Synergy Assessment of River Health Values from a Symbiotic Perspective: A Case Study of the Yellow River Basin in China

Abstract

Rivers are important carriers of water transmission, water supply, and water nourishment, and the virtuous cycle of their ecosystems is directly related to the degree of completion of the construction of ecological civilization and the high-quality development of the national economy. From the perspective of symbiosis theory, this paper constructs a river health value assessment index system and analyzes the symbiotic synergistic effect of nine provinces in the Yellow River Basin in China from 2000 to 2020 by using a logistic symbiosis evolution model. Health values at the Yellow River Basin scale and the provincial administrative area scale were also analyzed, and it was found that (1) the Yellow River Basin experienced a period of sub-par river health in the past, but with the implementation of ecological protection and high-quality development strategy in recent years, the health of the river showed an trend of improvement during the period of 2017–2020; (2) at the provincial administrative scale, the Yellow River Basin has significant differences, which are manifested in the obvious differences between provinces in terms of the functional value of river health provision and the economic functional value. In order to reduce the regional differences, it is recommended that the provinces work together and give full play to their own characteristics and strengths in the management of the watershed, so as to make up for the weaknesses of regional development and realize the synergistic development of the watershed; and (3) in terms of symbiosis level, rivers in the Yellow River Basin generally show parasitic relationships, and most of them exhibit natural ecological diversity and competitiveness with socio-economics. Therefore, a more comprehensive consideration of the balanced development of each function is needed in river health management in the future to achieve integrated watershed health. These results suggest that the development of river ecological health in the Yellow River Basin requires the joint efforts of the whole of society as well as regional synergy and integrated management at the policy level to achieve more sustainable and balanced watershed development.

1. Introduction

Like the arteries of the earth, rivers are a source of life and civilization, forming an important part of the natural resources and ecosystems that provide a necessary basis for human survival. In the 1970s, the concept of river health was first proposed in the United States [1]. A healthy river is defined as one that achieves a balance or compromise between socio-economic, ecological, and environmental values and whose social and natural functions are developed in harmony [2]. The health value of a river reflects the human perception of its functioning; therefore, a healthy river should have both a high social service value and a high natural restoration value. However, in the context of high social and economic development, it has become increasingly difficult to realize the ideal river health value. River territory has undergone large-scale engineering construction, expanding service functions such as power generation, navigation, and aquaculture, addressing the resource needs of scientific and technological development, and meeting the needs of the urbanization process and economic development. At the same time, irrational development and utilization have also led to rivers facing crises, e.g., frequent water pollution accidents and deteriorating water quality and ecological environment along rivers, attracting widespread attention [3]. It can be seen that China is facing the double pressure of economic development and environmental protection, i.e., developing the economy while considering sustainable development and protecting the environment as much as possible. Under these circumstances, it is unreasonable to assess the value of river health by constructing river health value criteria only from a single perspective of economic development or environmental protection. Thus, scientific assessment of river health values and rational assessment of the trend of river health values in the natural ecological–socio-economic composite system are of great theoretical and practical significance for the discussion of these issues and the formulation of scientific river management objectives and decision-making bases.

The theory of ecosystem services originated in the 1960s and in recent years has been explored by the Daily [4] research group of the Ecological Society of America, which defines ecosystem services as the conditions and processes that natural ecosystems and their species can provide in order to meet the needs of human life. River ecosystem services are those benefits that humans derive directly or indirectly from river ecosystems. They include aquatic products, raw materials, and all direct or indirect services provided by rivers for human survival. In fact, a river ecosystem consists of a main river as the main running-water-type composite ecosystem, and the flow in the river channel is the first element of the formation of the river. River ecosystems are the main tool for the transportation of materials and energy and are an indispensable and important part of the global water cycle; with regulation, support, and improvement of the global ecological environment, the provision of water resources for human beings, the production of aquatic products and other service functions, as well as the utility of said service functions can be provided. The value of rivers’ service functions constitutes the value of river ecosystem services. Natural environment accounting is an emerging discipline and mainly involves the environmental management system of each accounting subject and the impact of economic activities on the environment. Based on this, ecological and environmental accounting is an accounting activity that combines accounting and environmental ecology from the perspective of social interests and maintenance of environmental and ecological balance; accordingly, this is used to assess the impact of socio-economic activities on the ecological environment. It entails assessing the value of assets, costs, benefits, etc., in the environment. However, it is very difficult to assess elements such as species disappearance, resource depletion, air pollution, and global warming in monetary terms and, thus, the principle of cost–benefit analysis is utilized to extrapolate the value of environmental assets, costs, benefits, etc., through supply and demand and known quantities and has become the main valuation method of environmental accounting. In 1879, Anton de Baty (de Berry) first introduced the concept of “symbiosis”, which is defined as different species living together [5]. The theory of symbiosis was initially proposed in the field of natural sciences and gradually applied to the field of social sciences, the essence of which lies in the formation of a specific symbiotic pattern between symbiotic units in a specific symbiotic environment. The three elements of symbiosis are the symbiotic unit, symbiotic pattern, and symbiotic environment. A river is a symbiotic system, and the natural ecosystem and socio-economic system of the river are symbiotic units within the system. River ecosystems are formed on the basis of symbiotic mechanisms, including soil, rocks, air, water, and organisms co-existing in a symbiotic system. The core concept of symbiosis is “the interdependence of living organisms for survival in a given area”, which is closely related to human survival and production activities. A river ecosystem is a self-regulating feedback system capable of evolving and developing through competition and symbiotic interactions [6]. Healthy river ecosystems not only have stable biochemical structures and excellent social service functions but also exhibit characteristics such as inclusiveness, openness, and sustainability. Therefore, in order to better plan the river channel management, improve the overall condition of water quality, promote the development of the ecological environment for the good, and realize the harmonious coexistence of humans and nature in the river basin, research on the value of river health is extremely important and necessary. Based on the above theoretical analysis, this paper constructs a theoretical analysis framework of a symbiotic-functional synergistic system for the health value of rivers, as shown in Figure 1.

At present, the academic community has yet to reach a unified conclusion on the criteria and assessment methods for river health. From a comprehensive point of view, the assessment of river health has relative characteristics, and different countries, regions, river sections, and types of rivers, faced with different economic development needs and human expectations, will require changes in river health assessment standards. Many indicators reflect the health of rivers, and the selection of indicators is a critical step in the assessment of river health, which is related to the scientificity and accuracy of the assessment results. Scholars at home and abroad have relentlessly explored the indicator systems reflecting river health status, such as Saxena et al. [7]. With sufficient scientific experience and understanding in this field, a river health index can be defined by taking algae, macroinvertebrates, and fish species as measurable parameters and conventional physicochemical characteristics of river water. Liu et al. [8], using tolerance values of macroinvertebrates and tolerance values related to biological indicators, investigated the ecological status of headwater streams, mainstems, and tributaries of the Yellow River in the upper reaches of the Yangtze River, and the bioindexes indicated that the ecological health of the upstream rivers was poorer than that of the downstream tributaries. Gao et al. [9] suggested that water pollution could be monitored by using indicator species, and they investigated the health status of rivers by using the data of four zooplankton surveys from China’s Pearl River Delta. The researchers found that the indicator species showed significant positive correlations with water body clarity, total nitrogen, and total phosphorus. Shan et al. [10] studied eight river flow characteristics—river morphology, flow, water quality, river habitat, aquatic organisms, riparian zones, flood safety, and water supply level—to establish a river health assessment index system. It was also applied to the health assessment of the Luan River subriver to verify the rationality of the indicator framework. The research results of river health value assessment methods at home and abroad can be categorized into three types: predictive modeling method, bio-index method, and multi-indicator assessment method. For example, Sadat et al. [11] proposed a combination of fuzzy material element (FME), harmony degree evaluation (HDE), and gray correlation analysis (GRA), which was used to map the health of the Gui, Nen, and downstream Huang San regulated rivers at the reach scale. In doing so, it was found that altered flow dynamics affected the river health index (RHI) in the upstream Nen and downstream Huang River reaches, respectively. Aura et al. [12] demonstrated the application of the multi-metric phytoplankton bio-integrity index methodology to the Kenyan portion of Lake Victoria, and concluded that the bio-index methodology is a decision-support tool for the effective management and sustainable utilization of water resources. Kim et al. [13] also applied the analytic hierarchy process (AHP) methodology to assess expert judgments on the relative importance of different socio-economic factors affecting damage to river ecosystems.

To summarize, the research results of scholars at home and abroad on the value of river health provide research perspectives and methodological models that can be used in China to carry out related research, and they have important reference value for Chinse researchers seeking to carry out river health management work scientifically. However, there are still some shortcomings in the existing research: (1) Most of the existing research focuses on the ecological and economic values of river health but less on the social values of river health. The researchers have not paid enough attention to the fact that a healthy river basin results from the dynamic and balanced development of mutual symbiosis and coexistence between nature and society. (2) Existing research lacks uniform standards and norms in the selection of indicators, the selection of indicators is one-sided, and the setting of indicator weights is highly subjective, which leads to the lack of a comprehensive and mature assessment indicator system with strong applicability and operability. (3) Most of the studies focus on a single spatial scale (e.g., a river section or the whole river) and a time scale (e.g., a certain year or a certain period). In contrast, fewer studies analyze the scale effect of the health value of the river at different spatial scales (e.g., taking into account the river section, the river as a whole, the upper, middle, lower, and middle reaches of the watershed, and the scope of the administrative region) and at different time scales (e.g., different years and periods over a long time series).

Based on the shortcomings of the existing research, this paper presents our in-depth research on river health value assessment methods and enhancement strategies and offers innovative discussions of the following three aspects: (1) This paper establishes a symbiosis mechanism for the river basin health value based on symbiosis theory, entirely focusing on the fact that a healthy river is the result of the dynamic and balanced development of the natural ecology and the socio-economy, hinging on symbiosis and coexistence with each other. The theory of natural ecology and social economy as symbiotic units, combined with the synergistic play of functions, comprehensively considers the ecological value, economic value, and social value of river health and researches the assessment of the river health value from a multi-level and multi-dimensional perspective. (2) A systematic river health value assessment index system consisting of five first-level indicators—supply function value, regulating function value, economic function value, support function value, and recreational function value—is constructed. A river health value assessment method based on the synergistic functional value is constructed by utilizing the market value method, opportunity cost method, shadow engineering method, substitution cost method, results reference method, and other value assessment methods. (3) A method for analyzing the distribution balance of river health value is proposed. To analyze the river basin scale and provincial administrative area scale within the river basin and to provide the basis for river health value management, the definition standard and calculation method of the distribution balance of river health value are proposed. Based on this, this paper establishes a river health value assessment system for the Yellow River Basin that comprehensively considers socio-economic development and ecological environmental protection and quantifies and assesses the spatial and temporal trends of river health value and the symbiotic evolution pattern of river health value in the Yellow River Basin from 2000 to 2020, to enrich and improve the theoretical system of river health value assessment, and to provide a theoretical basis for China’s scientific formulation of policies related to the management of river health. In addition, it provides a practical reference for maintaining the ecological health of rivers in the river basin and guaranteeing the safety of river water sources.

2. Methodology

2.1. Study Area and Data

As one of the earliest birthplaces of human civilization and an essential origin point of Chinese civilization, the Yellow River Basin is honored as the “Mother River” of China. The Yellow River is made up of “several” subrivers, mainly distributed in nine provinces, including Henan, Shaanxi, Inner Mongolia, and Shanxi (Figure 2). The ecosystem of the Yellow River not only provides essential water resources for production and life but also accounts for about 15% of the nation’s arable land in the basin. Because of its essential role in socio-economic development, ecological resource protection, and agricultural food production, the Yellow River Basin was chosen as the most critical research object for this study, and 20 years of data from nine provinces from 2000 to 2020 were selected as the study sample. The calculation and assessment data came from the China Statistical Yearbook [14], China Rural Statistical Yearbook [15], China Environmental Statistical Yearbook [16], China Electric Power Statistical Yearbook [17], the China River Sediment Bulletin [18], China Fisheries Statistical Yearbook [19] and provincial water resource bulletins.

2.2. Model Setting

According to the principles of comprehensiveness, representativeness, simplicity, and objectivity, the river health value is an integrated concept that unifies the natural ecological value and socio-economic value of rivers, and a healthy river system should satisfy both the adaptation to socio-economic development and ecological environmental protection needs [20]. Drawing on the methods and principles of ecosystem service value assessment, we constructed a 12-item index system while considering five aspects (

Table 1. Indicator system for river health value assessment.

Service Classification	Assessment of Indicators	Description of Indicators	Assessment Methodology
Supply function	Bioresources	Mainly economic species such as aquatic products	Market value approach
	Water resources	Water supply, including water for domestic use, industry, and agriculture	Market value approach
Adjustment function	Climate regulation	Evaporation from the surface of the water, regulating the temperature	Opportunity cost approach
	Water purification	Self-purifying capacity of rivers to clean up pollutants	Alternative cost method
	Sand transport capacity	Sediment transport in the study area	Market value approach
	Containment and flood control	Flood prevention	Shadow engineering approach
Economic function	Generation of electricity from water utilities	Production of electricity resources from hydroelectric facilities	Market value approach
	Value of river navigation	Water supply for river navigation	Market value approach
	Fisheries industry	Gross value of fisheries	Market value approach
Supported functions	Biodiversity conservation	Types of plant and animal resources	Results-based approach
Recreational function	Teaching and research	Provision of scientific research materials and laboratory space for academic fields	Results-based approach
	Leisure and entertainment	Provide places for recreation, tourism, and other activities	Results-based approach

), namely, the supply function value, regulating function value, economic function value, support function value, and cultural and recreational function value of rivers, from the perspective of the service value of rivers to human beings, to scientifically characterize the outstanding service value of rivers to nature and human activities. (1) Supply function value. The value of the river supply function refers to the products and resources directly provided by river ecosystems for social production and human life, such as the supply of freshwater, reeds, fish, shrimp, medicines, and other material products. (2) Regulatory function value. The value of the river regulating function refers to the river ecosystem through its regulation of the provision of services and benefits for human beings, such as climate regulation, water purification, sand transfer capacity, storage, and flood regulation. (3) Economic function value. The river economic function value is a kind of present value; it can be expressed through a certain form, but we can also use the market value method to assess its value identification. Examples of this aspect include water conservancy facilities, power generation, river navigation value, and fisheries. (4) Support function value. The value of the river support function refers to the river ecosystem’s ability to provide support for the entire ecosystem and maintenance of a function, to ensure the normal implementation of other service functions of the basin, to maintain the integrity of the regional ecological environment and natural conditions, and to provide a place for living organisms to flourish and reproduce, such as the maintenance of species diversity and so on. (5) Value of recreational function. Rivers can provide many utility values for society, including education, scientific research, culture, and other aspects.

2.3. Data Sources and Methods

(1)

Estimation of the value of the supply function

①

Methods for estimating the value of biological resources

Rivers are among the most productive of natural ecosystems, and the biological resources they provide are mainly aquatic products. Based on the data in the Rural Statistics Yearbook [15], the market value method [21] was applied to calculate the economic value of aquatic product production, using the following formula:

$$V_1=T\cdot P$$

where V₁ is the total value of biological resources, unit: CNY; T is the production of the main biological resources of the river, unit: tons/year; and P is the market unit price of the corresponding biological resources, unit: CNY/kg. In this study, based on the availability of data, P was selected as a price indicator of the average price of the key monitoring aquatic products of the Ministry of Agriculture in 2017, and the fluctuation range of the average price was 15.50~17.50 CNY/kg with an average value of 16.33 CNY/kg.

②

Methods for estimating the value of water resources

Rivers not only provide important water resources for human life and agricultural irrigation, but also play an indispensable role in flood control. The formula for calculating the value of river water resources is as follows:

$$V_2={\displaystyle \sum Q_i\cdot P_i}$$

where V₂ is the total value of water resources, unit: CNY; Q_i is the amount of water abstracted by each industry, unit: t/m³; and P_i is the unit price of water for the corresponding industry, unit: CNY/m³. This study adopted the market value method, and according to the availability of data, the non-agricultural water supply in accordance with the average raw water price of 0.125 CNY/m³ as stipulated in the document Development and Reform Price [2013] [22] No. 540, and the agricultural water supply in accordance with the raw water price of 0.01 CNY/m³ as stipulated in the document Development and Reform Price [2005] [23] No. 582.

(2)

Estimating the value of regulatory functions

①

Methods for estimating the value of climate regulation

River systems transport a steady stream of water and air to the atmosphere through evaporation of water from the river surface, thereby increasing air humidity and decreasing air temperature to achieve climate regulation. The river climate regulation value was calculated by using the following formula:

$$V_3=E\cdot S\cdot P$$

where V₃ is the total value of climate regulation, unit: CNY; E is the evaporation of the river water surface, unit: mm; S is the area of the river water body, unit: km²; and P is the unit price of water resources. This study adopted the opportunity cost method [24], based on the data availability, in accordance with the raw water price standard stipulated in the document Development and Reform Price [2013] No. 540 [22], that is, taking the average price of non-agricultural water supply as 0.125 CNY/m³.

②

Methods for estimating the value of water purification

The Yellow River is an important water source in China and plays an important role in the socio-economic development of the nine provinces along the river. The value of purified water quality in the Yellow River Basin was calculated by using the following formula:

$$V_4=W\cdot P$$

where V₄ is the value of river purification water quality, unit: CNY; W is the volume of bearing wastewater discharge, unit: t; P is the operating cost of wastewater treatment plant, unit: CNY/t. This study adopted the alternative cost method, and the data on wastewater discharge came from the China Environmental Statistics Yearbook. After investigating, we found that the current operating costs of domestic wastewater treatment plants range from 0.51 CNY/t to 3.01 CNY/t, with an average operating cost of 1.38 CNY/t, including an average of 0.37 CNY/t for construction costs, 0.81 CNY/t for wastewater treatment costs, and 0.20 CNY/t for sludge treatment costs [25].

③

Methods for estimating the value of sand transport capacity

Sediment is regarded as an abundant natural renewable resource, and the demand for sand in the field of construction engineering has gradually risen in the past few years. Accordingly, the potential for exploitation of sediment resources is huge, bringing significant economic benefits. The value of the river sand transfer capacity was calculated by using the following formula:

$$V_5=S\cdot P$$

where V₅ is the total value of sand transport capacity, unit: CNY; S is the amount of sand transport, unit: t; and P is the price of sand and gravel transported by ship, unit: CNY/t. This study adopted the market value method, and the data on sand transport were sourced from the China River Sediment Bulletin. Through comprehensive analysis of the main domestic waterways, sand and gravel types, transport distance, and other factors, we determined the average value of China’s inland waterway ship transport of sand and gravel to be 30 CNY/t [26].

④

Methods for estimating the value of flood storage

The Yellow River Basin Water Conservancy Hub Project has played a great role in flood storage and other aspects, and the value of flood storage in the Yellow River Basin was calculated by using the following formula:

$$V_6=C\cdot P$$

where V₆ is the value of flood regulation in the basin, unit: CNY; C is the total reservoir capacity of completed reservoirs, unit: m³; and P is the price of constructing reservoir capacity, unit: CNY/m³. In this study, the shadow engineering method was used to calculate the reservoir capacity of the Yellow River Basin Water Conservancy Hub as its annual flood regulation volume, and according to the statistical analysis of the construction costs of water conservancy projects in China, the national average annual input cost of reservoir capacity was determined to be 0.67 CNY/m³ [27].

(3)

Estimation of the value of economic functions

①

Methods for estimating the value of electricity generation from water facilities

The Yellow River Basin Water Conservancy Hub is a comprehensive water conservancy project integrating power generation, irrigation, flood control, and bulldozing prevention, which provides abundant power to the provinces along the Yellow River Basin while playing other functional roles. The value of power generation in the Yellow River Basin was calculated by using the following formula:

$$V_7=Q\cdot P$$

where V₇ is the total value of electricity generated by water conservancy facilities, unit: CNY; Q is the social electricity consumption, unit: Kw-h; and P the average feed-in tariff of the national power generation enterprises, unit: CNY/Kw-h. This study adopted the market value method, and the electricity consumption of the whole society was determined from the Electric Power Statistical Yearbook. According to the survey statistics, the average feed-in tariff of national power generation enterprises is 0.39 CNY/Kw-h.

②

Methods for estimating the value of river navigation

Yellow River shipping is of great significance for local transportation along the nine provinces (regions) of the Yellow River. Promoting the economic development of the basin, optimizing the layout of transportation, and developing river navigation help to protect the health of the Yellow River. The formula for calculating the value of river navigation in the Yellow River Basin was as follows:

$$V_8=Y\cdot P$$

where V₈ is the total value of river shipping, unit: CNY; Y is the turnover of shipping various loads; and P is the average value of the unit of water transportation of various loads, unit: CNY/ton. This study used the market value method, the turnover of shipping various loads came from the China Statistical Yearbook, and the average price of the unit of loads came from a sample survey of the Yellow River’s passenger and cargo transportation, giving us a result of 0.06 CNY/ton.

③

Methods for estimating the value of fisheries

Calculation of fisheries using the market value method can be performed based on data from the China Fisheries Statistical Yearbook [19]. There are a total of 121 species (or subspecies) of fish in the main stream of the Yellow River, and there are 98 species of pure freshwater fish in the main stream, accounting for 78.4% of the total. The main economic fish species are Wah’s yarrowfish, northern copperfish (pigeonfish), carp, and crucian carp.

(4)

Estimating the value of support functions

①

Methodology for estimating the conservation value of biodiversity

River basins interact with river water bodies in terms of water quantity through surface water and groundwater, and changes in water levels directly shape the ecological characteristics and landscape patterns of rivers. This means rivers present diverse types, have rich biological species and other characteristics, and play a crucial role in biodiversity and other aspects. The calculation formula for the biodiversity conservation value of the Yellow River Basin is as follows:

$$V_{10}=H\cdot P$$

where V₁₀ is the value of river biodiversity conservation, unit: CNY; H is the area of water bodies in the Yellow River Basin, unit: hm²; and P is the value of biological habitat per unit area, unit: CNY/hm².

(5)

Estimated value of recreational functions

①

Methods for estimating the value of teaching and research

The watershed is considered to be the birthplace of natural science civilization, and it is rich in cultural heritage and historical value. It has long been the first choice of domestic and foreign researchers and scholars for learning and teaching, and it is generally one of the most fruitful and diverse centers of research in the current academic world. The value of teaching and research in the watershed was calculated by using the following formula:

$$V_{11}=H\cdot P$$

where V₁₁ is the value of teaching and research, unit: CNY; H is the watershed area, unit: hm²; and P is the value of education and research per unit area of the watershed, unit: CNY/hm². In this study, the results reference method was adopted. Due to the lack of specific statistical data, the average educational and scientific research value of China’s wetland ecosystems estimated by Chen Zhongxin et al. was used as a reference [28], that is, 382 CNY/hm².

②

Recreation value estimation method

The Yellow River Basin has beautiful natural landscapes along the route, with rich natural ecological resources and scenery, possessing high tourism value and expected to create significant economic gains. The leisure tourism value of the Yellow River Basin was calculated by using the following formula:

$$V_{12}=A\cdot P$$

where V₁₂ is the recreational value, unit: CNY; A is the area of water bodies in the Yellow River Basin, unit: hm²; and P is the recreational value per unit area of the watershed, unit: CNY/hm². This study adopted the result reference method, due to the lack of specific statistical data, making reference to Xie Gao Di et al. [29]. These scholars estimated China’s lakes and wetland resources to have an educational and scientific research value of 3840.2 CNY/hm².

3. Logistic Coevolutionary Model of River Health Values

The health value of rivers has the compound attributes of both natural ecological and socio-economic systems. The natural system of rivers not only provides humans with basic water for production and life but also has important social service functions, and the health value of rivers is a direct reflection of the service functions of rivers. Therefore, the river health value can be regarded as a symbiotic environment composed of two symbiotic units, the natural system of the river and the social system of the river, whose symbiotic environment is constrained by the economic level, resource environment, and other conditions. It can be objectively evaluated with the help of the logistic symbiosis model on the assessment indexes, which describes the development process of the symbiotic evolution of the river health value, so as to make the evaluation standard of the river health value more scientific and rational. The specific process of model construction is as follows [30,31].

The river health value assessment model contains a variety of indicators with different scales and widely varying values, so in this study, we adopted the entropy weighting method for objective evaluation of each part of the model. The specific method can be found by referring to the literature [29].

①

The 12 indicators in the indicator stratum were standardized, mainly using the extreme value standardization method:

$$\begin{array}{c}Positive Indicators:X_{ij}^{\prime }=\frac{X_{ij}-\min X_{ij}}{\max X_{ij}-\min X_{ij}}\end{array}$$

$$\begin{array}{c}Negative Indicator:X_{ij}^{\prime }=\frac{\max X_{ij}-X_{ij}}{\max X_{ij}-\min X_{ij}}\end{array}$$

where X′_ij and X′_ij represent the original and normalized values of the jth (j = 1, 2, ⋯, m) indicator for the ith (i = 1, 2, ⋯, n) year, and max X_ij and min X_ij represent the maximum and minimum values in the jth column of the indicator, respectively.

②

Indicator weights were calculated. The weight of the jth indicator (or column) in year (or row) i was P_ij:

$$P_{ij}=X_{ij}^{\prime }/{\displaystyle \sum _{i=1}^n{X}_{ij}^{\prime }}$$

③

We found the entropy value of the indicator. The entropy value E_j of the jth indicator was as follows:

$$E_j=-\ln {(n)}^{-1}{\displaystyle \sum _{i=1}^n{P}_{ij}}\ln (P_{ij})$$

where n is the number of years (or the number of rows); 0 ≤ E_j ≤ 1; and when P_ij = 0, P_ijlnP_ij = 0.

④

We found the coefficient of variation of the indicator D_j:

$$D_j=1-E_j$$

When the values of the jth indicator are equal, E_j = Emax = 1, so it is necessary to use the coefficient of variation D_j to weigh the size of the weights; a larger coefficient of variation represents a greater the amount of information and thus a greater value of the weights.

⑤

We calculated the weighting result W_j:

$$W_j=D_j/{\displaystyle \sum _{j=1}^m{D}_j}$$

$${\displaystyle \sum _{i=1}^m{W}_i}=1$$

The results of the entropy weighting method were derived to find the weights of the indicators for river health values (

Table 2. River health value indicator weights.

Service Classification	Assessment of Indicators	Entropy Weight
Supply function	Bioresources	0.07
	Water resources	0.11
Adjustment function	Climate regulation	0.12
	Water purification	0.06
	Sand transport capacity	0.05
	Containment and flood control	0.08
Economic function	Generation of electricity from water utilities	0.07
	Value of river navigation	0.08
	Fisheries industry	0.07
Supported functions	Biodiversity conservation	0.09
Recreational function	Teaching and research	0.09
	Leisure and entertainment	0.09

).

Let the population density of the natural ecosystem and socio-economic system of the river be N₁ and N₂, the natural growth rate of the two be r₁ and r₂, the maximum environmental capacity that the population can bear under the influence of the natural ecosystem and socio-economic system be K, and let $N_i(t)$ denote the level of development of the river’s natural and social system at the time $t$. The slope of the straight line of the natural ecological and socio-economic systems of the river at $[t_T,t_{T+1}]$ is $\Delta N_{\mathrm{i}}^{T+1}$, and the slope of the straight line of the natural ecological system is

$$\Delta N_{\mathrm{i}}^{T+1}=\Delta N_{\mathrm{i}}^{T+1}-\Delta N_{\mathrm{i}}^T$$

(1)

$$aver\Delta N_{\mathrm{i}}^{T+1}=(\frac{\Delta N_{\mathrm{i}}^T+N_{\mathrm{i}}^{T+1}}{2})$$

(2)

$$r_1=\frac{K\Delta N_1^{T+1}}{aver\Delta N_1^{T+1}(K-aver\Delta N_1^{T+1})}$$

(3)

$$r_2=\frac{K\Delta N_2^{T+1}}{aver\Delta N_2^{T+1}(K-aver\Delta N_2^{T+1})}$$

(4)

After collapsing (1), (2), (3) and (4), the population growth equation for the health value of the river is

$$\frac{d{N}_1(t)}{d_t}=r_1\left[1-\frac{N_1(t)}{K}+\alpha \times N_2(t)\right]N_1(t),t\in [t_T,t_{T+1}]$$

(5)

$$\frac{d{N}_2(t)}{d_t}=r_2\left[1-\frac{N_2(t)}{K}+\beta \times N_1(t)\right]N_2(t),t\in [t_T,t_{T+1}]$$

(6)

Among them, $\alpha$ and $\beta$ are the coefficients of mutual symbiosis between the socio-economic ecology and natural ecology of the river, and the symbiosis relationship is judged by measuring the range of their results (

Table 3. Symbiotic behavioral patterns.

Symbiosis Value	Behavioral Model	Characteristics of Performance
α < 0, β < 0	Inverse symbiosis	A certain victimization between socio-economics and natural ecology
α = 0, β = 0	Parallelism	A need for mutual harmonization between socio-economic and natural ecosystems
α > 0, β < 0 or α < 0, β > 0	Parasitic	The natural ecology is the beneficiary and the socio-economy is the victim
α > 0, β = 0 or α = 0, β > 0	Positively biased symbiosis	A relationship between the socio-economy and the natural ecology that tends to favor the benefits of the natural ecology
α < 0, β = 0 or α = 0, β < 0	Reverse bias symbiosis	A relationship between socio-economic and natural ecology that favors socio-economic benefits
α > 0, β > 0	Mutually beneficial symbiosis	Relationships between socio-economic and natural ecosystems are positive, with both benefiting from cooperation

).

4. Results

4.1. Analysis of the Results of River Health Value Assessment in the Yellow River Basin Based on the Watershed Scale

In terms of the river health value in the Yellow River Basin, as a whole, it can be seen from Figure 3 that the proportion of the supply function between 2000 and 2020 shows a yearly decrease, from 26% in 2000 to 10% in 2020; the proportion of the regulation function between 2000 and 2020 also shows a yearly decrease, from 25% in 2000 to 13% in 2020; the share of the value of economic functions increases year by year from 2000 to 2020, from 45% in 2000 to 75% in 2020; and the share of the value of supportive and recreational functions is smaller and shows a decreasing trend year by year.

Regarding service categorization, according to Figure 4, the economic function value of rivers in the Yellow River Basin is significantly higher than the other four value types from 2000 to 2020. This is followed by the supply function value and the regulation function value, while the support function value and the recreation function value are the lowest, and the difference between the two is insignificant. Specifically, the economic functional value of river health in the Yellow River Basin increased from 229.661 billion CNY in 2000 to 144.6684 billion CNY in 2020, showing a significant incremental trend, especially after 2006. The reason for the increase is that the Chinese government has adopted a series of policies to support the development of water conservancy, shipping, and fisheries in the areas along the Yellow River Basin by providing financial support and enacting and implementing laws and regulations in order to promote the development of the related industries. From 2000 to 2020, the value of the supply function and the value of the regulating function of the river health in the Yellow River Basin were relatively close to each other, and an overall trend of fluctuating growth was found. However, the supply function value shows a gradual decline after 2015, mainly due to the apparent decrease in the value of biological resources. On the one hand, the construction of reservoirs and water conservancy projects and the regulation of water flow in the previous period may have changed the hydrological conditions and ecosystem structure of the Yellow River, negatively affecting fish migration, migration, and reproduction. On the other hand, the Yellow River Basin is relatively rich in biological resources. Coupled with the fact that China’s economy was in a period of rapid development at that time, agricultural expansion, urbanization, and other land use changes in the lower reaches of the Yellow River may have led to fragmentation of the ecosystem and loss of habitat, and fishery resources in the river may have declined as a result of overfishing, depriving some species of their suitable habitat and worsening their living conditions.

The support and recreational function values are significantly lower than the others, with larger increases from 2000 to 2014, a more moderate growth trend after 2015, and less pronounced changes overall. The main reason for the change in the value of the support functions is the relatively weak biodiversity base of the Yellow River Basin. The Chinese government attaches great importance to the restoration of the ecological quality of the Yellow River Basin, and ecological compensation and restoration programs have been implemented in the basin area to compensate for or restore biological habitats affected by development, agriculture, or other human activities. In addition, advanced scientific and technological tools, such as remote sensing technology and GIS (geographic information systems), have made monitoring, evaluating, and managing biological habitats more efficient and precise. This helps scientists and policymakers to better understand habitat changes and take conservation measures accordingly. The main reason for the change in the value of recreational functions is that the Yellow River Basin is one of the largest rivers in China. Its geography, climate, and water resources provide rich teaching and research materials for the study of geography and environmental sciences as well as history and culture, attracting the attention of researchers to analyze and study cases of different ecological environments.

In terms of the value volume of each assessment index (Figure 5), the value volumes of biological resources, storage and flood regulation, power generation of water conservancy facilities, and fishery are high, followed by sand transfer capacity, river navigation, and water purification. In contrast, the value volumes of climate regulation, leisure and recreation, water resources, biodiversity protection, and teaching and research are relatively small. In addition, over the past 20 years, the value of biological resources and water resources has shown a trend of rapid increase followed by a gradual decrease.

Climate regulation, storage and flood regulation, water conservancy facility power generation, biodiversity conservation, teaching and research, and recreation values as a whole show a continuously increasing trend, mainly related to the relevant policies in the study period. The water conservancy facilities’ power generation value indicator has the highest growth rate among them. Around 2006, relevant documents such as the Yellow River Basin Flood Control Plan, Jin-Shaan-Yu Yellow River Golden Triangle Regional Cooperation Plan, and the Law of the People’s Republic of China on the Protection of the Yellow River emphasized the strengthening of backbone project construction for flood control, the improvement of the non-engineering flood control measures, and the promotion of Yellow River management. This indicates that the government has increased and improved water conservancy facilities, including hydropower stations, reservoirs, and irrigation systems, by promoting policies and regulations. Infrastructural construction usually improves efficiency and output value and increases economic benefits. Teaching, research, and recreation are valuable because the Yellow River Basin is home to many natural and cultural landscapes, such as the Hukou Waterfall, the Yellow River Water Conservancy Scenic Area, and the Yellow River Wetland Park. In recent years, provinces and cities have integrated the natural ecological landscapes of the Yellow River with history and culture by uniting colleges and universities, scientific research institutes, social organizations, and other essential forces to carry out high-quality studies along the Yellow River Basin, which has boosted the income of the Yellow River Basin tourism economy.

The values of water purification and fisheries show a trend of change that first decreases, then increases sharply, and then stabilizes. Stimulated by government policies, society’s concern for clean water and the sustainable development of the Yellow River’s ecology increased, thus raising the value of water purification. Similarly, the need for economic development in the early period led to agricultural expansion, prompting overfishing of the river’s fishery resources, but the implementation of the government’s operational adjustments to the Yellow River’s closed season in the later period, prioritizing bioremediation and habitat conservation, limited the economic development of the fishery industry.

The value of sand transport capacity and the value of river navigation show a fluctuating trend of “increase-decrease-increase.” Land use changes in the Yellow River Basin, such as deforestation, grassland degradation, and agricultural expansion, may directly impact the sand transport capacity of the basin. Unreasonable land use may lead to soil erosion and increase the amount of sand transported by the river. Soil and water conservation measures implemented by the government, such as the construction of terraces and the planting of soil and water conservation forests, reduce soil erosion to a certain extent, thus affecting the amount of sand transport. In addition, the frequent occurrence of extreme weather events in the Yellow River Basin in recent years, if it continues, may lead to floods and droughts, affecting the hydrological cycle of some rivers and causing some fluctuations in the amount of sand transported and shipping activities. Fluctuations in the value of inland navigation may be related to the development status of the regional economy in the Yellow River Basin. Regions with a higher level of economic development may increase the demand for inland navigation and reduce the problem of river siltation due to sand transport, thus affecting the value of inland navigation.

4.2. Analysis of the Results of River Health Value Assessment in the Yellow River Basin Based on the Provincial Administrative District Scale

By estimating the five major functional values of river health in the Yellow River Basin and its 12 indicators (Figure 6), the total value of river health in the Yellow River Basin from 2000 to 2020 could be obtained. Among them, during the period of 2000–2020, the supply function value of river health in the Yellow River Basin accounts for the largest proportion in Shandong Province (accounting for about 76.56%), and the total value of the supply function in Shandong Province is 2728.782 billion CNY; Qinghai Province accounts for a smaller proportion of only 0.12%, with a total value of 4.415 billion CNY. The regulating function value of river health in the Yellow River Basin accounts for the largest proportion in Henan Province (25.24%), with a total value of 853.664 billion CNY; in Ningxia Province, it accounts for a smaller proportion of 8.9%, with a total value of 46.431 billion CNY. The largest proportion of the value of river health economic function in the Yellow River Basin is in Shandong Province (28.36%), with a total value of 313.7348 billion CNY, while Qinghai Province accounts for a smaller proportion of 359.999 billion CNY, with a total value of 4.415 billion CNY. The total value of river health support function is 359.968 billion CNY; the largest proportion of the value in the Yellow River Basin is in Qinghai Province (46.68%), with a total value of 67.754 billion CNY, and the smallest proportion of 1.01% is in Ningxia Province, with a total value of 1.467 billion CNY. The largest proportion of the value of the river health recreation and culture function in the Yellow River Basin is in Qinghai Province (28.36%), with a total value of 313.7348 billion CNY, and the smallest proportion is in Ningxia Province, with a total value of 1.467 billion CNY. The largest share of the value of river health and recreation functions in the Yellow River Basin is in Qinghai Province (46.68%), with a total value of river health and recreation functions of 131.453 billion CNY; the total value of river health and recreation functions in Inner Mongolia is 45.743 billion CNY, with a proportion of 16.24%; the proportions in Shandong and Sichuan Provinces are 14.36% and 10.15%, respectively, with total values of river health and recreation functions of 40.443 and 28.577 billion CNY; and Henan, Gansu, Shaanxi, Shanxi, and Ningxia Provinces account for smaller proportions of 5.91%, 2.09%, 1.97%, 1.59%, and 1.01%, respectively, where the total values of river health and recreation functions are 16.631, 5.896, 5.557, 4.471, and 2.846 billion CNY, respectively.

4.3. Analysis of the Results for the Coefficient of Coexistence for River Health Value Assessment in the Yellow River Basin

According to the weights assigned with the entropy weighting method, as shown in Table 2, the population density of the natural ecological development of the river basin in the nine provinces of the Yellow River Basin N1, the population density of the socio-economic development of the river basin N2, and the environmental capacity of the river basin K were calculated. This paper only lists five years’ results (

Table 4. Natural ecological-socio-economic evaluation of river health in nine Yellow River provinces.

Provinces	Norm	2000	2005	2010	2015	2020	Provinces	Norm	2000	2005	2010	2015	2020
Qinghai	Natural ecological level	0.71	0.62	0.52	0.43	0.41	Shanxi	Natural ecological level	0.18	0.10	0.08	0.08	0.06
	Socio-economic level	0.11	0.21	0.35	0.44	0.46		Socio-economic level	0.79	0.87	0.90	0.90	0.92
	Environmental capacity	0.18	0.17	0.13	0.12	0.12		Environmental capacity	0.04	0.03	0.02	0.02	0.01
Sichuan	Natural ecological level	0.23	0.17	0.14	0.17	0.16	Shaanxi	Natural ecological level	0.51	0.40	0.26	0.15	0.17
	Socio-economic level	0.50	0.60	0.68	0.67	0.70		Socio-economic level	0.44	0.55	0.71	0.80	0.79
	Environmental capacity	0.28	0.23	0.18	0.16	0.14		Environmental capacity	0.06	0.05	0.03	0.05	0.04
Gansu	Natural ecological level	0.34	0.25	0.18	0.14	0.12	Henan	Natural ecological level	0.51	0.34	0.24	0.19	0.24
	Socio-economic level	0.61	0.71	0.79	0.84	0.87		Socio-economic level	0.40	0.56	0.69	0.72	0.68
	Environmental capacity	0.05	0.04	0.03	0.02	0.01		Environmental capacity	0.09	0.10	0.07	0.09	0.08
Ningxia	Natural ecological level	0.25	0.13	0.10	0.06	0.06	Shandong	Natural ecological level	0.08	0.10	0.07	0.04	0.07
	Socio-economic level	0.64	0.81	0.87	0.92	0.93		Socio-economic level	0.47	0.59	0.70	0.76	0.78
	Environmental capacity	0.11	0.06	0.03	0.02	0.02		Environmental capacity	0.45	0.32	0.23	0.20	0.16
Inner Mongolia	Natural ecological level	0.41	0.24	0.20	0.09	0.09
	Socio-economic level	0.40	0.66	0.75	0.86	0.89
	Environmental capacity	0.19	0.10	0.06	0.05	0.03

). The table shows that during the 20 years from 2000 to 2020, the natural ecological level and environmental capacity of the nine provinces in the Yellow River Basin gradually decreased. The overall socio-economic level rose steadily, except for Shandong Province and Sichuan Province. The natural ecological level of the rest of the provinces was higher than their environmental capacity, which indicates that the results of ecological construction in these six provinces showed. The ecological levels of Shandong Province and Sichuan Province were below their environmental capacity. Most of the natural ecological levels of the nine provinces in the Yellow River Basin showed a decreasing trend, mainly because industrial and agricultural activities led to many pollutants (e.g., fertilizers, pesticides, and industrial wastewater) entering the Yellow River and affecting the water quality. This may lead to the eutrophication of water, accumulation of ecotoxins, and death of aquatic organisms. Large-scale land use changes, such as urbanization and agricultural expansion, may lead to soil erosion and sand loss, affecting the sand transport capacity of the Yellow River. Decreased sand transport capacity may lead to siltation of the river and degradation of the watershed. Large-scale water conservancy projects, such as reservoir construction and embankment construction, may change the Yellow River’s natural water flow and flood regulation mechanism. This may lead to a loss of the original ecological balance of the river ecosystem, affecting ecological processes such as fish spawning and bird migration. Changing climate patterns may also lead to changes in precipitation distribution and temperature, which in turn may affect the water cycle and ecosystem of the Yellow River Basin. Irregular rainfall, droughts, and temperature changes may negatively affect vegetation and water availability.

The socio-economic level of the nine provinces in the Yellow River Basin is on a straight upward trend, mainly because the value of hydropower generation from water conservancy facilities is becoming increasingly important in the health value of the rivers in the Yellow River Basin. With the national policy of “energy conservation and emission reduction,” hydropower has become the first renewable energy choice. The Yellow River Basin should prioritize the development of the hydropower industry in future power construction according to the local conditions, to further enhance the comprehensive benefits of hydropower in the rivers. Furthermore, to promote the economic development of the basin, optimize the layout of transportation, and develop river navigation in a way that helps to protect the health of the river, attention should be paid to the construction of river navigation infrastructure, increasing the capital investment, scientific dredging of waterways, and effective enhancement of the navigation value of the Yellow River Basin rivers. At the same time, as the material basis of fishery production, realizing the sustainable use of fishery resources is a necessary condition for realizing the sustainable development of fisheries, and the construction of eco-fisheries and recreational fisheries should be vigorously promoted and strengthened by increasing scientific and technological investment. At the same time, scientific, reasonable, and feasible management measures should also be taken to strengthen the management of fishery resources in river basins and scientifically guide fishermen along rivers to develop aquaculture that will help realize the sustainable use of fishery resources.

The environmental capacity also shows a slow downward trend, which the interaction of multiple factors may cause. Firstly, the carrying capacity of the water environment in the Yellow River Basin is low. Secondly, human activities such as industrialization, urbanization, and agricultural expansion may destroy biological habitats in the Yellow River Basin. Important ecosystems such as wetlands, grasslands, and forests can be threatened, affecting the survival of many plants and animals. In addition, overfishing and irrational fishery management may lead to the gradual depletion of fishery resources in the Yellow River, affecting the ecological balance of the waters. Many tourists and related facilities can introduce garbage, pollutants, and artificial damage, hurting the natural environment.

We substituted the basic index evaluation results in Table 2 into Equations (3) and (4) to derive the endogenous growth rates of marine ecology and marine economy r₁ and r₂, and then we substituted the basic index evaluation results and endogenous growth rate into Equations (5) and (6) to obtain the symbiosis coefficients α and β. For better clarity in representing α as the horizontal axis and β as the vertical axis data, the nine provinces of the Yellow River were divided into the upper, middle, and lower watersheds, to create three diagrams of symbiosis of the river’s natural ecology and river’s socio-economic situation (Figure 7).

In the figure, it can be seen that most of the river’s natural ecology and socio-economy in the upper, middle, and lower Yellow River Basin show a parasitic relationship, indicating a kind of interdependence between the two. In this case, the river’s socio-economy (the host) provides resources, while the river’s natural ecology (the parasite) benefits from them. This relationship may indicate that the river’s natural ecology plays a vital role in the sustainable development of the river’s socio-economy. In contrast, the growth of the river’s socio-economy may directly or indirectly affect the river’s natural ecosystem. Gansu, Ningxia, Inner Mongolia, Shanxi, and Shaanxi are distributed in Quadrant 4 in a parasitic relationship. The natural ecology is the beneficiary while the socio-economy is the victim, which may indicate that the development of the river socio-economy negatively affects the natural ecosystem.

In contrast, the health and stability of the natural ecosystem positively affect the river economy. The pattern suggests that the socio-economy may fully recognize the value of these ecosystem services, resulting in the river being inappropriately exploited and utilized. The socio-economic system being seen as a victim implies that it may be exposed to certain risks and losses when ecosystems are disrupted. This may include problems such as resource scarcity and environmental degradation. The beneficiary party is the natural ecosystem, suggesting that river water resources may be over-utilized and that the socio-economic system fails to fully appreciate the scarcity of water resources and the importance of sustainable management.

The coefficients of coexistence in Shandong Province are distributed in the third quadrant, with reverse symmetrical coexistence. This means there is an inverse relationship between river socio-economics and river natural ecology in Shandong Province, where natural ecosystems may be damaged while pursuing economic growth. This competing relationship is a challenge for sustainable development because excessive damage to natural ecosystems may have adverse economic and social impacts in the long term. Current investments in ecological conservation do not translate directly into economic benefits in the short term. This may require more integrated and long-term strategies to realize the economic and ecological linkage effects.

Most of the coefficients of symbiosis in Sichuan Province are concentrated around the zero point, and the two develop independently, with the symbiosis mode being concurrent. The symbiosis model is often regarded as an ideal situation for sustainable development because it emphasizes the coordination between socio-economic and natural ecosystems. It provides an opportunity for a balance between sustainable use of resources, ecological protection, and economic growth. This model suggests that Sichuan Province achieves a certain balance in the allocation of factors of production, i.e., rational use of resources such as land, water, and workforce. Although the concurrent model provides favorable conditions for sustainable development, attention needs to be paid to the ability to adapt to change. External factors such as climate change and market fluctuations may impact the economy and the ecosystem, and flexible management strategies are needed to adapt to these changes.

The ecological coefficients of symbiosis in Qinghai Province are mainly distributed in the positive direction of the α-axis, showing a biased co-pattern of ecological benefit. This pattern suggests that Qinghai Province has a relationship between socio-economy and natural ecology that favors natural ecological benefit, and that socio-economic development is likely to promote the ecological level, highlighting the importance of ecological benefit in sustainable development. Despite ecological benefits, focusing on ecological construction may lead to a slowdown in economic development. This may reflect the challenges faced in balancing the economy and ecology. For this biased co-beneficial model, developing sustainable development strategies becomes crucial. Ways must be found to establish a virtuous circle between economic development and ecological conservation rather than contradiction and opposition. Long-term planning and investment will be particularly critical, given the economic and ecological trade-offs that may occur in the short term with the altruistic model.

The river socio-economic–ecological coefficient of symbiosis in Ningxia Province is mainly distributed in the negative direction of the β-axis, showing a biased symbiosis pattern of economic victimization. The biased symbiosis pattern indicates that in Ningxia Province’s development strategy, the economy is prioritized, while the ecological environment protection is relatively lower. This may reflect the phenomenon that some local governments pursue economic growth in the short term while, in relative terms, neglecting the ecological environment. Socio-economic development is hampered when focusing on natural ecological construction. This may reflect that investment in ecological environment construction may lead to the diversion of resources from economic construction, which may negatively impact economic development in the current period. At the same time, it implies that Ningxia Province focuses more on rapid socio-economic growth in the short term, while it may face persistent ecological and environmental challenges in the long term. The main reason for this pattern is that Ningxia Province relies mainly on resource-intensive industries in its economy, though it feels pressure to protect the environment. In the short term, it may be more inclined to pursue resource development and neglect ecological protection. In addition, the policy orientation and assessment mechanism of local governments may focus excessively on economic achievements in the short term, with less consideration given to the long-term impacts of ecological and environmental protection. This may lead the government to favor economic development in its decision-making.

5. Conclusions

5.1. Research Conclusions

(1) At the watershed scale, the Yellow River Basin experienced a period of river subhealth. However, thanks to the implementation of ecological protection and high-quality development strategy in recent years, the river’s health improved in 2017–2020. This indicates that the implementation of ecological protection and high-quality development strategy has positively impacted the health of the Yellow River Basin. (2) The differences in the Yellow River Basin are particularly evident at the provincial administrative scale. Shandong Province had the most significant river health supply and economic function values from 2000 to 2020, highlighting its economic position in the basin. On the contrary, Qinghai Province’s rivers contributed the greatest health-supporting and recreational function values, while Henan Province reached the maximum value in the regulating function. Regional differences should be narrowed as soon as possible to synergize the characteristics and strengths of each province in watershed management and to compensate for the weaknesses of regional development. (3) From the symbiosis perspective, rivers in the Yellow River Basin are generally parasitic, and most show the diversity and competitiveness of the natural ecology in relation to the socio-economy. Therefore, a more comprehensive consideration of the balanced development of each function is needed in river health management in the future in order to achieve integrated watershed health.

5.2. Recommendations

The river is a socio-economic–natural ecological complex ecosystem, where the health value of the river is subject to a variety of factors. A healthy river should have the ability to renew and sustain, but at the same time, have the structural integrity, functional integrity, and ecological and environmental benefits required to meet the reasonable needs for the development of human society. According to the theory of symbiosis, its essence lies in synergy and cooperation. The synergy between the river and its neighboring organisms and environmental elements is the key to maintaining the whole ecosystem’s balance. Based on the above empirical model, the assessment of the river health value in the Yellow River Basin can be extended to the monitoring and assessment of river health in the Yangtze River, as well as in other river basins, to better assess the symbiotic relationship between economic growth and ecological protection of rivers, to manage the long-term planning and investment in the river health value, and to realize sustainable development in which human beings and nature live in harmony. In addition, efforts should be made to adapt the current national river health policy to meet actual needs. Furthermore, future research should consider different regions and different rivers, according to local conditions, to support the development of different river health value assessment index systems, further quantification of river land use, water consumption, irrigation systems, and farmers’ education. In addition, further factors should be added into the analytical framework, and researchers should continue to improve the theory and methodology of the river health value assessment, in order to measure the value of river health more comprehensively.