In order to calculate the percentage of drinkable water on earth, we’ll have to start large and "filter" our way through.
One could assume that water shortage shouldn't be much of a concern for humans when considering how much water is in the ocean, especially when 70% of the earth’s surface is covered in it (Bureau of Reclamation, 2017).
That’s 326 million cubic miles of endless blue sea occupying the expanse in between our seven continents.
Of the waters occupying 70% of the earth’s surface, only 3% is considered freshwater. Furthermore, about 2.6% of this freshwater is inaccessible to humans. They’re either locked up in polar ice caps and glaciers, stored in the atmosphere or soil, are highly polluted or are too far underneath the earth’s surface to be extracted.
This leaves us with roughly 0.4% of the earth’s water which is usable and drinkable to be shared among the 7 billion of its inhabitants (World Atlas, 2018).
The United States Geological Survey provides a visual illustration (represented in spheres) as to the amount of available water in comparison to the size of the earth.
The largest sphere represents all of the water on earth (oceans, ice caps, lakes, rivers, groundwater) and has a volume of 332,500,000 cubic miles.
The second-largest sphere, with a volume of 2,551,100 cubic miles, represents the earth’s freshwater supply in liquid form. 99% of the liquid freshwater is groundwater, much of which is far too deep to be accessible.
The remainder of the earth’s freshwater exists in lakes and rivers, represented by the tiniest sphere, with a volume of 22,339 cubic miles (Perlman, 2016).
The earth’s surface waters travel through a complex network of flowing rivers and streams. Rivers can obtain their water from two sources: base flow and runoff. Base flow is when the river collects its water from water-saturated areas in the ground, adding to its volume. Runoff is when the force of gravity naturally pulls water downhill from higher to lower altitudes. They usually start as small creeks in the mountains, and then gradually merge with larger streams as they flow downward, eventually forming large rivers which empty out into the ocean.
The Hydrologic Cycle
Water Conflicts Around the World
• Violence erupts in 1992 over a dispute between Uzbekistan and Turkmenistan regarding the contested Tyuyamuyun reservoir. It continues to be a highly disputed water source in the region today (Factbook).
• In 2010, dozens of people were killed in Pakistan’s tribal region due to a water dispute which lasted over two weeks. According to a senior government official in the Kurram district which borders Afghanistan, the Mangal tribe stopped water irrigation on lands belonging to the Tori tribe. In total, 116 people were killed and 165 were injured (CNN, 2010).
• Four farmers were hacked to death in northeast Tanzania over the disputed Pangani River Basin in 2013 (Factbook).
• In 2016, 18 people were killed and 200 more were injured when the Indian Army clashed with economic protestors surrounding the highly-contested Munak canal, a water source that supplies New Dehli with three-fifths of its freshwater supply (Factbook).
• The drought-stricken conditions of major parts of Somalia often force herders to sell more of their livestock than they can afford to make a living with. This lack of economic stability fuels recruitment appeal with militant groups such as Al Shabaab, which provide cash incentives and other benefits to their soldiers. Other illicit activities such as pirating and livestock raiding are seen as reasonable alternatives to the declining stability of animal herding (Factbook).
Change is Needed
70% of the earth is covered in water, yet only 3% of it is fresh. Of that 3%, 2.6 of it is locked away in glaciers and polar ice caps. That leaves us with 0.4% of the earth’s water, in the form of rivers and underground aquifers, to try to utilize for our consumption and societal development. It is no wonder that in developing regions where clean water sources cross national boundaries, it often finds itself in conflict among those trying to secure a means to a healthy living.
With humans being made up of 60% water, our natural instinct might be to fight for it. But by collaborating to find ways to access the untapped groundwater beneath us, helping to conserve clean water use, and preventing further pollution of our clean water sources, it is possible for all peoples to have access to clean water.
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Bureau of Reclamation. (2017, April 10). Water Facts - Worldwide Water. Retrieved from https://www.usbr.gov/mp/arwec/water-facts-ww-water-sup.html
CNN. (2010, September). Water conflict in Pakistan's tribal region leaves dozens dead. Retrieved from http://www.cnn.com/2010/WORLD/meast/09/19/pakistan.water.dispute/
Factbook. (n.d.). Mapping environmental conflicts and cooperation. Retrieved from https://factbook.ecc-platform.org/
Groundwater Association. (2012, September). Information on Earth's water - National Groundwater Association. Retrieved from http://www.ngwa.org/Fundamentals/teachers/Pages/information-on-earth-water.aspx
National Geographic. (2017, January 27). Competing for Clean Water Has Led to a Crisis. Retrieved from https://www.nationalgeographic.com/environment/freshwater/freshwater-crisis/
Ocean Service. (n.d.). Can humans drink seawater? Retrieved from https://oceanservice.noaa.gov/facts/drinksw.html
Perlman, H. (2016, December 2). Where is Earth's water? USGS Water-Science School. Retrieved from https://water.usgs.gov/edu/earthwherewater.html
Perlman, H. (2016, December 2). How Much Water is on and in the Earth. Retrieved from https://water.usgs.gov/edu/gallery/global-water-volume.html
Postel, S. (2010, June). How Much Longer Until We Run Out of Enough Drinkable Water? Retrieved from https://www.alternet.org/story/147334/how_much_longer_until_we_run_out_of_enough_drinkable_water
Shahan, Z. (2017, October 24). How Much Clean Water is Available for Human Use? Retrieved from https://insteading.com/blog/clean-water-human/
United Nations. (2007). Water scarcity. Retrieved from http://www.un.org/waterforlifedecade/scarcity.shtml
World Atlas. (2018, February 14). What Percentage of the Earth's Water Is Drinkable? Retrieved from https://www.worldatlas.com/articles/what-percentage-of-the-earth-s-water-is-drinkable.html
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