Agriculture is an essential driving force in the management of water use. Especially in Southern European countries, irrigation is an essential element of agricultural production and agricultural water use has a substantial share in total water use (exceeding 50%). The presented work contributes to the assessment of impacts of irrigated agriculture on water resources at European scale. We developed a modeling approach to estimate irrigation water requirements and regional irrigation water demands in the EU at high spatial resolution. The modeling approach was applied for a first assessment of irrigation water requirements.
A prerequisite of the analysis was the compilation of a European Irrigation Map (EIM), providing information on the distribution of irrigated areas in EU25 for modeling studies. The EIM complements the underlying European land use map (Grizzetti et al. 2007), combining FSS statistics on irrigated area and crop area and information from the Global Map of Irrigated Areas (Siebert et al. 2005). The map was used to derive irrigated areas (as total and per crop) for spatial modeling units.
To estimate irrigation water requirements we applied the soil water and crop growth model EPIC that was implemented in a European agricultural modeling system EAGLE and calculates water and nutrient flows at a spatial resolution of 10x10 km raster cells. Different irrigation strategies were defined to analyze the effect of application rates and irrigation intervals on water requirement. The final results were given per raster cell and per crop, based on the most efficient irrigation strategy (maintaining optimum yield with lowest irrigation).
We show that allowing higher soil water deficit does not automatically lead to non-tolerable reduction of crop yields and soil moisture. Irrigation requirements (irrigation per unit irrigated area) in Europe range up to 2368 mm/yr in average per cell. Water demands (volume for defined spatial units) are calculated subsequently based on the irrigated area within each cell.
Resulting water abstractions were calculated using rules-of-thumb values of irrigation efficiency and conveyance efficiency. A comparison with reported national statistics on water abstraction data showed considerable discrepancies for many countries, indicating not only model uncertainties, but also illustrating shortcomings of national statistics. Such a comparison is a useful tool to check the consistency of both, model assumptions and underlying statistical information.
The results provide a spatial overview on irrigation water demands in Europe and allow analysis of agricultural pressures on water resources in Europe at a considerable high spatial resolution. Being based on a single methodology applied to official data sources, the estimation supports inter-comparison of national statistics, which are based on different methodological approaches. This pilot assessment was based on irrigation and land use statistics from the years 2000 and 2003. The methodology was designed for application in an operational context, allowing future updates of the assessment corresponding to statistical data. The approach can therefore principally be applied and extended to track ongoing development or run future scenarios of land use and climate. Future improvements will rely on the development of the underlying statistical information and on the incorporation and improvement of crop specific information.JRC.H.5-Rural, water and ecosystem resource
