Establishment of an Evaluation Indicator System and Evaluation Criteria for the Weihe River Ecological Watersheds

Abstract

Ecological watersheds (eco-watersheds) are of great significance for boosting the construction of ecological civilization and realizing the ecological protection and high-quality development of watersheds. In order to establish a scientific eco-watershed evaluation index system, this paper refers to the river health evaluation index system, the water resources coupling evaluation index system, and the happy river evaluation index system, and reviews the development process of the ecological watershed evaluation index system. According to the eco-watershed theoretical system, combined with the relevant contents of policies and regulations, thousands of evaluation indicators that have been collected are screened using the theoretical analysis method and the frequency analysis method. Finally, a comprehensive evaluation index system of Weihe River eco-watersheds was constructed, including three first-level indicators: watershed water resources, socio-economic, and ecological. These were further subdivided into eight second-level indicators, namely water security, water resources, water economy, water management, water culture, water environment, water ecology, and water landscape. These second-level indicators were then further broken down into 60 third-level indicators. On the basis of determining the evaluation standards of Weihe River eco-watersheds, the evaluation weights were determined using the gray correlation method and the AHP-entropy comprehensive weight method (comprehensive weight), resulting in the establishment of an evaluation model and a coupling model for the eco-watersheds of the Weihe River. The results of the Weihe River eco-watershed evaluation model and the coupled coordination degree evaluation model show that, from 2019 to 2021, both the gray correlation analysis weights and comprehensive weight evaluation show a yearly increasing trend; the evaluation results are in the eligible status and below; and the evaluation grade is in the fourth-level eco-watersheds and below. Based on the evaluation results of each dimension, when comparing the gray correlation analysis weights with the evaluation of the comprehensive weights, the latter align more closely with the actual Weihe River Watershed. When comparing the evaluation results of the Henan Weihe River Watershed with those of the Handan Weihe River Watershed, the latter’s results, influenced by the scheduling of the Yuecheng Reservoir, are relatively better. Furthermore, in the evaluation of coupling coordination, the water resources subsystem is less coupled to other subsystems due to the 2021 flood. Therefore, in order to effectively improve the level of eco-watersheds, scientific and reasonable water resources scheduling programs should be developed.

1. Introduction

The watershed is the basic unit of the water cycle, which has nurtured human civilization [1]. By integrating the system theory into the watershed system, the socio-ecological system (SES) has been formed, which is closely and organically linked with the social-economic and ecological elements centered on water resources in the watershed [2,3]. The process of recognizing and studying the social-ecological system of watersheds has gone through a multi-level stage of alternating academic and policy evolution. From engineering water conservancy to environmental water conservancy to resource water conservancy and finally to ecological water conservancy, water management concepts have iterated, and also incorporated the feedback of the reality of watershed social-ecological system [4]. This process has included the river health concept [5], the concept of watershed water resources system coupling [6], the concept of the happy river [7], and the eco-watershed concept [8] of continuous deepening and extension. Accompanied by the practical application of various concepts, determining the river and watershed, and whether they meet the construction standards of the corresponding concepts, determines the reality of the interaction between scientific research and practical application. An evaluation index system is an organic whole with an internal structure composed of multiple indicators that characterize the characteristics of various aspects of the evaluation object and their interconnections, and it is an effective way to apply system theory ideas to solve the complex problems in the watershed system [9]. It can be seen that in the process of eco-watershed research and management, the scientific use of the evaluation index system, the evaluation of the current situation of the eco-watershed research, and the establishment of evaluation criteria and development objectives that are consistent with eco-watersheds is of great practical significance for watershed management. However, the concept of the eco-watershed existed for a relatively short period of time, and the theoretical system of eco-watersheds needs to be further improved, especially regarding the lack of a corresponding evaluation index system and evaluation standards. Therefore, on the basis of further improving the theory system of eco-watersheds, an evaluation index system based on the theory system of eco-watersheds and the corresponding evaluation standards should be constructed, which is of great theoretical and practical value for the scientific evaluation of the ecological level of the watersheds and the formulation of the corresponding policies and measures.

With the deepening of the connotation of the watershed socio-ecological evaluation system, the evaluation scale has progressed through the evaluation model from a section of river to a river, and finally formed the watershed scale [5,10,11], and the evaluation hierarchy has progressed through the evaluation model from a single level to multiple levels with the target level as the evaluation result [12,13]. With the rapid economic development of developed countries at the end of the 19th century, the situation of water pollution in the watershed is becoming more and more prominent. In Europe, for the Rhine, Danube, and other river sections having high pollution, systems were constructed to evaluate the water quality as the goal of the single-level evaluation system, assessing evaluation indicators such as BOD, COD, intestinal flora, and total bacterial counts, to carry out the evaluation from the water environment dimensions [14]. In 1972, river health was first proposed in the U.S. Federal Water Pollution Control Act Amendments, and the connotation of river health was enriched. Developed countries such as the United States, the United Kingdom, and Australia have taken rivers as a scale, and proposed a multi-level evaluation indicator system that includes biology, hydrological situation, spatial geomorphology, and water quality, and developed an evaluation system from the dimensions of water environment and water ecology [15]. At the beginning of the 21st century, river health evaluation was introduced into China, and China’s concern for human–water harmony relations is now more prominent, focusing on balancing interests and meeting the needs of human society, based on the continuation of the river health evaluation structure. A system of evaluation indicators has been gradually developed that includes five guideline layers: hydrological, water quality, biological, physical habitat, and economic service functions, mainly from the water environment and water ecology dimensions of the evaluation system. At the same time, it began to incorporate the concepts of water security, water economy, water landscape, and other dimensions [16]. In 2019, the Chinese government put forward the river governance goal of “building a happy river”, and the construction of a happy river is a new goal for river development and governance in China in the new period. This is an upgrade of the theory of river health, and the concept of a happy river takes into account the ecological health of the river and the economy, culture, and well-being of human society. Attempts have been made to explore the construction of a happy river evaluation index system from the dimensions of water security, water resources, water environment, water ecology, water culture, water economy, etc. [17]. At the same time, the coupled evaluation system of water resources at the scale of the watershed is also gradually emphasized by research teams at home and abroad, and develops from simple system coupling into the coupled system based on the theoretical system, and constructs the evaluation index system of the three subsystems of water resources, socio-economics, and ecology [18]. The connotation of the eco-watershed evaluation index system integrates the essence of the evolution of the river health and happiness river evaluation index system, as well as the concept of the coupled water resources evaluation index system on the scale of the watershed and the theory of coupled coordination of the three subsystems. A multi-level ecological watershed evaluation index system, with the three major subsystems of watershed water resources, socio-economic, and ecological, and eight dimensions of water security, water resources, water economy, water management, water culture, water environment, water ecology, and water landscape, has been formed.

Carrying out the construction of an eco-watershed evaluation index system, formulating eco-watershed standards, evaluating the effect of ecological protection, and proposing eco-watershed ecological evaluation and comprehensive safeguard technology are the basis of practicing eco-watershed theory. To date, scholars at home and abroad have carried out a large number of basic studies related to eco-watershed evaluation systems, which can be categorized into three major categories. The first category is the river health evaluation system. The concept of river health is a new concept that accompanies the concept of ecosystem health, and the emphasis on river aquatic organisms and ecosystems has prompted the concept of river health [19]. Due to the inherent complexity of river ecosystems, different disciplinary backgrounds, and evaluation perspectives of researchers, there is a variety of river health evaluation models constructed by governmental agencies, professional groups, and academics [20,21,22]. The second category is system coupling and evaluation models. As human beings are facing the increasingly prominent contradiction between resources (especially water resources), socio-economics, and the ecological environment, determining how to realize the coordinated development between resources, socio-economics, and ecological environment has become an important goal of human development [23]. Therefore, there is increasing attention on and practice in the application of coupled system evaluation modeling, including examining the interconnections between resource, ecological, and economic systems, developing a dynamic coupling model, and elucidating the operational mechanisms within the model [24,25,26]. Such modeling is utilized for watershed management practices, and practical optimization of the model is implemented [27,28,29]. Li W [30] emphasized the importance of coordinating development among subsystems, particularly economic, social, and environmental subsystems, as a crucial aspect of urban sustainability that directly impacts the quality of urbanization. Liu Y [31] established a comprehensive index system for evaluating the coupled coordination of socio-economic and water-environmental quality subsystems in a watershed. Luo Z [32] proposed a new framework for evaluating Socio-Economic-Water-Ecological (SWE) coordinated development by integrating distributed Socio-Economic-Water-Ecological (SEWE) models with coordinated regulatory models. The third category is the happy river evaluation system. The “happy river” is an organic combination of the subjective feeling of “happiness” and the objective existence of “river”, which is an important carrier and focus for implementing the concept of human–water harmony [33]. Chen Maoshan [34], based on the Marxist concept of happiness, elaborated on the connotation of the “happy river”, and put forward the evaluation index system and evaluation method of happy river. The research group of happy river [35] gives the definition of the happy river and constructs the evaluation index system of the happy river. Zuo Qiting [36] highlighted the definition of the “happy river”, constructing a happy river evaluation system within the framework of ultimately realizing harmony between people and rivers. Tang Kewang [37] believes that the concept of the “happy river” should include two levels of meaning: one is the psychological satisfaction of watershed residents on the relationship between people and water, and the other is the external factors affecting this satisfaction, especially the modernization level of water governance. The evaluation system has been constructed accordingly.

By summarizing and analyzing the above three major types of evaluation systems, it can be seen that there are four characteristics of constructing an evaluation index system: (1) It is difficult to form a common evaluation index system for rivers and watersheds under different geographic climate, economic, and cultural characteristics. (2) The selection of evaluation indicators under different theoretical systems does not necessarily emphasize completeness in the strict sense. (3) The number of indicators under a specific guideline layer should not exceed nine. (4) Within a certain period of time, the indicator system and standards for the same evaluation object should be relatively stable, while in the long run, the construction of the indicator system is a dynamic process of continuous improvement. Two major deficiencies are identified: (1) The mainstream theory system is mainly the river health theory system and the coupled system theory system with water activities as the core, and the latest proposal in recent years, from the people-oriented happy river theory system. With the concept of ecological civilization construction in watershed management, there is an urgent need to explore the ecological watershed theory system on the scale of the watershed, and the construction of the eco-watershed theory system provides theoretical support for watershed management. (2) The river health evaluation system, the water resources–economy–ecology coupling evaluation system, and the happy river evaluation system are used to evaluate different systems. These commonly used evaluation methods are limited to a single system and lack a global nature, and there is a lack of research on the eco-watershed evaluation system that integrates the river system, water resources, economic and social development, and ecosystems on the scale of the watershed.

The main research contents and realization objectives of this paper are to (1) build a multi-indicator assessment system for eco-watersheds based on the constructed eco-watershed theoretical system; and (2) propose an evaluation standard for ecological watersheds.

2. Methods

2.1. Framework for Constructing an Eco-Watershed Evaluation Indicator System

The definition of eco-watershed evaluation is as follows: comprehensively considering the social-economic-ecological issues of watersheds, concentrating on the natural and artificial regulation of water cycles, and achieving the high-quality and sustainable development of watershed ecological civilization and social economy under the premise of maintaining the health of watershed ecosystem structure and function. Through the overall planning, design, construction, and management operation of watersheds, the life and production activities are compatible with the carrying capacity of the ecosystem. Holistic, multidimensional, and integrated ecological water conservancy concepts are utilized to establish models for ecological protection, reasonable water resource development, and efficient utilization in watersheds. Multi-level, multi-objective, and phased coordination of key factors, including ecological, environmental, social, and economic subsystems, is adopted to ensure green mountains, clean waters, smooth rivers, beautiful lakes, and green shores in watersheds, thus achieving coordinated development of social-economic-ecological systems in watersheds. Eco-watershed theory is built on the basis of ecological civilization construction theory and ecological water conservancy theory, with the basic law of the watershed water cycle as the core. It utilizes system theory ideas, resulting in the three major sub-systems of watershed water resources, socio-economics, and ecology. The connotation of the three subsystems aligns with the three major concepts of nature-following, nature-respecting, and nature-protecting, and thus derives from the eight dimensions of water security, water resources, water economy, water management, water culture, water environment, water ecology, and water landscape, which builds up the basic theoretical framework of the eco-watershed theoretical system (Figure 1).

The top-level design of the eight dimensions has scientifically, systematically, and comprehensively deconstructed the eco-watershed theoretical system. It has also proposed new concepts and goals for the construction of ecological civilization in China. In order to further decompose the scientific content embedded in the eight dimensions of water security, water resources, water economy, water management, water culture, water environment, water ecology, and water landscape, this paper refers to the “Interpretation of the Essentials of the Protection Law of the Yangtze River of the People’s Republic of China”, the “Law of the People’s Republic of China on the Protection of the Yellow River”, and the “Shandong Province Yellow River Watershed Eco-Protection and High-Quality Development Plan”. The paper combines scientific theories with the carrying capacity of life, production, and ecosystems, thus forming the policy planning layers of the watershed water resources subsystem, the socio-economic subsystem, and the ecological subsystem of the eco-watershed evaluation index system (

Table 1. Policy planning layers.

Target Level	Three-Major- Subsystem Level	Eight-Dimension Level	Policy Planning Level
			Level 1	Level 2
Eco- watershed	Watershed Water Resources subsystem	water security	Construction and management of disaster prevention and mitigation engineering systems	Engineering flood control measures
				Non-engineering flood control measures
			Emergency response capacity for disaster defense	Flood monitoring
				Early warning capability
				Losses from droughts and floods
				Storm water monitoring
		water resources	Scale of water resources in the Watershed	Surface water resources
				Groundwater resources
			Systematic optimization of water allocation	Basic ecological water
				Water for production
				Security of water supply in urban and rural areas
			Water-saving society	Water conservation in agriculture
				Industrial water conservation
				Water conservation in urban and rural areas
	Socio- economic subsystem	water economy	Development of the primary sector
			Development of the secondary sector
			Development of the tertiary sector
			Comprehensive state of economic development	Integrated water use benefits
				Water markets
				Integrated economic development
				Financial income and expenditure
			Hydroelectric power
		water management	Status of watershed management	Population status
				Status of infrastructure
			Watershed management measures	Administration management
				Land management
				Assurance management
		water culture	Systematic protection of historical and cultural heritage
			Building a modern cultural industry chain
			Laws and regulations
			Public survey
	Ecological subsystem	water environment	Atmospheric conditions in the Watershed
			Soil conditions in the watershed
			Watershed waters	Composite water quality index
				Composite pollution index
		water ecology	Biological indicators
			Vegetation indicators
			In-stream abiotic ecological indicators
			Off-channel abiotic ecological indicators
		water landscape	River and riparian conditions
			Landscape Amenity Properties
			Landscape value
			level of satisfaction

), and finally forming the framework of the eco-watershed evaluation index system.

2.2. Methodology for Constructing an Eco-Watershed Evaluation Index System

2.2.1. Principles for Selecting Eco-Watershed Evaluation Indicators

The selection of indicators is the basis for the construction of the eco-watershed evaluation indicator system. By analyzing and summarizing the development process of the construction of the evaluation indicator system, as well as the progress of research at home and abroad, it can be made clear that the selection of evaluation indicators should follow the following principles:

(1)

Principle of structural integrity.

In different river watersheds and regions, because of their unique climate and geography, humanities, and economic characteristics, as well as differences in policies and regulations, it is difficult to form the same set of evaluation index systems. This requires the establishment of a complete theoretical evaluation system framework when constructing the evaluation index system. Under the framework of this evaluation system, a well-structured eco-watershed evaluation indicator system is constructed.

(2)

Principle of scientificity and accessibility.

Based on the framework structure of the evaluation system, when selecting evaluation indicators, the scientific connotation of the indicators should be fully understood, and the indicators with clear concepts, strong relevance to the framework of the indicator system, and ease of understanding should be selected. The selection of indicators should take into account the cost and accuracy of obtaining them, and the quantitative indicators should be calculated directly or indirectly using the data released by the national statistical department, supplemented by the data from observation statistics.

(3)

Principle of combining quantitative and qualitative data.

As far as possible, quantitative data corresponding to the framework of the evaluation index system should be selected as indicators. In some watersheds and regions, due to the differences in government statistical data or the difficulties in data collection, qualitative indicators can be adopted, such as assigning scores by experts or through social surveys. Use qualitative means or quantitative data to ensure the objectivity and reliability of data as much as possible.

(4)

The principle of conforming to the characteristics of evaluation watersheds and regions.

For different evaluation watersheds and regions, when selecting indicators, the characteristics of the watersheds should be taken into consideration, and evaluation indicators that highlight the characteristics of the watersheds should be selected, to build an evaluation indicator system that aligns with and fully reflects the characteristics of the watersheds.

2.2.2. Process of Screening Indicators for the Evaluation of the Weihe River Eco-Watershed

(1)

Initial screening of indicators

The eco-watershed evaluation index system is the development and synthesis of the river health, happy river, and water resources coupling evaluation index systems, and the construction of the eco-watershed evaluation index system should fully understand the utilization of the indicators from each evaluation index system. In this paper, we searched the related evaluation index literature with the theme of “ecological watershed, river health, water resources coupling evaluation system, happy river”, and obtained more than 120 papers, including master’s theses, doctoral dissertations, Chinese EI papers, and SCI papers. We selected over 70 papers with representativeness and a complete index system, and summarized them in 8 dimensions (water security, water resources, water economy, water management, water culture, water environment, water ecology, and water landscape) by applying the frequency analysis method, so as to obtain the results of the preliminary screening of the evaluation index system for eco-watersheds. In the statistical process, different expression indicators with similar connotations and characteristics were unified and summarized. The indicators were processed as accurately and comprehensively as possible to achieve the goal of scientific evaluation.

(2)

Finalization of evaluation indicators

According to the framework of the theoretical evaluation index system of eco-watersheds, the initial screening results of eco-watershed evaluation indicators, the guidelines issued by the Ministry of Water Resources titled “River and Lake Health Evaluation Guidelines (for Trial Implementation)” [38], “China’s River and Lake Well-Being Index Report 2020” [39], and the current situation of the characteristics of the Weihe River Watershed, the final determination was made of the watersheds of the three major sub-systems watershed water resources, socio-economy, and ecology. Water security, water resources, water economy, and water management, water culture, water environment, water ecology, and water landscape are the 8 dimensions of the Weihe River eco-watershed evaluation index system. These 8 dimensions comprise 60 evaluation indicators, where “+” represents a positive indicator, “−” represents a negative indicator, and “±” represents a bi-directional indicator in the characteristics. The specific indicator results are shown in

Table 2. Weihe River eco-watershed evaluation index system.

Level 1 Indicators	Level 2 Indicators	Level 3 Indicators	Combined Weights	Gray Correlation Weights	Characteristic	Unit	Connotation of Indicators
Watershed Water Resources subsystem (AB) 0.32695	Water security (A) Combined weights: 0.19505 Gray correlation weights: 0.129	1. Achievement rate of flood control engineering measures (A1)	0.1057	0.1206	+	%	Levee flood control standard compliance rate, reservoir flood control standard compliance rate and flood storage area flood control standard compliance rate of three tertiary indicators comprehensive assessment, weighted 0.4, 0.4, 0.2, respectively [39].
		2. Achievement rate of flood control non-engineering measures (A2)	0.04775	0.1208	+	%	The compliance rate of flood control non-engineering measures mainly refers to the scoring of annual engineering management assessment information, reflecting the management of flood control engineering measures.
		3. Rate of change of flood capacity (A3)	0.0842	0.1213	+	%	Interannual flow change value/flow in the base year (same cross-section, same water level) × 100%, interannual change in river flooding capacity, reflecting progress in clearing water-blocking obstacles and river flooding standards [40].
		4. Flood resilience (A4)	0.0465	0.1219	+		The weights of economic strength of the watershed, development level, rescue and relief capacity, and post-disaster recovery action power are 0.3, 0.2, 0.25, and 0.25, respectively. the expert assigns points [39].
		5. Number of rainstorms with daily rainfall greater than 50 mm (A5)	0.3534	0.1334	±	Day	Reflects concentrated regional rainfall and is closely related to rain and flooding [41].
		6. Flood warning and forecasting capacity (A6)	0.14525	0.1212	+		Reflects the establishment of digital twins in watersheds and the implementation of the “four preemptions” policy [40].
		7. Quantity of rainfall (A7)	0.12325	0.1279	±	mm	The depth of the water layer, in millimeters, that lands on the ground at a point or on a unit area within a certain period of time, which visually reflects the rainfall situation in the watershed [42].
		8. Aridity index (A8)	0.09395	0.1329	−		The aridity index is the ratio of annual evaporation to annual rainfall [43].
	Water resources (B) Combined weights: 0.1319 Gray correlation weights: 0.1336	9. modulus of water yield (B1)	0.2855	0.1225	+	104 m3·km−2	Modulus of water yield = total water resources/calculated area, reflecting total water resources production and distribution [43].
		10. Groundwater production modulus (B2)	0.082	0.1199	+	104 m3·km−2	Groundwater production modulus = total groundwater resources/calculated area, reflecting the total amount of groundwater resources, their distribution and the amount that can be extracted [44].
		11. Proportion of water used for industrial purposes (B3)	0.0741	0.1261	−	%	Industrial water consumption as a percentage of total water supply, reflecting industrial water use and water conservation [43].
		12. Proportion of water used for agricultural irrigation (B4)	0.05735	0.1224	−	%	Proportion of water used for agricultural irrigation to total water supply, reflecting the use of water for agricultural irrigation [44].
		13. Average acre-feet of water used for farm irrigation (B5)	0.08275	0.1277	−	m3·km−2	Total water resources available/total area of cultivated land, reflecting the relationship between water resources and the carrying capacity of cultivated land [45].
		14. Proportion of water used for urban integrated living (B6)	0.1315	0.1321	−	%	The proportion of the town’s combined domestic water use to the total water supply, reflecting the town’s combined water use [46].
		15. Per capita integrated water use (B7)	0.1411	0.1274	−	m3/per	The level of regional per capita water supply, reflecting regional per capita water use efficiency and water conservation [41].
		16. Proportion of water used for ecological purposes (B8)	0.1457	0.122	+	%	The ratio of ecological water use to total water supply, reflecting comprehensive ecological water use [47].
Socio- economic subsystem (CDE) 0.29515	Water economy (C) Combined weights: 0.11285 Gray correlation weights: 0.1213	17. Percentage of primary sector (C1)	0.0957	0.1205	−	%	Primary sector as a percentage of GDP, reflecting the development of the primary sector [48].
		18. Percentage of secondary industry (C2)	0.10535	0.1221	−	%	The ratio of the secondary sector to GDP, reflecting the development of the secondary sector [49].
		19. Water consumption of 10,000 yuan of industrial added value (C3)	0.1339	0.1388	−	m3/104 RMB	Reflecting the level of water consumption of 10,000 yuan of industrial added value, industrial water consumption (m3)/industrial added value (10,000 yuan) [50].
		20. Percentage of tertiary sector (C4)	0.10405	0.1203	+	%	The ratio of the tertiary sector to GDP, reflecting the development of the tertiary sector [51].
		21. Water consumption per 10,000 GDP (C5)	0.14575	0.1202	−	m3/104 RMB	Reflects the level of water use in the watershed in terms of 10,000 yuan of gross domestic product (GDP) [52].
		22. GDP per capita (C6)	0.1341	0.1361	+	104 RMB/per	Reflects the per capita share of GDP in the watershed [53].
		23. Engel’s coefficient (C7)	0.15545	0.12	−		An indicator of the level of standard of living, amount spent on food ÷ total amount spent × 100% [54].
		24. Investment in water, environment and utilities management as a share of GDP (C8)	0.1257	0.122	+	%	Reflect investment in water-related infrastructure in the watershed [48].
	Water management (D) Combined weights: 0.0976 Gray correlation weights: 0.1242	25. Regional population density (D1)	0.1109	0.1212	±	per·km−2	Population density = total population/total area, reflecting regional economic management [55].
		26. Water resources monitoring capacity (D2)	0.14985	0.1188	+	−	Reflecting the establishment of water resources monitoring infrastructure and digital platforms in the watershed [7].
		27. urbanization level (D3)	0.0833	0.1179	+	%	The urbanization rate is a measure of urbanization, i.e., the share of urban population in the total population [30].
		28. Public green space per capita (D4)	0.0789	0.14	+	m2/per	The average area of public green space occupied by urban residents is an important indicator of the quality of life and living environment of urban residents [56].
		29. Degree of assurance of water supply (D5)	0.19915	0.1314	+	%	Percentage of the number of days in a year on which the day-to-day level or flow of a river or lake reaches the guaranteed level or flow of the water supply as a percentage of the total number of days in the year [38].
		30. Ward beds per 1000 population (D6)	0.06355	0.1191	+	/1000 per	Total number of hospital beds in the watershed/total population of the watershed [57].
		31. Per capita expenditure on education (D7)	0.12735	0.1331	+	RMB	Level of basic investment in education per capita in the watershed, reflecting the state of educational development [48].
		32. Water penetration rate (D8)	0.187	0.1185	+	%	Refers to the number of people using piped water in the watershed as a percentage of the total population. Indicator reflecting the civilized state of people’s lives [28].
	Water culture (E) Combined weights: 0.0847 Gray correlation weights: 0.1236	33. Historic Water Cultural Heritage Excavation and Preservation Index (E1)	0.2002	0.2747	+		Quantity and quality of historic water culture development and preservation in the watershed, with reference to expert opinion [35].
		34. Modern Water Culture Creation and Innovation Index (E2)	0.25425	0.2472	+		Quantity and quality of modern water cultural product construction in the watershed, with reference to expert opinion [58].
		35. Public Water Culture Satisfaction Index (E3)	0.26925	0.226	+		Watershed Public Water Culture Satisfaction Questionnaire [59].
		36. Degree of construction of water laws and regulations (E4)	0.2763	0.252	+		Watershed Public Questionnaire [7].
Ecological subsystem (FGH) 0.37795	Water environment (F) Combined weights: 0.1837 Gray correlation weights: 0.1185	37. Percentage of water categories 1–3 (F1)	0.1317	0.128	+	%	Proportion of water monitoring sections in categories 1–3 out of the total number of sections monitored [35].
		38. poor quality five sections (F2)	0.1645	0.119	−	%	Proportion of poorly classified water monitoring sections to the total number of sections monitored [35].
		39. Comprehensive status of surface water quality (F3)	0.16735	0.1206	+		Integrated water quality evaluation of monitoring sections [60].
		40. Water quality of urban centralized drinking water sources (F4)	0.0859	0.1285	+		Comprehensive assessment of water quality in drinking water sources [61].
		41. Harmless treatment of urban domestic waste (F5)	0.10975	0.1206	+	%	Amount of non-hazardous domestic waste disposed of/total amount of domestic waste [57].
		42. Overall air quality (F6)	0.1513	0.1282	+		Comprehensive air quality assessment of monitoring stations [62].
		43. Sewage treatment rate (F7)	0.09545	0.1364	+	%	Total sewage treated/total sewage generated [63]
		44. Extent of unauthorized exploitation of the shoreline of waters (F8)	0.09405	0.1187	−		The rate of standardized construction of river outfalls, the reasonable degree of layout of river and lake outfalls, and the situation of “four chaotic” rivers and lakes, with weights of 0.2, 0.2, and 0.6 respectively [38].
	Water ecology (G) Combined weights: 0.1087 Gray correlation weights: 0.1198	45. Status of waterbirds (G1)	0.09145	0.1251	+		Combined with on-site observation of the species and number of birds recorded in the river and lake as the basis for assigning points [38].
		46. Fish retention index (G2)	0.1376	0.1274	+		Status of differences between current fish species counts and historical reference point fish species counts [38].
		47. Status of aquatic plant communities (G3)	0.0702	0.1261	+		The aquatic plant community includes aquatic plants, submerged plants, floating leaves and floating plants, and wet plants. A survey of aquatic plant species, abundance, and invasive status of exotic species was conducted in the cross section area [38].
		48. Vertical continuity (G4)	0.0519	0.1303	+		Evaluation of the number of buildings or facilities affecting the connectivity of the river within the unit length of the river, with ecological flow or ecological water security, overfishing facilities and normal operation is not included in the statistical scope [38].
		49. Degree of variability in flow processes (G5)	0.1012	0.1259	+	%	Calculation of the average deviation of the measured monthly runoff from the natural monthly runoff for the evaluation year [38].
		50. average monthly traffic (G6)	0.29245	0.1156	+	m3·s−1	Measured average monthly flow values that reflect the overall annual flow of the river [38].
		51. Riparian width index (G7)	0.1098	0.1248	+	%	Refers to the proportion of riparian length per unit of stream length that meets the width requirement [38].
		52. Level of ecological flow satisfaction (G8)	0.1454	0.1249	+	%	The number of days meeting ecological flows as a percentage of the number of days in each water period [38].
	Water landscape (H) Combined weights: 0.08555 Gray correlation weights: 0.1299	57. Availability rate (H1)	0.28275	0.254	+	%	The number of days meeting navigational requirements for water depth as a percentage of the year [44].
		58. Degree of naturalness of bank slopes (H2)	0.27105	0.2539	+	%	Includes river (lake) bank stability and shoreline vegetation cover [38].
		59. Water Landscape Conservation Utilization Index (H3)	0.21525	0.2322	+		Quality and quantity of waterscape protection and utilization in the watershed, refer to the questionnaire [32].
		60. Public satisfaction with the water ecosystem (H4)	0.23095	0.2598	+		Questionnaire [52].

Notes: “+” means positive indicator, “−” means negative indicator, and “±” means bidirectional indicator.

.

(3)

Establishment of evaluation index system standard of Weihe River eco-watershed

The standard determination of eco-watershed evaluation indexes has a strong background characteristic of the development of the times, and should not blindly follow the global development level but should be based on the country, watershed, and regional development stage. The standard should be determined according to the specific time and place; otherwise, it could hinder the development of eco-watersheds and undermine efforts to improve policies and measures or progress beyond the current stage. In this paper, according to the current situation of the Weihe River Watershed, we refer to the following types of standards: ① the relevant evaluation standards issued by the state, industry, or local governments. ② Evaluation criteria formulated in the literature related to river health, happy river, and water resources coupling evaluation. ③ Current values or target values related to water resources management in the watershed and regional socio-economic development. ④ Expert consultation. The evaluation index system standard of the Weihe River eco-watershed is formulated, and the specific index standard is shown in

Table 3. Weihe River eco-watershed evaluation index system.

Indicator	Indicator Standard Value
	Excellence	Good	Moderate	Eligible	Poor	Bad
A1	[100,95)	[95,90)	[90,85)	[85,70)	[70,50)	[50,0)
A2	[100,95)	[95,90)	[90,85)	[85,70)	[70,50)	[50,0)
A3	[100,90)	[90,80)	[80,70)	[70,60)	[60,30)	[30,0)
A4	[100,98)	[98,85)	[85,75)	[75,60)	[60,30)	[30,0)
A5	[6,5)	[5,4)	[4,3)	[3,2)	[2,1)	≤1
		[7,6)	[8,7)	[9,8)	[10,9)	>10
A6	[100,98)	[98,90)	[90,75)	[75,60)	[60,30)	[30,0)
A7	[750,950)	[750,600)	[600,500)	[500,400)	[400,300)	≤300
		[1100,950)	[1200,1100)	[1300,1200)	[1400,1300)	>1400
A8	≤0.6	[1.1,0.6)	[1.6,1.1)	[2,1.6)	[2.4,2)	>2.4
B1	>60	[60,50)	[50,40)	[40,25)	[25,10)	≤10
B2	>25	[25,21)	[50,40)	[40,25)	[25,10)	≤10
B3	≤10	[12,10)	[14,12)	[17,14)	[20,17)	>20
B4	≤45	[50,45)	[55,50)	[60,55)	[65,60)	>65
B5	≤90	[140,90)	[190,140)	[270,190)	[350,270)	>350
B6	≤12	[14,12)	[16,14)	[19,16)	[22,19)	>22
B7	≤100	[150,100)	[200,150)	[250,200)	[300,250)	>300
B8	>21	[21,17)	[17,13)	[13,9)	[9,5)	≤5
C1	≤5	[7,5)	[9,7)	[12,9)	[15,12)	>15
C2	≤30	[36,30)	[42,36)	[51,42)	[60,51)	>60
C3	≤15	[18,15)	[22,18)	[26,22)	[30,26)	>30
C4	>65	[65,56)	[56,47)	[47,38)	[38,30)	≤30
C5	≤40	[55,40)	[70,55)	[85,70)	[100,85)	>100
C6	>6.5	[6.5,5.6)	[5.6,4.7)	[4.7,3.8)	[3.8,3)	≤3
C7	≤20	[25,20)	[30,25)	[35,30)	[40,35)	>40
C8	>15	[15,12)	[12,9)	[9,6)	[6,3)	≤3
D1	[1100,900)	[900,700)	[700,500)	[500,300)	[300,100)	≤100
		[1300,1100)	[1500,1300)	[1700,1500)	[1900,1700)	>1900
D2	[100,95)	[95,90)	[90,85)	[85,70)	[70,50)	[50,0)
D3	>80	[80,70)	[70,60)	[60,50)	[50,40)	≤40
D4	>20	[20,17)	[17,14)	[14,10)	[10,6)	≤6
D5	100	(100,95)	[95,80)	[80,60)	[60,20)	≤20
D6	>12	[12,10)	[10,8)	[8,6)	[6,4)	≤4
D7	>4000	[4000,3400)	[3400,2800)	[2800,2000)	[2000,1200)	≤1200
D8	100	(100,99.5)	[99.5,99.1)	[99.1,98.5)	[98.5,97.9)	≤97.9
E1	[100,90)	[90,80)	[80,70)	[70,60)	[60,30)	[30,0)
E2	[100,90)	[90,80)	[80,70)	[70,60)	[60,30)	[30,0)
E3	[100,90)	[90,80)	[80,70)	[70,60)	[60,30)	[30,0)
E4	[100,90)	[90,80)	[80,70)	[70,60)	[60,30)	[30,0)
F1	[100,90)	[90,75)	[75,60)	[60,40)	[40,20)	[20,0)
F2	0	[10,0)	[20,10)	[35,20)	[50,35)	[50,0)
F3	Excellent	Good	light pollution	moderate pollution	heavy pollution
	100	80	60	30	0
F4	[100,80)	[80,60)	[60,40)	[40,20)	[20,0)	0
F5	100	(100,99.5)	[99.5,99)	[99,98)	[98,97)	≤97
F6	Excellent	Good	light pollution	moderate pollution	heavy pollution	severe pollution
	100	80	60	40	20	0
F7	100	(100,98)	[98,96)	[96,93)	[93,90)	≤90
F8	[100,90)	[90,80)	[80,70)	[70,60)	[60,30)	[30,0)
G1	[100,90)	[90,80)	[80,70)	[70,60)	[60,30)	[30,0)
G2	[100,75)	[75,50)	[50,25)	[25,5)	[5,0)	0
G3	[100,90)	[90,80)	[80,70)	[70,60)	[60,30)	[30,0)
G4	[100,80)	[80,60)	[60,40)	[40,20)	[20,0)	0
G5	≤0.05	[0.1,0.05)	[0.5,0.1)	[2.5,0.5)	[5,2.5)	>5
G6	[100,90)	[90,80)	[80,60)	[60,40)	[40,20)	[20,0)
G7	[100,80)	[80,60)	[60,40)	[40,20)	[20,0)	0
G8	>40	[40,30)	[30,20)	[20,10)	[10,0)	0
H1	[100,95)	[95,80)	[80,65)	[65,50)	[50,25)	[25,0)
H2	[100,75)	[75,50)	[50,25)	[25,5)	[5,0)	0
H3	[100,90)	[90,80)	[80,70)	[70,60)	[60,30)	[30,0)
H4	[100,90)	[90,80)	[80,70)	[70,60)	[60,30)	[30,0)

Notes: [100,90) means a range 100–90, and the range includes 100 but does not include 90.

and

Table 4. Grading criteria for evaluation of ecological watersheds.

Value	Level	Situation
≥90	Level 1 eco-watershed	Excellence
(90,80]	Level 2 eco-watershed	Good
(80,70]	Level 3 eco-watershed	Moderate
(70,60]	Level 4 eco-watershed	Eligible
(60,30]	Level 5 eco-watershed	Poor
(30,0]	Level 6 eco-watershed	Bad

Notes: (90,80] means a range 90–80, and the range includes 80 but does not include 90.

, which show the grading criteria for ecological watershed evaluation [38].

2.3. Integrated Evaluation Methodology and Coupled Coordination Model

2.3.1. Percentage of Single Indicators

Indicators are divided into qualitative indicators and quantitative indicators. To facilitate unified calculation, qualitative indicators are obtained by percentage scoring, while quantitative indicators are obtained using the fuzzy affiliation function method, which uniformly maps the indicators to [0,100] by the five indicator characteristic node values of a (j), b (i), c (h), d (g), e (f) (bidirectional indicators take 10 characteristic node values). The characteristic node values corresponding to the single-indicator affiliation are set in turn as 0, 30, 60, 80, and 100. Ultimately, based on the acquired data and their attributes, the affiliation value of each indicator is calculated using the affiliation calculation formula.

2.3.2. Determination of Weights

Weight determination is mainly divided into three methods: the subjective assignment method (hierarchical analysis, expert consultation method, binomial coefficient method, ring score method, etc.), the objective assignment method (principal component analysis, entropy weight method, gray correlation method, etc.), and the equal weight assignment method. In the actual study, one or more weight assignment methods can be selected as needed.

2.3.3. Integrated Evaluation Model

The comprehensive evaluation score of 8 dimensions is obtained by accumulating the product of each evaluation index score and its corresponding weight. The evaluation results of 8 dimensions are then weighted according to certain weights to finally obtain the evaluation score of ecological watersheds and determine the grade of ecological watersheds.

2.3.4. Coupled Coordination Degree Model

Construct a composite evaluation index as follows:

$$\left\{\begin{array}{c}f(x)={\displaystyle \sum _{i=1}^n}{\alpha }_i·x_i\\ g(y)={\displaystyle \sum _{i=1}^m}{\beta }_i·y_i\\ h(z)={\displaystyle \sum _{i=1}^k}{\gamma }_i·z_i\end{array}\right.$$

(1)

In the formula, f(x), g(y), h(z) represent the comprehensive benefits of each subsystem, respectively; α_i, β_i, γ_i are the weights of each indicator in each subsystem, respectively; x_i, y_i, z_i are the dimensionless values describing each indicator, respectively.

This paper involves three subsystems: watershed water resources, socio-economic subsystems, and ecological subsystems. A system coupling model is constructed as follows:

$$C={\left({\displaystyle \frac{f\left(x\right)·g\left(y\right)·h\left(z\right)}{{\left[\frac{\left(f(x\right)+g\left(y\right)+h\left(z\right)}{3}\right]}^3}}\right)}^{{\displaystyle \frac{1}{3}}}$$

(2)

In the formula, C is the coupling degree, which ranges from 0 to 1. Values of C between 0 and 0.3 indicate the low-level coupling stage, those between 0.3 and 0.5 represent the fly down stage, those between 0.5 and 0.8 signify the friction stage, and those between 0.8 and 1.0 denote the high-level coupling stage.

According to the coupling degree model of watershed water resources, socio-economic subsystems, and ecosystems, the coupling coordination degree D of the system can be calculated. In this paper, we consider that the watershed water resources subsystem, socio-economic subsystem, and ecological subsystem are equally important, i.e., α = β = γ = 1/3, and we calculate the comprehensive evaluation index T of the watershed water resources, socio-economic, and ecological subsystems as follows:

$$D=\sqrt{C·T}$$

(3)

$$T=\alpha ·f\left(x\right)+\beta ·g\left(y\right)+\gamma ·h\left(z\right)$$

(4)

In the formula, C is the degree of coupling, D is the degree of coupling coordination, T is the comprehensive evaluation index of the level of coupling coordination and development, and α, β, and γ are the weights of each subsystem, respectively.

In this paper, based on references to research papers, the coupled coordinated development types and criteria are classified as shown in

Table 5. Types and criteria for coupled and coordinated development.

D	(0.9~1]	(0.8~0.9]	(0.7~0.8]	(0.6~0.7]	(0.5~0.6]	(0.4~0.5]	(0.3~0.4]	(0.2~0.3]	(0.1~0.2]	(0~0.1]
Type of coordination	high quality harmonize	favorable harmonize	intermediate harmonize	elementary harmonize	barely harmonize	close to disorders	mildly disorders	moderately disorders	severity disorders	Extreme disorders

Notes: (0.9~1] means a range 0.9–1, and the range includes 1 but does not include 0.9.

:

3. Study Area and Data

3.1. Overview of the Weihe River Watershed

Weihe River is one of the sources of the Zhangwei South Canal, which belongs to the Haihe River Watershed, located between 112–116 degrees east longitude and 35–37 degrees north latitude, east of Taihang Mountain, south of the Yellow River, and north of the Zhanghe River. The total length of the main stream is 329 km, with a watershed area of 15,229 km², of which the mountainous areas account for about 60%. Weihe River originates in Lingchuan County, Shanxi Province, and Duohuo town, and the main tributaries are Yu River, Qi River, Tang River, Anyang River, etc., in Handan City, Hebei Province, Guantao County, and Xu Wancang, and Zhang River, which convergences into the Wei Canal. The Zhangwei Canal in Handan City includes Zhang River, Wei River, and Wei Canal, with a watershed area of 3624.9 square kilometers, of which the Wei River is 55 km long. The resident population in the watershed is 29,788,000, and GDP is 155.53 billion yuan, of which the resident population of Handan City is 9,367,000, and GDP is 434.63 billion yuan (at the end of 2022). The watershed is an important grain and cotton producing area, with wheat, corn, and cereals as the main food crops, and cotton, soybeans, and peanuts as cash crops. Industries in the watershed are developing rapidly, mainly power generation, iron and steel production, textiles, and various chemical industries. Handan City, as the confluence of the Zhangwei River Watershed and affected by the Zhanghe River Yecheng Reservoir dispatch, is an important node in the evaluation of the Weihe River Watershed [38,64].

3.2. Data Sources

The data related to the evaluation indicators of the Wei River Ecological Watershed mainly come from the management agencies of the Wei River Watershed, local statistical yearbooks, statistical bulletins, and fieldwork information from 2019 to 2021, including the Zhangwei South Canal Hydrological Query System, water quality test reports from the Hydrological Center of the Wei River Bureau, project management data, water administration data, water resources information from the Wei River Bureau and Handan River Bureau, statistical yearbooks of the municipalities in the watershed, questionnaire surveys, and expert scores.

4. Results and Discussions

4.1. Analysis of Results

The Weihe River eco-watershed evaluation system of the three first-level indicators—the watershed water resources subsystem, socio-economic subsystem, and ecological subsystem; the eight secondary indicators—water security, water resources, water economy, water management, water culture, water environment, water ecology, and water landscape; and sixty tertiary indicator weights are shown in Table 1.

4.1.1. Synthetic Assessment

(1)

Watershed water resources subsystem

The water security scores are shown in Figure 2. As a whole, due to the more obvious differences in the assignment, the gray correlation method assigns relatively balanced weights, while the comprehensive weights assign more weight to the indicator of A5 and less weight to the indicators of A2, A3, and A4, resulting in an obvious difference in the overall scores. With more consideration of A5, the occurrence of a major flood in 2021 is given a relatively high score, while a severe drought in 2019 is given a relatively low score. The comparison between the Weihe River in Henan and in Handan reveals that, despite differences in scores resulting from allocated weights, Henan scored higher than Handan overall in 2019. This was primarily due to the initiation of Weihe River governance rehabilitation in Henan and a significant increase in compliance with flood control engineering measures. However, by 2020 and 2021, Handan’s scores surpassed those of Henan, largely attributed to variations in rainfall patterns. The absence of large-scale water control projects with regulating and storage functions along the mainstream of the Weihe River Watershed in Henan became evident after heavy rainfall events, significantly impacting water security within the watershed.

Water resources scores are shown in Figure 2. The overall trend of the two weight fittings is basically the same. The indicator weight of B1 in the comprehensive weight is higher, resulting in higher comprehensive evaluation scores within Henan in 2021; for the rest of the years, the overall score of the gray correlation is higher than that of the comprehensive weight. This is mainly because the overall distribution of the gray correlation weight is more evenly distributed, and B3 and B4 in the comprehensive weight are less heavily weighted. Among them, a comparison was made between the situation of Handan and the Weihe River Watershed in Henan, revealing significant differences between 2021 and 2020. The primary factor behind these differences lies in the impact of water resource regulation by Yuecheng Reservoir on Handan and its jurisdiction over the Weihe River Watershed during both years, enabling effective allocation of water resources. In the Weihe River Watershed, watershed replenishment led to rational allocation of water resources across various water systems under adequate supply conditions. Consequently, overall scores for 2021 and 2020 were relatively favorable. However, in 2020, there existed an imbalance in the allocation of water for residential use, production, and ecological purposes in Handan; thus, while the overall score improved compared to previous years, it remained lower than that of Henan for the Weihe River Watershed. In 2019, the Weihe River Watershed experienced an overall dry state with very low watershed levels. Nevertheless, regulation by Yuecheng Reservoir’s management of water resources at that time resulted in slightly higher overall levels compared to those within Henan’s portion of the Weihe River Watershed

(2)

Socio-economic subsystem

The water economy score is shown in Figure 3. The two weights fit well, and the comparison of the situation between Handan and Henan of the Weihe River Watershed shows that the water economy level of Handan was higher than that of the Weihe River Watershed in Henan in 2019; furthermore, Handan was seriously affected by the epidemic, and the water economy situation was lower than that of the Weihe River Watershed in Henan in 2020 and 2021.This pertains to the economic models of the two regions. The northwestern part of Henan serves as a significant agricultural production area, and its response to the epidemic has been relatively gradual. Conversely, Handan, with a population close to 10 million, is a medium-sized city whose economic indicators exhibit heightened sensitivity to the epidemic. Nevertheless, owing to various national measures, there were indications of economic improvement in 2021. A comparison between Handan and the Weihe River Watershed in Henan reveals that Handan’s water economy level surpassed that of the Weihe River Watershed in 2019. However, due to its high population density and the susceptibility of its economic model to the epidemic, Handan’s water economy situation was inferior to that of the Weihe River Watershed in Henan in both 2020 and 2021.

The water management scores are shown in Figure 3, with a high degree of fit of the two weights. Between 2019 and 2021, the water management scores in Handan and Henan showed an increasing trend. Except for the lower score of the population density index in the watershed, all other indicators showed an increasing trend. The main reason for this was the improvement of government management concepts and the corresponding increase in fiscal investment. However, the lower population density was a relatively complex factor, affected by factors such as the fertility rate and the pandemic. A comparison of the water management situation in the Weihe River Watershed in Handan and Henan shows that the overall water management level in Handan is higher than that in the Weihe River Watershed in Henan. In 2021, there was a significant increase in the water management score in Handan. In addition, the water management score was around 60 points, with a relatively weak overall level. The level of water management was affected by the development level of the region, including economic conditions and government policies.

The water culture scores are shown in Figure 3, with a high degree of fit of the two weights. The comparison between Handan and Henan of the Weihe River Watershed shows that the level of water culture creation in Henan is overall higher than that in the Weihe River Watershed in Handan. The dimension of water culture primarily manifests in the preservation of historical water culture and the establishment of contemporary water culture. The overall level of water culture in the Weihe River in Henan and Handan has exhibited a slight upward trend from 2019 to 2021, but the increase was marginal, resulting in an overall poor level. The development of water culture along the Weihe River Watershed is predominantly focused on preserving historical sites and significant geographical locations, such as the Grand Canal Wharf Site in Huaxian County, Henan Province, and the Yecheng Ruins in Linzhang County, Handan City. However, compared with developed areas, there remains a considerable gap in terms of both development and protection efforts for water cultural heritage. A comparison between the levels of water culture along the Weihe River Watershed reveals that Henan possesses numerous invaluable treasures related to its rich history as a cradle of Chinese civilization; this natural advantage provides fertile ground for advancing historical water culture. Nevertheless, further efforts are needed to enhance and expand upon the historical aspects of water culture along the Weihe River Watershed while drawing inspiration from developed regions to establish a modern corridor for nurturing contemporary water culture.

(3)

Ecological subsystem

The water environment scores are shown in Figure 4, with a high fit of the two weights. Since the comprehensive implementation of the river chief system in the Weihe River Watershed in 2018, the cleaning up of “four messes” in the watershed has been steadily promoted, and the water environment has improved markedly. In particular, with the increase in rainfall in the watershed, the self-renewal rate of the water environment has increased. In 2021, the water environment score in the Weihe River Watershed was close to 80 points, which was the highest level in all eight dimensions. The water environment in the Weihe River Watershed has gradually improved from poor, Class V water quality to a good water environment, which is a result of the firm implementation of the river chief system. The overall water environment level from 2019 to 2021 showed an upward trend and Handan’s water environment level was slightly higher than that of Henan. The water environment has a holistic and systematic nature; thus, it forms a connected large system within the entire watershed. No area can be left untouched; therefore, we can see similar overall evaluation scores within a year from the evaluation results and steady upward trends annually.

The water ecology scores are shown in Figure 4. The two weighting trends are basically the same, but the gray correlation weighting scores are higher than the composite weighting scores. The primary factor is the relatively balanced overall distribution of gray relational weight, whereas the comprehensive weight allocates greater weight to average monthly flow. However, the score for average monthly flow is notably low. Ensuring a reasonable range for monthly flow in the Weihe River Watershed proves challenging due to the absence of controllable water diversion projects on its main stream. Both weight scores are low, indicating a highly fragile water ecological condition in the Weihe River Watershed. Although extensive implementation of the river chief system since 2018 has led to initial improvements in the water environment within the watershed, restoring biological indicators such as water birds, fish, and aquatic plants in water ecology is a protracted process that necessitates stable physical ecological indicators as a foundation. Despite replenishment of groundwater and surface water resources by floodwater inflow post-floods, ensuring the ecological flow degree in rivers, river continuity, natural rhythm, and other ecological indicators remains difficult. Consequently, at present, the water ecological condition of the Weihe River remains poor and is undergoing an overall recovery phase.

The water landscape scores are shown in Figure 4, with a high fit of the two weights. The overall water landscape level in the Weihe River Watershed exhibited a slight upward trend from 2019 to 2021, with a minimal annual growth rate and an overall score that did not reach a high level. The Weihe River Watershed primarily serves to provide flood control, drainage, and water resources for crops along its banks. Originating from the Taihang Mountains, the Weihe River Watershed benefits from its natural geographical advantages of being situated near water, resulting in numerous picturesque water landscapes. However, these landscapes are relatively scattered at specific key points due to the functional attributes of the watershed, leading to a very low water landscape rate. A comparison between Handan and Henan within the Weihe River Watershed reveals that the former has a higher score than the latter due to differences in the naturalness of riverbanks. The implementation of management projects has compromised this naturalness and aesthetics, consequently reducing the water landscape score. In conclusion, enhancing the water landscape level in the Weihe River Watershed should be based on achievements in the water environment and ecology while incorporating relevant knowledge of landscape design. Additionally, referencing advanced experiences from developed countries sharing similar latitudes as Europe and United States can help create distinctive regional features in building beautiful water landscapes.

(4)

Ecological watersheds

The comprehensive eco-watershed evaluation of the eight secondary indicators of the score, the Weihe River eco-watershed evaluation of gray correlation weights, and the integrated weights of the final score are shown in Figure 5. The gray correlation evaluation of the Weihe River Watershed in Henan in 2021 indicates an eligible status, belonging to the fourth level of eco-watersheds. Similarly, the gray correlation evaluation of Handan in 2021 also shows an eligible status, belonging to the fourth level of ecological watersheds. In contrast, the remaining years are in poor condition and belong to the fifth level of ecological watersheds. As a whole, the two weights fit well, and the level of ecological watersheds from 2019 to 2021 shows an overall upward trend. However, based on the analysis of the weighting of indicators in each dimension, the comprehensive weighting can better highlight the characteristics of the Weihe River Watershed construction, and the use of comprehensive weighting is more appropriate. By comparing the scores of the Weihe River Watershed within Handan and Henan, it can be seen that the overall level of Handan is slightly higher than that of the Weihe River Watershed within Henan. For the Weihe River Watershed, the years from 2019 to 2021 were extremely complex. The river chief system, which was implemented in 2018, showed initial results in early 2019. In 2019, the Weihe River Watershed faced a serious drought. The epidemic that swept across the country in 2019 began to gradually affect the major administrative regions of the Weihe River Watershed. In 2020, the Weihe River governance rehabilitation work began, and the water conservancy infrastructure in the Weihe River Watershed was upgraded and improved. In 2021, the Weihe River Watershed experienced a once-in-a-century flood. At the same time, various measures and laws were implemented, including rural revitalization and blue-sky projects, which played an important role in the construction of the Weihe River ecological watershed.

4.1.2. Evaluation of Coupling and Coupling Coordination

(1) Using the integrated evaluation model of the three major subsystems of watershed water resources, socio-economic, and ecological subsystems in the Weihe River eco-watershed, the integrated evaluation index of the Weihe River Watershed in Henan Province and the Weihe River Watershed in Handan City for 2019–2021 is calculated as shown in Figure 6. It can be seen that, under the influence of drought in 2019 and flooding in 2021, the subsystems of watershed water resources have undergone a larger change, and the subsystems of watershed water resources in Henan exhibit an overall improving trend, characterized by a year-on-year increase in the watershed’s water resources. However, the uncoordinated annual water supply poses a significant threat to water security. In comparison to Handan, the ecological subsystem in Henan demonstrates a slower growth rate and relatively lower overall level. In Henan, there are no major water control projects along the main stream of the Weihe river. The river primarily functions as a flood control channel while also providing irrigation support. However, due to challenges in balancing annual water resources, occasional riverbed drying occurs, leading to an extremely fragile ecological condition. However, in Handan, the confluence of the Weihe River and the Zhanghe River exhibits an improved overall water ecology attributed to the regulation and storage of Yuecheng Reservoir. Concurrently, recent years have witnessed a discernible impact of legal measures and the deepening river chief system on the water environment’s influence on river channels, leading to a consistent upward trend in ecological subsystems; the socio-economic subsystem of Handan experienced slower growth from 2019 to 2021 under the influence of the epidemic. Prior to the emergence of the epidemic at the end of 2019, Handan’s overall economic situation outperformed that of the Henan. However, as the epidemic progressed, Handan experienced a slowdown in economic growth. This can be attributed to the fact that Henan’s economic support was primarily driven by industrial and agricultural sectors, whereas Handan, being a comprehensive city with a large population, was more susceptible to the impact of the epidemic. The comprehensive assessment trend for the Weihe River Watershed showed consistent improvement year by year, with Handan generally maintaining better conditions than Henan due to the regulatory function of Yuecheng Reservoir.

(2) The evaluation results of the coupling degree and coupling coordination degree are shown in

Table 6. Results of the coupling and coordination of the three major subsystems in the Weihe River ecological watershed.

District	Year	Coupling Stage		Coupling Type
		Coupling	Degree of Coupling	Degree of Coupling Coordination	Type of Coordination
He’nan	2021	0.9812	high level	0.6561	elementary harmonize
He’nan	2020	0.9941	high level	0.6343	elementary harmonize
He’nan	2019	0.981	high level	0.5916	barely harmonize
Handan	2021	0.9853	high level	0.6712	elementary harmonize
Handan	2020	0.9978	high level	0.6355	elementary harmonize
Handan	2019	0.9332	high level	0.5881	barely harmonize

. As shown in Figure 7, from the overall view, the coupling degree has been in the stage of a high level of coupling, but it showed a decreasing trend in 2021. In 2021, a large flood occurred in the Wei River Watershed, and the water resources subsystem of the watershed was improved, thus resulting in a decrease in the coupling degree.

In 2019, the coordinated development of the Weihe River Watershed was barely achieved, whereas from 2020 to 2021, it was elementarily coordinated. Moreover, the allocation of water resources, socio-economic factors, and the ecological structure of the Weihe River Watershed was optimized year by year.

4.2. Discussion

Water security problems in the Weihe River Watershed are highly prominent and complex. The main stem of the Weihe River lacks water transfer control projects, making it vulnerable to drought and flooding, particularly evident during the drought of 2019 and the flood of 2021, which have significantly impacted the Weihe River Watershed. However, as the Zhangwei River Watershed merges with that of the Handan River, it benefits from the Yecheng Reservoir’s flood control measures on the Zhanghe River, and it utilizes the Weihe River flood storage area to mitigate the effects of flooding. This provides a certain degree of elasticity. In recent years, the water environment in the Weihe River Watershed has been gradually improved through the full implementation of the river management system and various local environmental protection policies and measures, but the instability of water resources still affects the recovery of the water ecology in the Weihe River Watershed. Handan City, regulated by the Yucheng Reservoir, has a better water environment and a healthier water ecology compared to the entire watershed. Being a densely populated large city, Handan City’s water economy has been significantly impacted by the epidemic from 2019 to 2022. By comparing the evaluation results of the Henan Weihe River Watershed with the Handan Weihe River Watershed, it can be seen that the controlled water transfer project is very important for guaranteeing the water security of the watershed, improving the water environment and water ecology, as well as regulating the water use of the three living things and improving the water economy.

5. Conclusions

This paper considers the years 2019 to 2021 as the baseline period. Based on the theoretical framework of ecological watersheds and in alignment with relevant policies and regulations, it establishes a comprehensive evaluation index system for the Weihe River eco-watershed. This system comprises three first-level indicators: watershed water resources, social economy, and ecology. These are further subdivided into eight second-level indicators, namely, water security, water resources, water economy, water management, water culture, water environment, water ecology, and water landscape. Additionally, there are 60 third-level indicators to provide a detailed assessment. On the basis of determining the evaluation standard of the Weihe River eco-watershed, the evaluation of the Weihe River eco-watershed and coupling coordination degree was carried out. The results showed that from 2019 to 2021, the Handan Weihe River Watershed and the Henan Weihe River Watershed showed a yearly increasing trend in the evaluation of gray correlation analysis weights and comprehensive weights. The evaluation results were in the eligible status and below, with the evaluation grade being in the fourth-level eco-watershed and below. In the evaluation of the two weights, the five dimensions of water economy, water management, water culture, water environment, and water landscape showed a higher degree of fit, demonstrating stronger consistency of the two weights. Conversely, the three dimensions of water security, water resources, and water ecology showed a poorer degree of fit, indicating that the comprehensive weights better reflect the actual situation. In the comparison between the Weihe River Watershed in Henan and that in Handan, the scores for five dimensions—water security, water management, water environment, water ecology, and water landscape—are higher in Handan. On the other hand, Henan scores higher in three dimensions—water resources, water economy, and water culture. Additionally, Handan scores relatively higher in terms of the impact of Yecheng Reservoir dispatching. In comparing the evaluation of the degree of coordination and coupling, the degree of coupling decreases as a result of the 2021 flood, necessitating the watershed to develop a scientifically sound scheduling program to enhance the coupling degree of the subsystems.

According to the evaluation comparison between the Henan Weihe River Watershed and the Handan Weihe River Watershed, it can be seen that the level of the eco-watershed rating can be effectively improved through the construction of water transfer control projects and the development of scientific and reasonable scheduling programs. The main stream of Weihe River lacks a controlling water transfer project, so it can be evaluated scientifically and a reservoir can be constructed for ecological scheduling of water for the three living things in the Weihe River Watershed. Tributaries of Weihe River have a total of 19 large and medium-sized reservoirs, such as Panshi Reservoir, Baoquan Reservoir, Xiaonanhai Reservoir, and Zhangwu Reservoir. Thus, it is possible to establish a joint scheduling program of reservoirs, to use water resources in the watershed fully, efficiently, and safely, and to enhance the level of eco-watersheds of Weihe River in an orderly and gradual manner.