SOUTH AMERICA'S SERIOUS : WATER ESSAY

A vanishing lifeline. The second-largest river in South America is drying up in a prolonged drought. The future unveils - it is now sure, of a vanishing economic lifeline in South America.

The fisherman woke up early on a recent morning, banged on the fuel containers on his small boat to make sure he had enough for the day and set out on the Parana river, fishing net in hand.

The outing was a waste of time. The river, an economic lifeline in South America, has shrunk significantly in a severe drought, and the effects are damaging lives and livelihoods along its banks and well beyond.

''I didn't catch a single fish,'' said the 68-year-old fisherman, Juan Carlos Garate, pointing to patches of grass sprouting where there used to be water. '' Everything is dry.''

The Paran's reduced flow, at its lowest level since the 1940s, has upended delicate ecosystems in the vast area that straddles Brazil, Argentina and Paraguay, and it has left scores of communities scrambling for fresh water.

In a region that depends heavily on rivers to generate power and to transport the agricultural commodities that are a pillar of national economies, the retreat of the continent's second-largest river has also hurt business, increasing the costs of energy production and shipping.

Experts say deforestation in the Amazon and rain patterns altered by a warming planet are helping fuel the drought. Much of the humidity that turns into the rain that feeds the tributaries of the Parana originates in the Amazon rainforests, where trees release water vapor in a process that scientists call ''flying rivers.''

Rampant deforestation has disrupted this flow, weakening the streams that feed the large rivers in the basin and transforming the landscape.

''This is much more than a water problem,'' said Lucas Micheloud, a Rosario-based member of the Argentine Association of Environmental lawyers. Frequent fires, he said, are turning resource-rich rain forests into savannahs.

Although water level varies in different locations, on average the Parana is now 10.5 feet below its normal flow, according to Juan Borus, an expert at Argentina's government-run National Water Institute who has been studying the river for more than three decades.

The situation is likely to worsen, at least through the beginning of November, which is ordinarily the beginning of the rainy season in the region.

But the drought could last longer. Experts say climate change has made it harder to make accurate predictions.

Extreme events like the drought affecting much of South America are becoming '' more frequent and more intense,'' said Lincoln Alves, a researcher at Brazil's National Institute of Space Research who worked on the latest report by the United Nations Intergovernmental Panel on Climate Change.

Argentina declared a six-month emergency for the Parana River-region in late July, calling the crisis the worst in 77 years. Government officials say they were caught off guard.

'' We never thought we were going to reach the levels we are now,'' said Gabriel Fuks, who leads a team that coordinates the government's response to crises across the country. '' We were not prepared for this emergency.''

The biggest priority for the government is assisting the approximately 60 cities along the river that are running dangerously low on water, Mr. Fuks said.

In Parana, a riverside city some 125 miles from Rosario, a pump that supplies 15 percent of the water to the city of 250,000 stopped working recently because the water level was too low. City officials had to hastily devise a solution, said Leonardo Marsilli, the city's technical coordinator of water services.

All along the river, the low water levels are affecting daily life.

For Luciano Fabion Carrizo, a 15-year-old who lives in EI Espinillo, the same river island community as Mr. Garate, the fisherman, the sudden disappearance of water means he now has to walk two hours to get to school.

The commute used to take him 15 minutes by boat. It now all sums to a vanishing economic lifeline in South America.

The World Students Society thanks author Daniel Politi.