Assessing the Effect of the Basket of Benefits on the Interaction between Transboundary River Countries: Application of Evolutionary Game Theory

Transboundary Rivers are important common water resources that could bring benefit set or basket of benefits in areas of social, environmental, commercial, and political, for all countries located in the shared basin. The basket of benefits gained from the cooperation between countries effectively achieves the desired stable point of interaction, which is not considered in many studies in this field. In this paper, a model was presented based on evolutionary game theory in which the strategies of countries in using water of a transboundary river were analyzed and evaluated. Evolutionary stable strategies (ESS) were examined and countries’ behaviors were analyzed based on changes in their revenue interests. This model was applied to a basin shared with three countries and provided a framework for recognizing the behavior and management of countries' interests depending on whether they are upstream or downstream. Finally, numerical simulation was done to examine the evolutionary process of strategies and the effect of parameters on interactions between countries. The results of the simulation demonstrated the significant effect of the upstream country's basket of benefits (benefits other than water consumption benefits) on the interactions between countries and the final strategic stable point. Upstream country’s basket of benefits obtained from choosing cooperation strategy was changed to -1, -2, 2, and 5 percent compared to its water benefit obtained from choosing non-cooperation strategy by upstream country. The speed of convergence of the possibility of cooperation or non-cooperation of the upstream country was examined. It was concluded that even a one percent increase in the basket of benefits related to the water benefit would be lead to tripartite cooperation between countries. These results can be a theoretical guide for countries living in a transboundary river basin to interact with each other considering the role of benefits other than water benefits.