-Hangzhou Ecological Economic Zone; vigorously supporting the planning and construction of the Yangtze River Intercity, Zhenjiang-Xuancheng Intercity, Taizhou-Changzhou-Liyang Intercity, Taizhou-Wuxi-Changzhou-Yixing Intercity, and other railways; and accelerating regional integration. Other approaches include supporting Nanjing and Hangzhou in expanding the coverage of the urban rail transit network; accelerating the construction of rail transit projects in Nanjing-Gaochun, Nanjing-Liyang, Nanjing-Jurong, and Changzhou-Jintan; and promoting the extension of Hangzhou rail transit to Yuhang, Anji, Deqing, and other regions. Turning to aviation opportunities, it is important to support the construction of general aviation airports in regions where conditions permit, and to conduct general aviation policy trials. Finally, more financial support is needed for regional rural road upgrades, and to effectively increase the density of urban and rural road networks along the Nanjing-Hangzhou line.

4.3.3. On-Site Urbanization Model of Population Driven by Agricultural Modernization

The county and town economies in southern Jiangsu and northern Zhejiang are very developed, with a high urbanization rate of the resident population. However, the existing household registration system creates barriers that make it difficult for farmers who “leave the land and not leave their hometown” to truly enjoy equal urban public services. This highlights the need to actively implement a rural vitalization strategy and lead the in-situ urbanization of the rural agricultural population. Given the wide-area rural space along the Nanjing-Hangzhou Ecological Economic Zone, it is important to rely on a large number of farmers, and the new small and medium-sized towns with agriculture as their main body, to both carry and create an ecological, intelligent, technological, and highly efficient cultural-ecological-industrial complex with rural characteristics [36,37]. For example, the construction of characteristic towns could be combined with the building of pastoral complexes and modern agricultural service complexes. As another example, leading enterprises with ecological agriculture as their main business can lead the construction of ecological manufacturing complexes, and leisure and entertainment complexes. Guiding farmers to urbanize in-situ has popularized rural revitalization and provides opportunities for rural industrial development. This also retains effective “guardians” and “watchers” of the beautiful ecological environment along the route [38]. Therefore, combining the classification and assessment of land and space, actively implementing a rural vitalization strategy, promoting ecological environmental protection, and realizing the urbanization of the rural population in situ are important options when exploring the high-quality development of the Nanjing-Hangzhou Eco-economic Zone and developing new urbanization.

4.3.4. New Pattern of Urban and Village Space Guided by the Rural Vitalization Strategy

To achieve the rural vitalization strategy, it is important to maximize the attractiveness and driving force of the high-quality regional ecological environment in the Nanjing-Hangzhou Ecological Economic Zone to develop productive service functions, and to build a spatial pattern system of “city-township-village” along the route. Cities, driven by innovation, can lead industrial development, and promote improvements in the urbanization level and the quality of space. Villages and towns with leading characteristics can realize the integrated development of “habitation-industry-culture” and apply the urbanization path based on township characteristics. With the help of rural revitalization, villages can revitalize industrial development and create new ecologically livable rural areas.

5. Conclusions and Discussion

This paper studied the Nanjing-Hangzhou Eco-economic Zone and constructed a green development evaluation system in the context of the regional integration of the Yangtze River Delta. Based on comparative analysis and evaluation of the green development functions of different urban development axes in the Yangtze River Delta, the paper highlights the shortcomings in the green development process of the Nanjing-Hangzhou Ecological Economic Zone, and proposes corresponding spatial optimization strategies based on the spatial mapping of the problems. The paper’s main conclusions are as follows:

(1) This paper builds a green development evaluation system in the context of regional integration from the five dimensions of industry, employment, science and technology, ecology, and people’s livelihood, evaluated and analyzed the economic performance, social welfare, innovation drive, environmental load, green governance, and other green development levels of different urban development axes and their green development in the Yangtze River Delta region. The results show that, on the whole, benefiting from the implementation of the national macro policy of green development and the new development concept, the overall green and high-quality development level of the Shanghai-Nanjing-Hangzhou urban agglomeration in the Yangtze River Delta region is increasing year by year. In particular, under the implementation of the new policy, the green development performance of urban agglomeration has increased significantly, and with the reduction of the policy effect, the overall green development performance remains at a high and stable state. The level of green and high-quality development of each city is distributed in a step-like and hierarchical manner, and the overall level of green development in the Nanjing-Hangzhou Ecological Economic Zone is lower than the Shanghai-Nanjing Golden Axis and the Shanghai-Hangzhou Silver Axis. Based on the evaluation results of the green development subsystem, the green development index in the Yangtze River Delta region is affected by significant differences in the effects of factors, among which the innovation-driving factor has the most significant impact, the economic benefit factor has the least impact, and the social welfare factor has an irregular fluctuation. Based on the perspective of spatial and temporal characteristics of each urban belt in the Yangtze River Delta, the Nanjing-Hangzhou Eco-economic Zone performs significantly better than the Shanghai-Nanjing and Shanghai-Hangzhou development axes in terms of environmental load control and green governance index. However, the three indicators of driving innovation, economic performance, and social welfare are weaker compared to the “Gold edge” of Shanghai-Nanjing and the “Silver edge” of Shanghai-Hangzhou. This is spatially manifested as structural problems, such as the strong stems and weak branches of the urban structure in the Nanjing-Hangzhou Ecological Economic Zone; an industrial structure approach that focuses on Nanjing rather than Hangzhou; and an emphasis on quantity rather than quality with respect to urbanization.

(2) Based on the problems revealed by the spatial mapping of the green development of the Nanjing-Hangzhou Ecological Economic Zone, this study highlights the overall concept that strengths and weaknesses make up for shortcomings. As such, the following optimization strategies based on green development are proposed. To address the problem of lagging innovation, the regional division of labor should be optimized to strengthen the driving role of central cities. In the case of low economic performance, efforts should be made to cultivate and grow new drivers, to advance the development of regional green economic industries, and to build a well-established green economic system. The improve upon the weakening of social welfare, we should actively implement a rural vitalization strategy, focus on exploring new urbanization models, and build a new pattern of green development in the Nanjing-Hangzhou Eco-economic Zone from the perspectives of guiding population agglomeration and co-constructing and sharing infrastructure.

Our study also has some limitations. For example, the index system needs to be further optimized, as the selection of the dimensions evaluated, the acquisition of data, and other factors may impact the scientific nature and objectivity of the evaluation results. In addition, the paper focuses on a macro-level evaluation, the Nanjing-Hangzhou Ecological Economic Zone, the Shanghai-Nanjing Urban Axis, and the Shanghai-Hangzhou Development Axis. There remain opportunities to further research and evaluate cities, districts, and counties within each region [39].