Abstract
The International Programme for Technology and Research in Irrigation and Drainage (IPTRID) and the Italian National Committee of the International Commission on Irrigation and Drainage (ITALโICID) decided it would be worth extending a previous paper on Italy's available water resources to a detailed study on the partitioning of precipitation between evaporation, groundwater storage (saturated and unsaturated zone) and runoff with the aim of estimating the potentially renewable water resources of the country. The information is gained through a water balance model approach, using monthly climate data from the time series 1971โ2000 estimated over 544 grid points of the whole of the Italian territory, made available by the CRAโCentral Office for Crop Ecology (CRAโUCEA). The goal of this study was to evaluate the fraction of precipitation that does not return to the atmosphere through the evaporation process or remains in soil storage and that includes both surface and subsurface runoff including effective infiltration. The results obtained by using a GIS system may provide useful information on the evolution of the hydroclimatic conditions in Italy and a picture of the runoff amounts in terms of time and space. This information can be used for national planning purposes and for activating strategies to protect and conserve water resources, especially with regard to irrigation management. Copyright ยฉ 2008 John Wiley & Sons, Ltd.