An improved water footprint methodology linking global consumption to local water resources: a case of Spanish tomatoes

A water footprint (WF) measures the total water consumed by a nation, business or individual by calculating the total water used during the production of goods and services. This paper extends the existing methods for WF to more localised levels for crops grown partly in open systems and partly in plastic-covered houses with multi-seasonal harvesting, such as the horticulture industry in Spain. This improvement makes it possible to visualise the links of EU tomato consumption to precise production sites in Spain and opens a debate to the usefulness of such findings. This paper also compares existing ecological methodologies with WF and argues that both life cycle analysis (LCA) and ecological footprint (EF) models could benefit from WF methods. Our results show that the EU consumes 957,000 tons of Spanish fresh tomatoes annually, which evaporates 71 Mm(3)/yr of water and would require 7 Mm(3)/yr of water to dilute leached nitrates in Spain. In Spain, tomato production alone evaporates 297 Mm(3)/yr and pollutes 29 Mm(3)/yr of freshwater. Depending upon the local agro-climatic character, status of water resources, total tomato production volumes and production system, the impact of EU consumption of fresh tomatoes on Spanish freshwater is very location specific. The authors suggest that business now seek to report and address negative impacts on the environment. WF opens the door to complex water relationships and provides vital information for policy actors, business leaders, regulators and managers to their draw, dependence and responsibilities on this increasingly scarce resource.