Water Resources Across Europe - Confronting Water Scarcity and Drought
European Environmental Agency, 2009
- Climate models predict a general future increase in precipitation in northern Europe and a decrease in southern Europe. Seasonally, a large increase in winter precipitation is predicted for mid and northern Europe, while many parts of Europe are expected to experience drier summers.
- The predicted fall in winter retention as snow, earlier snowmelt and reduced summer precipitation are expected to reduce river flows in summer, when demand for water is typically at its highest.
Problems of water abstraction
- Since rivers, lakes, wetlands and groundwater are connected, excessive abstraction from anyone of them can impact upon the others.
- River flow strongly influences water quality, with lower flow diminishing the river's ability to dilute pollutants.
- Low river flows represent a particular risk to migratory fish that require sufficient flow to trigger upstream movement towards spawning grounds. In order to drift-feed, young salmons likewise require a flow of sufficient velocity and prefer to avoid shallow water.
- Excessive abstraction can also affect terrestrial ecosystems, leading to the drying out of woodland, forests, heathland, dunes and fens, making them less suitable for characteristic plant and animal life.
- Dry soil surfaces absorb less rainfall water, so that more water runs at the surface into watercourses (thereby also washing pollutants into the water).
- Excessive groundwater abstraction from a coastal aquifer causes the freshwater level to lower and seawater to flow into the aquifer — a process known as saline intrusion. Large areas of the Mediterranean coastline have been affected by saline intrusion.
Problems of water supply measures
- Desalination uses considerable amounts of energy to evaporate water or force it though membranes. Spain is the largest user of desalination technologies in the western world. Globally, it ranks fourth behind Saudi Arabia, the United Arab Emirates and Kuwait, and first in the use of desalinated water for agriculture.
- Reservoirs may induce deterioration of the river system, especially downstream of the reservoir. Since dams interrupt the natural continuity of a river, fragmentation of the river ecosystem occurs, often with marked ecological consequences. In particular, the dam may obstruct access to spawning sites for migratory fish, the problem being especially acute for fish such as salmon, trout, eel and sturgeon. Much of the sediment carried into reservoirs becomes trapped and settles to the bottom. Not only does this sedimentation reduce the lifespan of the reservoir but water released by the dam is also depleted in sediment and organic material that would otherwise contribute to the fertility of the floodplains and estuaries downstream. This depletion also leads to a reduction in the quality and extent of the downstream aquatic habitat.
Water abstraction by agriculture
- Agriculture accounts for around 24% of total want to use in the EU. In northern Europe, water use for livestock (drinking, cleaning livestock housing) is relatively more important than in southern Europe, were water use for irrigation prevails. In northern Europe, irrigation systems are often used only temporarily during periods of water shortage.
- Only about 30% of water abstracted percolates back to groundwater, while 70% does not return to a water body.
- Measures for more sustainable use of water in agriculture: wastewater re-use, improved irrigation efficiency (drip systems, timing of irrigation based on on-site, real-time microclimatic and soil humidity sensors), modification of agricultural practice (drought-tolerant varieties, varieties whose water demand coincides with times of water availability, no tillage farming).
- Political measures: water pricing, awareness raising and information for farmers, drought management plans (including the mapping of water stress and the identification of warning or alert systems and sector-specific measures, such as temporary restrictions on irrigating water-intensive crops).
- The worst times when the CAP offered high levels of support to water intensive crops (maize, rice, cotton) are over. The main instrument to reduce agricultural water abstraction in the future will not be a reform of subsidies but adequate water pricing.