China's provincial grey water footprint characteristic and driving forces

Grey water footprint (GWF), as a measure of water pollution in terms of the amount of water needed to dilute pollutants, has drawn great attention due to the necessity to respond to water contamination and water scarcity challenges. Under such a circumstance, this study aims to reveal China's national and provincial GWF features from 2003 to 2015, and to identify the corresponding driving forces by using the Kaya equation and the Logarithmic Mean Division Index (LMDI) decomposition method. Results show that the national total GWF declined from 1418 billion m³ in 2003 to 1655 billion m³ in 2015, and the industrial GWF reduction was the main reason for this decrease. Domestic GWF was the dominant component, particularly for service dominated provinces such as Beijing, Shanghai, Hainan, etc., with proportion up to about 80%. Southern and eastern provinces had higher GWF but lower GWF intensity (GWF per unit GDP), and water scarce northern provinces exhibited higher GWF load although they had lower GWF. The GWF intensity experienced a decreasing trend, with economy effect and intensity effect being the main driving forces, particularly for Tibet. Technology effect and exploitation effect (ratio of water use to water resource) were the main barriers for less developed provinces. Finally, policy recommendations are proposed to alleviate future GWF challenges of China, such as improving the discharge standards of WWTP (wastewater treatment plant), promoting wastewater recycling, reducing GWF intensity and GWF load through industrial structure and trade structure adjustment.