The irrigation water demand of the grapevine (Vitis vinifera L.) cv. Italy was estimated and spatialized in San Francisco River Basin, in order to subsidize the agricultural project planning and water resource management. Historical data series relative to 81 climatic stations distributed throughout the basin were used. The maximum daily values and the annual total values of the reference evapotranspiration (ETo), crop evapotranspiration (ETc), supplementary demand of the crop and the supplementary irrigation demand (70% efficiency) were calculated for each station. According to the results, the following conclusions were drawn: (a) in a large area of the basin, the maximum daily ETc varied from 4.5 to 5.7 mm d-1, with an annual mean of 943 mm; (b) the supplementary annual demand of the crop averaged 839.5 mm, corresponding to 103.5 mm less than ETc; and (c) the irrigation system operating with 70% efficiency instead of 90% implies an increment of 18,808,755 m³ water per year only in the microregions of Juazeiro, BA and Petrolina, PE.
water requirement; Vitis vinifera L.; spatial distribution
