Improvement of irrigation efficiency

Soil moisture, also referred to as ‘green water’, is the component of the water cycle that is accessible for the roots of plants. 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 32% of total water withdrawal, but it reaches around 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 usually only in dry summer periods.  

According to the latest IPCC report (AR6), 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, while the demand will decrease in parts of northern Europe where precipitation is likely to increase. The energy sector (hydroelectric power) will put additional strain on water resources. With these developments, more robust water management and policies are required to manage the increasing competing demand between different sectors and usages. 

Some ways irrigation efficiency can be improved are: 

• A shift from the gravity irrigation to modern pressurised systems (e.g. drip and sprinkler irrigation) . This provides improved conveyance efficiency and reduced water demand for irrigation. Also known as micro-irrigation, or drip irrigation technology, this system saves water and energy by reducing crop transpiration, evaporation and surface level runoffs.
• Deficit irrigation (irrigation below full crop-water requirements) aiming at the maximum production per unit of water consumed. A small, but growing amount of attention has been paid to this approach. Water productivity increases under deficit irrigation. However, the application of this technique requires adjustments in the agricultural systems. As crop response to water stress varies considerably, a sound knowledge of crop behaviour is needed to apply this technology. 
• Improved irrigation timing (climate-smart or precision irrigation). This is based on improved weather forecasting, hydrological monitoring, early warning systems, improved information and communication technology (ICT) and weather-based agro-advisory services for prevention and preparedness (see adaptation option on precision agriculture). 

• Different techniques can be applied to specific crops. For example, intermittent/automated irrigation(alternate wetting and drying) can be considered for paddies. It uses water efficiently, reduces labour costs, and increases yields (Masseroni et al. 2018). This technique is quite specific to rice and may not apply to other crops. 

Improved irrigation can be complemented by other water saving options (see for example the option on water reuse to counteract water scarcity and soil water deficiency. If renewable energy sources (e.g. solar power pumps) are used to power these innovative irrigation systems, water saving also combines with climate change mitigation.  

IPCC categories

Structural and physical: Technological options

Stakeholder participation

Several stakeholders may be involved in any action to re-organise irrigation systems and infrastructures, for their remarkable social, economic and environmental consequences. Not only the main actors of the agricultural sector should be involved, but also those of the sectors competing with agriculture for the same water resources. Possible neighbouring industries could be involved to secure solar powered pumps or invest in climate smart technologies. Given the positive expected effects on the water cycle as a whole, environmental associations and NGO’s are expected to be proactive in encouraging the use of innovative systems to improve irrigation. Spreading awareness about water overuse and sustainable use - especially within the agricultural sector is essential, and can lead to potential positive impacts at landscape levels.

Success and Limiting Factors

Without adaptation in water irrigation practices at farm level, crop failure is likely in drought prone areas, especially considering the worst climate scenarios. When adaptation in irrigation systems is implemented, farms can be much better prepared to face water scarcity driven by climate change. The functioning  of landscapes can be restored or sustained through water reuse and storage. Energy can be saved through efficient irrigation planning and implementation. Saving of energy and water costs is one of the biggest incentives that can boost the use efficient irrigation systems. The cost of energy is increasing and water tariffs, though highly variable across different countries, can be relevant at farm levels 

However, farmers are oftentimes reluctant to apply innovative management practices, because any change of customary practice is costly and requires effort. Lack of knowledge, technological capability or site-specific scientific evidence are also obstacles. Systems for authorising water abstraction and water pricing mechanisms in EU countries contain many exemptions for agricultural water use.  The Common Agriculture Policy (CAP) has been funding projects and practices expected to improve the sustainable water use However, still few incentives are available for farmers to implement more efficient technologies (Special report by the European Court Auditors, 2021).

Costs and Benefits

Water prices and irrigation costs are extremely varied locally, each having a different tariff for water use. Some pay per hectare and get unlimited water use, some pay per volume pumped from river. Other communities charge per litre of use (Esteve et al., 2015). Therefore, the use of new efficient irrigation systems that reduce the overall amount of water used by farmers can have different impacts on cost saving, depending on different locations. Pumps can cost between 3000-46000  euro. Those costs depend on if they are diesel or electric, and if the monitoring tools and switches are included. The pipeline can vary from 3,20-9,80 EUR/m for portable pipes or 5,70-18,50 EUR/m for underground pipes, depending on diameter (DG ENV, 2012). 

The irrigation adaptation measures show benefits in all areas with high agricultural share of freshwater use. The benefits can only be realized if the conserved water is stored for efficient and climate-smart use (i.e. dry days, with efficient irrigation methods).  

The implementation of best management practices in irrigation is often accompanied by educational programs for farmers, thus improving their knowledge and climate change awareness.  

Improved irrigation systems that efficiently use water resources minimise the impacts on the whole water cycle, with positive effects on the entire ecosystem. Energy saving and the reduction of greenhouses gas emissions are other benefits, especially if the energy efficient system is combined with using solar pumps.  

Legal Aspects

The EU CAP provides subsidies for irrigation adaptation measures that involve sustainable water use. Some measures are compulsory for farmers, while others depend on farmers' voluntary participation. Moreover, both the EU Water Framework Directives and the CAP’s cross-compliance mechanism (i.e. payments conditional on environmental obligations) are intended to safeguard the European surface and groundwater bodies.  

Switching to more efficient irrigation systems and to improved water management in agricultural land can be supported by the CAP. Examples of supported actions include measures of knowledge and information transfer as well as actions for investments in physical assets, such as infrastructure related to the supply and saving of water.  

Implementation Time

With the correct technology, training and resources, Irrigation adaptation measures can be implemented relatively quickly (2-5 years). This might require some local structural changes. 

Life Time

The Life-time varies between 5 and 15 years, depending on the specific measure. The long term efficiency of this option to cope with water scarcity in the agriculture sector also depends on the severity of climate change that will be experienced in the European regions. 

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