Alternative evaluation and selection based on order degree entropy: A case study of the Haihe River basin in China

Achieving sustainable and harmonious development for a river basin that has severe issues of water shortage and water pollution requires water resource regulation and management. Advanced computer models are commonly used to simulate the water cycle for different regulation alternatives. However, there are usually too many alternatives to consider and the decision-makers are overburdened with the quantity and complexity of information generated by the models. It is necessary to evaluate these alternatives and reduce their number before selection by decision-makers. Using synergy methodology, this paper attempts to set the order parameters of resource, social, economic, ecological and environmental subsystems in the water cycle system and calculate their order degree, which reflects the sequence of the subsystem. On this basis, information entropy theory is applied to establish the function of order degree entropy of the water cycle system, which shows the evolution direction. According to this function and the concept of entropy, a lower value of order degree entropy indicates that the system has a greater order degree and will evolve toward order, and the lower the value, the better the corresponding subsystem, the more harmonious and organized the whole water cycle system, and the more optimal the corresponding alternative. The alternatives can be evaluated and selected by comparing the values of the entropy. The application of the proposed methodology is discussed and illustrated in a case study of the Haihe River basin.