Water basin stress, transboundary river stress, and the depletion of groundwater and aquifers constitute an ever-increasing problem, especially in semi-arid and arid regions. This growing water stress and depletion contribute mightily to global water scarcity,[i],[ii],[iii] which is further exacerbated by population and economic growth and climate change.[iv],[v],[vi]
The ground water that humans rely on today accumulated over long periods in vast underground aquifers.[vii] Today groundwater is an important source of fresh water to over one-quarter of the world’s population. Human activity has depleted two-thirds of the world`s largest aquifers beyond sustainable thresholds, and pushed one-third into significant stress.[viii]
This overexploitation of groundwater and aquifers is a growing phenomenon,[ix] and is happening in regions important to agriculture, especially in Asia and North America.[x],[xi],[xii] These regions are important to global food security, and were impacted by severe and prolonged drought during the Little Ice Age’s four grand solar minima.
On the surface, human activity’s impact is no different than it is below the surface. More than 60 percent of the world’s largest rivers have already been dammed,[xiii],[xiv] with more than 40,000 large dams in existence today.[xv] Many more thousands of hydroelectric dam projects are also in progress or are in the planning stages.[xvi]
River outflows have markedly declined in major river systems because of the over-extraction of water, especially for agricultural use.[xvii] Asia, Europe, and North America are the biggest continental users of irrigation, while India, China, and the USA are the three top country users of irrigation.[xviii],[xix]
Rivers also unite nations and communities, with more than 260 large rivers crossing more than one country. Their combined water basins cover nearly half the planet’s land surface area.[xx] These transboundary river systems highlight big problems, with an estimated one-third to one-half of transboundary river populations already impacted by water stress and scarcity.[xxi]
As such, transboundary river systems are potential sources of conflict. The already high level of water stress associated with transboundary river systems will be exacerbated by ongoing economic and population growth, and by future droughts. Increasing water stress combined with a lack of international, cooperative water agreements[xxii],[xxiii] means we are facing increased risks to our global food security, and will face the prospect of conflict during times of extreme drought.[xxiv],[xxv]
Agriculture Is the Thirstiest of All Sectors
Agriculture is the main global user of land, with 1.5 billion hectares used for crops and 3.5 billion hectares used for grazing livestock.[xxvi] Agriculture is also the biggest user of freshwater resources by far, accounting for between 70 percent and 90 percent of freshwater extractions.[xxvii],[xxviii],[xxix]
Human food and non-food crops account for seventy percent of agricultural water use, while animal production consumes the balance, mostly for growing animal feed crops (i.e., maize and soybeans).[xxx]
Forty percent of global crops are produced using irrigation, on less than one-fifth of the world’s cropland. Six nations, led by India, China, and the USA, account for half of the irrigation water used.[xxxi] This concentration of food production in just a small number of stressed water basins, in areas that were impacted by the Little Ice Age’s grand solar minima, presents a challenge to global food security as we enter this grand solar minimum.
The world’s staple food crops, including wheat, rice, maize, barley, sugarcane, soybeans, and ten other vegetables, account for more than half of global crop production and two-thirds of crop irrigation.[xxxii] On the other hand, non-food crops like cotton, tobacco, coffee, tea, cocoa, spices, and rubber, while not the largest crops, are thirsty water consumers on a per ton yield basis.[xxxiii]
The relatively high cost of treating and delivering water has led governments to subsidize water for agricultural use, as well as subsidizing the cost of implementing efficient irrigation systems. Paradoxically, however, this use of subsidies incentivizes greater water use and increases water basin depletion. More land gets irrigated and farmers change to higher value but thirstier crops, and less water is returned to groundwater storage.[xxxiv],[xxxv]
Sustainable Industrial Use of Water
Industrial use of water varies according to stage of economic development. In China and the USA industrial water use accounts for about one-fifth of total water extractions, whereas in Europe it’s about 40%, while at the global level average industrial use is about 5%.[xxxvi],[xxxvii]
Industry’s move toward sustainable water use would be facilitated by policies directed toward ensuring that companies interact with their water basin and environment in a sustainable and non-polluting manner.[xxxviii],[xxxix]
Water is crucial to many industrial processes. The biggest industrial user of water is the energy and electricity production sector,[xl] with mining and quarrying, construction, and manufacturing (i.e., food, beverages, chemicals, and paper) also being big water users.[xli] Water is generally used in industrial processes to wash, rinse, heat, cool, dilute and mix substances, and to drive turbines.
Supporting Urbanization and Megacity Growth with Sustainable Water Resources
Domestic water consumption competes with the demands from agriculture and industry, and accounts for about 4 percent of total water extractions.[xlii] Big cities located in stressed water basins and arid and semi-arid regions will be vulnerable to drought in this grand solar minimum.
Giving this water supply vulnerability some context, in the space of 50 years after 1950 there was a five-fold increase in the number of world cities exceeding one million inhabitants.[xliii] Similarly, the population of the world’s 100 largest cities grew to more than 6 million inhabitants per city on average.[xliv] This means that more than half of the world’s population currently lives in cities, rising to over two-thirds in some regions, such as Europe.[xlv],[xlvi],[xlvii]
Rapid urbanization and overall population growth are relentless, particularly in regions such as Asia and Africa.[xlviii] They present fundamental challenges to city planners’ abilities to manage ever-scarcer water resources.
The second big urbanization trend is that coastal population growth outpaces non-coastal population growth. Between 30 and 40 percent of the world’s population live within 100 kilometers of a coast.[xlix],[l]
In fact, two-thirds of cities with more than 5 million inhabitants as well as most of the world’s megacities are ten meters or less above sea level. This grouping of populations near the coast occurs in the majority of the world’s nations. While this proximity to the coast poses risks to cities (i.e., coastal flooding), important opportunities are also afforded for the decentralization of municipal freshwater supply through renewable energy desalination.[li],[lii],[liii],[liv]
[i] A.S. Richey at al., 2015, “Quantifying renewable groundwater stress with GRACE.” Water Resources Research. 51, 5217–5238, doi:10.1002/2015WR017349, and NASA via https://www.nasa.gov/jpl/grace/study-third-of-big-groundwater-basins-in-distress.
[ii] H. Munia et al., “Water stress in global transboundary river basins: significance of upstream water use on downstream stress.” Environment Research Letter 11 (2016) 014002. doi:10.1088/1748-9326/11/1/014002 http://iopscience.iop.org/article/10.1088/1748-9326/11/1/014002/pdf.
[iii] Tom Gleeson et al., “Water balance of global aquifers revealed by groundwater footprint.” Nature Volume 488, 197–200 (09 August 2012). doi:10.1038/nature11295.
[iv] C.A. Schlosser et al., 2014, “The future of global water stress: An integrated assessment.” Earth’s Future, 2: 341-361. doi:10.1002/2014EF000238.
[v] R.B. Jackson et al., 2001, “Water in a Changing World.” Ecological Applications, 11: 1027-1045. doi:10.1890/1051-0761(2001)011[1027:WIACW]2.0.CO;2.
[vi] R. Quentin Grafton et al., “Global insights into water resources, climate change and governance.” Nature Climate Change Volume 3, 315–321 (2013). DOI: 10.1038/NCLIMATE1746.
[vii] The United States Geological Survey. Ground water. https://pubs.usgs.gov/gip/gw/gw_a.html, https://pubs.usgs.gov/gip/gw/how_a.html.
[viii] A.S. Richey et al., 2015, “Quantifying renewable groundwater stress with GRACE.” Water Resources Research, 51, 5217–5238, doi:10.1002/2015WR017349, and NASA via https://www.nasa.gov/jpl/grace/study-third-of-big-groundwater-basins-in-distress.
[ix] Y. Wada et al., 2010, “Global depletion of groundwater resources.” Geophysical Research Letters, 37, L20402, doi: 10.1029/2010GL044571.
[x] Tom Gleeson et al., “Water balance of global aquifers revealed by groundwater footprint.” Nature Volume 488, 197–200 (09 August 2012). doi:10.1038/nature11295.
[xi] R.B. Jackson et al., 2001, “Water in a Changing World.” Ecological Applications, 11: 1027-1045. doi:10.1890/1051-0761(2001)011[1027:WIACW]2.0.CO;2
[xii] V.M. Tiwari et al., 2009, “Dwindling groundwater resources in northern India, from satellite gravity observations.” Geophysical Research Letters, 36, L18401, doi: 10.1029/2009GL039401.
[xiii] Christer Nilsson et al., “Fragmentation and Flow Regulation of the World’s Large River Systems.” Science 15 Apr 2005: Volume 308, Issue 5720, 405-408. DOI: 10.1126/science.1107887.
[xiv] Muhammad Mizanur Rahaman and Olli Varis, 2005, “Integrated water resources management: evolution, prospects and future challenges.” Sustainability: Science, Practice and Policy, 1:1, 15-21, DOI: 10.1080/15487733.2005.11907961.
[xv] R.B. Jackson et al., 2001, “Water in a Changing World.” Ecological Applications, 11: 1027-1045. doi:10.1890/1051-0761(2001)011[1027:WIACW]2.0.CO;2
[xvi] C. Zarfl et al., “A global boom in hydropower dam construction.” Aquatic Sciences (2015) 77: 161. https://doi.org/10.1007/s00027-014-0377-0.
[xvii] R. Quentin Grafton et al., “Global insights into water resources, climate change and governance.” Nature Climate Change Volume 3, 315–321 (2013). DOI: 10.1038/NCLIMATE1746.
[xviii] Prasad S. Thenkabail et al., “Global irrigated area map (GIAM), derived from remote sensing, for the end of the last millennium.” International Journal of Remote Sensing. Volume 30, 2009 – Issue 14. https://doi.org/10.1080/01431160802698919.
[xix] M.M. Mekonnen and A.Y. Hoekstra, “The green, blue and grey water footprint of crops and derived crop products.” Hydrology and Earth System Sciences, 15, 1577-1600, https://doi.org/10.5194/hess-15-1577-2011, 2011.
[xx] Aaron T. Wolf et al., “International River Basins of the World.” 387-427 21 Jul 2010. https://doi.org/10.1080/07900629948682.
[xxi] H Munia et al., “Water stress in global transboundary river basins: significance of upstream water use on downstream stress.” Environment Research Letter 11 (2016) 014002. doi:10.1088/1748-9326/11/1/014002 http://iopscience.iop.org/article/10.1088/1748-9326/11/1/014002/pdf.
[xxii] Global Water Security. Intelligence Community Assessment, ICA 2012-08, 2 February 2012. https://www.dni.gov/files/documents/Special%20Report_ICA%20Global%20Water%20Security.pdf
[xxiii] Muhammad Mizanur Rahaman and Olli Varis, 2005, Integrated water resources management: evolution, prospects and future challenges, Sustainability: Science, Practice and Policy, 1:1, 15-21, DOI: 10.1080/15487733.2005.11907961.
[xxiv] U.S. Government Global Water Strategy, 2017. https://www.usaid.gov/sites/default/files/documents/1865/Global_Water_Strategy_2017_final_508v2.pdf.
[xxv] Global Water Security. Intelligence Community Assessment, ICA 2012-08, 2 February 2012. https://www.dni.gov/files/documents/Special%20Report_ICA%20Global%20Water%20Security.pdf
[xxvi] S. Mark Howden et al., “Adapting agriculture to climate change.” Proceedings of the National Academy of Sciences Dec 2007, 104 (50) 19691-19696; DOI: 10.1073/pnas.0701890104.
[xxvii] Rosegrant, Mark W et al., “Water for Agriculture: Maintaining Food Security Under Growing Scarcity (November 2009).” Annual Review of Environment and Resources, Volume 34, 205-222, 2009. Available at SSRN: https://ssrn.com/abstract=1599085 or http://dx.doi.org/10.1146/annurev.environ.030308.090351.
[xxviii] Arjen Y. Hoekstra, Mesfin M. Mekonnen, “The water footprint of humanity.” Proceedings of the National Academy of Sciences Feb 2012, 109 (9) 3232-3237; DOI: 10.1073/pnas.1109936109.
[xxix] Global Water Security. Intelligence Community Assessment, ICA 2012-08, 2 February 2012. https://www.dni.gov/files/documents/Special%20Report_ICA%20Global%20Water%20Security.pdf
[xxx] M.M. Mekonnen, A.Y. Hoekstra, 2012, “A global assessment of the Water Footprint of Farm Animal Products.” Ecosystems, 15(3), 401-415. DOI: 10.1007/s10021-011-9517-8.
[xxxi] M.M. Mekonnen, A.Y. Hoekstra, “The green, blue and grey water footprint of crops and derived crop products.” Hydrology and Earth System Sciences, 15, 1577-1600, https://doi.org/10.5194/hess-15-1577-2011, 2011.
[xxxii] Kate A. Brauman, et al. “Improvements in crop water productivity increase water sustainability and food security—a global analysis.” Environmental Research Letters. 8 (2013) 024030 (7pp). doi:10.1088/1748-9326/8/2/024030.
[xxxiii] M.M. Mekonnen, A.Y. Hoekstra, “The green, blue and grey water footprint of crops and derived crop products.” Hydrology and Earth System Sciences, 15, 1577-1600, https://doi.org/10.5194/hess-15-1577-2011, 2011.
[xxxiv] Lisa Pfeiffer and C.Y. Cynthia Lin, “Does Efficient Irrigation Technology Lead to Reduced Groundwater Extraction? Empirical Evidence.” Journal of Environmental Economics and Management. Volume 67, Issue 2, March 2014, 189-208. https://doi.org/10.1016/j.jeem.2013.12.002.
[xxxv] Frank A. Ward, Manuel Pulido-Velazquez, “Water conservation in irrigation can increase water use.” Proceedings of the National Academy of Sciences Nov 2008, 105 (47) 18215-18220; DOI: 10.1073/pnas.0805554105.
[xxxvi] Arjen Y. Hoekstra, Mesfin M. Mekonnen, “The water footprint of humanity.” Proceedings of the National Academy of Sciences Feb 2012, 109 (9) 3232-3237; DOI: 10.1073/pnas.1109936109.
[xxxvii] European Commission. “Water use in industry. Cooling for electricity production dominates water use in industry.” http://ec.europa.eu/eurostat/statistics-explained/index.php/Archive:Water_use_in_industry.
[xxxviii] European Commission. Enterprise and Industry. Sustainable Industry – Going for Growth and Resource Efficiency. Report Authors. Authors: Koen Rademaekers, Sahar Samir Zaki, Matthew Smith. Ref. Ares(2014)1209330 – 16/04/2014. https://ec.europa.eu/docsroom/documents/5188/attachments/1/translations/en/renditions/pdf.
[xxxix] United Nations Industrial Development Organization. See Flagship publications. Industrial Development Report 2018. Demand for Manufacturing: Driving Inclusive and Sustainable Industrial Development.
[xl] European Commission. Water use in industry. Cooling for electricity production dominates water use in industry. http://ec.europa.eu/eurostat/statistics-explained/index.php/Archive:Water_use_in_industry.
[xli] European Commission. Enterprise and Industry. Sustainable Industry – Going for Growth & Resource Efficiency. Report Authors. Authors: Koen Rademaekers, Sahar Samir Zaki, Matthew Smith. Ref. Ares(2014)1209330 – 16/04/2014. https://ec.europa.eu/docsroom/documents/5188/attachments/1/translations/en/renditions/pdf.
[xlii] Arjen Y. Hoekstra, Mesfin M. Mekonnen, “The water footprint of humanity.” Proceedings of the National Academy of Sciences Feb 2012, 109 (9) 3232-3237; DOI: 10.1073/pnas.1109936109.
[xliii] K.C. Seto et al., 2011, “A Meta-Analysis of Global Urban Land Expansion.” PLoS ONE 6(8): e23777. doi:10.1371/journal.pone.0023777.
[xliv] David Satterthwaite et al., “Adapting to Climate Change in Urban Areas. The possibilities and constraints in low- and middle-income nations.” http://pubs.iied.org/pdfs/10549IIED.pdf.
[xlv] M. Kummu et al., 2011, “How Close Do We Live to Water? A Global Analysis of Population Distance to Freshwater Bodies.” PLoS ONE 6(6): e20578. doi:10.1371/journal.pone.0020578.
[xlvi] David Satterthwaite et al., “Adapting to Climate Change in Urban Areas. The possibilities and constraints in low- and middle-income nations.” http://pubs.iied.org/pdfs/10549IIED.pdf.
[xlvii] European Commission: Cities of Tomorrow. Challenges, visions, ways forward. http://ec.europa.eu/regional_policy/sources/docgener/studies/pdf/citiesoftomorrow/citiesoftomorrow_final.pdf.
[xlviii] K.C. Seto et al., 2011, “A Meta-Analysis of Global Urban Land Expansion.” PLoS ONE 6(8): e23777. https://doi.org/10.1371/journal.pone.0023777.
[xlix] US Census: Coastal Areas. https://www.census.gov/topics/preparedness/about/coastal-areas.html
[l] The World Bank (2010). The International Bank for Reconstruction and Development. Climate Risks and Adaptation In Asian Coastal Megacities. A Synthesis Report.
[li] K.C. Seto et al., 2011, “A Meta-Analysis of Global Urban Land Expansion.” PLoS ONE 6(8): e23777. doi:10.1371/journal.pone.0023777.
[lii] B. Neumann et al., “Future Coastal Population Growth and Exposure to Sea-Level Rise and Coastal Flooding – A Global Assessment.” Kumar L, ed. PLoS ONE. 2015;10(3):e0118571. doi:10.1371/journal.pone.0118571.
[liii] R.J. Nicholls, “Coastal megacities and climate change.” GeoJournal (1995) 37: 369. https://doi.org/10.1007/BF00814018.
[liv] Gordon McGranahan, et al. “The rising tide: assessing the risks of climate change and human settlements in low elevation coastal zones.” Environment and Urbanization. Volume19, Issue 1, 17 – 37. April 1, 2007. https://doi.org/10.1177/0956247807076960.
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