Irrigation Scenario vs Climate Change Scenario

Crop water requirement depends on irrigation scenario. That is, it depends on a group of data files including climate, rain, crop and soil. Hence, modifications in the values of some of these variables (e.g. temperature, rainfall or insolation) can bring a stop to or initiate more expensive agricultural practices. In this communication we use an irrigation model, recommended by FAO, to simulate the effects of a hypothetical climate change scenario. In particular, we consider the impact of changes in temperature or in rainfall frequency on the irrigation demand of maize, sunflower and alfalfa cultures in the central part of the Ebro River Valley (NE of Spain). The simulation has been done with CropWat 4, a freely available software package distributed by FAO. Results show that a warmer climate increases crop water requirements, irrigation requirements and field water supplies corresponding to all considered crops and different temporal horizon. The same schema is applied to analyse the adjustment of new citrus cultures in the south of Catalonia (Spain) with similar results. The computed values should be used only as a guide to the likely effect of water shortage on crop yield, but they must be considered to alert policymakers about new cultures and new climatic indicators.