Global Versus Local Water Footprint Assessment: the Case of Cyprus

Abstract

The formulation of appropriate policies towards improving water resource management requires prompt and accurate information on water use. Soil water balance models provide the means to estimate agricultural water use, in the absence of metered data. This paper presents the spatiotemporal model that was used to assess the blue and green water footprint of crop production in Cyprus, for the period 1995-2009. Furthermore, the paper quantifies the difference between the results of this study with the estimates from the advanced global water use assessments of Siebert and Döll (2010) and Mekonnen and Hoekstra (2011) for Cyprus. The results of the local model show that, on average, total agricultural water use in Cyprus was 506 Mm3 /year, of which 63% is attributed to green water and 37% to blue water. Blue water use ranged from 160 Mm3 /year to 214 Mm3 /year, while green water ranged from 169 Mm3 /year to 441 Mm3 /year. The global versus local comparison revealed that the Siebert and Döll (2010) estimates for Cyprus were 72% lower for total green water use and 41% higher for blue water use, for the period 1998-2002. In the case of the Mekonnen and Hoekstra (2011) estimates, the total green water use was identical with the result of the local model, while blue water use was 43% higher in the global model, for the period 1996-2005. The discrepancies between the results of global and local models are attributed to the different input data, modelling assumptions and parameters adopted by each model. From a policy perspective, global models are not particularly useful as they provide average or static results with high uncertainty level related to data limitations. On the other hand, the local model captured the inter-annual effects of climate variability on crop water use and the results provided can potentially guide policy decisions to a sustainable green-blue water use strategy.