MOSAIC: Sucking the continent dry
FARMERS in India, Pakistan, Vietnam, and northern China are setting themselves up for drought and famine in decades to come by pushing wells deep into the ground, emptying underground reserves at a rate faster than precipitation can replenish them.
A generation ago, Indian farmers in the state of Gujarat used bullocks to lift water from shallow wells in leather buckets. Now they haul it from 300 metres below ground using electric pumps. But that technological revolution is about to have devastating consequences.
So much water is being drawn from underground reserves that they, and the pumps they feed, are running dry, turning fields that have been productive for generations into desert.
The world’s leading water scientists warned that this little-heralded crisis is repeating itself across Asia, and could cause widespread famines in the decades to come.
India is at the epicentre of the pump revolution. Using technology adapted from the oil industry, smallholder farmers have drilled 21 million tube wells into the saturated strata beneath their fields.
Every year, farmers bring another million wells into service, most of them outside the control of the state irrigation authorities.
But this massive, unregulated expansion of pumps and wells is threatening to suck India dry. “Nobody knows where the tube wells are or who owns them. There is no way anyone can control what happens to them,” says Tushaar Shah, of the International Water Management Institute “When the balloon bursts, untold anarchy will be the lot of rural India,” he says.
Shah’s research suggests that the pumps, which transformed Indian farming, bring 200 cubic kilometres of water to the surface each year. But only a fraction of that is replaced by the monsoon rains. Farmers risk turning some land into desert within five to 10 years.
The same revolution is being replicated across Asia, with millions of tube wells pumping up precious underground water reserves in water-stressed countries like Pakistan and Vietnam. In northern China as well, the country’s “bread basket,” 30 cubic kilometres more water is being pumped to the surface each year by farmers than is replaced by the rain. Groundwater is used to produce 40 per cent of the country’s grain, and Chinese officials have warned that water shortages will soon make the country dependent on grain imports.
Vietnam has quadrupled its number of tube wells in the past decade to one million, and water tables are plunging in the Pakistani Punjab, which produces 90 per cent of the country’s food. — Samina Iqbal
Scanning for cure
HEADACHES can be primary or a disorder by itself or can be secondary to a mild systemic infection or a brain tumour, states a recent issue of the British Medical Journal. Brain tumours account for less than 0.1 per cent of the life time prevalence of headache. The question is whether a brain scan is justified in every case of headache.
Headaches with a changing pattern, onset of seizures or headache associated with systemic illness including fever, personality change, new onset headache in the early morning, or headache worsening with coughing, sneezing or straining should be viewed with concern.
Studies have given a low yield of positive findings in headache patients undergoing a brain scan. In a series of 1825 patients with migraine headache and a normal neurological examination, 21 tumours were detected.
These patients then need a scan. Bilateral, non-throbbing headache without nausea and with no sensitivity to light, sound or smell, would give a two per cent yield. The focus could be narrowed to featureless headache made worse by jarring, head movement, coughing, sneezing or straining. But it can be presumed that 98 in every scans will be normal.
Scans have been performed for reasons of re-assurance of patients, relatives and spouses. Most often the reassurance a patient seeks is a diagnosis or an explanation of the problem, which is not difficult in primary headache cases. If a scan is being ordered, it should be made clear to the patient why is it being done. Otherwise the patient will come back with a normal scan seeking an explanation. If this cannot be provided it will cause all the more anxiety.— Dr Fatema Jawad
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