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.