Water security is critical for the survival of communities and nations. It represents a major challenge, especially in parts of the world facing increasing water scarcity, such as arid and semi-arid regions or densely populated areas. Water security also directly affects food security, as most of the world’s water is used in agriculture for food production. The water/food/energy security nexus was recently identified as one of three
important risk clusters that may threaten economic growth and political and social stability in the future.
Water security hinges on balancing water supply with water demand, both of which are subject to change
over time. Since there are limits to augmenting the water supply, demand management through economic,
administrative, and technical measures is essential for achieving water security. Water management should aim
at the sustainable use of renewable water resources and the planned depletion of nonrenewable water resources within well-defined time frames.
Where possible, this should be supplemented by the use of unconventional water sources such as treated waste water and desalination. Serious threats to water security include population growth (which intensifies water scarcity), pollution (which renders some water resources unusable), and climate change
(which may alter the amount and time distribution of precipitation in some parts of the world and increase the
water requirements for food production due to higher temperatures).
The Water-Food-Energy Nexus
Ancient water-food-energy nexus.../OliBac © Flickr
Freshwater has been the constant and essential companion of homo sapiens throughout our history. In modern times, we have risked even greater dependence by adopting means of wealth creation characterised by gargantuan thirst.
Industry accounts for 22% of freshwater use, the largest share of which is consumed by the energy sector. Water is used in great quantities for cooling in thermal and nuclear power generation, as well as in the extraction of coal and oil. Protests against new fossil fuel technologies such as gas fracking and oil sands are inspired in part by fears of wastage and pollution of water.
Although the relative needs of agriculture vary widely – from just 3% in the UK to 83% in India – this sector currently accounts for the largest global share of freshwater at about 70%. The dynamic expansion of food production in Asia over the last 40 years – often described as the “green revolution” - has been achieved through modern farming methods which require high input of water.
...and modern: Eggborough cooling towers, UK/fatedsnowfox © Flickr
Households consume the remaining small share of 8% but demand the highest quality standards for safe drinking. Despite considerable humanitarian endeavour over the last three decades, almost 900 million people continue to lack access to safe water.
The close dependence of industry and agriculture on freshwater ensures that any scarcity is likely to impose upward pressure on food and energy prices. This is the scenario that strikes fear into political leaders struggling to restore economic health. Prudent stewardship of the water cycle is nevertheless a virtue honoured more in the breach than in the observance.
News headlines provide constant reminders of this failing. The drought in the Horn of Africa demands emergency food aid for over 12 million people and has led to the first UN declaration of famine in over 20 years.
Water Cycle
The water cycle
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.
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, water is a renewable source of energy and life. However, unlike other renewable resources such as sun, wind and tide, freshwater is not plentiful. It is a finite resource.
The current global per capita availability of freshwater from rivers, lakes, aquifers and rainfall averages a potentially healthy 6,000 cubic metres per annum. Availability of 1,000 cubic metres per annum within a country or region is regarded as sufficient to meet the needs of households, agriculture, industry - and to sustain local ecosystems.
A state of water scarcity exists below that threshold. Below 1,700 cubic metres, short term periods of "water stress" may be experienced. Average annual consumption in the US is just under 3,000 cubic metres; in Syria and Jordan, availability is falling towards 500 cubic metres; in Yemen the figure is now below 200.
Freshwater is very unevenly distributed and scarcity is normally assessed within regions or individual river basins. “Water security”, the inverse of scarcity, implies consistent and affordable access to unpolluted freshwater for all categories of user.
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