Grey water footprint combined with ecological network analysis for assessing regional water quality metabolism

Water pollution is a serious problem in Dianchi Lake Basin, which has resulted in severe pressure on the sustainable utilization of local water resources. This study investigates and quantifies the various water quality change processes involved in a regional water metabolism system by using grey water footprint. Furthermore, an ecological network model of the water quality change processes in water metabolism system is generated and an ecological network analysis is conducted to understand the underlying principles and analyze the importance of the compartments of water quality metabolism. This study provides insights into the status of water quality metabolism in water metabolism system and determines the reasons for the deteriorating water quality. It describes and quantifies 22 water quality change processes and builds the ecological network model to evaluate the metabolic effects of water quality in Dianchi Lake Basin. Results show that the pollutants from urban daily life water use are the main influencing factor on the water quality metabolism in Dianchi Lake Basin water metabolism system. The weight of the grey water footprint of the pollution source from urban daily life water use is the largest, which accounts for approximately 50% of the total weight (100%). Thus, management should exert significant effort to control pollutants from the water use of urban residents. By analyzing the interoperability between the components of the ecological network model, this study determines that all the water quality metabolic effects in Dianchi Lake Basin are poor from 2006 to 2013 (the values of mutualism indices M from 2006 to 2013 are all less than 1). The analysis results can be used to interpret the problems encountered in water quality metabolism in regional water metabolism systems. The proposed improvement measures could support the decision-making process regarding future investments for the optimization of pollution treatment and the sustainability of urban water use.