Due to increasing pressure on Europe’s freshwater resources, driven by changing climatic conditions, population growth, and shifting dietary and energy patterns, the interest in water-use efficiency is enormous. Especially water-use efficiency in agriculture is a hot topic, since agriculture uses around 40% of the all water abstracted from Europe’s groundwater and surface water resources on an annual basis (EEA, 2018).
There are three perspectives on water-use efficiency (Hoekstra, 2020). From the production perspective, we can address the question of how to produce a given crop with less water. From the geographic perspective on water-use efficiency, we can ask the question of where we can best produce what from a water point of view. Lastly, from the consumption perspective we can pose the question of how to best fulfil certain consumer needs with less water. The consumer perspective thus addresses the issue of demand and questions what actually is produced.
Nearly all attention and advancements around water-use efficiency in agriculture have focused on the production perspective. Food cannot be grown without water, because transpiration by plants is an essential element of plant growth. Strategies to increase crop water productivity therefore should aim at reducing the non-beneficial part of evapotranspiration from a crop field, which includes water evaporated during the application of irrigation water to the field and the water that evaporates from the bare soil and the leaves without contributing to biomass growth. This can be achieved by specific forms of tillage and mulching of the soil, or by installing more efficient irrigation systems (Chukalla et al., 2015). The replacement of sprinkler by drip irrigation systems in arid regions such as the Segura basin in Spain is a good example of the latter (Aldaya et al., 2019). In addition, since water productivity is a function of water use and crop yield, increasing yields by adopting good agricultural practices and optimal crop cultivars is an effective way to enhance water-use efficiency in agriculture. Such yield improvements have largely contributed to improved crop water productivity in Europe, especially in the past century.
The risk of solely focusing on the production perspective of water-use efficiency is that we end up producing the wrong crops in Europe most efficiently. Think of efficient large-scale production of water-demanding almonds, olives, tomatoes and fruits in Southern Europe for export. When we take the geographic perspective, we will look where we can best produce certain crops from a water point of view. Several local and global studies have shown that significant water savings can be achieved, maintaining current production levels, if crops would be produced in different places than they are at the moment (Davis et al., 2017a;b).
When we consider the water-use efficiency of food from a consumption perspective, we look at how we can fulfil the food needs of European consumers with less water. This can be done by changing our dietary patterns, particularly by replacing meat and dairy by suitable plant alternatives, maintaining the same nutritional value but reducing the water footprint per kilocalorie or per gram of protein. Food consumption patterns and associated water footprints largely vary across the North, South, East and West of Europe, but in all regions substantial water savings can be achieved by adopting diets according to regional health standards, and even more when meat and dairy products are replaced by nutritionally equivalent plant-based alternatives (Vanham et al., 2013).
Talking about changing production and especially consumption patterns is way more difficult than implementing best practices in the current agro-food system. Yet solutions from all perspectives on water-use efficiency will be required to tackle the nexus challenge of sufficient and nutritious food for all Europeans while sustainably managing Europe’s freshwater resources. To achieve sustainable water use, we need to reduce overall water consumption in all those catchments where overdraft currently affects local ecosystems and biodiversity, which particularly occurs in Southern Europe, and reduce the water pollution as a result of excessive use of fertilizers and pesticides, which happens throughout Europe. Better agricultural practices, smarter choices on what to produce where, and adjustments in diets are all essential elements of the solution. Finally, given that forty percent of Europe’s water footprint lies outside Europe (Hoekstra, 2011), we need to consider and reduce the external environmental impacts of Europe’s food consumption as well.
Aldaya, M.M., Custodio, E., Llamas, R., Fernández, M.F., García, J. & Ródenas, M.A. (2019) An academic analysis with recommendations for water management and planning at the basin scale: A review of water planning in the Segura River Basin, Science of the Total Environment, 662: 755-768.
Chukalla, A.D., Krol , M.S. & Hoekstra, A.Y. (2015) Green and blue water footprint reduction in irrigated agriculture: Effect of irrigation techniques, irrigation strategies and mulching, Hydrology and Earth System Sciences, 19(12): 4877-4891.
EEA (2018) EEA Environmental indicator report 2018, available online: https://www.eea.europa.eu/airs/2018.
Hoekstra, A.Y. (2011) How sustainable is Europe’s water footprint? Water and Wastewater International, 26(2): 24-26.
Hoekstra, A.Y. (2020) The water footprint of modern consumer society: second edition, Routledge, London, UK. https://www.routledge.com/The-Water-Footprint-of-Modern-Consumer-Society/Hoekstra/p/book/9781138354784
Davis K.F., Seveso A, Rulli M.C. & D’Odorico P (2017a) Water savings of crop redistribution in the United States. Water, 9(2): 83.
Davis K.F., Rulli M.C., Seveso A. & D’Odorico P. (2017b) Increased food production and reduced water use through optimized crop distribution, Nature Geoscience 10: 919–92.
Vanham, D., Hoekstra, A.Y. & Bidoglio, G. (2013) Potential water saving through changes in European diets, Environment International, 61: 45-56.