Research advances in virtual water

The virtual water research has become the focus of the Water Science, and the virtual water has played an important role in solving the water crisis and food security crisis. The research achievements in the virtual water research are reviewed from seven aspects of virtual water concepts, quantitative studies, strategies, water footprints, virtual water trade and flow patterns, relationship among virtual water, water resources and food resources, and virtual water for ecological compensation. Meanwhile, the future researches in this field are prospected: (1) systematic researches on virtual water should be strengthened according to the paradigm of characteristics, structure, pattern and mechanism; (2) researches on agricultural ecological compensation mechanism based on the perspective of virtual water should be highlighted; (3) the theory of water right should be innovated by its combining with the virtual water thought; (4) the green area may be appropriately reduced and the cultivated area be raised according to the value of the ecological service function of the farmland ecological system and the position and function of virtual water in the green water. In this case, the good ecological environment will be maintained and the food production may be promoted.