Water, water, everywhere… but where?

One can live without food for almost a month but survive no longer than a week without water. Yet, although almost half of the world’s population live in water-scarce countries, there actually is enough of this precious liquid for everyone.

The UN recommends that a person needs minimum of 50 litres of water a day for drinking, washing, cooking and sanitation, which over a billion people do not have access to. According to UNESCO, the world’s population are appropriating 54% of all the accessible freshwater contained in rivers, lakes and underground aquifers. If per capita consumption of water resources continues to rise at its current rate, humankind could be using over 90% of all available freshwater within 25 years, leaving just 10% for all other living beings.

water dropFreshwater lakes and swamps account for a mere 0.29% of the Earth’s freshwater. 20% of all freshwater is in one lake, Lake Baikal in Asia. Another 20% is stored in the Great Lakes, Huron, Michigan, and Superior. Rivers hold only about 0.006% of total freshwater reserves. Mankind essentially uses only a drop in the bucket of the total available water supply.

So where is all the water?

Antarctica, which is thought to hold about 75% of the world’s fresh water (and 90% of the world’s ice). In fact, almost 10 percent of the world’s land mass is currently covered with glaciers, mostly in Antarctica and Greenland. But it will take more than a Zippo to melt it for daily use.

Towing icebergs for fresh water is an old but often debated concept. Given that 9/10ths of an iceberg is underwater, it acts the same as a type of big barge. In the 1930s, Barnes Wallis suggested using tugs to tow large fabric bags – waterpods – to transport water at a fraction of the cost of building water tankers. (After all, today oil is transported by towing it in huge bags.) In the 1970s, Saudi Arabia considered towing icebergs and Thames Water of London again suggested it in 2006. But, until it happens, where’s the rest of the water?

Underground water

For the United States, one crucial source is the huge underground reservoir which stretches from Texas to South Dakota, the 800-mile Ogallala aquifer. It provides an estimated third of all US irrigation water. In fact, 95% of the United States’ fresh water is underground.

In Libya, the Great Man Made River Project, as it’s called, is pumping some 6 million cubic metres of water a day from aquifers in the desert, providing irrigation for 150 000 hectares of land. Many countries have turned to aquifers to quench peoples’ thirst.

Aquifers form over thousands of years, but many had been cut off from their original natural sources and are being steadily depleted. In some areas, like Mexico City, aquifer levels dropped by 90 – 150cm (3 – 5 ft) a year, essentially sinking whole areas.

The big, big blue lagoon

No, not the sea. A reservoir of water three times the volume of all the oceans lies deep beneath the Earth’s surface, according to New Scientist. It won’t be easy getting it out – it’s 700 km (435 miles) underground. But is might just be the reservoir of the future.

Water factoids

World Water Day is celebrated on March, 22nd every year.
One kilogram (2.5 pounds) of grain-fed beef needs at least 15 cubic metres of water, while a kilogram of cereals needs only up to three cubic metres.
Between 6 and 9 million people die annually of thirst.
70% of the water used worldwide is used for agriculture.
Australia is the continent with the least rainfall, apart from Antarctica.

Water withdrawals for industry:
World: 22% of total water use
High-income countries: 59% of total water use
Low-income countries: 8% of total water use

Water science for schools

02/07/2010. Category: nature. Tags: .

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