An ever-thirstier region

South Asia’s water

Nov 19th 2011

Extract from the article ( Unquenchable thirst :: A growing rivalry between India, Pakistan and China over the region’s great rivers may be threatening South Asia’s peace ) from | The Economist

An ever-thirstier region

The scarcity of water in South Asia will become harder to manage as demand rises. South Asia’s population of 1.5 billion is growing by 1.7% a year, says the World Bank, which means an extra 25m or so mouths to water and feed: imagine dropping North Korea’s entire population on the region each year. Greater wealth in South Asia brings with it a soaring demand for food, especially for water-intensive meat and other protein. Industry and energy-producers also use water, though unlike farms they return it, eventually, to the rivers.

Worse, overall supply will not only fail to keep up with rising demand but is likely to fall (unless a cheap way is found to turn sea water fresh). The Himalayan glaciers are melting. A Dutch study last year of the western Himalayas reckoned that shrunken glaciers will cut the flow of the Indus by some 8% by mid-century. Flows may also get less regular, especially if glacial dams form, withholding water, and then collapse, causing floods.

Others give even scarier predictions. Sundeep Waslekar, who heads a Mumbai think-tank, the Strategic Foresight Group, which has picked water as a long-term threat to Asian stability, sees a “mega-arc of hydro insecurity” emerging from western China along the Himalayas to the Middle East and farther west. The strain of bigger populations, diminishing water tables and a changing climate could all conspire to produce a storm of troubles. South Asia is especially vulnerable: Mr Waslekar sees a cut of 20% in total available fresh water over the next two decades.

The greatest threat of all would be from any change to the monsoon, which delivers most of the region’s fresh water each summer. Here, again, worries arise. Indian meteorologists who have studied rainfall data from 1901 to 2004 have noted signs in recent decades of more dry spells within the peak monsoon months. If these lead to weaker, or less predictable, monsoons in future (though this year’s was about normal) the consequences for farmers could be dire.

In any case, the cost of running short of water is already becoming clearer. The Lancet, a British medical journal, reported last year that up to 77m Bangladeshis had been poisoned by arsenic—the largest mass-poisoning in history. It was the result of villagers pumping up groundwater from ever deeper aquifers. The same poison is now entering crops and more of the food chain.

Filthy water and bad sanitation spread diseases, such as diarrhoea and cholera, which kill hundreds of thousands of Indian children every year, says Unicef, the UN’s children’s agency. Several South Asian rivers, suffering from weaker flows, have become a sludge of human and animal waste, dangerous to drink and wash in and unsafe even for watering crops.

All over the region water tables are dropping as bore holes drive deeper. In the dry season even some of the larger rivers slow to a trickle. Knut Oberhagemann, a water expert in Dhaka, Bangladesh, says that the flow of the mighty Ganges where it enters Bangladesh is at times a pitiful few hundred cubic metres a second, so low that “you can walk across the river”. When the same river, at this point called the Padma, reaches the coast, it is often so feeble that the sea intrudes, poisoning the land with salt.

The same problem curses the delta of the Indus in Pakistan. There a semi-desert was turned into some of the most fertile land on earth by British-built irrigation canals. But as the sea encroaches on low, flat land, rivers at times are flowing backwards, laments a local environmental activist. Take away the fresh water—around 60% of which is now lost to seepage and evaporation because of the bad management of those canals—and the desert will eventually come back.