Improvement of irrigation efficiency (2015)
Soil moisture, also referred to as ‘green water’, is the component of the water cycle that is accessible by the roots of plants, enabling them to grow. Soil moisture drops in periods of deficient precipitation. Irrigation is the most widely used way to combat the soil water deficiency and, accordingly, by far the prevalent water use in agriculture. In Europe, agriculture accounts for approximately 23.6% of total water withdrawal, but it reaches 80% and above in the Mediterranean countries. The role and the impact of irrigation varies across the regions and prevailing climatic conditions: while in southern Europe irrigation is an essential ingredient of agricultural production, in Central and Northern Europe fields are irrigated sporadically and mostly in dry summer periods. In Italy or Spain, the water withdrawals for agriculture can be as high as 80%.
The expected climate change impacts on agriculture, however, will most likely reverse these initial water savings. According to the latest IPCC report, soil water content in Southern Europe will decline; saturation conditions and drainage will be increasingly rare and restricted to periods in winter and spring. Consequently, the irrigation water demand may increase substantially for the Mediterranean region. Irrigation will become necessary in some other parts of Europe, such as Ireland, while the demand will decrease in parts of northern Europe where precipitation is likely to increase. The energy sector will put additional strain on water resources. Biomass production for energy purposes is expected to increase from 2 M toe in 2003 to 102-142 M toe in 2030. This will moderately increase the water demand. In this contest, more robust water management and policies are required in order to manage the competing demand between agriculture and other sectors (energy, conservation and human settlements).
A shift from the gravity irrigation to modern pressurised systems (e.g. drip and sprinkler irrigation) and improved conveyance efficiency provide an opportunity for reduced water demand in irrigation, but at a cost and with possible negative side effects (impacts on soil quality) . A small, but growing amount of attention has been paid to deficit irrigation; or more specifically, irrigation below full crop-water requirements (evapotranspiration) aiming at the maximum production per unit of water consumed. Water productivity increases under deficit irrigation, but the application of this technique requires adjustments in the agricultural systems, imposing changes at different levels.
- Stakeholder participation
- Success and Limiting Factors
- Costs and Benefits
- Legal Aspects
- Implementation Time
Stakeholders should be involved in any attempt to re-organise irrigation systems and infrastructures, for their remarkable social, economic and environmental consequences. Not only the main actor of the agricultural sectors should be involved, but also those of the sectors competing with agriculture for the same water resources. A hidden stakeholder is the environment, in that the re-organisation of irrigation systems has remarkable effects on the water cycle as a whole, and water lost because of low efficiency irrigation system may have important positive side effects for the environment.
Success and Limiting Factors
Farmers are oftentimes reluctant to apply best management practices, because change of customary practice is costly and requires effort. Lack of knowledge or case specific scientific evidences are also obstacles. Given that the water price and the fixed costs of water provision for agriculture are heavily subsidised (OECD 2008), there are few incentives for farmers in many EU countries to implement more efficient technologies. Water pricing and recovery of the costs of irrigation investment, operation, and maintenance have been contentious issues for many decades.
Costs and Benefits
The measure shows evident benefits in all areas with high agricultural share of freshwater use. The positive benefits can only be realized if the conserved water is not immediately relocated and used for new crops and extended irrigation. Consideration should be paid to the reduced return flow and thus reduced water availability downstream. Implementation of best management practices is accompanied by farmer educational programs, works of extension services and social context. If appropriate knowledge is not available, and does not agree with traditional practices, then typically the implementation does not work. Except cases where activities are directly profit-enhancing, in the absence of clear regulatory authority the only motivation farmers have for reducing pollution is the hope of avoiding increased future regulation. Management practices are more likely to be adopted when the cost to farms is reduced.
The EU policies throughout which the measure could be promoted include Water Framework Directive (WFD, water pricing), EU Drought Policy, Common Agricultural Policy (CAP) and Rural Development, and European Cohesion Fund. WFD: Increasing the price of water for irrigation will provide an incentive for more efficient water use in agriculture. Even more so if the price scheme will include scarcity component linked to the actual or expected water availability. Attention should be paid to the combined effect of energy and water prices on farm level. CAP: The agricultural demand for water declined between 1997 and 2005 by about 20% on average in Eastern Europe and some 56% in Western Europe, a trend attributed to a decrease in irrigable areas in some countries and more efficient water use in others (EEA 2009). The recent reforms of the Common Agricultural Policy (EC 2003) helped to curb water demand for irrigation. Particularly, the ‘decoupling’ subsidies for specific crops and encouraging the modernization and the sustainability of the farming practices had positive effects on water consumption. An additional reduction in water demand may occur through the reform of the Common Market Organisation of fruit and vegetables and the wine sector. The unintended side effects of the measure (extension of irrigated land) can be controlled by defining requirements, which, only if met, would allow to access the funding schemes for new irrigation technology. These requirements may include minimum net water saving at the river basin scale or limiting the extension of irrigated land.