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http://www.economist.com/news/asia/21697886-bad-weather-and-bad-policy-aggravate-awful-drought-salt-earth

SHADED by a tree, an elderly farmer gestures hopefully at the scrawny green shoots poking from his small plot in Vietnam’s Mekong river delta. The sugar crop he planted earlier in the year has already failed once, poisoned by dry and salty soil. Fresh growth from the cut-back plants now offers a second chance, but without rain it may go the same way. The farmer is lucky to have a pond full of fish, which he shares with his neighbours. But he says his family will have to find other work this year to make ends meet.

Tales such as this are common on the tiny island of Cu Lao Dung in the delta’s southern reaches (see map), five minutes from the mainland by scooter-crammed ferry. During the annual dry season surrounding waters always turn salty, as brine from the sea pushes up the delta’s channels. But this is an exceptionally dry year, with river levels at 90-year lows. The water has become unusually concentrated with salt, which is spreading more extensively. The salt is creeping through the farmland like damp up a wall.

Drought is plaguing much of mainland South-East Asia, including Myanmar, Laos and Cambodia. Thailand’s shortages are the worst for two decades (though urbanites still splashed around during Songkran, its annual water festival in mid-April). Vietnam has been hit as hard as any. The Mekong basin is home to one-fifth of the population. It produces about half of the country’s rice. The government says the amount available for export in the three months to June will be 11% less than originally forecast. Drought in the country’s Central Highlands has affected a third of coffee plantations there and now endangers the region’s supply of drinking water. These woes are weighing on the economy. Growth in the first quarter slowed by half a percent year-on-year to 5.5%.

The immediate cause is El Niño, a recurring weather phenomenon which causes downpours in the Americas but heat and drought in much of Asia. Scientists believe that El Niño’s effects are growing stronger as global temperatures rise. Last year it was blamed for exacerbating annual fires on farmland in Indonesia, which smothered much of the region in a noxious haze.

People living near the Mekong say there is another problem: hydroelectric dams built in China near the head of the river that are holding up its flow. Since March China has loosened some of the dam gates, ostensibly as a favour to its neighbours. But locals say the effect on water levels has been measly. The episode has only heightened fears that China (with which Vietnam has an enormous trade deficit and an intense territorial dispute) can use water flow to hold the country to ransom.

The dams are certainly stripping the Mekong of essential sediment. But many of Vietnam’s water woes are self-inflicted. In the delta, for example, a booming population has built more than 1m wells since the 1960s. These have made saline contamination worse, and are also causing subsidence. In 2014 an American study found that the delta, which mostly lies less than two metres above sea level, could be nearly a metre lower by 2050.

A related problem is the ruling Communist Party’s obsession with maximising rice production. Straining to hit absurd targets—inspired by memories of post-war food shortages—the government has pushed delta farmers to produce three rice crops per year.

This policy has caused the poisoning of paddies with pesticides and has discouraged farming of more profitable, less thirsty crops. It has also prompted the building of a massive network of dykes, canals and sluice gates, which spread pollution from fertilisers and pesticides and restrict the flow of sediment. Koos Neefjes, a climate-change expert in Hanoi, the capital, reckons all this infrastructure has done more to harm the delta than China’s dams.

Fixing this will mean taking on powerful state-owned rice traders and exporters, who benefit from intensive production. Nguyen Xuan Phuc, who took over as prime minister in early April, is said to be a competent technocrat. But he may not have the political strength to carry out difficult reforms. Some simple remedies would be useful, however. Giving farmers earlier warning of drought would help avoid pointless ploughing and planting, says Nguyen Huu Thien, an environmentalist. He says the authorities may soon be caught out by La Niña, a sodden period which often follows El Niño’s parching.

At a roadside café in Cu Lao Dung, young sugar farmers moan about their lot. Life would be easier if they could work at tea stalls, they say, with cooling banana-leaf roofs. Or perhaps on coconut farms, where trees need watering only every few days. Each year supplies of safe drinking water get a little tighter, says one. He worries that in ten years there will be no fresh water at all.