Combining GIS and FAO’s crop water productivity model for the estimation of water footprinting in a temporary river catchment

In the arid and semi-arid areas such as those in southern Europe, the correct management of water is of fundamental importance as well as the estimation of water consumption associated with human activities. Considering a temporary river catchment, the Water Footprint (WF) methodology allows direct and indirect estimation of water consumption required for the production of a given product. Furthermore, the WF estimation often involves the use of Geographic Information Systems (GIS) that allows to process climate, land use and soil type data. With the intent of strengthening existing methodologies applied on a basin scale, this study deals with the estimation of WF in a temporary river catchment combining GIS and FAO’s (Food and Agriculture Organization of the United Nations) crop water productivity model. In detail, with reference to each municipality in the Candelaro catchment area (2330 km2, Southern Italy), the blue and green component of WF was calculated for the agricultural products. Additionally, the role of treated wastewater, intended as a strategy of water deficit compensation on basin scale, was addressed. Results showed a WF of 686 Mm3/year with a greater contribution from the green than the blue component. The wheat was the cultivation that required the largest quantity of rainwater while tomato was the product that contributed to the increased demand for irrigation water, which accounted for about 50% of the blue component. The other agricultural products that contributed to the demand for blue water were grapes and olive trees. Finally, the treated wastewater can substantially contribute to covering the water deficit; results showed a contribution of 30%–40% of water savings.