Research on agricultural grey water footprint/efficiency and identification of influencing factors in Henan Province

Agricultural water pollution control is the key to alleviating the water crisis and promoting regional sustainable development. Grey water footprint (GWF) is an effective method that uses water consumption to measure water quality issues. In this study, we calculated agricultural GWF and its efficiency in 18 prefecture-level cities in Henan Province from 2001 to 2021 and analyzed their temporal and spatial characteristics using ArcGIS and the standard deviational ellipse (SDE) method. A logarithmic mean divisia index (LMDI) decomposition model was established to disassemble GWF efficiency into five key driving effects, and then, 18 prefecture-level cities were divided into seven driving modes. Results showed that (1) the agricultural GWF in Henan Province was mainly produced by the planting industry and mostly came from phosphate fertilizer. In terms of time, the agricultural GWF appeared in an inverted "U" shape from 2001 to 2021 and reached its peak in 2012. In spatial distribution, it is generally higher in the south than in the north. (2) Agricultural GWF efficiency in Henan Province presented an overall upward trend, and the SDE mean center moved from Zhengzhou to Xuchang from northeast to southwest in the south of Zhengzhou before 2017 and from northwest to southeast in Xuchang after 2017. (3) According to the contribution value of the five drivers of agricultural GWF efficiency, the 18 prefecture-level cities in Henan Province are divided into seven driving modes; thus, different agricultural water pollution controls and industrial structure adjustment management can be targeted.