Abstract
Abstract. China is a water-stressed country, and agriculture consumes the bulk of its water resources. Assessing the virtual water content (VWC) of crops is one important way to develop efficient water management measures to alleviate water resource conflicts among different sectors. In this research, the VWC of rice, a major crop in China, is taken as the research object. China covers a vast land area, and the VWC of rice varies widely between different regions. The VWC of rice in China is assessed and the spatial characteristics are also analysed. The total VWC is the total volume of freshwater both consumed and affected by pollution during the crop production process, including both direct and indirect water use. Prior calculation frameworks of the VWC of crops did not contain all of the virtual water content of crops. In addition to the calculation of green, blue and grey water – the direct water in VWC – the indirect water use of rice was also calculated, using an input–output model. The percentages of direct green, blue, grey and indirect water in the total VWC of rice in China were found to be 43.8, 28.2, 27.6, and 0.4%. The total VWC of rice generally showed a roughly three-tiered distribution, and decreased from southeast to northwest. The higher values of direct green water usage were mainly concentrated in Southeast and Southwest China, while the values were relatively low in Northwest China and Inner Mongolia. The higher direct blue water values were mainly concentrated in the eastern and southern coastal regions and Northwest China, and low values were mainly concentrated in Southwest China. Grey water values were relatively high in Shanxi and Guangxi provinces and low in Northeast and Northwest China. The regions with high values for indirect water were randomly distributed but the regions with low values were mainly concentrated in Northwest and Southwest China. For the regions with relatively high total VWC the high values of blue water made the largest contribution, although for the country as a whole the direct green water is the most important contributor.
Highlights
The term virtual water was first proposed by Allan (1994) and defined as the water embodied in traded products
Assessing the virtual water content (VWC) of products is the basis for developing such water resource management practices
Northwest and Southwest China are relatively underdeveloped with relatively low VWCindirect of rice
Summary
The term virtual water was first proposed by Allan (1994) and defined as the water embodied in traded products. The virtual water content of a product is the freshwater embodied in the product, not in the real sense, but in the virtual sense. It refers to the volume of the freshwater both consumed and affected by pollution in producing the product, measured over its full production chain (Hoekstra et al, 2011). In water-stressed regions, limited water resources should be used efficiently by not allocating the majority of resources to the production of waterintensive products, but being made available for other economic purposes that can contribute more to the regional value added by consuming less water (Allan, 2002; Chapagain and Hoekstra, 2008). Assessing the virtual water content (VWC) of products is the basis for developing such water resource management practices
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