Virtual water is for computing water resources. It doesn’t matter where the water comes from. (rain water ,river water, groundwater etc) Importing a amount of virtual water does not always have a bad influence on nthe environment. It is more efficient and economical to import food from countries which have flourishing agriculture with abundant water then to import water(and grow food domestically). Japan imports a good deal of virtual water not for the water shortage but for agricultural land shortage. It is not “virtual water trade” but “virtual agricultural trade”. But this also means that world water issues affect Japanese food situation. On the other hand, if we don’t buy from foreign counties, we’ll suffer serious damage when something happen to the agriculture in Japan. Then what should we do?
As you see from this figure, Japan imports most crops from US. To decrease the affect of world water issues, we should better imports from many different countries