A structure-efficiency based performance evaluation of the urban water cycle in northern China and its policy implications

Understanding the urban water cycle is critical, as the watershed water cycle is greatly influenced by cities under the processes of urbanization with problems of high frequency of water shortage, environment deterioration and ecological degradation. Different from traditional evaluation method which focuses on one or some component of the whole system, this research aims to propose an innovative framework to evaluate the performance of the urban water cycle by means of the structure-efficiency index (SE_index). This index aggregates key indicators from structure and efficiency aspects (i.e. S_index and E_index), based on the water balance principle (which considers a multi-source water distribution process, water consumption process, and the wastewater treatment and discharge process). An entropy weight method is used to determine the weights of different indicators in an objective way. The performance levels of the urban water cycle of case study cities in Haihe River basin are evaluated, and key indicators are identified by sensitivity analysis. Four city categories with different structures or efficiency characteristics are presented by cluster analysis technique and their associated policy implications are discussed. For cities with relatively low S_index and E_index values (such as Xingtai, Hebi, Shjiazhuang and Hebi), it is meaningful to both optimize their urban water cycle structure and improve the efficiency of the water supply and different water use sectors. Although cities such as Beijing and Tianjin have relatively high S_index and E_index values, there is still room for them to make structure optimization compared with other cities in the basin. The proposed SE_index and its application can help provide quantitative information on the urban water cycle performance status to promote sustainable urban water policy making and related infrastructure planning. (C) 2015 Elsevier B.V. All rights reserved.