A multi-objective approach for transboundary river water allocation

The allocation of water to the stakeholders of a large basin involves conflicting objectives, since increasing the allocated water to one stakeholder leads to a reduction in water allocated to other stakeholders. The consideration of conflicting objectives is inevitable when the basin is a transboundary basin, where a river crosses at least one political border, either a border within a nation or an international boundary. This paper proposes a multi-objective optimization model for sharing water among stakeholders of a transboundary river, assuming that the stakeholders cooperate. Here, the cooperation implies a balanced water allocation to stakeholders since shortage in each stakeholder have negative impacts on others. Each objective function of the multi-objective model represents the water profit of a stakeholder; which has to be maximized. To reach a cooperative solution, a new method for transforming the multi-objective formulation to a three-step single objective formulation is proposed. The solution guarantees each stakeholder's profit which is larger than a percentage of its highest possible profit obtained in the case when the percentage of profit is equal for all stakeholders. The proposed model formulation was applied to the Sefidrud River where eight provinces are the stakeholders competing for water resources of this basin.