Emergy Synthesis and Its Application on Water Efficiency of Water Ecological-Economic System

Water ecological-economic system (WEES) is a coupling system of traditional water resource system (WS) and eco-environment, social economy system. Water efficiency is an important index and comprehensively reflects the economic development phases, industrial structure, water resources condition, facilities and equipments of water using, management level and technology advancement of water resource. The traditional indices of water efficiency are water use per unit production value, irrigation water use per unit area and domestic water daily used by every man. The different dimensions of the indices restrict the intercomparison of different water use departments. On the basis of Odum's well-known concept of emergy as a unified measure for environmental resources, human or animal labors and industrial products, this paper study the emergy fluxes of Zhengzhou water ecological-economic system and put forward a series emergy indices of water efficiency. The same dimension of emergy indices provides great convenience to the intercomparison of different water use departments.