Water extraction games in river basins from the perspective of complex network: a case study in the Hanjiang river basin, China

Abstract

As the global water crisis intensifies, human water extraction activities exert an increasingly profound impact on the sustainability of water resources. The distribution of water user groups in river basins exhibits distinct network characteristics, with pronounced asymmetric externalities in water extraction. However, current research lacks adequate investigation into the impact of these features. This study develops an evolutionary game model on weighted and directed water use networks, using the Hanjiang River Basin in China as a case study to analyze network characteristics and water extraction dynamics. The results reveal that the network exhibits significant strength assortativity and small-world properties. The network topology and player payoff structures drive water extraction dynamics, leading to diverse behavioral patterns. Under initial conditions, cooperative water extraction emerges as the dominant strategy in the network, with an average cooperation ratio of 0.7031 over 100 rounds in noiseless simulations. Cooperation is primarily observed in the midstream and downstream sections of the basin. Key parameters that drive cooperation, including marginal benefit, penalty coefficient, and marginal cost, reflect important institutional and environmental factors shaping users’ decisions. As noise intensifies, decision randomness increases, significantly undermining the strategic superiority of the dominant strategy and reducing the amplitude of phase oscillations among nodes. When cooperative extraction is favored under the given network and payoff structure, reducing controllable uncertainty can effectively promote cooperation. The study provides key insights for sustainable river basin management.