Coupling coordination and spatiotemporal dynamic evolution of the water-energy-food-land (WEFL) nexus in the Yangtze River Economic Belt, China

Analysis of water resources carrying capacity and obstacle factors in Gansu section of the Wei River basin using combined weighting TOPSIS model

Water resource carrying capacity is an important indicator for measuring sustainable development. Given the rapid economic and social development in China today, coordinating the sustainable development of water resources, socio-economy, and eco-environment has become an urgent problem to be solved. This study takes the Gansu section of Wei River mainstream basin (GWRB) as a case study and constructs a three-dimensional WRCC evaluation system and status standards. Based on this research framework, we analyzed the trends in WRCC changes of GWRB from 2008 to 2022. Additionally, we conducted an in-depth study of the internal relationships and influencing factors within the WRCC system. The results show that the combination weighting method of multi-weight models avoids the one-sidedness of single weighting, leading to a more realistic distribution of weights. The result status standard derived from the indicator status standard prevents a disconnect between the result and the status, making the evaluation more rational and accurate. The WRCC of the GWRB increased from 0.098 (overloaded) in 2008 to 0.621 (weakly bearable) in 2022. During this period, the eco-environmental system improved from critical to bearable, while the socio-economic system improved from overloaded to weakly bearable. Due to geographical and climatic limitations, the water resource system continued to bear significant pressure and remained in overloaded state for most of the time. The key factors limiting the further improvement of WRCC in the GWRB are per capita water resources, utilization rate of water resources, COD emission per 10,000 yuan of GDP, ecological water use rate, water consumption per 10,000 GDP and agricultural water use rate. To improve the WRCC, we propose a series of targeted recommendations based on the research findings. The proposed research framework can also serve as a reference for related studies in arid and semi-arid regions.

Coupling coordination development of water resources-economy-ecology system in Shanxi Province based on system dynamics

The interaction between water resources, economy, and ecology significantly influences regional security and stability. This study developed an index system for assessing the coupling of water resources, economy, and ecology in Shanxi Province. Subsequently, a coupling coordination degree model for water resources, economy, and ecology was established to assess and analyze the coupling coordination levels. Additionally, the study employed a grey correlation analysis to investigate the impact of 21 indicators on the system's coupling coordination. A system dynamics simulation model was then constructed to forecast various coupling coordination scenarios up to 2035. Key findings included: (1) An overall upward trend in the comprehensive evaluation index of water resources, economy, and ecology. (2) Significant developmental disparities among the eleven cities in Shanxi Province, with some cities showing a decline in 2015. (3) The economic subsystem indicators in the water resources-economy-ecology model had a 34.02% correlation, exerting a marginally greater impact on the system's coupling coordination than other subsystems, with GDP per capita being the most influential indicator. (4) Scenario simulations predict that the highest level of coupling coordination, reaching a coupling coordination degree of 0.94, will be achieved in 2035 under Scenario 5(pursuing comprehensive development). This study elucidates the interrelationship between water resources, the economy, and the ecosystem in Shanxi Province, and proposes a programme for adjusting indicators to support future sustainable development in the region.

Spatiotemporal evolution and driving factors of the coupling coordination of the population‒land‒water‒industry system in the lower Yellow River

Exploring the interaction and coupling effects within the population‒land‒water‒industry (PLWI) system is conducive to promoting high-quality regional sustainable development. Taking the lower Yellow River during the period from 2000 to 2020 as a research sample, this study used the entropy weight TOPSIS method, the coupling coordination degree (CCD) model and kernel density estimation to synthetically evaluate the CCD of the PLWI system. The GeoDetector model was applied to explore the factors influencing the CCD of the PLWI system considering the nonlinear relationship. The major results can be summarized as follows: (1) From 2000 to 2020, the comprehensive development index (CDI) of the population, land, water and industry subsystems followed a gradual upward trend in the lower Yellow River, increasing by 0.293, 0.033, 0.111 and 0.369, respectively. However, the CDI of the land subsystem varied greatly between regions. Some cities, such as Jinan, Jining and Binzhou, experienced large declines in the CDI of the land subsystem, from 0.433, 0.534 and 0.572 to 0.358, 0.481 and 0.522, respectively. (2) The CCD of the PLWI system in the lower Yellow River showed an upward trend, increasing from 0.481 to 0.678, and became more concentrated during 2000-2020. Most of the region transitioned from near disorder to primary coordination. (3) Factors such as number of health technicians per 10,000 people, average salary, number of college students per 10,000 people, per capita GDP and per capita education expenditure were critical to the coordinated development of the PLWI system, the explanatory powers were 0.644, 0.639, 0.610, 0.498 and 0.455, respectively. Finally, this study proposed three policy recommendations to improve coupling coordination in the lower Yellow River Basin: Improving population quality, promoting green technology and rational land planning.

Coordination analysis and evaluation of population, water resources, economy, and ecosystem coupling in the Tuha region of China

The non-coordination between the socio-economic systems and ecosystems of a region is a crucial obstacle to sustainable development. To reveal the relationships between complex urban systems and achieve the goal of sustainable and coordinated urban development, we constructed a coupling coordination degree model (CCDM) and coupling angle model (CAM) and analyzed the degree of coupling coordination and evolution process among the population, water resources, economy, and ecology (PWEE) system of the Tuha region for 2005-2020. The results indicated that: (1) During 2005-2020, the comprehensive development index (CDI) of the population, water resources and economy subsystems was 0.21-0.65, with the three subsystems portraying an overall increase; the average values of the RSEI at five-year intervals were 0.29, 0.28, 0.28, and 0.26, indicating a downward trend in the environmental quality. (2) The coupling coordination effect of the PWEE system portrayed a low level; the coupling coordination degree (CCD) values were 0.28-0.58, portraying a fluctuating upward trend. The level of CCD increased from low disorder to marginal coordination. (3) The PWEE system's scissor difference reflects large evolutionary characteristics. The ecological support capacity was not observed until the late stage. We conclude that the PWEE composite system of the region is in a stage of disordered development. These findings significantly bolster the theoretical underpinnings of sustainable development studies, offering essential scientific theories and methodological frameworks for crafting sustainable development policies tailored to urban systems in the Tuha region.

Analysis of the factors influencing the water-energy-food system stress in China

Water, energy and food security are at the heart of the UN 2030 Agenda for Sustainable Development. Maintaining water-energy-food (WEF) system security is critical to sustainable socio-economic development. To clarify the trends in China's WEF system stress, this paper analyses the spatial and temporal heterogeneity of WEF system stress using panel data for 30 Chinese provinces from 2002 to 2020. Using an extended STIRPAT model, we discuss the influencing factors of WEF system stress and forecast the WEF system stress index (WEF_SI) for 2021-2030. We find that China's WEF_SI has a significant positive spatial autocorrelation, with energy stress being the dominant stress in China's WEF system. Second, GDP per capita, urban population density, education level per capita, technology level and effective irrigated area have spatial and temporal heterogeneity in their effects on WEF system stress. Third, the prediction results show that China's WEF system stress will decrease in 2021-2030 but to a lesser extent. The government should coordinate the relationship between water, energy and food based on the evolutionary characteristics and projected trends of each element and formulate differentiated policies according to the resource endowment of each region to promote the coordinated development of the WEF system.

An approach to complex transboundary water management in Central Asia: Evolutionary cooperation in transboundary basins under the water-energy-food-ecosystem nexus

Water-related issues in transboundary basins are generally complicated by the challenges of climate change, the historical evolution of the basin characteristics, and the different interests of the riparian countries. Therefore, dealing with water-sharing and water cooperation problems among basin countries needs to be based on multi-factor system analysis in the context of regional water, energy, food (land) resources, and ecosystems. In the present study, the Aral Sea basin in Central Asia, where transboundary water problems are extremely prominent and complex, was selected as the research area. Firstly, the characteristics of the water-energy-food-ecosystem nexus of the Aral Sea basin are analyzed. Then, based on the game theory, a multi-objective game model is constructed, and the multi-objective evolutionary game process and evolutionary stable strategies (ESSs) of both the upstream and downstream countries are explored. Finally, the evolutionary stable strategy under the intervention of the basin commission is simulated. The results show that there are obvious reciprocal feedbacks among water, land, energy, and ecosystem in the Aral Sea basin, and the uneven distribution of natural resources, fragile ecosystems, and conflicting demands of multiple actors lead to the unstable evolution of the nexus. Driven by the maximization of upstream and downstream countries' respective interests, the optimal stabilization strategy of the system cannot be realized. Whereas, the introduction of the basin commission intervention and its restraint mechanism is conducive to promoting cooperation and maximizing the overall benefits of the basin. The incentives and penalties of the basin commission have significant effects on whether the system can reach Pareto optimality, and higher incentive coefficient and penalty coefficient help the system converge to the ideal state more quickly. The evolution of the water-energy-food-ecosystem nexus based on the perspective of the whole basin can provide theoretical support for dealing with the transboundary water conflicts, and the cooperation strategy aiming at maximizing the overall benefits of the basin can provide decision-making basis for promoting transboundary water cooperation and synergistic development of the water-energy-food-ecosystem nexus.