Water Allocation
From Water Wiki
Water is all around us. It is in our oceans, lakes, rivers, streams, underground and in the atmosphere. The same amount of water that exists today has existed throughout history, and will never change. Water covers nearly 70% of the Earth's surface. However, only 3% of the water on Earth is freshwater, and about two-thirds of this is frozen in glaciers and polar ice caps. The rest of the freshwater is mostly groundwater or surface water, flowing through streams and rivers. The amount of water that is accessible in a certain location is limited, and may change over time.
All living creatures need water to sustain life. At the same time, water is needed in agriculture to grow crops. Businesses and industry also require water to run their processes and serve the public. Water must also be left to flow naturally in the environment to maintain the habitats of living creatures, and for navigation purposes. Some or all of these usersare competing for the same amount of water that is accessible in any given location. Economists call this a competition for a scarce resource. Because the amount of water in a certain location is limited, it must be allocated between the different users. This takes on an economic, political and social perspective. Even in locations where water is abundant, political decisions about who has the right to withdraw or use water must be laid out to prevent potential conflict, and to protect downstream use. The water allocation problem changes as the size of the region in question increases, from a local area, to a watershed or a river basin, to a state, to a region, as the number of downstream users increases.
The global state of freshwater resources has been assessed by a large group of scientists. Among their conclusions:
more than 1 billion people live under hydrologic conditions that generate no appreciable supply of renewable fresh water. An additional 4 billion (65% of world population) is served by only 50% of total annual renewable runoff that is positioned in dry to only moderately wet conditions, with concomitant pressure on that resource base. Only about 15% live with relative water abundance.
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From 5% to possibly 25% of global freshwater use exceeds long-term accessible supply. Overuse implies delivery of freshwater services
through engineered water transfers or nonrenewable groundwater supplies that are currently being depleted. Much of this water is used for irrigation with irretrievable losses in water-scarce regions. All continents record overuse. In the relatively dry Middle East and North Africa, non-sustainable use is exacerbated, with current rates of freshwater use equivalent to 115% of total renewable runoff.
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Water scarcity is a globally significant and accelerating condition for 1–2 billion people worldwide, leading to problems with food production, human health, and economic development.[1]
This systematic assessment of global water problems accords with journalistic accounts:
Public fountains are dry in Barcelona, Spain, a city so parched there’s a €9,000 ($13,000) fine if you’re caught watering your flowers. A tanker ship docked there this month carrying 5 million gallons of precious fresh water – and officials are scrambling to line up more such shipments to slake public thirst. Barcelona is not alone. Cyprus will ferry water from Greece this summer. Australian cities are buying water from that nation’s farmers and building desalination plants. Thirsty China plans to divert Himalayan water. And 18 million southern Californians are bracing for their first water-rationing in years. Water, Dow Chemical Chairman Andrew Liveris told the World Economic Forum in February, “is the oil of this century.” Developed nations have taken cheap, abundant fresh water largely for granted. Now global population growth, pollution, and climate change are shaping a new view of water as “blue gold.” [2]
