Estimation of the volume of virtual water exported in agricultural products. California as a case study

California is the state with the highest income from export of agricultural products in the United States. The total exported water is defined as the physical water contained in crops transported outside a geographic border plus the water lost as induced evapotranspiration as a result of crop irrigation. As a consequence of environmental conditions, the evapotranspiration water is no longer available inside the local hydrologic cycle. In this research, a data set for California's 50 most exported agricultural commodities (in the period 2000-2012), has been used to quantify exported water. The results show that, on average, the overall exported water in California's agricultural products was 2.88x10(10) m(3) yr(-1), equivalent to 68.3% of the total water used in agricultural irrigation. The majority of the exported water is in the form of induced evapotranspiration, totaling 67.7% of the annual total water used in irrigation. The physical water content contained in crops was approximately 2.32x10(8) m(3) yr(-1), representing less than 1% of the total water used in irrigation and of the induced evapotranspiration.