Rivers of Food study: References and methods

Posted on 20 September 2021

References and methods for the WWF microsite on the central role of rivers in global food production

In September 2021, WWF launched Rivers of Food, which highlights that 1/3 of global food production depends on rivers.

The interactive site outlines the four key ways that rivers support global food production, including freshwater fisheries, deltas, irrigation and flood recession agriculture.

It also highlights how we need to transform the way we manage rivers if we are going to sustainably feed 10 billion people by 2050. And that we all have a role to play...

Explore Rivers of Food to find out more. And for those who want to dive even deeper into the science and research, you can find all the key references below:

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Rather than weigh the microsite down with references, we decided to make a full list of references and methods available here:


  • For the discussion of planetary boundaries, see:

    • Steffen, W., Richardson, K., Rockström, J., Cornell, S.E., Fetzer, I., Bennett, E.M., Biggs, R., Carpenter, S.R., De Vries, W., De Wit, C.A. and Folke, C., 2015. Planetary boundaries: Guiding human development on a changing planet. Science, 347(6223).

  • “Species populations have declined 68% since 1970”:

    • Almond, R.E.A., Grooten, M. and Peterson, T. et al, 2020. Living Planet Report 2020-Bending the curve of biodiversity loss. WWF.

  • “Global food systems generate 29% of greenhouse gas emissions"IPCC. 2019.
    • Climate Change and Land: an IPCC Special Report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. Intergovernmental Panel on Climate Change. www.ipcc.ch/srccl
    • Poore, J. and Nemecek, T. 2018. Reducing food’s environmental impacts through producers and consumers. Science 360:987-992.
  • “Currently, agricultural land occupies 40% of all habitable land and land conversion is the main driver…”
    • Willett, W., Rockström, J., Loken, B., et al. 2019. Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet 393:447–92.
    • Ramankutty, N., Mehrabi, Z., Waha, K. et al. 2018. Trends in global agricultural land use: Implications for environmental health and food security. Annual Review of Plant Biology 69:789-815.
    • Tilman, D., Clark, M., Williams, D.R. et al. 2017. Future threats to biodiversity and pathways to their prevention. Nature 546(7656):73.
  • Water depletion statistics:

    • WWF’s Water Risk Filter

    • Brauman, K.A., Richter, B.D., Postel, S., Malsy, M., Flörke, M. and Blum, J.D., 2016. Water depletion: An improved metric for incorporating seasonal and dry-year water scarcity into water risk assessments

    • Water depletion: Improved metric for seasonal and dry-year water scarcity. Elementa: Science of the Anthropocene, 4.

Flow of food

  • Fisheries data:
    • Food and Agriculture Organization. (2019). Fishery and aquaculture statistics. Global aquaculture production 1950–2017 (FishstatJ). Rome, Italy: FAO Fisheries and Aquaculture Department. Retrieved from www.fao.org/fishery/statistics/software/fishstatj/en
    • Ainsworth, Rachel, Ian G. Cowx, and S. J. Funge-Smith. "A review of major river basins and large lakes relevant to inland fisheries." (2021). Food and Agricultural Organization
    • The most recent data from FAO reports that inland fisheries (rivers and lakes) account for 12 million tons annually, which is about 13% of global fish harvest.  However, because much of the inland fish harvest is unreported, several scientific estimates indicate that inland fisheries may make an even greater contribution to global diets.  Etienne Fluet-Chouinard and co-authors synthesized household surveys of food consumption — “counting the fish eaten rather than the fish caught” — and estimated that actual global harvests of freshwater fish are 65% larger than previously reported.  We use this estimate to show that inland fisheries represent 19% of global capture fisheries; Fluet-Chouinard, E., Funge-Smith, S. and McIntyre, P.B., 2018. Global hidden harvest of freshwater fish revealed by household surveys. Proceedings of the National Academy of Sciences, 115(29), pp.7623-7628.
  • Deltas:

    • Edmonds, D.A., Caldwell, R.L., Brondizio, E.S. and Siani, S.M., 2020. Coastal flooding will disproportionately impact people on river deltas. Nature communications, 11(1), pp.1-8.

    • Syvitski, J. P. M. & Saito, Y. Morphodynamics of deltas under the infuence of humans. Glob. Planet. Change 57, 261–282 (2007).

  • Food production from deltas and from irrigation using river water were calculated by Mesfin Mekonnen at the University of Alabama using global data and methods from:

    • Mekonnen, M.M. & Hoekstra, A.Y. (2011) The green, blue and grey water footprint of crops and derived crop products, Hydrology and Earth System Sciences, 15(5): 1577-1600.

  • Linkages between groundwater used for irrigation and river flows:

    • Graaf, Inge E. M. de, Tom Gleeson, L. P. H. (Rens) van Beek, Edwin H. Sutanudjaja, and Marc F. P. Bierkens. “Environmental Flow Limits to Global Groundwater Pumping.” Nature 574, no. 7776 (October 2019): 90–94. https://doi.org/10.1038/s41586-019-1594-4.

  • Flood recession agriculture:

    • Area under flood recession agriculture was a combination of “flood recession cropping area non-equipped” and “cultivated wetlands and inland valley bottoms non-eqipped” from Food and Agriculture’s Aquastat Database: http://www.fao.org/aquastat/en/databases/maindatabase/


  • Nature positive food production
    • Hodson, E., Niggli, U., Kitajima, K., Lal, R., Sadoff, C. (2021).A paper from the Scientific Group of the UN Food Systems Summit. BOOST NATURE POSITIVE PRODUCTION.
    • WWF 2021. Farming with Biodiversity. Towards nature-positive production at scale. WWF International, Gland, Switzerland.
  • Sustainable fisheries and aquaculture

    • WWF. 2021. The World’s Forgotten Fishes.

    • Inland Fisheries Alliance

  • Maintain free-flowing rivers:

    • WWF and TNC. 2021. A brighter future: tackling the climate crisis and protecting nature with the right renewables in the right places. https://brighterfuture.panda.org/

    • Opperman, J, J et al.. “Connected and Flowing: A Renewable Future for Rivers, Climate, and People.” WWF and The Nature Conservancy, Washington, DC, 2019.

    • Thieme, M.L., D. Tickner, G. Grill, J.P. Carvallo, M. Goichot, J. Hartmann, J. Higgins, et al. “Navigating Trade-Offs between Dams and River Conservation.” Global Sustainability 4 (2021): e17. https://doi.org/10.1017/sus.2021.15.

  • Healthy and sustainable diets
    • WWF. 2021. Planet-based diets.Willett, W., Rockström, J., Loken, B., et al. 2019. Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet 393:447–92.
    • Springmann, M., Clark, M., Mason-D’Croz, D., et al. 2018. Options for keeping the food system within environmental limits. Nature 562: 519-525.
    • IPBES. 2019. Summary for policymakers of the global assessment report on biodiversity and ecosystem services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. IPBES secretariat, Bonn, Germany.
  • Valuing rivers and Emergency Recovery Plan for freshwater biodiversity

    • Opperman, J., Orr, S., Baleta, H., Garrick, D., Goichot, M., McCoy, A., Morgan, A., Turley, L. and Vermeulen, A., 2018. Valuing Rivers: How the diverse benefits of healthy rivers underpin economies.

    • Tickner, D., Opperman, J.J., Abell, R. et al. 2020. Bending the curve of global freshwater biodiversity loss: an emergency recovery plan. BioScience, 70(4), pp.330-342.

Jeff Opperman, Brent Loken, Nasser Olwero, Stuart Orr, and Michele Thieme, WWF
Brian Richter, Sustainable Waters
Mesfin Mekonnen, University of Alabama
Thomas Batzel and Isabel Kezman, University of Virginia

Thanks to those who contributed data and guidance: Simon FungeSmith of FAO, Rachel Ainsworth from the University of Hull in England, Stefan Siebert from University of Gottingen in Germany, Inge de Graaf from Wageningen University in the Netherlands, and Tom Gleeson at University of Victoria in Canada

This research was led by the WWF Freshwater and Food Practices and Global Science Team and supported by the Pictet Group Foundation.

Water sourced from an irrigation project, which diverts water from the river to farmland. Rwenzori Mountains, Uganda.
© WWF / Simon Rawles

Related links

Cover of Rivers of Food study by WWF into central role of rivers in global food production
A local woman holds up a dried fish fillet as people pass through the Luangwa Bridge Market, Zambia
© James Suter / Black Bean Productions / WWF-US
Aerial shot of a winding river, Amazon rainforest, Loreto region, Peru.
© Brent Stirton / Getty Images
Farmers grow rice in the rainy season. They were soaked with water and mud to be prepared for planting.
© Shutterstock / SantiPhotoSS / WWF