The water footprint and virtual water exports of Spanish tomatoes

D. CHICO et al. 9the volume of freshwater used to produce the product, measuredalong the full supply chain. It is a multi-dimensionalindicator, showing water consumption volumes by sourceand polluted volumes by type of pollution; all componentsof a total water footprint are specified geographically andtemporally (Hoekstra et al., 2009). The blue water footprintrefers to consumption of blue water resources (surface andgroundwater) along the supply chain of a product. ‘Consumption’refers to loss of water from the available groundsurfacewater body in a catchment area. This fraction thatevaporates is incorporated into a product, or returns to anothercatchment area. The green water footprint refers toconsumption of green water resources (rainwater stored inthe soil as soil moisture). The grey water footprint refers topollution and is defined by the volume of freshwater thatis required to assimilate the load of pollutants to meet existingambient water quality standards.The present study analyses the water footprint of tomatoproduction in Spain. In particular, it focuses on the green,blue (surface and groundwater) and grey water footprint oftomato production in the different Spanish provinces. Differenttypes of tomato production systems are analysed:open-air (irrigated and rainfed) and greenhouse. For eachof them, the respective water footprint was studied in thedifferent times of the year; early, middle and late season.To complete the analysis of the tomato sector with a socioeconomicperspective, evaluations of apparent water productivity(€/m 3 ) and virtual water exports of tomato are alsoreported.2. METHOD AND DATAThe present study estimates the green, blue and grey waterfootprint of 1 kilogram of tomato fruit produced in Spain