Optimal allocation of water to competing stakeholders in a shared watershed

This paper proposes a mathematical model for allocating water to stakeholders of a shared watershed. Each stakeholder in the basin has a water demand and a water profit; however, the available water cannot meet the demands of all stakeholders. This shortage raises a conflict between stakeholders as they use a common resource. To reach an agreement between the stakeholders in water allocation, first a model was developed to obtain the highest possible profit that a stakeholder can achieve if the stakeholder is allowed to utilize as much as possible water after satisfying the basin environmental demands (flows). Then, another model was introduced which allocates water to each stakeholder such that the minimum ratio of stakeholders' profits to their highest possible profits is maximized. It is shown that the obtained solution is non-dominated in terms of considering each stakeholder profit as an objective, which means that none of the objective functions can be improved in value without degrading some of the other objective values. The proposed method is applied to the Sefidrud River basin, which is one of the biggest rivers in Iran. The stakeholders of this basin are eight administrative provinces that compete for utilizing more water while the Basin's water resources could not satisfy all stakeholders' water requirements. The model's results show that it can successfully be used for sustainable conflict resolution in a shared basin because the model satisfies the environmental water requirement in the entire basin and provides equitably the same ratio of the stakeholders' highest possible profits for them. For the case of this study, the proposed approach allocates water to the stakeholders in such a way that they could obtain at least 65 % of their highest possible profits in average.