Impact of grain virtual water flow on surface water and groundwater in China

Abstract

Virtual water flow can alleviate the pressure of regional water resources. Differences in water resources endowment and industrial structure among regions cause regional differences in water use in China. Water use in agriculture, especially irrigation, heavily relies on both surface water and groundwater. Virtual water flow may have different influence on the utilization and exploitation of regional surface water and groundwater. However, few studies have separately investigated the impacts of virtual water transfer on them. According to virtual water theory, contribution rate and regional differences, this study evaluates the effects of virtual water flow on water resources among provinces in China. The results indicate most regions mainly rely on surface water that accounts for less than 50% of surface water supply in only four provinces, namely Hebei, Henan, Beijing, and Shanxi. In the Northern region and mainly in North China, the dependence on groundwater is very high. The total virtual water flow in China increased from 75.8 Gm³ in 1998 to 124.6 Gm³ in 2014 and showed a trend from the northeast and central regions to the south and western regions. Given the decrease in the scale of virtual water export, the decline of groundwater level in North China is not further aggravated. Water-saving irrigation is the main method to improve the efficiency of irrigation water use. The results of the study can aid in improving the sustainability of surface water and groundwater management in the grain production process via identifying dominant areas.