A modelling platform for climate change impact on local and regional crop water requirements

The impact of climate change on agriculture is projected to be more severe over the coming years due to changing intensity, magnitude and distribution of precipitation, soil water content, atmospheric water vapor, higher temperatures, and thus larger evapotranspiration. This will have significant consequences for irrigation requirements, especially in semi-arid area of Southern Europe, which is recognised as a climate change hotspot. Since the total water use to satisfy agricultural demand is currently about 25% of total water withdrawal in Europe and up to 80% in some Mediterranean countries, improvements in water management are needed to cope with worsening climate conditions. Although several crop models (e.g. EPIC, WOFOST, CERES-Maize) and hydrological models (e.g., DREAM, SWAT, HYDRUS) have been developed, the call for developing models able to couple crop growth, soil water balance, and irrigation practices to assess agricultural water management both at local and regional scale is increasing. In this work, the Simulation of Evapotranspiration of Applied Water (SIMETAW#) model is implemented in R programming language with two new versions able to estimate crop water consumption, irrigation demand and scheduling at local (SIMETAW_R) and regional scale (SIMETAW_GIS platform) using extensive climate and environmental geospatial datasets. SIMETAW_R was validated in ten experimental sites, and SIMETAW_GIS performance in Mediterranean countries was assessed by estimating the impact of climate change on maize, wheat, and wine grape water requirements in the past (1976–2005) and future climate conditions (2036–2065), under RCP4.5 and RCP8.5 scenarios. Results show that in Mediterranean countries, maize, wheat, and grape production will require on average about 13%, 16%, and 10% more water, respectively, under future climate. This represents a considerable challenge for water resources management, especially with demand increasing in other sectors. The tool showed great potential in estimating climate change impact on crop water consumption and irrigation requirements, both at local and regional scale, and offers new analytical skills for water resources management planners for improved decision-making.