Study on Quantitative Model of Water Resource Ecological Compensation in Yangtze River Basin Based on Water Footprint–Decoupling Analysis Methodology

Abstract

Establishing a standard model for water resource ecological compensation, based on water quantity and quality, is one of the current research hotspots in the field of ecological economy. This paper calculates the water footprint from 2011 to 2021, constructs an inter-provincial water resource ecological compensation model in the Yangtze River Basin, and discusses the horizontal compensation of water resource ecology in the Yangtze River Basin. Firstly, the water footprint method and the water footprint ecological load index are used to evaluate and analyze the overall water resource utilization in the basin and in various administrative regions within the basin; secondly, the decoupling analysis method is used to study the coordinated relationship between water resource utilization and economic development among different administrative regions; finally, the identity of the compensation subject and object are determined on the basis of the calculation of ecological surplus and deficit of water resources in each administrative region, and the compensation standards are quantitatively calculated. The results indicate the following: (1) Over the 11 years, the overall water footprint of the Yangtze River Basin and its provinces has shown a growth trend, with significant differences in the quantity of water footprints among different administrative regions, and the average water footprint exhibits a decreasing distribution from “midstream—downstream—upstream”. There are significant differences in the water footprint ecological load index among provinces, with the load index showing a trend of being higher in the east and lower in the west. (2) From the perspective of the decoupling index, there has been no state of dis-coordination in the Yangtze River Basin overall over the 11 years, with 2016, 2018, and 2019 being in a high-quality coordinated state, while the other years were in a primary coordinated state. (3) In terms of horizontal payment for ecological compensation, Tibet, Yunnan, and Qinghai have consistently been regions receiving ecological compensation, while Shanghai, Jiangsu, Anhui, Hubei, Hunan, and Chongqing have been determined as compensation subjects required to make payments over the years.

1. Introduction

The Yangtze River Basin, as one of the more economically developed and densely populated areas in China, plays a crucial role in the regional economic development of the country. However, in recent years, the dual pressures of water resource scarcity and the deterioration of the water ecological environment faced by the Yangtze River Basin have become increasingly severe. The rapid development of the economy and the advancement of industrialization and urbanization have led to a demand for a certain amount of water resources for living, agriculture, and industry. Therefore, the concept of the water footprint has emerged [1],which refers to the total amount of water resources required for all products and services consumed by a country, a region, or an individual over a certain period of time. Wang et al. defined the water footprint through the concept of the ecological footprint, which refers to the amount of water resources required to produce the products and services consumed by a certain population (individuals, cities, or countries) under a certain material living standard. It characterizes the actual amount of water resources needed to sustain human consumption [2]. A water footprint can be categorized into a blue water footprint, which refers to surface and groundwater resources consumed by human activities, a green water footprint, which refers to the soil water utilized in the form of evapotranspiration during crop production, and a gray water footprint, which refers to water resources polluted by human activities. Therefore, the water footprint is also considered a measure of the total amount of water resources directly or indirectly consumed and polluted by human production activities [3,4]. However, within the same watershed, the water footprint varies across different regions, and the total amount of water resources also differs. This manifests in the fact that when a region’s water footprint exceeds its total water resources, that region will inevitably encroach upon the water supply of other regions, thereby becoming a beneficiary of the ecological and environmental benefits of water resources within the watershed. Conversely, when a region’s water footprint is less than its total water resources, the water supply of that region is encroached upon by other regions, thus becoming a victim of the ecological and environmental benefits of water resources.

To address the development contradictions among regions, it is necessary to take measures to balance the interests of all parties and jointly promote the sustainable development of the water resource ecosystem within the basin. Ecological compensation can redistribute ecological benefits and economic interests, internalizing external effects, and becoming an important means to promote ecological civilization construction and achieve social justice [5]. Implementing ecological compensation to balance the interests of various regions is a significant initiative for building an ecologically civilized and harmonious society. In order to further alleviate the imbalanced contradictions regarding ecological environment and economic interests among different regions, and to establish a long-term ecological compensation mechanism for mutual assistance and benefit sharing among regions, the current ecological compensation policy is gradually shifting from vertical ecological compensation to horizontal ecological compensation models [6,7]. The implementation of the “Ecological Protection Compensation Regulations” starting from 1 June 2024, marks a new stage of legal governance for the ecological protection compensation mechanism, but cross-regional coordination of ecological compensation remains a challenge in policy implementation. Before ecological compensation, it is essential to determine the subject and object of compensation, the compensation standards, and the compensation measures. The calculation of compensation standards is of the utmost importance in improving the ecological compensation mechanism. As the total amount of water resource consumption, the water footprint, which is complementary to ecological compensation, can help people intuitively realize the increasing scarcity of water resources, and the difference between it and the total amount of regional water resources is also the basis for measuring ecological compensation. Therefore, it is of great significance to conduct research on large-scale inter-administrative watershed ecological compensation, as it plays an important role in promoting ecological environmental protection in large watersheds, advancing the modernization of watershed governance, coordinating and balancing the interests between ecologically protected and ecologically benefited areas, improving the framework of the ecological compensation system, and facilitating the coordinated and sustainable development of economic construction and ecological civilization construction in the watersheds.

2. Literature Review

In the context of the continuous development of society, water resources have been exposed to an increasing number of problems, which has led many researchers to study water resources in order to find solutions to the current water resource problems. As early as 1993, Allan proposed the concept of “virtual water” to calculate the total amount of water required for the production of products and services, which prompted the academic community to recognize the importance of virtual water for the study of regional water use and security [8]. In 2002, Hoekstra proposed the concept of a “water footprint”, which is based on the study of virtual water. It is defined as the total amount of water required to produce all the goods and services consumed by a country, region, or person in a given period of time. The water footprint is a visual representation of the footprints of water in the production and service processes, and it provides a new perspective for measuring water consumption. Since 2002, Hoekstra et al. have analyzed the water footprint on a global scale. Hoekstra and Hung estimated the virtual water volume based on the world’s foreign trade in agricultural products, the world’s foreign trade in live animals, and the products of the livestock industry from 1995 to 1999 [9]. Vanham et al. used the water footprint theory to analyze the water consumption of different diets in 28 countries of the European Union [10]. Schyns and Hoekstra evaluated the water footprint of Morocco and analyzed its added value [11]. Yin et al. used the input–output and bi-proportional algorithms to calculate and analyze the water footprint of the Yellow River Basin; the results showed that the primary industry had the highest water use coefficient, and there were big differences in the coefficients of the water use in the different provinces [12]. Demeke et al. changed the previous problem of focusing mainly on the analysis of spatial changes by examining the spatial and temporal changes in the global cotton water footprint and assessing the unsustainable water footprint [13]. Of course there is no lack of other scale studies. Chen et al. measured and comparatively analyzed the carbon–water footprint of per capita food consumption of urban and rural residents in 31 provinces and cities, in China, from 2000 to 2020, and suggested to start from the perspective of per capita food consumption in order to alleviate water consumption [14]. Guo et al. quantified the spatial and temporal characteristics of energy production, energy structure, and the blue water footprint of energy production at the municipal scale [15]. Zhang et al. conducted an in-depth decoupling analysis of the link between an agricultural gray water footprint and agricultural economic growth in the Yellow River Basin, exploring the decoupling status of agricultural water pollution and agricultural economic growth, as well as the key driving factors [16]. In addition, economic efficiency is one of the pillars of freshwater resource allocation. In order to evaluate the reasonableness of water resources, in terms of utilization efficiency and effectiveness, some scholars evaluated the water footprint per unit of production and the water footprint per unit of economic efficiency of the main cash crops of red dates, jujube, wheat, Portuguese grapes, and almonds in arid and water-scarce areas [17,18,19,20,21]. Nie et al. analyzed the spatial and temporal evolution characteristics of the water footprints of major crops in the Guanzhong region from 2000 to 2020, and used the method of through-traffic analysis to conduct an in-depth investigation of the factors affecting the regional differences in the water footprints of crops [22]. This provides a reference to the policymakers to formulate appropriate sustainable development strategies. Evaluating water utilization in terms of water footprints can effectively reflect the flow of water resources in economic activities and essentially reveal the impact of human consumption patterns on water resources.

In terms of the ecological basin, the main focus is on the study of ecological basin stakeholders and subject–objects, as well as the measurement of ecological compensation standards. Many scholars have researched the theories related to stakeholders and subject–objects of ecological compensation in watersheds. Grimble R et al. proposed that the key to accurately defining stakeholders is to find out the economic interest links among them by analyzing the main stakeholders in the practice of natural resource management [23]. Freeman et al. proposed that ecological compensation should cover different categories of stakeholders, mainly including governments at all levels, enterprises, landowners, etc. [24]. Shu, in analyzing the interest relationship between providers and beneficiaries, proposed that the stakeholders include the governments, enterprises, the masses, and other interest groups in the upstream and downstream areas [25]. For the definition of compensation subject and object, Pagiola et al. proposed that users, as direct beneficiaries, hold more information related to the value of the service, and should be recognized as the subject of compensation [26]; while Engel et al. proposed that based on the ecological resources having obvious public attributes, the government should be the subject of compensation, which can highlight the cost advantage [27]. At this stage, the ecological compensation mechanism is gradually moving towards horizontal marketization and diversification, and Yuan believes that the basin ecological compensation standard mainly consists of three parts: the minimum limit of the compensation standard, the protection compensation caused by the upstream area’s water conservation, and the compensation for the water quality and quantity pollution caused by the competition between the upstream and downstream areas [28]; the basin ecological compensation should be based on the horizontal compensation of the upstream and downstream local governments of the basin, and the central government should share the amount of compensation with the downstream beneficiary provinces [29].

Currently, scholars have explored and proposed the ecosystem service value method, opportunity cost method, condition value method, and other compensation standard accounting methods. The earliest proposed method is the ecosystem service value method, which focuses on the ecological value of the watershed as the compensation standard. Loomis et al. measured the watershed value of the Platte River from the perspective of ecosystem service value [30]; Clot et al. determined the compensation value by conducting an ecosystem service value assessment of the District of Columbia [31]. In addition, the opportunity cost approach focuses on maximizing the economic benefits of the upstream region due to the loss of water resource protection as the ultimate compensation criterion. Thu Thuy et al. suggest that applying the opportunity cost to determine the payment criterion is an effective way to improve the efficiency of compensation [32]; Munoz-Pina et al. suggest that the criterion should be adjusted by taking into account the value of the user’s benefits when applying the opportunity cost approach to determine the criterion [33]; Le Coq argues that compensation rates should be approved based on the actual opportunity cost of the sacrificing party [34]. The conditional value method (CVM) is an accounting method that determines the standard based on the willingness of the subject to compensate and the willingness of the object to be compensated. Morana et al. [35], Bienabe et al. [36], and Arlene et al. [37] explored the willingness to be compensated of the relevant residents in different cases. In addition, some scholars have combined various methods to make them more applicable. Xue et al. constructed a model of the small-scale ecological regional compensation mechanism based on the externality theory, using economic mathematics, and measured the amount of ecological compensation for three administrative districts in the Qinghai Lake Basin [38]. Wang et al. took Yongding River as an example and used the restoration cost method to measure the ecological compensation standard of water quality and water quantity [39]. Zhang et al. proposed a four-level compensation standard of “minimum—basic—full—maximum” based on direct costs, equalization of basic public services in water, opportunity losses, and comprehensive compensation [40]. Liu et al. took the Yellow River Basin as an example and proposed a framework for the allocation of PES funds derived from the patch generation land use simulation (PLUS) model and the ecosystem service value (ESV) valuation method [41]. Jiao et al., based on the water footprint method, the insurance pricing model, and the ecosystem service value model, analyzed the water footprints and the ecological carrying capacity of water resources in the Beijing–Tianjin–Hebei region, and determined the insurance compensation amount and ecological compensation standard in each region [42]. Chen et al. used the middle and upper reaches of the Yangtze River as the study area, calculated the ecosystem service flow (ESF) of the eight provinces in the region, using the gravity model, and constructed the HEC standard accounting model to determine the compensation standard [43].

To summarize, extensive research has been conducted both domestically and internationally on water footprints and ecological compensation; however, there are still some shortcomings. Firstly, the research on water footprints primarily focuses on analyzing their efficiency and benefits based on calculations of water footprints, with less consideration given to the situation of water environment pollution. Secondly, current studies on ecological compensation for water resources predominantly address linear watershed ecological compensation and point source ecological compensation. Although research on area-based ecological compensation among provinces within an entire watershed has also been initiated, the responsibilities among various provinces in the region remain unclear. Furthermore, the commonly used accounting methods have largely failed to consider the coordinated relationship between water resource usage and economic development across different administrative regions, resulting in compensation standards that do not align with the ultimate goals of compensation, thereby lacking fairness and efficiency. Geng et al. argued that a water footprint can take into account both conservation and pollution when constructing ecological compensation standard models, revealing water resource utilization efficiency and ecological pressure, quantifying the direct or indirect utilization and impact on water resources, and ensuring that the compensation mechanism adapts to the changes in water resource conditions over time and with economic development [44]. Therefore, it is necessary to explore and improve the methods for determining compensation standards that are more applicable and scientific, based on the characteristics and actual conditions of the Yangtze River Basin. The specific contributions of this article are as follows:

(1)

From the dual perspectives of water quantity and water quality, the water footprint ecological load index is incorporated to analyze the water footprint more comprehensively. Since ecological compensation aims to protect the stability of ecosystems, incorporating the water footprint ecological load index is a more reasonable consideration of the pollution affecting the water environment.

(2)

In light of the characteristics of ecological compensation in large inter-administrative river basins, a method is proposed to define the subject and object based on the impact of administrative actions on river basin water resources, thereby determining the payers of the compensation standards.

(3)

The coordinated relationship between water resource utilization and economic development in different regions is analyzed, and an improved method for establishing compensation standards for large inter-administrative river basins, based on water footprint–decoupling analysis, is proposed to determine scientifically sound compensation standards for large inter-administrative river basins.

3. Materials and Methods

3.1. Research Area

The Yangtze River Basin, as one of the important areas for economic development and population concentration in China, has its main stream passing through Qinghai Province, Tibet Autonomous Region, Sichuan Province, Yunnan Province, Chongqing Municipality, Hubei Province, Hunan Province, Jiangxi Province, Anhui Province, Jiangsu Province, and Shanghai Municipality, covering a total area of 1.8 million km²; this accounts for 18.8% of China’s land area, with the water flow accounting for approximately 35% of China’s total water flow. The Yangtze River Basin contains rich ecological resources and has become a concentrated area for important ecological conservation and construction in China. Due to the extensive economic development model implemented in various regions of the Yangtze River Basin and the neglect of environmental conservation over the years, there has been significant damage to the ecological environment of the Yangtze River Basin, such as functional degradation of the Yangtze River water ecosystem, severe water pollution, high risks to water resource security, non-compliance of sewage discharge from coastal towns, and the expansion of the scope of agricultural surface pollution. These serious environmental pollution issues have led to increasingly prominent contradictions between development and conservation in the Yangtze River Basin, as well as imbalances between economic development and ecological conservation that urgently need to be addressed (Figure 1).

3.2. Measurement Model of the Regional Water Footprint

3.2.1. Calculation Model of the Regional Water Footprint

The water footprint is calculated based on the amount of water resources used by humans and the products they provide, thereby determining the actual consumption of water resources by humans. It can be applied to the study of subjects of varying spatial sizes, from a household to a country and even to the global consumption of water resources; even a single product or service can be the subject of water footprint research. The calculation of the water footprint primarily employs a bottom-up approach, constructing water footprint accounts from the consumer’s perspective [45], with the following equation:

$$WF=WFT+WFI+WFD+WFE$$

(1)

where WF is the overall water footprint of the region for a certain period of time, WFA, WFI, WFD, and WFE are the water footprint of agricultural and livestock products, the water footprint of industrial products, the water footprint of domestic use, and the ecological water footprint, respectively.

Considering the availability of data, this paper takes 10 representative agricultural and livestock products, such as grains, vegetables, edible oils, pork, beef and mutton, poultry, eggs, dairy products, fish, and fruits, as the subject of this study, and takes the sum of the products of the virtual water content per unit of each product and the total production as the water footprint of agricultural and livestock products. The equation is as follows:

$$WFA={\displaystyle \sum P_i\times V{W}_i}$$

(2)

where P_i is the total amount of production of the ith product, and VW_i is the virtual water content per unit of product of the ith product.

3.2.2. Water Footprint Ecological Load Index Model

The quantity and quality of water resources are influenced by human production and operational activities. The availability of water resources is constrained by both water quantity and quality, and the requirements for water quantity and quality vary across different regions and industries. The water footprint reflects the impact of human consumption patterns on total amount of water resources, without addressing the differences in water quality across various regions and industries, nor does it reflect the pressure on the water environment in a specific area [46]. Therefore, this paper introduces the water footprint ecological load index to measure the water resource environmental quality of a certain area, based on the standards: “Class III standards apply to the secondary protection zones of centralized drinking water surface water sources, wintering grounds for fish and shrimp, migratory pathways, aquaculture areas, and other fishery areas and swimming areas” [47]. Using Class III water as the standard, it is defined as the ratio of the water footprint to the total amount of water resources that exceed the Class III (including Class III) water quality standards. This indicator reflects the intensity of the total water resource occupation in the region relative to the total amount of compliant water resources, accommodating both the occupation of water resources and the total compliant amount in different regions. A larger water footprint ecological load index indicates greater environmental pressure on water resources in that area, with the calculation equation as follows:

$${\lambda }_j={\displaystyle \frac{W{F}_j}{Q_j}}$$

(3)

where λ_j is the ecological load index of water footprint in region j, WF_j is the water footprint of region j, and Q_j is the total water resources in region j that exceed the water quality standard of Class III (including Class III).

3.3. Measurement of Total Water Availability

The total amount of available water resources refers to the maximum volume of water that can be utilized in a one-time manner from local water resources, based on a comprehensive consideration of water usage for living, production, and ecological environments, through economically reasonable and technically feasible measures within a foreseeable period. The calculation method for the available water resources varies depending on the research objectives and fields, and there is no fixed pattern. Based on actual conditions and drawing on the practical operations of most regions, both domestically and internationally [48], the calculation equation in this paper is as follows:

$$WR=W{R}_S+W{R}_G=W{R}_G+\rho \times P_r$$

(4)

where WR is the total amount of local water resources available; WR_S is the amount of surface water resources; WR_G is the amount of groundwater resources; ρ is the depletion coefficient of non-duplicated water between groundwater and surface water resources; and P_r is the base flow of the basin.

3.4. Analysis Model of the Coordination Degree of Water Resource Utilization and Economic Development in River Basins Based on Decoupling Analysis

The determination of compensation standards for large river basins, as a systematic project, should comprehensively consider the coordination between water resource usage and economic development in various administrative regions within the basin before accounting. This provides quantitative analysis and basis for the final confirmation of compensation standards. Therefore, the choice is made to adopt a decoupling analysis method to construct an analytical model of the coordinated relationship between water resource utilization and economic development in the basin.

The most widely used concept in decoupling theory is the “decoupling” concept proposed by the OECD (2003), which breaks the link between environmental pressure and economic development [49]. This theory posits that there are primarily two types of relationships between environmental pressure and economic development: coupling and decoupling. Coupling refers to the simultaneous increase in resource environmental pressure with economic growth, indicating a positive relationship between the two. Decoupling, on the other hand, refers to the phenomenon where resource environmental pressure decreases alongside economic growth, indicating a reverse relationship between the two. Based on decoupling theory, decoupling can be further divided into absolute decoupling and relative decoupling. The former refers to a declining growth rate of resource environmental pressure when the economy grows; the latter refers to a relatively smaller growth rate of resource environmental pressure when the economy grows. Thus, it can be seen that absolute decoupling represents the optimal state of achieving maximum economic growth with the minimum resource environmental consumption.

Currently, there are various methods for measuring the decoupling status, with the most frequently used being the decoupling index method [50]. The Vehmas decoupling index method determines the type and degree of decoupling based on changes in environmental pressure and economic growth, thereby evaluating the degree of coordinated development between water resource environments and the economy. It comprehensively considers multiple aspects such as economic growth, resource consumption, and environmental pollution, which is related to the water footprint ecological load index proposed in this paper. Coordinated development essentially refers to the balanced development and mutual promotion among elements within or between various subsystems. This paper, based on the research of Vehmas [51] and Yang [52], treats the Yangtze River Basin as a whole, measuring economic growth and water resource consumption using GDP and the water footprint, respectively. It constructs a decoupling evaluation model for the coordinated development of water resource utilization and the economy across large inter-administrative river basins, revealing long-term trends through time series analysis. The specifics are as follows:

$$D_f={\displaystyle \frac{GD{P}_t-GD{P}_{t-1}}{GD{P}_{t-1}}}-{\displaystyle \frac{WF{P}_t-WF{P}_{t-1}}{WF{P}_{t-1}}}$$

(5)

where $D_f$ is the water use decoupling index; ${GDP}_t$ and ${GDP}_{t-1}$ denote the gross domestic product (GDP) in period t and period t − 1, respectively; ${\displaystyle \frac{GD{P}_t-GD{P}_{t-1}}{GD{P}_{t-1}}}$ is the growth rate of GDP in period t; ${WFP}_t$ and ${WFP}_{t-1}$ denote the total water footprint in period t and period t − 1, respectively; and ${\displaystyle \frac{WF{P}_t-WF{P}_{t-1}}{WF{P}_{t-1}}}$ is the growth rate of the total water footprint in period t.

When ${\displaystyle \frac{GD{P}_t-GD{P}_{t-1}}{GD{P}_{t-1}}}$ < 0, it indicates economic recession in a certain period of time; this paper does not evaluate the relationship between water resource utilization and economic development in the region.

When ${\displaystyle \frac{GD{P}_t-GD{P}_{t-1}}{GD{P}_{t-1}}}$ > 0, the positive and negative cases are discussed in separate cases.

When ${\displaystyle \frac{WF{P}_t-WF{P}_{t-1}}{WF{P}_{t-1}}}$ < 0 and $D_f>0$, it indicates that the region’s water use and economic development are at an absolute decoupled optimum, i.e., a state of high-quality harmonization.

When ${\displaystyle \frac{WF{P}_t-WF{P}_{t-1}}{WF{P}_{t-1}}}$ > 0 and $D_f>0$, it indicates that the region’s water use and economic development are in a state of relative decoupling, i.e., a state of primary harmonization.

When $D_f\le 0$, it indicates that the region’s water resource utilization and economic development are not decoupled and are in a state of disharmony.

3.5. Quantitative Modeling of Ecological Compensation for Water Resources

3.5.1. Model for Measuring the Amount of Water Resource Ecological Compensation

Due to the public goods nature of water resources, the status of different regions within the same watershed is equal. The responsibility for the protection of water resources must be shared collectively, and the amount paid for ecological compensation should balance with the amount received. This means that the total of the final payment and the amount received should sum to zero, which is defined as the ecological compensation zero-sum model. The ecological compensation zero-sum model emphasizes the balance of water resource value, aiming to avoid excessive consumption of water resources or additional harm to the ecological environment. It also focuses on the balance of interests between both parties in ecological compensation, making it more adaptable to different ecological environments and compensation needs. Therefore, it is suitable for analyzing the different economic structures and water resource utilization patterns among various regions in the Yangtze River Basin. Let WR_j represent the total water resources in region j, WF_j represent the water footprint in region j, and Q_j be the amount of water resources in region j that meet or exceed Class III (including Class III) water quality standards. This paper defines ${\beta }_j$ as the ratio of the difference between the total water resources and water footprint in region j to the amount of water resources that meet standards in that region, representing the ecological surplus (deficit) of water resources under unit standard water quality in region j. The calculation equation is as follows:

$${\beta }_j={\displaystyle \frac{W{R}_j-W{F}_j}{Q_j}}$$

(6)

The difference between the total sum of water resources and the total sum of water footprints in the watershed area, divided by the total amount of qualified water resources in the watershed, represents the ecological surplus (deficit) of water resources under standard water quality of the watershed unit, designated as $\beta$. The equation is as follows:

$$\beta ={\displaystyle \frac{{\displaystyle \sum W{R}_j}-{\displaystyle \sum W{F}_j}}{{\displaystyle \sum Q_j}}}$$

(7)

The ecological compensation model for region j is as follows:

$$TEC=\left({\beta }_j-\beta \right)\times Q_j\times V$$

(8)

where TEC is the total ecological compensation value and V is the value of the unit of water resources.

3.5.2. Determination of the Subject and Object of Ecological Compensation for Water Resources

The theory of externalities serves as the basis for determining the subjects and objects of ecological compensation for water resources. The externalities generated by the water resource environment during the processes of production and consumption manifest in two aspects: first, the external costs resulting from the damage to the ecological environment caused by the development and utilization of water resources; second, the external benefits arising from the ecological protection effects formed by the rational development and utilization of water resources. Since external costs and benefits are not reflected in production and business activities, the ecological benefits generated by water resource environmental protection are enjoyed by others without compensation, and the destructive behaviors towards the water resource environment do not receive the necessary penalties, making it difficult to achieve Pareto optimality in the field of water resource environmental protection. Considering that the available amount of water resources in each region is fixed, when the water footprint generated by socio-economic development in a region exceeds its available water resources, it will inevitably encroach upon the available water resources of other regions, resulting in a water resource deficit. Conversely, when the water footprint generated by economic activities in a region is less than its available water resources, it indicates that the region is in a state of water resource surplus and can provide surplus water resources to other regions.

Water resources possess the attributes of public goods, and there exist situations of water resource deficits or surpluses for the entire basin. Considering the differences in water quality in the upper, middle, and lower reaches of the basin, it is necessary to introduce water quality as a factor in the ecological compensation standards. Based on the ecological deficit (surplus) of water resources under the standard water quality of the entire basin, areas where the ecological deficit (surplus) of water resources under the standard water quality exceeds the benchmark are considered objects of ecological compensation, as these areas exhibit positive externalities and should receive compensation. Conversely, areas with an ecological deficit (surplus) under the standard water quality less than the benchmark are regarded as subjects of ecological compensation, as these areas exhibit negative externalities and should pay compensation. The difference between the two is one of the key bases for calculating the ecological compensation standards for water resources.

3.5.3. Quantitative Standards for Water Resource Ecological Compensation

Considering that freshwater resources are primarily used in the production and consumption processes within the basin, the value of water resources is taken as another criterion for calculating ecological compensation value [53]. In a market economy, the value of water resources is reflected through its market price [54,55,56], therefore, the market price of water resources can be used to calculate the amount of ecological compensation.

The reasons for adopting the value of water resources to calculate the quantitative standards for water resource ecological compensation are as follows: (1) Ecological compensation based on the water footprint is essentially a compensation for socio-economic consumption of water resources. When the water resources used in a region exceed its total water resources, it will inevitably encroach upon the water resources of other regions. Therefore, the calculation basis for ecological compensation in this paper is based on water resources. (2) In the standards for water resource ecological compensation, only the portion of water resources that exceeds the benchmark (the ecological surplus or deficit of water resources under the unit standard water quality for the entire watershed) is used as the calculation standard. That is, the difference in the volume of water resources between the ecological deficit (surplus) of a region under unit standard water quality and the ecological deficit (surplus) of water resources for the entire watershed under unit standard water quality. Based on the concept of water footprints and the above two points, the compensation standard in this paper is determined based on the market price of water resources.

3.6. Data Sources

This paper selects water resource data from 11 provinces along the Yangtze River, from 2011 to 2021, for research. Due to the wide variety of industrial products, the calculation of virtual water content is relatively complex, and data acquisition is restricted. Additionally, its proportion in the overall water footprint is small. This paper directly uses industrial water consumption as a substitute. The domestic and ecological water footprint includes urban and rural domestic water consumption, as well as the water resources necessary for the normal functioning of ecosystems. This paper follows the approach of Zhang et al. [57], using domestic water consumption and ecological water consumption as substitutes.

Therefore, the study includes 9 types of data: total production of agricultural and livestock products, industrial water consumption, domestic water consumption, ecological water consumption, water resources that exceed Class III (including Class III) water quality standards, surface water resources, groundwater resources, GDP, and value of water resources. The total production of agricultural and livestock products, as well as GDP, is sourced from the China Statistical Yearbook; the data on industrial water consumption, domestic water consumption, ecological water consumption, surface water resources, and groundwater resources are sourced from the water resource bulletins of various provinces. The data on water resources that exceed Class III (including Class III) water quality standards come from provincial ecological environment status bulletin. The value of water resources is determined based on market price, using the average of the levied price for surface and groundwater resources across the 11 provinces in the Yangtze River Basin. The agricultural water footprint of the 11 provinces along the main stream of the Yangtze River is calculated using virtual water content.

The virtual water content of agricultural and livestock products is primarily based on the research findings of Hoekstra et al., as shown in

Table 1. Virtual water content of agricultural and livestock products, m³/kg.

Products	Grains	Vegetables	Edible Oil	Pork	Beef and Mutton
Virtual water content	1.13	0.15	5.24	3.65	19.80
Products	Poultry	Eggs	Milk	Fish	Fruits
Virtual water content	3.50	3.80	1.90	5.00	1.00

.

For the missing data in certain years, linear regression fitting was performed using SPSS software(IBM SPSS Statistics 27) to fill in the gaps. First, the results of the independent samples t-test indicated no significant differences, suggesting that the data are missing completely at random. Subsequently, the variables that needed to be filled were added to the quantitative variables to establish a regression equation, using predicted values to fill in the missing values. This may enhance the relationships between variables and underestimate the variance of variables, etc. Therefore, after data imputation, other models such as neural networks were attempted, comparing different imputation methods such as mean imputation, maximum likelihood estimation, and multiple imputation, to improve accuracy and reliability.

4. Results and Discussion

4.1. Calculation Results and Analysis of the Water Footprint of the Yangtze River Basin

4.1.1. Analysis of Water Footprint Results by Province

Table 2. Water footprint measurement results of 11 provinces and cities in the Yangtze River Basin from 2011 to 2021. Unit: billion m³.

Year	2011	2012	2013	2014	2015	2016	2017	2018	2019	2020	2021	Average
Shanghai	16.54	15.59	16.09	14.83	14.25	13.68	13.53	13.31	12.66	12.35	13.21	14.19
Jiangsu	116.09	118.70	122.50	125.96	127.50	127.15	127.04	127.30	127.04	126.65	131.10	125.18
Anhui	100.75	106.67	107.50	112.07	116.36	105.93	104.97	105.59	105.55	105.95	110.96	107.48
Jiangxi	68.55	70.23	72.43	74.31	75.57	75.02	75.04	74.53	73.18	72.49	77.13	73.50
Hubei	107.57	112.23	114.01	117.55	122.84	121.85	120.52	120.26	116.74	117.00	126.71	117.93
Hunan	104.63	107.64	107.93	111.18	113.19	113.29	113.76	114.87	111.64	111.21	119.49	111.71
Chongqing	35.50	36.15	37.37	38.30	38.92	39.52	39.21	39.77	39.70	39.34	42.09	38.72
Sichuan	116.47	118.26	121.30	122.76	126.76	128.93	128.68	130.14	127.42	130.64	136.77	126.19
Yunnan	54.46	57.82	59.81	62.89	64.00	64.98	67.65	68.82	69.14	71.57	78.01	65.38
Xizang	6.92	6.91	7.14	7.10	7.38	7.53	8.55	8.11	8.28	8.30	8.26	7.68
Qinghai	8.74	8.70	8.83	9.03	9.37	9.68	9.82	9.93	10.49	11.12	11.56	9.75
total	736.21	758.92	774.90	795.98	816.14	807.55	808.76	812.62	801.85	806.61	855.31	797.71

presents the water footprint results for the eleven provinces in the Yangtze River Basin, from 2011 to 2021, calculated using Equation (1). It can be observed from Table 2 that the overall average water footprint for the eleven provinces in the Yangtze River Basin, from 2011 to 2021, is 797.71 billion m³. Figure 2 is based on the annual average of the total water footprint for the eleven provinces in the Yangtze River Basin from 2011 to 2021. According to the trend shown in Figure 2, the evolution of the water footprint in the Yangtze River Basin during the study period experienced two phases. The first phase, from 2011 to 2015, saw a rapid increase in the water footprint of the Yangtze River Basin, rising from 716.44 billion m³ to 816.14 billion m³, an increase of 13.92%. Against the backdrop of the central government’s comprehensive implementation of a package of policies, the economic development level in the Yangtze River Basin steadily grew, reflected in the accelerated rise of the water footprint. The second phase spans from 2016 to 2021. With the economic growth rate slowing down and the continuous optimization of the economic structure following the entry into the new normal, the water footprint of the Yangtze River Basin has shown a fluctuating upward trend. There was a significant decrease in 2016, followed by a gradual recovery, reaching 812.62 billion m³ in 2018. In 2019, it declined to 801.85 billion m³, and then continued to rise, reaching 855.31 billion m³ in 2021.

In terms of spatial distribution, the eleven provinces in the Yangtze River Basin can be categorized based on geographical location into the upstream regions (Qinghai, Tibet, Yunnan, Sichuan, Chongqing), the midstream regions (Hunan, Hubei, Jiangxi, Anhui), and the downstream regions (Jiangsu, Shanghai). Figure 3 illustrates the average annual total water footprint for each of the upstream, midstream, and downstream regions. It can be observed from the figure that the average water footprint shows a decreasing distribution of “midstream—downstream—upstream”. In 2015, the water footprint in the upper, middle, and lower reaches of the Yangtze River basin increased compared to 2010, with the upper reaches experiencing the largest increase of 21.56%, followed by the middle reaches at 9.56%, and the lower reaches with the smallest increase of 6.42%. This is closely related to China’s development strategy and the economic development of the Yangtze River basin: the upstream region has unique geological and geomorphological characteristics, a high proportion of the primary industry, a gradually developing secondary industry, abundant natural resources, a significant share of heavy industry, and a fragile ecological environment. While promoting the rise of emerging industries through digital intelligence technology, it is also necessary to restrain the disorderly expansion of heavy chemical industries; additionally, the high altitude results in low population density and relatively slow economic development, with a historically low water footprint. However, under the continuous promotion of the national high-quality development strategy, regional economic development has been significant, with the green new energy industry rising, gradually transforming from traditional agriculture to a dual-driven model of industry and services, and the effects of regional cooperation and industrial chain coordination are evident, leading to the largest increase in water footprint. The midstream region, benefiting from its superior geographical location and water resource conditions, has promoted the development of various industries, forming a complete industrial system with a high proportion of the secondary industry. Each province has its own industrial characteristics: Hubei Province’s leading industries include automobile manufacturing, equipment manufacturing, steel, and textiles; Hunan Province’s leading industries include machinery, food, building materials, electronic information, and tourism; Anhui Province’s leading industries include electronic information, automobile manufacturing, equipment manufacturing, and energy; Jiangxi Province’s leading industries include electronic information, automobile manufacturing, building materials, and aviation. The well-developed water conservancy facilities and strong agricultural foundation make the midstream region an important grain and cotton production area, with the output value of the primary industry exceeding the national average, thus resulting in the highest total regional water footprint. In recent years, the midstream has exhibited significant industrial cluster effects and active regional cooperation, shaping a unique industrial development pattern, with a certain increase in the water footprint. The downstream region is economically developed but suffers from severe water quality issues. Centered around Shanghai, the tertiary industry accounts for a very high proportion, with modern service industries highly developed and high-tech industries rising, while still retaining some high-end manufacturing. The highly optimized industrial structure, efficient use of water resources, and the strictest implementation of water resource management systems have resulted in a total water footprint that is relatively lower than that of the midstream region, with a modest increase. From the perspective of provinces, the Yangtze River Basin exhibits characteristics of significant water footprints in major agricultural and populous provinces. For instance, the water footprints of Jiangsu, Anhui, Hubei, Hunan, and Sichuan are notably higher than the average level of the Yangtze River Basin, with Sichuan having the largest water footprint, averaging 126.19 billion m³ over the years. In contrast, Tibet and Qinghai have relatively smaller water footprints, with Tibet being the province with the smallest water footprint in the Yangtze River Basin, averaging 7.68 billion m³ over the years.

4.1.2. Spatial and Temporal Analysis of Water Footprint Measurement Results by Industry

Table 3. Trend of water footprint change by industry in the Yangtze River Basin, 2011–2021. Unit: billion m³.

Year	2011	2012	2013	2014	2015	2016	2017	2018	2019	2020	2021	Average
Water footprint of agriculturaland livestock product	626.00	651.50	665.72	688.88	705.84	695.59	697.03	699.87	690.12	704.17	746.12	688.26
Industrial product water footprint	78.11	76.98	77.44	74.62	75.74	75.86	74.85	74.38	72.50	62.19	65.41	73.46
Domestic water footprint	30.38	28.64	29.69	30.37	32.33	33.54	34.20	35.41	35.88	35.33	36.98	32.98
Ecological water footprint	1.72	1.80	2.05	2.11	2.23	2.56	2.68	2.96	3.35	4.92	6.80	3.02
Total	736.21	758.92	774.90	795.98	816.14	807.55	808.76	812.62	801.85	806.61	855.31	797.71

illustrates the dynamic changes in the water footprint of various industries in the Yangtze River Basin from 2011 to 2021. The total water footprint for each industry in a given year is derived from the sum of the water footprints of each province. The agricultural water footprint is calculated based on Equation (2), and its data, along with the water footprints of other industries, are sourced from the provincial water resource bulletins. The water footprint of agricultural and livestock products is the largest, accounting for 86.28% of the total water footprint; the water footprint of industrial products follows, making up 9.21% of the total; while the domestic and ecological water footprints are relatively small, comprising only 4.13% and 0.38% of the total water footprint, respectively. The water usage for agricultural and livestock products is a primary aspect of water resource utilization in the Yangtze River Basin. As shown in Figure 4, from 2011 to 2015, the water footprint of agricultural and livestock products exhibited an increasing trend. Between 2016 and 2020, it fluctuated between 690.12 billion m³ and 704.17 billion m³, rising to 746.12 billion m³ in 2021. During the study period, the water footprint of industrial products showed a fluctuating downward trend, attributed to the enhancement of sustainable development concepts in the Yangtze River Basin and adjustments in industrial structure.

The average water footprint of various industries across the provinces in the Yangtze River Basin over an 11-year period is shown in Figure 5. The construction of the Three Gorges Dam plays a crucial role in the allocation of water resources in the Yangtze River Basin and is an important guarantee for the high-quality agricultural development in regions such as Jiangsu, Anhui, Hunan, and Hubei, which are also significant grain-producing areas in China. Consequently, the water footprints of agricultural and livestock products in Jiangsu, Anhui, Hubei, Hunan, and Sichuan are relatively high, directly leading to a higher overall water footprint in these regions. Jiangsu has the largest industrial product water footprint and domestic water footprint within the Yangtze River Basin. As an important province in China’s economy, it boasts a highly developed manufacturing industry, a high level of urbanization, and an increase in residents’ living standards, which, along with industrial concentration and population aggregation, has driven the growth of domestic water demand, resulting in a correspondingly high water footprint. Tibet and Qinghai, located in the Qinghai–Tibet Plateau, have abundant water resources primarily distributed in river sources and glaciers, but the actual available freshwater resources are relatively limited. The high altitude and cold climate conditions restrict the development of certain industries. Low population density, relatively underdeveloped economy, and a weak industrial foundation all contribute to lower water footprints for both industrial products and domestic use. Furthermore, the ecological water footprints of the provinces in the Yangtze River Basin are relatively low, accounting for the smallest proportion of the overall water footprint.

4.2. Calculation Results of Water Footprint Ecological Load Index

The changes in the water footprint ecological load index across eleven provinces in the Yangtze River Basin from 2011–2021 are shown in Figure 6 and Figure 7. The data are calculated according to Equation (3), and since the units for both sides of the ratio are billion m³, this index is not listed with units. Given that the ecological load index of the water footprint in Shanghai and Jiangsu provinces is significantly higher than that of the other nine provinces, this paper employs two graphs to distinctly reflect the dynamic changes of Shanghai and Jiangsu and the remaining nine provinces. Shown in Figure 6 is Shanghai and Jiangsu, the other nine regions are depicted in Figure 7. Except for Shanghai, which fluctuates greatly, all other provinces have small fluctuation trends, and most of them show fluctuating decreasing trends.

In terms of spatial distribution, there are significant differences between different provinces within the Yangtze River Basin. As shown in Figure 8, the average water footprint ecological load index over 11 years for the eleven provinces is categorized into five classes using the natural segment point method; the first category is an ultra-high load zone, such as Shanghai, where the water footprint ecological load index is 23.12, far exceeding the average level of the Yangtze River Basin. Although Shanghai has a relatively low water footprint due to its highly optimized industrial structure compared to other mid and lower reach provinces, which indicates an efficient utilization of water resources, the total amount of water resources in Shanghai, which meet or exceed Class III water quality standards, is small, resulting in the highest ecological load index of the water footprint and significant environmental pressure on water resources. The second category is the area with high load, such as Jiangsu. The ecological load index of Jiangsu’s water footprint has been relatively high over the years, primarily due to its developed manufacturing industry, industrial concentration, dense urban areas along the river, and high population density. As a result, Jiangsu’s water footprint exceeds that of other midstream and downstream provinces, coupled with limited compliant water volume, leading to a higher load index. The third category is the moderate load area, which includes Anhui and Hubei, where the rapid industrialization and urbanization processes, along with significant grain production bases, have led to an increasing demand for water resources. The fourth category is the low load area, which includes Jiangxi, Hunan, Chongqing, Sichuan, and Yunnan. In these five regions, water resources are relatively abundant, and the population density is relatively low. There are fewer high-water-consuming industries, and the total amount of compliant water resources is also relatively high, resulting in a relatively low ecological load index of the water footprint. The fifth category is the ultra-low load area, including the provinces of Tibet and Qinghai. These regions possess rich water resources in river sources and glaciers, have a relatively large environmental capacity, and the high altitude and cold climate conditions contribute to a lower population density and underdeveloped economy, thus resulting in less environmental pressure on water resources (

Table 4. Water footprint ecological load index of the Yangtze River Basin from 2011 to 2021.

Year	2011	2012	2013	2014	2015	2016	2017	2018	2019	2020	2021	Average
Shanghai	69.43	38.71	48.01	14.97	17.53	16.03	20.97	15.29	6.41	3.34	3.60	23.118
Jiangsu	2.91	4.25	6.06	4.25	2.75	2.10	4.30	4.63	7.79	2.60	2.96	4.056
Anhui	2.16	1.94	2.47	1.93	1.62	1.07	1.66	1.54	2.42	0.96	1.50	1.752
Jiangxi	0.67	0.33	0.60	0.54	0.38	0.34	0.46	0.66	0.36	0.43	0.55	0.484
Hubei	1.48	1.43	1.51	1.33	1.25	0.83	0.99	1.46	2.00	0.67	1.08	1.275
Hunan	0.93	0.54	0.69	0.62	0.59	0.52	0.60	0.86	0.53	0.53	0.67	0.644
Chongqing	0.69	0.76	0.79	0.60	0.85	0.65	0.60	0.76	0.80	0.51	0.56	0.688
Sichuan	0.52	0.41	0.49	0.48	0.57	0.55	0.52	0.44	0.46	0.40	0.47	0.484
Yunnan	0.75	0.68	0.69	0.63	0.53	0.48	0.45	0.43	0.61	0.50	0.59	0.577
Xizang	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.017
Qinghai	0.12	0.10	0.14	0.12	0.16	0.16	0.13	0.11	0.12	0.11	0.14	0.128

).

4.3. Analysis of the Coordinated Relationship Between Water Resource Utilization and Economic Development in the Yangtze River Basin

According to Equation (5) and the relevant data on the water footprint of the Yangtze River Basin during the period of 2011–2021, the GDP growth rate, the water footprint growth rate, decoupling index, and corresponding analysis results for the Yangtze River Basin during this period can be obtained, as shown in

Table 5. Evaluation of the relationship between water resource utilization and economic development in the Yangtze River Basin, 2011–2021.

Year	Rate of Change in GDP (%)	Rate of Change in Water Footprint (%)	Decoupling Index	Evaluation Results
2011	20.97	2.61	0.18	Relative decoupling, primary coordination
2012	12.45	1.93	0.11	Relative decoupling, primary coordination
2013	12.20	2.40	0.10	Relative decoupling, primary coordination
2014	10.03	1.67	0.08	Relative decoupling, primary coordination
2015	8.00	2.14	0.06	Relative decoupling, primary coordination
2016	10.31	−0.42	0.11	Absolute decoupling, high-quality coordination
2017	11.64	1.40	0.10	Relative decoupling, primary coordination
2018	11.38	−0.05	0.11	Absolute decoupling, high-quality coordination
2019	8.32	−0.61	0.09	Absolute decoupling, high-quality coordination
2020	4.02	0.72	0.03	Relative decoupling, primary coordination
2021	12.05	5.60	0.06	Relative decoupling, primary coordination

. It can be observed that the GDP variation rate in the Yangtze River Basin from 2011 to 2021 has always been a positive number. In other words, the overall GDP of the Yangtze River Basin has increased compared to the previous year over the years. The largest increase occurred in 2011, with a GDP growth rate of 20.97%, while the smallest increase was in 2015, with an 8.00% growth compared to the previous year. Meanwhile, from 2011 to 2021, the overall water footprint growth rate of the Yangtze River Basin was positive in all years except for 2016, 2018, and 2019, which recorded negative values. Among these, the largest increase occurred in 2021, with a growth of 5.60%, while the smallest change was in 2020, with an increase of only 0.72%. Based on the calculations of GDP growth rate and water footprint growth rate, combined with Equation (5), the decoupling index of the Yangtze River Basin over the years was derived, leading to the following conclusion: overall, there was no state of imbalance in the Yangtze River Basin from 2011 to 2021. In 2016, 2018, and 2019, it was in a high-quality coordinated state, meaning that while the economy was growing, the rate of water resource consumption decreased; in the other years, it was in a primary coordinated state, indicating that while the economy was growing, water resource consumption increased at a lower rate.

4.4. Ecological Compensation Standards and Spatial Analysis Among Provinces in the Yangtze River Basin

By consulting relevant statistical data, it can be concluded that the average price for the utilization of surface and groundwater resources in the eleven provincial-level administrative regions of the Yangtze River Basin is V = 0.15 yuan/m³.

Based on the aforementioned quantitative accounting results of the water footprint in various administrative regions of the Yangtze River Basin, it is possible to derive the identities of compensation subjects and objects, ecological compensation standards, and their dynamic changes during the period from 2011 to 2021. The compensation standards listed in

Table 6. Ecological compensation standards for 11 provinces in the Yangtze River basin. Unit: CNY billion.

Year	Shanghai	Jiangsu	Anhui	Jiangxi	Hubei	Hunan	Chongqing	Sichuan	Yunnan	Xizang	Qinghai
2011	−2.19	−12.96	−9.51	−2.21	−10.11	−7.04	−1.39	−0.35	8.72	32.61	4.42
2012	−1.86	−14.61	−10.22	3.49	−11.39	−3.40	−2.38	0.72	9.39	25.72	4.54
2013	−2.02	−15.67	−10.68	1.27	−11.05	−4.52	−2.12	−0.06	9.98	31.33	3.54
2014	−1.60	−15.31	−9.84	2.12	−11.10	−4.21	−1.32	−0.78	8.40	29.37	4.26
2015	−1.24	−13.93	−9.22	3.52	−10.73	−2.81	−2.48	−2.67	9.26	27.23	3.08
2016	−1.21	−13.39	−6.14	2.28	−8.99	−3.70	−2.29	−5.23	9.40	26.83	2.43
2017	−1.57	−15.62	−9.24	−0.07	−9.51	−4.26	−1.51	−2.84	10.30	30.38	3.94
2018	−1.48	−15.57	−8.65	−2.77	−11.64	−7.53	−2.20	1.71	10.27	32.26	5.60
2019	−1.33	−16.84	−11.10	4.12	−12.81	−1.40	−2.32	0.93	3.93	31.53	5.29
2020	−1.30	−15.18	−6.57	−0.44	−6.69	−3.71	−1.23	0.13	3.57	26.75	4.69
2021	−1.45	−15.44	−8.89	−0.67	−9.87	−4.31	−0.63	1.65	2.66	32.16	4.78

represent the compensation amounts that should be obtained, calculated using Formulas (6)–(8). When the value is positive, it indicates that the water resource utilization status of the administrative region is in “surplus”, and it is determined to be a compensation object, thus entitled to ecological compensation; conversely, when the compensation standard value is negative, it indicates that the water resource utilization status of the administrative region is in a “deficit”, and it is determined to be a compensation subject, thus required to pay ecological compensation.

According to the statistical data from Table 6, the compensation standards for Qinghai, Tibet, and Yunnan have been positive over the years, indicating that they should be compensated as compensation objects. In contrast, the compensation standards for Shanghai, Jiangsu, Anhui, Hubei, Hunan, and Chongqing have been negative over the years, indicating that they should pay compensation as compensation subjects. The remaining provinces, Jiangxi and Sichuan, have had both positive and negative ecological compensation standards from 2011 to 2021, resulting in inconsistent identities of compensation subjects and objects in different years. Specifically, Sichuan has been a compensation subject for 7 out of the 11 years, except for 2012 and the years 2018, 2019, 2020, and 2021, which were negative. Jiangxi, on the other hand, has been a compensation object for 7 out of the 11 years, except for 2011, 2017, 2018, and the years 2020 and 2021, which were positive.

From an annual perspective, eleven provinces have consistently had regions designated as compensation subjects or objects over the years. The years with the highest number of provinces designated as compensation subjects were 2011 and 2017, with three provinces designated as compensation objects, while the rest were compensation subjects. Based on the statistical results and the analysis above, it can be concluded that between 2011 and 2021, the majority of the eleven provinces in the Yangtze River Basin were compensation subjects, with three provinces consistently being compensation objects and eight provinces having instances of being compensation subjects, bearing greater pressure in terms of water resource utilization. The regional differences in compensation standards are influenced by factors such as the ecological environment, economic structure, and water resource utilization patterns of each area. The main objects of ecological compensation are primarily the provinces in upstream areas, while the compensation subjects are mostly concentrated in the midstream and downstream regions. To promote coordinated and sustainable regional development, it is necessary to adhere to the differences in ecological and economic models of each region. The ecological environment in upstream areas is weak, necessitating restrictions on the development of livestock farming and high-pollution industries. The midstream regions, while accelerating industrialization and urbanization, need to focus on balancing economic and ecological aspects. For instance, the construction of water conservancy projects not only promotes agricultural development but also enhances the utilization of water resources. Yunnan, as a compensation subject, fully leverages its biodiversity advantages to coordinate the development of ecology and economy. In downstream areas, where industries are concentrated and the population is dense, the costs of ecological compensation are gradually increasing. It is possible to reduce the water footprint through technological innovation and actively participate in ecological restoration projects. How to better align ecological compensation standards with local economic and social development strategies will be discussed in detail in the next section.

To facilitate analysis, the eleven provinces in the Yangtze River Basin are divided into two categories. The first category includes provinces that have experienced negative compensation standards in previous years, namely Shanghai, Jiangsu, Anhui, Jiangxi, Hubei, Hunan, Chongqing, and Sichuan, totaling eight administrative regions. The second category consists of provinces where the compensation standards have been positive in all previous years, including Yunnan, Tibet, and Qinghai, which are three administrative regions. According to the data in Table 6, the dynamic changes in compensation standards for the two categories of provincial administrative regions from 2011 to 2021 are illustrated in Figure 9 and Figure 10.

(1)

Provinces where the compensation standard has previously shown negative values

As shown in Figure 9, from the perspective of the first category, Shanghai, Jiangsu, Anhui, Hubei, Hunan, and Chongqing have been identified as compensation subjects over the years. Among them, Jiangsu has a large economic scale, maintaining a strong growth trend for many years. The industrial proportion in its industrial structure is high, with a highly developed manufacturing sector, a large population, and a dense urban belt along the river, all contributing to its consistently high water footprint. The compensation amount it needs to pay ranks first, with a minimum of CNY 12.96 billion and a maximum of CNY 16.84 billion over the years, averaging CNY 14.96 billion. In contrast, Shanghai has a highly optimized industrial structure, a relatively small water footprint, and efficient water resource management, resulting in a high water resource utilization efficiency. The compensation amount it needs to pay has a minimum of CNY 1.21 billion, a maximum of CNY 2.19 billion, and an average of CNY 1.57 billion. Secondly, among the provinces where both positive and negative values have appeared in the compensation standards, Sichuan has 6 years requiring compensation, with a maximum of CNY 5.23 billion and a minimum of CNY 60 million; Jiangxi has a total of 5 years requiring compensation, with a maximum of CNY 2.77 billion and a minimum of CNY 7 million. Among them, Jiangsu Province has the highest compensation amount as the compensating subject, with payments far exceeding those of the other seven provinces; Hubei ranks second as the compensating subject, and Anhui ranks third, closely related to the rapid economic development driven by the rise of industrial sectors and strong high-end manufacturing in these two provinces; the significant demand for water resources is attributed to its status as an important grain production base and the ongoing processes of industrialization and urbanization; Shanghai, as the compensating subject, has a relatively small compensation amount. It can be concluded that provincial-level administrative regions with a higher number of years and larger compensation amounts as compensating subjects are predominantly distributed in the midstream and downstream areas.

(2)

Provinces where the compensation standard has consistently been positive over the years

As shown in Figure 10, from the perspective of the second category, among the three administrative regions that should receive compensation, the ranking according to the average compensation standards from high to low is as follows: Tibet, Yunnan, and Qinghai. Tibet and Qinghai are located in the Qinghai–Tibet Plateau, where the population density is low and the ecological environment is fragile. The Qinghai–Tibet Plateau, as the source of the Yangtze River, possesses abundant water resources, with significant value in climate regulation and ecological protection. Yunnan is a hotspot for biodiversity, containing multiple national nature reserves and ecological function areas, and also has demands for water resources and ecological protection. Among them, the highest compensation standard amount that Tibet should receive is CNY 32.61 billion, the lowest is CNY 25.72 billion, and the average is CNY 29.65 billion; the highest compensation standard amount that Yunnan should receive is CNY 10.3 billion, the lowest is CNY 2.66 billion, and the average is CNY 7.81 billion; the highest compensation standard amount that Qinghai should receive is CNY 5.6 billion, the lowest is CNY 2.43 billion, and the average is CNY 4.23 billion.

The trends shown in Figure 10 indicate that between 2011 and 2021, there were significant differences in compensation standards among various provincial administrative regions in the Yangtze River Basin that should receive compensation. The disparity in compensation standards within the same administrative region across different years was also considerable. Among them, Yunnan exhibited the largest fluctuation, with the highest and lowest compensation amounts differing by a factor of 3.87; Qinghai followed closely, with a difference of 2.31 times between the highest and lowest compensation amounts over the years. Due to their important and unique geographical environments, Tibet and Qinghai, which are rich in water resources but have fragile ecological environments, low population densities, and underdeveloped industries, require greater investment in water resource ecological protection. Therefore, long-term and stable ecological compensation policies need to be implemented to ensure sustainable ecological protection. Yunnan, with its biodiversity, includes several national nature reserves and ecological functional areas, and its complex and sensitive ecological environment will place greater emphasis on promoting a balance between ecology and economy in its ecological compensation mechanism, with compensation amounts adjusted according to economic development needs and ecological protection outcomes. Based on the statistical results and the analysis above, it can be concluded that between 2011 and 2021, there is significant differences in the compensation standards among different administrative regions in the Yangtze River Basin, as well as within the same administrative region across different years. Notably, Tibet, as the object of compensation, ranked among the highest in terms of compensation standards, with amounts far exceeding those of other regions. Additionally, it is evident that provincial-level administrative regions with higher compensation amounts are generally distributed in the upstream areas.

(3)

Analysis of ecological compensation type transfer

According to the measurement results of the ecological compensation standards in eleven provinces of the Yangtze River Basin, they are divided into four categories: high payment regions, low payment regions, high compensation regions, and low compensation regions. Figure 11, Figure 12 and Figure 13, respectively, represent the distribution of ecological compensation types in the eleven provinces for the years 2011, 2016, and 2021. From the perspective of structural hierarchy distribution, the high payment regions and low payment regions account for a significant proportion in the horizontal ecological compensation types, while the proportions of high compensation regions and low compensation regions have consistently remained small. In terms of development trends, the number of low payment regions and high compensation regions is gradually decreasing, while the number of low compensation regions is gradually increasing. Among them, Sichuan, being located in the upper reaches of the Yangtze River and an important grain production base, has seen its traditional liquor industry continuously inherit and innovate alongside further improvements in infrastructure, with technology empowering intelligent manufacturing to lead economic growth. With the continuous promotion of the horizontal ecological protection compensation mechanism, cross-provincial ecological protection compensation cooperation is encouraged through fiscal transfer payments, incentive policies, and other means, transforming from initially low payment regions to low compensation regions, and shifting from compensation subjects to compensation objects.

4.5. Suggestions for the Implementation of Ecological Compensation in River Basins

With the development of society, various technologies, including remote sensing, GIS, and big data, have been employed to monitor and quantify water resource-related data more accurately. This provides reliable data support for the method proposed in this paper, which determines the compensation subject and object based on the calculation of ecological surplus and deficit of water resources. This method is more suitable for regions with differences in economic development and water footprints, emphasizing the balance of interests between compensation subjects and objects, which is conducive to promoting cooperation among various regions within the river basin. However, during the implementation process, issues such as inter-regional coordination and the supervision and enforcement of compensation mechanisms are unavoidable. The following suggestions are proposed to address these issues:

First, coordinate the ecological cooperation and construction among various administrative regions within the basin, and improve the horizontal ecological protection compensation mechanism. The management institutions of the Yangtze River Basin still face issues such as weak management and unclear responsibilities. The Yangtze River Basin is characterized by strong comprehensiveness, wide coverage, long duration, and complex administrative divisions. Therefore, it is crucial to break the predicament of fragmented management and self-governance among different regions of the large basin. Within the framework of sustainable development, government departments should adhere to the principle of “whoever damages compensates, whoever protects is compensated”, clarify the ecological compensation assessment objectives for the Yangtze River Basin, refine and standardize the regulations on horizontal ecological compensation among provincial regions within the basin as outlined in the Yangtze River Protection Law, and promote comprehensive coverage of horizontal compensation in the Yangtze River Basin.

Secondly, it is essential to continuously improve the overall system for ecological compensation payments. The status of water resource utilization and the identities of the compensation subjects and objects in the Yangtze River Basin vary dynamically from year to year. The compensation standards are calculated based on the spatial units of the basin, covering not only basic elements such as water quality and quantity but also considering the functions of other environmental factors in the ecological protection of the basin. It is evident that the payment and acquisition of ecological compensation in the Yangtze River Basin is a complex undertaking. Therefore, to ensure the smooth payment and acquisition of ecological compensation amounts, it is necessary for government departments to establish and continuously improve the overall system for ecological compensation payments, build a horizontal ecological compensation big data platform, fully leverage the coordinating role of the Yangtze River Water Resources Commission in the basin, and utilize the mechanism of the provincial river and lake chiefs’ joint conference in the Yangtze River Basin for unified coordination and management of compensation funds throughout the basin. Regions can jointly contribute to establish a horizontal ecological compensation fund for the Yangtze River Basin, with benefits tilted towards areas that “protect well and contribute significantly”, thereby enhancing the positive incentive effects of the compensation mechanism on the Yangtze River Basin.

Thirdly, a diversified ecological compensation model should be established to broaden compensation channels through the industrial chain. On one hand, the regions receiving compensation can comprehensively choose from various ecological compensation models, including financial compensation, policy compensation, industrial compensation, and technological compensation. For instance, they can actively collaborate with upstream and downstream administrative regions within the watershed to develop in different locations, attract enterprises and talent, jointly construct digital infrastructure for the upstream and downstream of the watershed, focus on the research and development of key core technologies in the region, empower the development of green industrial clusters in the watershed with digital technology, and foster new industries, new business formats, and new models in the watershed, thereby driving employment and fiscal revenue for residents in water environment protection areas. On the other hand, in addition to the singular fiscal transfer payments between various administrative district governments, joint efforts and means should be utilized for collective fundraising. This can be achieved by charging environmental taxes, water resource compensation taxes, etc., to make water resource users pay, and exploring the establishment of market trading mechanisms for cross-regional pollutant discharge rights, carbon emission rights, and water usage rights. Additionally, the establishment of ecological banks can be explored to promote the development of green funds, green credit, and green bonds, attracting investors through market-oriented approaches, and encouraging social capital to participate in the management and development of ecological products such as ecological protection and restoration projects, the integrated development of tourism and leisure, and green low-carbon industries, thus promoting the realization of the value of ecological products in the watershed and further advancing and ensuring the sustainability of large-scale ecological protection efforts in the watershed.

Finally, the ecological compensation standards should be integrated with regional economic development strategies. The ecological compensation standards will vary by region due to differences in ecological environments, economic structures, and water resource utilization patterns. Therefore, their formulation must consider the disparities in ecological status, economic models, conservation investments, and opportunity costs for development across different regions. However, the ecological compensation in the Yangtze River Basin is extensive, with rich compensation content but insufficient funding. Based on the “Yangtze River Protection Law”, the following explorations can be conducted in conjunction with economic development strategies: (1) In the upstream regions where the ecological environment is weak, limiting the development of agriculture, animal husbandry, and high-pollution industries, a collaborative working mechanism can be established in the upper reaches of the Yangtze River, utilizing plans such as the “Outline of the Yangtze Economic Belt Development Plan” and the “Construction Plan for the ‘Six Rivers’ Ecological Corridor in the Chengdu–Chongqing Economic Circle (2022–2035)” to strengthen the ecological barrier and create new opportunities for green development by constructing large-scale wind and photovoltaic energy projects in desert and Gobi regions. (2) The midstream regions should continue to optimize the coordinated development of economic growth and ecological protection. Guided by the main functional area planning, development intensity should be controlled, promoting a circular economy and advancing traditional industries towards intelligent, green, and high-end directions while vigorously cultivating cutting-edge technology industries. New paths for ecological priority and green development should be explored, and mechanisms for realizing the value of ecological products should be accelerated. For instance, Yunnan can fully utilize its biodiversity advantages to coordinate the development of ecological economy. As one of the important grain bases in China, the midstream regions can focus on grain production and circulation construction, utilizing modern information technology to optimize the agricultural product supply system and encourage cooperation with sales enterprises in brand building and market expansion. (3) In the downstream regions, where industries are concentrated and the population is dense, the cost of ecological compensation is gradually increasing. Building on the continuous implementation of the “Yangtze River Delta Integration Development”, the focus should be on cultivating new productive forces, promoting cross-regional collaboration around technological and industrial innovation, conserving and intensively utilizing water resources, reducing water footprints, actively participating in ecological restoration projects, and deepening regional cooperation to enable the wealthier regions to support the less affluent. (4) In terms of coordinated governance across the entire basin, the state has clarified the overall layout of major projects for the protection and restoration of important national ecosystems, centered on the “Three Zones and Four Belts”, which includes the ecological barrier area of the Qinghai–Tibet Plateau, key ecological areas of the Yangtze River, southern hilly mountainous areas, and coastal areas. At the same time, the coordinated economic development of the Yangtze River Basin faces several challenges: the unbalanced development between the upper, middle, and lower reaches, with significant disparities in consumption income, public services, and infrastructure; and certain special areas such as ecologically degraded regions, border areas, and resource-based areas are relatively underdeveloped, with a single industrial structure, posing significant challenges to regional development. Therefore, promoting refined zoning management across the entire Yangtze River Basin, implementing comprehensive policies, and coordinating the unified protection, restoration, and governance of ecological elements such as mountains, waters, forests, fields, lakes, and grasslands remain important pathways for the economic development and ecological protection of the Yangtze River Basin.

5. Conclusions and Prospect

5.1. Conclusions

This paper adopts the water footprint–decoupling analysis method to formulate a more scientific and rational ecological compensation standard for the Yangtze River Basin. Research indicates that from 2011 to 2021, the overall water footprint in the Yangtze River Basin, and its various administrative regions, exhibited a growth trend, with significant disparities in water footprint quantities among different administrative regions. In terms of average water footprints from upstream to downstream, a decreasing distribution of “midstream—downstream—upstream” is observed. Agriculture contributes the highest amount to the total water footprint, followed by industrial and domestic water footprints, with ecological water footprints being the lowest. There are notable differences in the water footprint load index among the eleven provinces and municipalities in the Yangtze River Basin, showing a trend of higher values in the east and lower values in the west. Among these, Tibet, Yunnan, and Qinghai have consistently been regions receiving ecological compensation, while Shanghai, Jiangsu, Anhui, Hubei, Hunan, and Chongqing have been determined as compensation subjects required to pay compensation over the years. It is evident that the compensation subjects required to pay are predominantly located in the midstream and downstream areas, while the regions receiving compensation are generally found in the upstream areas. To encourage regions with ecological surpluses to enhance the protection of water ecological environments, and to achieve fairness and efficiency in the development of the Yangtze River Economic Belt, regions with water ecological deficits should compensate regions with water ecological surpluses for the protection of water resource ecological environments. The ecological compensation model calculates the ecological compensation standards for the eleven provinces in the Yangtze River Basin, providing a reference for the amounts of ecological compensation received and paid by each province.

5.2. Limitations

Although the research presented in this paper has achieved certain results, there are still some limitations, such as the following:

(1)

The cultural, social, and other values that may be included in the value of water resources are difficult to quantify accurately.

(2)

This paper utilized data from 2011 to 2021, which can be further updated.

(3)

The collection of data on water footprints in remote or complex areas poses certain challenges.

5.3. Prospect

Based on existing scholars, this paper establishes a quantitative model of ecological compensation based on the calculation of water resource surplus and deficit status. In the subsequent research, the research subject can be further subdivided, allowing for an in-depth analysis of the social and cultural factors in various regions, comprehensively considering the cultural and other values of water resources in the region, and exploring the applicability of this method in other river basins from multiple perspectives.