A multiple criteria decision-making approach for water allocation of environmental flows considering the value trade-offs - A case study of Fen River in China

In the water-scarce basin, the allocation of environmental flows needs to achieve the equilibrium between ecological protection and economic development. One of the challenges is the lack of quantitative analysis of the value of water in the economy and ecosystem, which could not effectively support the decision-making. This paper proposed a new multi-criteria decision-making approach that considers the value trade-offs between the environmental flows and the economic water use of rivers. The value of environmental flows was assessed using the modified equivalent factor method combined with the hydraulic method, which considers the influences of the hydraulic characteristics of rivers on value assessment. The value of the economic water use was estimated using the modified Cobb-Douglas production function. The ideal point method was applied to obtain the optimal solution of the multi-criteria decision with the objective of maximum values of the economic water use and maximum values of environmental flows (or the value of multiple recommended environmental flows). This new method was applied to determine the optimal environmental flows in the Fen River, the second-largest tributary of the Yellow River of China. The results indicated that the reasonable environmental flows were 51.1 % or 40.4 % (considering the water shortage for development) of the natural runoff of the Fen River. This work could provide a valuable reference for determining the water allocation of environmental flows in the water shortage area of China.