Development Aspects Impressum Editors

Increasing water use efficiency in agriculture

The second avenue through which better WDM in the Mediterranean can pro- gress is the increase in water use efficiency – defined as the agricultural output per unit of water used – in both irrigated and rain-fed agriculture. At the core of this argument is not only the inherent inefficiency and suboptimal utilization of water resources in the agricultural sector, but also the need to make the most of available resources rather than relying on additional mobilization. The proposed alternative WDM strategy includes several key interventions aimed at increasing the efficiency of both green and blue water use. It is also argued here that higher water-use ef- ficiency is not alternative but rather complementary to better water pricing, and sometimes even a precondition.

The first required intervention is to enhance the efficiency of existing irrigation systems through the reduction of water losses. Overall water use efficiency in the region is far from being satisfactory. In 2005, average total water use efficiency in the region stood at between 50 and 85 per cent, with considerable variations between the northern, southern and eastern economies (Plan Bleu, 2009). A major share of water losses occurs in irrigation systems (87 per cent), accounting for 95 km³/year (Plan Bleu, 2009), which is about 34 per cent of total water demand. If the efficiency gap were addressed purely in terms of technological improve- ment, water savings would reach 86 km³/year by 2025 (Plan Bleu, 2008), which is almost 27 per cent of projected total water demand. For instance, deploying

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   Subsidies in agriculture often take the form of a “guaranteed price” through which a government or a supranational entity (such as the European Commission) covers any possible gap between a target price and the actual market price, thereby ensuring extra revenues to farmers, associated with the immuniza- tion against market variability and price oscillations. In this case, reducing subsidies would amount to reducing the guaranteed price.
   

micro-irrigation techniques would improve water delivery to plants considerably. A major constraint in their application is, however, the high maintenance cost of such equipment.

The second intervention concerns unlocking the potential of “green” (soil) wa- ter use in rain-fed crop production. As green water is highly correlated to a coun- try’s precipitation pattern, soil profile and climate, it is relatively scarcer than blue water in arid and semi-arid environments. Global food security is almost totally reliant upon it (Allan, 2011). It has been estimated that green water accounts for 84 per cent of total water use in agriculture and 94 per cent of the water “em- bedded” in agricultural exports globally (Fader and others, 2011). Increasing its productivity would make blue water available for higher-value uses while reducing the impacts on the environment. This argument is supported by consideration of the low opportunity cost associated with green water use and the relatively few negative externalities it causes on the environment (Aldaya, Allan and Hoekstra, 2010). Although the use of both types of water in agriculture is generally associ- ated with an overall degradation of water quality due to the use of fertilizers and pesticides, the impact of rain-fed crop production is indeed considerably smaller than irrigated agricultural systems, which, conversely, change irreversibly the natu- ral course of water flows (Yang and others, 2006). As suggested by Falkenmark and Rockström (2006), the maximization of green water potential in rain-fed ag- riculture goes hand in hand with an improvement in soil conditions through inte- grated land and water management (ILWM). By optimizing land use, green water productivity would be considerably raised, while water salinization, soil erosion and desertification would be reduced.
Finally, additional methods for increasing water-use efficiency in agriculture are water harvesting through both micro and macro water catchment techniques, supplementing rain-fed agriculture with freshwater and tailoring cropping patterns to the site-specific conditions and availability of water and land.

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