Latest research

Advancing water footprint assessment research: Challenges in monitoring progress towards Sustainable Development Goal 6.

Hoekstra, A.Y., Chapagain, A.K. and Van Oel, P.R. (2017) Water, 9(6): 438.

This editorial introduces the papers of a special issue on Water Footprint Assessment of the journal Water by relating them to Sustainable Development Goal (SDG) number 6 of the United Nations, the goal on water. It articulates how each paper drives the understanding needed to achieve target 6.3 on water quality and pollution and target 6.4 on water-use efficiency and water scarcity. It concludes that SDG 6 lacks any target on using green water more efficiently and, while addressing efficiency and sustainability of water use, it lacks a target on equitable sharing of water. It claims that the latter issue is also receiving limited attention in research. It asserts that understanding of water problems and proposed solutions will likely remain unbalance because focus is primarily on water-use efficiency in farming and industries at the local level and issues around equitable water use are largely being ignored.

Marginal cost curves for water footprint reduction in irrigated agriculture: Guiding a cost-effective reduction of crop water consumption to a permit or benchmark level.

Chukalla, A.D., Krol , M.S. and Hoekstra, A.Y. (2017)Hydrology and Earth System Sciences, 21: 3507-3524.

This study develops and applies a method to find the most cost-effective pathway to reduce the water footprint in irrigated crop production. Different cases are considered, including three crops (maize, tomato and potato); four types of environment (humid in UK, sub-humid in Italy, semi-arid in Spain and arid in Israel); three hydrologic years (wet, normal and dry years) and three soil types (loam, silty clay loam and sandy loam). It finds that, when aiming
at water footprint reduction, one can best improve the irrigation strategy first, next the mulching practice and finally the irrigation technique. Moving from a full to deficit irrigation strategy is found to be a no-regret measure: it reduces the water footprint by reducing water consumption at negligible yield reduction while reducing the cost for irrigation water and the associated costs for energy and labour. Next, moving from no to organic mulching has a high cost-effectiveness, reducing the water footprint significantly at low cost. Finally, changing from sprinkler or furrow to drip or subsurface drip irrigation reduces the water footprint, but at a significant cost.

Establishing and testing a catchment water footprint framework to inform sustainable irrigation water use for an aquifer under stress

Betsie le Roux, Michael van der Laan, Teunis Vahrmeijer, Keith L. Bristow, John G. Annandale (2017), Science of The Total Environment, Volumes 599–600, December 2017, Pages 1119–1129,

This study investigates the ability of water footprints to inform water resource management at catchment-scale was investigated on the Steenkoppies Aquifer, South Africa. By using the information to derive a water balance and develop a catchment water footprint framework, it finds that this simplified method gives important insights into the hydrology of the aquifer. The results of the study indicate that current irrigation on the Steenkoppies Aquifer is unsustainable. The report advocates that the water footprint methodology can be applied to other water-stressed aquifers around the world and can inform the sustainability of catchment scale water use in order to help set and meet sustainability targets.

The consideration of time step in calculating grey water footprints of agricultural cropping systems

X. Vergé, A. VanderZaag, W. Smith, B. Grant, R. Gordon (2017), Ecological Indicators, Volume 78, July 2017, Pages 31–36,

Grey water is an indicator of pollution in water footprint assessments. In this study, the grey water footprint for corn and soybean are calculated on daily to yearly time steps. It finds that the grey water footprint varied significantly when calculated for different time steps and that results are, therefore, highly dependent on the time step of calculation. The greatest annual footprint occurred when calculated daily (shortest time step); results ranged from 2.7 and 0.5 × 103 m3 ha−1 for corn and soybean respectively to zero. The effect of this issue extends beyond crop production as it is exported and amplified through feed rations to affect the grey water footprint from animal production. It suggests that in order to reconcile these problems, grey water calculation pathways should be reconsidered and standardized.

Dependencies of Europe’s economy on other parts of the world in terms of water resources

Ercin A.E., Chico D. and Chapagain A. K. (2016), Horizon2020 – IMPREX project, Technical Report D12.1, Water Footprint Network.

This study finds that the EU’s economy is dependent on the availability of water in other parts of the world for many crops such as soybeans, rice and cotton. That makes it vulnerable to increasing water scarcity and drought. In the near term, imports of soybeans, rice, sugar cane, cotton, almonds, pistachios and grapes are most likely to be affected because they come from areas that currently have significant or severe levels of water scarcity. Almost all of the crop products imported to the EU from India and Pakistan are sourced from locations with high levels of water scarcity. For instance, sugar cane and rice from these countries are categorized as “very highly vulnerable” to water scarcity. In the longer term, imports of products such as coffee and cocoa would be affected if climate change were to alter rainfall patterns and increase the risk of drought or other water-related problems in the countries of origin. This variation would have a far greater and negative impact on the EU’s economy.

The effect of different agricultural management practices on irrigation efficiency, water use efficiency and green and blue water footprint

Zhuo, L. and Hoekstra, A.Y. (2017) Front. Agr. Sci. Eng. (2017). doi: 10.15302/J-FASE-2017149.

This paper explores the effect of varying agricultural management practices on different water efficiency indicators: irrigation efficiency, crop water use efficiency, and green and blue water footprint. It takes winter wheat in an experimental field in Northern China as a case study and considers a dry, average and wet year.

Urban Water Atlas for Europe – a 360° view of water management in cities.

Gawlik, B.M., Easton, P., Koop, S., Van Leeuwen, K., Elelman, R., (eds.)(2017), European Commission, Publications Office of the European Union, Luxembourg. 160 pp. - European Commission and Joint Research Centre

This publication presents the first overview of urban water management in Europe. It explains and illustrates water in an unprecedented way, reflecting how water flows through the arteries of our cities. Informative texts, stunning photographs and fascinating artwork allows us to address and answer these and other questions. Leading experts in water sciences and technologies, together with climate change researchers have teamed up with artists and children in order to show how thirsty our cities really are and how we can cope with their growing demand for the most precious resource of our planet. The Urban Water Atlas for Europe sets the benchmark for 40 European cities, thus helping them to face one of the greatest global challenges with local solutions providing water for all. The Urban Water Atlas for Europe is more than just a normal atlas. It presents water as our unique source of life and as a meeting point between cities.

Water Footprint Assessment: Evolvement of a New Research Field

Hoekstra, A., Y. (2017), Water Resource Manager, DOI 10.1007/s11269-017-1618-5.

This paper reviews the evolution of Water Footprint Assessment as a new research field over the past fifteen years and reflects on the main issues of debate. It concludes that the rapid emergence of the new field and wide uptake of the water footprint concept in society has generated substantial discussion about what the concept and the research field can offer, and what it cannot.

Mapping of water footprint research: A bibliometric analysis during 2006–2015

Zhang, Y., Huang, K., Yu, Y., Yang, B. (2017), Journal of Cleaner Production, Volume 149.

This paper presents a bibliometric analysis of the research in the field of water footprint during the period 2006–2015, with information related to countries, institutions, journals, categories, top cited publications, keywords, hot issues and research trends. It finds that research on water footprint has increased sharply over the past decade, especially in the United States, China and the Netherlands. The findings provide a better understanding of characteristics of water footprint research and serve as a useful reference for future studies.

The water footprint of second-generation bioenergy: A comparison of biomass feedstocks and conversion techniques

Mathioudakis. V., Gerbens-Leenes, P.W., Van der Meer, T.H., Hoekstra, A.Y. (2017), Journal of Cleaner Production, Volume 148.

This paper calculates the water footprint of ten crop residue types and a few other second-generation bioenergy feedstocks (miscanthus, eucalyptus and pine). It estimates the water footprint of energy carriers produced through different conversion techniques, using the Global Water Footprint Standard. It asserts that second-generation bio-energy from crop residues has high potential to supply energy. In terms of feedstocks for bioenergy, it finds that miscanthus and wood have large water footprints and that crop residues have relatively small water footprints. It also finds that the water footprint of pyrolysis oil is smaller than bio-ethanol for the same feedstock and that the water footprint of sugar crop residue (beet or cane) is the smallest of all crop residues.

Water, land and carbon footprints of sheep and chicken meat produced in Tunisia under different farming systems

Ibidhi, R., Hoekstra. A.Y., Gerbens-Leenes, P. W., Chouchane, H. (2017), Ecological Indicators, Volume 77.

This paper uses footprint indicators (the water, land and carbon footprint) to assess natural resources use and greenhouse gas emissions for sheep and chicken meat produced in Tunisia in different farming systems in the period 1996–2005. It finds that chicken meat has a smaller water footprint, land footprint and carbon footprint than sheep meat. For sheep meat, the agro-pastoral system using cereal crop-residues is the production system with smallest water and land footprints, but the highest carbon footprint. The pastoral system using barley has larger water and land footprints than the agro-pastoral system using barley, but a comparable carbon footprint.

Trees, forests and water: Cool insights for a hot world

Ellison, D., Morris, C.E., Locatelli B., Sheil, D., Cohen, J., Murdiyarso, D., Gutierrez, V., van Noordwijk, M., Creed, I. F., Pokorny, J., Gaveau, D., Spracklen, D. V., Bargués Tobella, A., Ilstedt, U., Teuling, A.J., Gebrehiwot, S. G., Sands, D.C., Muys, B., Verbist, B., Springgay, E., Sugandi, Y., Sullivan, C.A., (2017), Global Environmental Change, Volume 43.

This paper reviews the advantages of forests highlighted in the literature on forest, water and energy cycle interactions. It asserts that forest, water and energy cycle interactions provide the foundation for achieving forest-based adaptation and mitigation goals. Forests can be used, in particular, to mitigate problems related to water scarcity and global warming. It concludes that, in addition to up- and downstream relationships, policy frameworks need to consider the transboundary nature of up- and downwind forest, water and energy cycle interactions. Alongside the local level, regional and continental policy-making frameworks are necessary for adequate consideration of transboundary forest, water and energy cycle interactions.