Modelling Irrigation Water Consumptions and Needs. Application to River Ave Basin

Abstract

The assessment of present and future water consumptions and needs for irrigation is of prime importance for water resources planning and management at basin level. As river Ave basin is being used as a Portuguese case study, a model has been developed for assessing present situation: agrometeorological data and crop systems and yield data provides the estimation of real evapotranspiration which can be used for a sequential water balance inside each homogeneous agricultural sub-region, so giving crop's consumptive use; estimated global irrigation efficiencies allows the calculation of total irrigation requirements; a final aggregation of results gives regional water consumption and needs. For forecasting future conditions another model has been developed: it uses the same agrometeorological and soil data but agricultural inputs are considered according scenarios of crop pattern evolution, development of agricultural technologies, crop yields increases and modernization of irrigation technologies. Results of application of such models are presented and discussed, showing their usefulness for coupling decisions on water and land use.