Water scarcity is a favourite topic for the headlines of doom, in company with overpopulation, climate chaos and nuclear war. The threat of a destabilising water crisis invariably wins attention in the annual Global Risks Reports published by the World Economic Forum.
In reality, our water woes reflect international political dysfunction as much as scarcity. If governments were more willing to collaborate in safeguarding the water cycle on which we all depend, and to share its beneficence fairly, they would discover that there is more than sufficient water to meet our needs.
The Covid-19 pandemic has exposed the shameful inequality of global access to water. Frequent handwashing was universally recommended as the first line of defence against the virus. Yet only 25% of sub-Saharan Africa’s population of one billion people have access to safe handwashing facilities in their homes, according to the most recent UN data.
The Water Cycle
Our planet is a miserly distributor of freshwater. Most water is rendered useless to humanity by dilution with salt in the ocean. Only 3% is available as freshwater, of which two thirds is locked up in ice and snow.
The water cycle is driven by evaporation from land and sea, condensing into clouds which have the potential for precipitation as rain. Again, nature is unkind in depositing almost 80% of rain over the sea.
from International Geosphere-Biosphere Programme
Of the rain that falls over land, only 40% finds its way as “blue water” into aquifers, lakes and rivers which are accessible supply sources. The “green water” balance is absorbed by the land, of great potential value to agriculture but notoriously fickle for that purpose in volume, timing, intensity and location.
Thanks to this natural cycle, the movement and action of water is a renewable source of energy and life. However, unlike other renewable resources such as sun, wind and tide, freshwater availability is not plentiful. And the amount of water on the planet is fixed, on the human timescale.
The advent of human civilization has superimposed its own version of the water cycle on nature. We extract water for our various contemporary uses and discharge whatever remains back into the natural cycle, rarely in its original condition.
For example. agro-chemical pollution through run-off of nitrates and phosphates causes eutrophication, the excessive growth of algae whose eventual decomposition removes oxygen from the water, killing the aquatic ecosystem.
Another profound interference with the natural water cycle is the construction of a major dam, or other deliberate disturbance of the natural course of a river. Examples include India’s controversial river-linking project to transfer freshwater from the north to south of the country. Further north, the fatal 2021 collapse of a dam on the Rishiganga river in the Himalayan district of Chamoli highlighted the delicate interaction of glaciers, lakes and rivers in the water cycle.
Quite apart from inevitable human displacement, altering the natural flow of a river can destroy sensitive delta ecosystems on which freshwater fishing and agriculture depend. The vast 1,285-megawatt Xayaburi Dam recently completed in Laos provokes concerns for agricultural output in Vietnam and fish catch in Cambodia, amongst many other cross-border impacts.
Similar unnatural degradation is found in aquifers, underground reserves charged by the passage of water through soil and rocks. If extraction exceeds the natural rate of recharge, the level of an aquifer will fall, eventually drying up altogether.
As aquifers lose volume, their water becomes more vulnerable to contamination by minerals from surrounding rocks. Large areas of South Asia are unable to utilise groundwater due to dangerous levels of arsenic or fluoride. In coastal regions, depleted aquifers increase the risk of saline intrusion.
Pioneering satellite-based measurement has revealed that 21 out of 37 of the world’s major aquifers are being exploited unsustainably. Many cities are located above degraded aquifers and are known to be sinking. This factor was one cause of the serious flooding in Bangkok towards the end of 2011.
“Freshwater use” is listed as one of nine planetary boundaries in the influential studies published by the Stockholm Resilience Centre. These endorse the assertions of hydrologists that, at global level, there is enough water to meet human needs. At regional level the picture is very different, with damage to some ecosystems approaching “tipping points” which can trigger abrupt change.
Lake Chad is one example. Misguided governance of the natural cycle of the Lake led to its area of water collapsing by 90% in the space of 30 years, affecting 20 million people.
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more Water Scarcity briefings (updated May 2021)
Causes of Water Scarcity
Climate Change and Water Scarcity
Solutions to Water Scarcity
Sustainable Development Goal for Water
Water Wars
Source material and useful links