虚拟水贸易作为一种调节工具,已成为水资源紧缺国家或地区增加本国或本地虚拟水、平衡区域水资源、缓解国家和地区的水资源短缺状况、保障本国或区域的水资源安全与粮食安全的重要手段之一。利用2003-2012年中国与非洲各国农产品贸易数据计算了中非农产品虚拟水流特征及其节水效应。结果表明,2003-2012年中国从非洲进口虚拟水总量为769.71×10~8 m~3,向非洲出口虚拟水总量为427.27×10~8 m~3,总体表现为虚拟水净进口。中国进口的虚拟水主要来源于莫桑比克、南非、布基纳法索、贝宁及马里等国家;中国出口的虚拟水主要流向南非、摩洛哥和科特迪瓦等国。中国虚拟水进口的农产品种类主要为棉花和果品等;而出口虚拟水产品主要为茶叶,其次是谷物和畜产品。中非虚拟水净贸易表现为水资源利用效率低的地区输向水资源利用效率高的地区,中非农产品贸易虚拟水为双方农产品消费需求和水资源保障提供支撑,却在全球尺度上造成年均5.91×10~8 m~3水资源的浪费,从全球水资源的高效利用角度看是不可持续的。
Virtual water trade is a useful tool for international resource adjustment and has already become an important means for countries or regions facing a scarcity of water resources to trade surplus resources in order to alleviate serious water shortage, so as to guarantee food security and sufficient water supply for essential needs. Here we calculate the quantity of virtual water represented by agricultural trade between China and Af rica from 2003 to 2012. The virtual water transfer features distinctive geographic and temporal pattern. From 2003 to 2012, the total amount of virtual water China imported from Africa was 769.71× 10^8 m^3 , the average virtual water was 76.97× 10^8 m^3/year, while the quantity exported to Africa was 427.27× 10^8 m^3. Hence there is a net import of virtual water. The countries that are major suppliers of virtual water to China are Mozam bique, South Africa, Burkina Faso, Benin and Mali. The major African importers of virtual water from Chinaare South Africa, Morocco, and the Ivory Coast. The agricultural products contributing most to virtual water import by China from Africa are cotton, fruits and animal products~ while products contributing significantly to visual water exports from China to Africa are tea, cereals and animal products. The overall balance of virtual water trade between China and Africa moves agricultural products from areas with low efficiency of water use to areas of higher efficiency of water use. This creates a negative impact on global water use efficiency, and a waste of 5.91 × 10^8 m^3 of water. From a bilateral perspective, the virtual water transfer associated with agricul rural trade between China and Africa has desirable water use efficiency benefits for both sides. However, from a global perspective, wasteful virtual water transfer such as this is not sustainable.