In addition, agricultural water use is unevenly spread. In some southern European regions, agriculture accounts for more than 80 % of water abstraction. And peak abstraction typically occurs in the summer when water is least available, maximizing detrimental impacts.
The EEA's recent report, Water resources across Europe — confronting water scarcity and drought, describes the grave impacts of excessive abstraction. Overexploiting resources increases the likelihood of severe water shortages during dry periods. But it also means diminished water quality (because pollutants are less diluted) and the risk of salt water intrusion into groundwater in coastal regions. River and lake ecosystems can also be severely affected, harming or killing plants and animals, when water levels drop or dry out completely.
The results are evident in many southern European regions. For example:
# in Turkey's Konya Basin, abstraction for irrigation — much of it drawn from illegally drilled wells — has severely reduced the surface area of the country's second largest lake, Lake Tuz;
# in Greece's Argolid Plain, chloride toxicity due to saltwater intrusion is apparent in leaf burns and defoliation; boreholes have dried up or been abandoned because of excessive salinity;
# in Cyprus, severe water shortages in 2008 necessitated importing water using tankers, cutting domestic supplies and significantly increasing prices.
Water use in agriculture is evidently becoming unsustainable in some parts of Europe, suggesting that regulatory and pricing mechanisms have failed to manage demand effectively.
Farmers shift to water-intensive irrigation methods because of the productivity gains on offer. In Spain, for example, the 14 % of agricultural land irrigated yields more than 60 % of the total value of agricultural products.
Clearly, however, farmers will only irrigate if increased yields outweigh the costs of installing irrigation systems and abstracting large amounts of water. In this regard, national and European policies have created unfortunate incentives. Farmers seldom pay the full resource and environmental cost of large, publicly managed irrigation systems (especially if laws proscribing or limiting abstraction are not effectively enforced). And until recent reforms, EU subsidies often incentivised water-intensive cultivation.
The scale of water use that ensues can be startling. WWF analysed the irrigation of four crops in Spain during 2004 and found that almost 1 billion m3 of water was used just producing surpluses over EU quotas. That equals the household consumption of more than 16 million people.
Climate change is likely to worsen the situation. First, hotter, drier summers will enhance pressures on water resources. Second, the EU and its Member States have committed that biofuels should provide 10 % of transport fuel by 2020. If growing demand for bioenergy is met using current first generation energy crops then agricultural water use will grow.
Which way now?
Irrigated agriculture is central to local and national economies in parts of Europe. In some areas, ceasing irrigation could lead to land abandonment and severe economic hardship. Agricultural water use must therefore be made more efficient not only to ensure enough water for irrigation but also for local people, a healthy environment and other economic sectors.
Water pricing represents the core mechanism to incentivise levels of water use that balance society's economic, environmental and social goals. Research demonstrates that if prices reflect true costs, illegal extraction is effectively policed, and water is paid for by volume then farmers will reduce irrigation or adopt measures to improve water efficiency. National and EU subsidies can provide additional inducements to adopt water saving techniques.
Once the incentives are in place, farmers can choose from a variety of technologies, practices and crops to reduce water use. Governments again have a crucial role to play here, providing information, advice and education to ensure that farmers are aware of the options, and supporting further research. Particular focus should go on ensuring that the introduction of energy crops to meet biofuels targets serves to reduce agricultural water demand, rather than increasing it.
Finally, after efforts to reduce demand have been exploited, farms can also take advantage of opportunities to draw on alternative supplies. In Cyprus and Spain, for example, treated wastewater has been used to irrigate crops with encouraging results.