1. Introduction
Water resources, energy, and food are essential strategic resources for sustaining human survival, promoting socio-economic growth, and maintaining regional sustainable development [
1,
2,
3]. China is currently undergoing an accelerated process of new industrialization and urbanization, resulting in tremendous demand for water, energy, and food [
4]. Although China possesses vast overall resource quantities, per capita resource availability is relatively low. There are distinct regional disparities in the distribution of water resources, energy production, and food supply. Water resources are concentrated in the southern regions, while agricultural production and energy reserves are concentrated in the northern regions. This unique distribution pattern leads to frequent occurrences of phenomena such as increased uncertainty in water resource demand, energy demand, and food supply in China. The inter-relationships and constraints among water, energy, and food have become increasingly prominent [
5].
Water, energy, and food systems are interdependent, and their interactions are highly complex. Water resources serve as the foundation for agricultural production, while activities such as agricultural machinery operation, fertilizer production, and food processing require significant energy inputs [
6]. Conversely, food production and supply chains also demand substantial water and energy resources. Therefore, changes in any of these systems may have significant impacts on the others. Water scarcity and pollution, for instance, can affect food production and supply, while frequent trading of energy-related commodities can exacerbate water resource depletion in neighboring cities, leading to spatial resource transfers [
7].
The coordinated development of China’s water resources, food, and energy systems has a significant impact on achieving sustainable development [
8,
9]. It is not only related to environmental protection, resource utilization efficiency, and food security but also plays an important role in economic development and social stability. Unreasonable development practices may have negative impacts on the environment. Coordinated development can promote green development, reduce pollutant emissions, and protect the ecological environment [
10]. Furthermore, it helps ensure the stability and security of the food supply. Scientific and reasonable management of water resources, improving agricultural irrigation efficiency, and enhancing agricultural production methods can increase food production and quality [
11]. Simultaneously, optimizing energy structures and improving the operational efficiency of agricultural production and supply chains can guarantee the stability of the food supply chain. The development and utilization of water resources, food, and energy are closely related to the ecological environment [
12]. Studying the coordinated development of the system can reduce water resources pollution and waste, promote the ecological, low-carbon, and sustainable development of agricultural production, and achieve eco-prioritized and green development of water resources, food, and energy.
As globalization continues to advance and resource scarcity increases, ensuring the supply of essential resources such as food, energy, and water poses a unique challenge to national sustainable development [
13]. This is not only because the demand for resource imports and exports from different countries or regions continues to grow but also due to the complex interrelationships within the food–energy–water system. Water plays a crucial role in energy production, including the extraction of renewable energy and unconventional fossil fuels, which are expected to play an important role in future energy security [
14]. The intricate relationship between food and water has become more complex due to the rapid growth of agricultural globalization and food trade. This has led to large-scale virtual water transfers between regions and significant roles in food and water security in some areas [
15].
Environmental regulation, as a policy tool and management mechanism, guides and adjusts the rational allocation and utilization of resources through internal and external constraints and incentives. It aims to eliminate or reduce externalities, excessive resource utilization, and environmental pollution, thereby achieving environmental optimization in the socio-economic context [
16] Can environmental regulation have an impact on the coordinated development of the water–energy–food system among regions in China? This is a highly debated issue. China, as one of the most populous countries in the world, faces challenges such as water scarcity, increasing energy demand, and food security [
17]. In this context, achieving coordinated development of the water, energy, and food systems among regions in China becomes a significant issue.
By introducing environmental access standards, resource taxation, emission permits, and other measures, environmental regulation aims to guide enterprises and individuals in the rational utilization of water resources, energy, and land resources, reduce pollution emissions and waste, and provide security for food production and supply [
18]. However, there are still many uncertainties regarding the impact of environmental regulation on the coordinated development of the water–energy–food system among regions in China [
19]. On the one hand, environmental regulation may promote optimized resource allocation between regions, foster efficient utilization and sustainable development, thereby improving the output and efficiency of water resources, energy, and food [
20,
21]. On the other hand, environmental regulation may exacerbate resource constraints in certain regions, result in imbalanced industrial restructuring, and thereby affect the supply and demand of water resources, energy, and food [
22]. Moreover, the implementation and effectiveness of environmental regulation may vary across different regions, leading to competition and coordination challenges among them [
23].
Therefore, it is of great significance to deeply investigate the impact of heterogeneous environmental regulation on the coordinated development of the water–energy–food system among regions in China. By assessing the implementation effectiveness, resource utilization efficiency, and economic benefits of different types of environmental regulation policies, scientific evidence and decision support can be provided to policymakers, promoting regional collaboration and sustainable utilization. In addition, it is necessary to explore the role of environmental regulation in resource allocation, cooperation mechanisms, and policy coordination among different regions, as well as how to address conflicts and conflicting interests between regions, in order to achieve more balanced development and sustainable resource utilization.
Compared to the existing literature on water–energy–food-related research, this study makes several contributions: (1) This study analyzes the space–time evolution characteristics of the water–energy–food system coupling coordination degree among 30 provinces in China, evaluating the differences in coordination degrees between different provinces. By analyzing data over a long time span, it can reveal the changes and trends of the system in different periods and regions, providing a foundation for understanding the patterns of system changes. (2) From the perspectives of foreign direct investment and industrial structural upgrading, this study examines the specific mechanisms through which environmental regulation affects the coupled coordination development of the water–energy–food system, providing decision support for governments and enterprises in formulating comprehensive policies and implementation plans. (3) This study reveals the spatial spillover effects of heterogeneous environmental regulation on the coupling coordination degree of the water–energy–food system and compares the specific impacts of formal and informal environmental regulation on the coupled coordination development of the water–energy–food system.
The remaining sections of this paper are structured as follows:
Section 2 provides the theoretical background, discussing the relevant theories that support the research and conceptualize the study.
Section 3 presents the research methodology, including the variables used and the sources of data.
Section 4 presents the research findings.
Section 5 discusses the implications of the research findings.
Section 6 summarizes the main conclusions and provides policy recommendations.
2. Theoretical Background
The WEF system is an integrated system that involves the interdependence and interaction among water resources, energy, and food [
24]. In this system, water resources are the fundamental requirement for agricultural development, while energy is a crucial driving force in promoting development across all sectors. Food is also one of the essential materials necessary for human survival. These three elements are interdependent and mutually constraining [
25]. In a situation where water is scarce, agricultural development will be limited, resulting in a decline in food production. At the same time, inadequate energy production capacity can also affect food production and economic development. Studying the WEF system as a whole can help to find new ways to reduce environmental pollution and improve resource utilization efficiency [
26].
Environmental and resource economics research focuses on issues related to resource utilization and environmental protection. Environmental regulation is one of its important research directions. Environmental regulation can take two forms: formal and informal. Formal environmental regulation is a set of environmental policies and measures developed and enforced by the government or legal regulations with clear legal effectiveness. Informal environmental regulation is a voluntary norm generated through industry associations, social organizations, or market mechanisms.
The theory of regional developmental differences is one of the important theoretical frameworks in economic geography and regional science. This theory holds that there are inherent differences in economic and social development among different regions, which are influenced by multiple factors such as geographical conditions, resource endowments, population distribution, and technological level. These factors collectively shape the economic structure, industrial layout, and development characteristics of a region.
In China’s WEF system, due to differences in geography, climate, and resource endowments, there are significant differences in water supply, food production, and energy consumption among different regions. Water resources, food, and energy are interrelated, and their development and utilization are closely linked and interdependent [
27]. When environmental regulations change the way water resources are managed, the mode of food production or energy consumption structure, it may have spillover effects on adjacent regions.
Due to differences in regional economic development, resource endowments, government management capabilities, and social participation levels, formal and informal environmental regulations also vary in different regions of China. If the research method divides China into eastern, central, and western regions, it will result in a hard division of boundary regions. This heterogeneous research makes it difficult to evaluate the impact of environmental regulations on different regions.
Spatial econometrics has become an essential research method for resource and environmental economics in recent years. By constructing different correlation matrices, spatial econometric models can study heterogeneity between regions without destroying the integrity of individual border regions. Common correlation matrices include adjacency matrices, geographical distance matrices, economic gap matrices, and economic geographic nested matrices. By using these different matrices, it is possible to assess the impact of heterogeneous environmental regulation on the development differences of the WEF system in different regions.
In a country like China with vast territory and diverse ecological environment, exploring the impact of environmental regulation on the WEF system in different regions is of great practical significance. Due to the diversity of different regions and environmental regulations, this issue involves complex factors and mechanisms. Existing research on environmental regulation mainly focuses on one aspect of the WEF system, and further discussion on the impact of heterogeneous environmental regulation on the coupled and coordinated development of the WEF system is still needed.
5. Discussion
By studying the spatiotemporal evolution trend of the coupling and coordination degree of the WEF system in 30 provinces of China from 2003 to 2020, as well as the impact of heterogeneous environmental regulations on the coupling and coordination degree of the WEF system, we found a significant growth trend in the coupling and coordination degree of the WEF system during the research period. Formal and informal environmental regulations have significant positive spatial spillover effects on the coordinated development of the WEF system. Compared with informal environmental regulation, formal environmental regulation has a stronger promotional effect on the coordinated development of the WEF system. Moreover, foreign direct investment and industrial structure are the key paths for heterogeneous environmental regulations to promote the coupling and coordination development of the WEF system.
This paper analyzes the impact of different types of environmental regulations on the coupling and coordination development of the WEF system, clarifying the key paths for environmental regulations to promote the coupling and coordination development of the WEF system. By studying the different impacts of formal and informal environmental regulations, policy suggestions and practical experience can be provided to promote cooperation and communication between regions, and potential solutions can be provided to improve the efficiency of environmental regulation policy guidance and promote the sustainable use of water, energy, and food resources. This research is of great significance for government decision making, policy formulation, and the development of strategies that ensure the long-term balance and resilience of China’s water–energy–food systems.
Since the proposal of location theory by Karl Wepman, the analysis of regional development differences has gradually expanded from geographical location to resource endowments, industrial structure, and policy orientation. The distribution pattern of the coupled coordination level of the WEF system in different regions can be explained from multiple levels such as economic development, geographical environment, and environmental regulatory policies. There are significant geographical differences in China’s conditions, with the western and southwestern regions either being in arid areas or mountainous areas with scarce water resources, which poses a restrictive impact on the development of the water–energy–food system [
5]. Different regions have significant differences in energy and food resource endowments; for example, the western part of a region may be rich in water resources, coal, or oil and gas, while its eastern part is relatively poor. The imbalance in resource endowments leads to differences in energy supply and food production capacity, which in turn affects the coordination level of the system.
There are significant differences in the economic development stage and industrial structure in various regions of China. The eastern coastal areas are economically developed, highly industrialized, and have greater energy needs, but with scarce water resources [
52]. Conversely, the western region is mainly agricultural-based with stronger food production capacity but relatively insufficient energy supply. This difference in development stage and industrial structure results in the water–energy–food system being poorly coordinated [
53,
54]. There are significant differences between southern and northern regions in water resource, energy, and food policies, with different investment and support efforts from the government, which directly impacts coupled coordination level of the system [
37]. Differences also exist in China’s emphasis on water resources and environmental protection, with some areas facing serious issues such as water pollution and overexploitation of water resources, which limit the coordinated development of the water–energy–food system.
Formal environmental regulations provide guidance and constraints for the coordinated development of the WEF system. Relevant departments carry out systematic planning and regulation according to regulatory requirements to ensure balance and coordination among subsystems. At the same time, formal environmental regulations can also promote the coordinated development of the WEF system through economic incentives and market mechanisms. Informal environmental regulations are usually based on social customs and moral norms, which can guide the public in self-restraint regarding the use of water resources, energy, and food. The formation of informal environmental regulations requires a certain degree of consensus and increased awareness.
Compared to informal environmental regulations, formal environmental regulations have higher coefficients and significance, indicating that they exert a stronger force on the degree of coupling and coordination within the local WEF system. Formal environmental regulations are formulated and enforced by the government and have mandatory enforcement power. The government can constrain and supervise various sectors and enterprises to manage and utilize resources according to regulations through laws, regulations, and policies. This mandatory enforcement compels all stakeholders to actively participate and comply with the standards, thereby enhancing the overall coordination of the WEF system.
Formal environmental regulations can promote the establishment of cross-border cooperation mechanisms among neighboring regions. By establishing common environmental protection standards and resource management policies, neighboring regions can cooperate and negotiate to address shared challenges related to water resources, energy, and food. This cooperation mechanism can facilitate resource sharing and optimal allocation, promoting the coordinated development of the WEF system in neighboring regions. Some regions may be rich in water resources but relatively scarce in energy and food, while others may have the opposite situation. Through formal environmental regulations, neighboring regions can establish resource exchange and mutual assistance mechanisms, achieve optimal resource utilization through rational resource allocation and cooperative relationships, and promote coupled coordination development [
55].
In an informal regulatory environment, neighboring regions can enhance cooperation through information sharing and experience transfer. Best practices in resource management, environmental protection, and agricultural production can be shared among regions to deepen understanding of issues, explore solutions, and learn from each other’s experiences within the framework of the WEF system. In an informal regulatory environment, market mechanisms can play a promoting role. Through free trade and supply–demand adjustment in the market, neighboring regions can allocate and exchange resources based on their resource endowments and demands. The role of market mechanisms can optimize resource allocation to some extent and promote the coordinated and harmonious development of the WEF system.
Formal environmental regulations have a stronger positive impact on the local WEF coupling and coordination than informal regulations, and their influence coefficients are more significant. Under the estimation of the geographical distance matrix, formal environmental regulations also have a greater impact on neighboring regions compared to informal regulations. However, when considering the economic factor, under the estimation of the economic geographical distance matrix, the impact of informal environmental regulations on neighboring regions is greater than that of formal environmental regulations, and the estimated coefficient is more significant. We believe that the reason behind this phenomenon may be the result of population interregional mobility, with economic factors being important drivers of population mobility. Based on this development, we believe that the economic development level between regions is an essential consideration in studying the impact of informal environmental regulations.
Formal environmental regulations exist in the form of laws and regulations, with clear constraints and enforceability. This provides legal protection for foreign investors, regulates their direct investment activities, ensures their legitimate rights and interests in economic activities, and reduces potential risks and uncertainties. In contrast, informal environmental regulations are often based on customs, conventions, or unwritten agreements, with weaker constraints and reliability. Formal environmental regulations often define investment conditions, procedures, and limitations through laws, policies, and institutions, enabling foreign investors to understand the legal framework and rules of the investment environment in advance and anticipate potential risks and limitations. This transparency and predictability help foreign investors formulate investment strategies and make informed decisions. Informal environmental regulations often lack clarity and predictability, and may involve subjectivity and variability, bringing uncertainties to foreign investment.
Formal environmental regulations, through government guidance and policy regulation, can effectively promote the upgrading of industrial structure. The government can use means such as laws, policies, and planning to clarify the direction, focus, and policy support for industrial development, guiding resources towards industries with high added value, technological intensity, and environmental friendliness. In comparison, informal environmental regulations often fail to provide clear government guidance and effective policy support, making it difficult to facilitate the orderly upgrading of industrial structure.
Formal environmental regulations, through mechanisms for industrial access and exit, can effectively regulate market competition and drive the optimization of industrial structure. The government can set relevant entry conditions and standards to restrict the growth of inefficient, highly polluting, or excessive production capacity, thereby promoting the transition of industrial structure towards a more competitive and sustainable direction [
39]. At the same time, the government can also encourage non-compliant enterprises to exit the market through policy regulation and financial support, in order to meet the requirements of industrial upgrading. Informal environmental regulations often fail to provide effective mechanisms for access and exit, leading to inadequate constraints and guidance in industrial structure adjustment.
It is necessary to balance the development of formal and informal environmental regulations. The impact of formal environmental regulations should outweigh that of informal environmental regulations, but this does not mean that the government needs to focus all attention on formal environmental regulations. Formal environmental regulations have mandatory enforcement, and violations will face legal sanctions. This form of regulation can compel enterprises and individuals to comply with environmental laws and regulations, ensuring the effective implementation of environmental standards. However, formal environmental regulations require enterprises to invest substantial resources in compliance transformation, equipment updates, and monitoring. This may increase operational costs for businesses, particularly for small and medium-sized enterprises, potentially posing a burden [
56].
Informal environmental regulations encourage the participation of stakeholders in environmental protection and promote environmental awareness and responsibility among enterprises and the public. This participation can enhance information sharing, cooperation, and negotiation, improving the effectiveness of environmental management [
57]. However, informal environmental regulations also lack legal enforceability, making it difficult to effectively supervise and punish non-compliant enterprises and individuals, potentially leading to environmental violations [
58].