Thursday, August 14, 2008

Water crisis plumbs new depths

Aug 14, 2008

By Michael Richardson, For The Straits Times

The Chinese government has made a huge effort to improve air quality and beautify Beijing for the Olympics. But it cannot apply a short-term fix to another problem that visitors to the Games will not see - the steady depletion of underground water supplies in northern China, where the capital is located.

A study published in June by Probe International, a Canadian environmental research group, found that over two-thirds of Beijing's water is being pumped from beneath the ground to compensate for dwindling surface water from reservoirs and rivers that once supplied the city.

It warned that the underground saturation level, known as the water table, is dropping because water is being pumped out faster than it can be replenished. Plans for long-distance water diversion will aggravate the impending crisis unless water is used much more efficiently.

Two years ago, the Bureau of Hydrology and Water Resources in Hebei province, a major source of water for both Beijing and Tianjin, issued a similarly stark warning.

It said that only severe overexploitation of underground water was making up for the shortfall between water from rain and rivers, and rapidly rising demand from urban residents, industries and agriculture.

Water shortage is not just a local issue affecting Beijing and its surrounding areas.

Mr Tushaar Shah is an Indian hydrologist with the International Water Management Institute, part of a worldwide network of farm research centres funded by the World Bank.

He estimates that India, China and Pakistan together pump 400 cu km of water out of the ground each year, about twice as much as is recharged by rain. These three countries, with a combined population of nearly 2.6 billion, account for more than half the world's use of underground water for agriculture.

However, they are not alone.

The drilling of millions of deep wells and the extensive use of farm pumps to bring water to the surface in the past 15 years in many parts of Asia have helped raise food production - but at a long-term cost of diminished underground water supplies.

Similar overexploitation of aquifers has taken place in the Middle East, South America, the United States and Australia.

Until a couple of years ago, the world was growing twice as much food as it did a generation earlier. However, it was using three times as much water to grow this food. Two-thirds of all the water irrigates crops. For example, it takes about 1,000 litres of water to grow 1kg of wheat and between 2,000 and 5,000 litres of water to produce 1kg of rice.

By some calculations, as much as 10 per cent of the world's food is being grown using underground water that is not being replaced by rain. As global warming intensifies, the implications for water security and food production are alarming.

China is the world's biggest grain producer. More than half of its wheat and a third of its corn are grown on the northern plain. However, the water table under the plain is falling fast.

Overpumping has largely depleted shallow aquifers, prompting well drillers to tap deep aquifers which scientists say are so far below the surface that they are not replenished by rainwater seepage.

Several years ago, the Geological Environmental Monitoring Unit in Beijing reported that under Hebei province, the average level of deep aquifers was dropping by nearly 3m a year.

When farmers in this semi-arid region are unable to continue drawing water from underground aquifers to irrigate their crops, production will decline.

Officials have said water shortages will soon make China dependent on grain imports. The World Bank has warned that China faces 'catastrophic consequences for future generations' unless water use and supply are brought back into balance.

In India, the situation is worse because farming is even more critical to human survival and economic growth than in China. Nearly 70 per cent of its people rely on agriculture, which accounts for about a quarter of the country's gross domestic product. Underground water, which now supplies 80 per cent of farm water, has become vital for sustaining crops.

As the water table in many parts of India falls, water shortages will become more widespread and the cost of pumping the remaining underground water to the surface will rise.

In a country where poverty is extensive, one-third of the land is semi-arid and rainfall is seasonal and erratic, this will make it difficult for many farmers to grow enough food unless they find ways to conserve rainwater and use it sparingly.

The writer is an energy and security specialist at the Institute of Southeast Asian Studies, Singapore.

[Water or water tech will be critical in the future. A solar-powered dragonfly could be a self-sustaining water source.]

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