Drinking Water: Supply, Scarcity and Debt
- Total volume = 1.40 billion cubic kilometres
- Freshwater = 35 million cubic kilometres (less than 3% of all water)
- Usable freshwater approx. 200,000 cubic kilometres (less than 1% of freshwater)
Water supply and water scarcityIn many countries, only a very small proportion of available water is actually extracted for use. The total resource that is available to a country or a region is usually termed the ‘supply’. The amount that we extract for use is termed the ‘withdrawal’.Water scarcity
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DefinitionsAbsolute scarcity in these terms (500 m3/person/year) is less than 1.5 cubic meters of water per person per day. This seems like a lot, but usually we are only thinking about the domestic portion of water use rather than the per capita water availability necessary to maintain a functioning economy. Lack of water availability can inhibit industrial and economic development.For general human health requirements, volumes required are as follow:
- Normal Recommended 50 litres per person per day
- Minimum Recommended 30 litres per person per day (5 litres for cooking and drinking, 25 litres for hygiene)
- Emergency Sphere guidelines 15 litres per person per day
Water debtIf the amount of ground water withdrawn exceeds natural inflow, there is a water debt. In such cases, water should be considered a non-renewable resource that is being mined. As the world’s population and industrial production of goods increase, the use of water will also accelerate. The world per capita use of water in 1975 was about 700 m3/year giving a total human use of 3850 km3/year. In 2006 the world use of water was about 6000 km3/year, which is a significant fraction of the naturally available fresh water.Some water-stressed countries withdraw considerably more water than is renewed annually, leading to significant ‘water debt’. Kuwait is currently the world’s most water scarce nation and also the worst water debt country, with an annual renewable freshwater supply of approximately 0.02 km3/year and an annual freshwater withdrawal of around 0.54 km3/year (2700% of available renewable supply). Saudi Arabia extracts the greatest volume of water (14.62 km3/year) beyond its renewable supply (2.4 km3/year) and uses seven times more than it has available, but UAE (1.91 km3/year debt and consumption 10 times renewable supply) and Libya (4 km3/year and nearly 8 times supply) are also in severe water debt.However, even relatively water-rich countries can exceed their renewable supply; Uzbekistan has approximately 50.4 km3/year renewable available freshwater but withdraws around 58.05 km3/year (115% of available supply). Uzbekistan has witnessed the deterioration of the Aral Sea and its associated industry.In comparison:
- The USA withdraws only around 20% of available renewable supply
- The UK withdraws only around 10% of available renewable supply
- Canada withdraws only around 1.5% of available renewable supply
- Brazil withdraws only around 0.5% of available renewable supply
Global use of waterWater use has increased exponentially over the last century. This is due not only to an increase in population and direct water need, but also that population’s associated consumption of food and manufactured goods which both consume water.Of the freshwater that is withdrawn for human use, in the industrial world, the bulk of water is used for industry. In developing countries the bulk is used for agriculture and in places like Afghanistan and Nepal, this is 99%. In all countries, domestic use is a small, but important part.
Agricultural water useAs the human population increases, there is growing concern that there won’t be sufficient water to grow the food required. Meat takes much more water to produce than cereals, and a steady increase in meat consumption has increased worldwide water stress. (See figure at the top of this page.)
Industrial water useManufacturing processes of various types often require large amounts of water. In many cases, these processes were developed at a time when water scarcity was less realised than it now is. Water conservation measures taken by industry can be improved with the development of new equipment and processes that require less water.
Domestic water useAlthough domestic water use accounts for only a small fraction of the total, it is concentrated in urban areas where it may cause local problems. There are many ways in which domestic water use could be reduced at a relatively small cost. Water pricing policies will become increasingly important. Public perception of water is based on price and availability.Above table sourced from The Open University under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence http://www.open.edu/openlearn/science-maths-technology/science/physics-and-astronomy/physics/renewable-energy All water that is piped into homes in the UK is treated to very high EU quality standards. Much of the water we use domestically is consumed in non-potable uses such as gardening and flushing toilets. Only uses including drinking, cooking and for baths and showers need to be potable for health reasons. These uses account for only around one-third of total supply.
HydropoliticsMany countries are facing a global water shortage that is linked to their food supply. There are a number of other ways in which water supply may affect world politics. Conflict events may fall into these categories:Control of Water Resources: Water supplies or access to water at the root of tensionsMilitary Tool: Water resources, or water systems themselves used by a nation or state as a weapon during military actionPolitical Tool: Water resources, or water systems themselves, used by a nation, state or non-state actors for a political goalTerrorism: Water resources, or water systems, as targets or tools of violence or coercion by a non-state actorMilitary Target: Water resource systems as targets of military actions by nations or statesDevelopment Disputes: Water resources or systems as source of contention in the context of social and economic development
ConclusionSustainability debates often focus upon energy supplies, and the depletion of non-renewable resources. Access to clean water is as much of a problem if not more so, and although considered a ubiquitous renewable resources, this is only the case if treated with care and consumed and treated in a sustainable manner.Think about: how would your lifestyle change if you moved from a situation of water plenty to water scarcity? For those of you living with water scarcity already, how does it affect you on a daily basis?
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