South America's second-largest river retreats to lowest levels in 77 years

DOWN RIVER

Years of drought have dropped the Parana river to levels not seen in 77 years, disrupting energy, commerce and ecology along its nearly 5,000 km route to the sea

The Parana, South America’s second-largest river behind only the Amazon, has retreated this year to its lowest level since its record low in 1944, hit by cyclical droughts and dwindling rainfall upriver in Brazil. Climate change threatens to worsen those trends.

The decline of the waterway, which knits together a huge swathe of the continent, has hurt river communities, snarled grains transport in Argentina and Paraguay and contributed to a rise in wildfires, damaging wetland ecosystems.

“This is historic. I’ve never seen it so low in my lifetime,” said Gustavo Alcides Diaz, an Argentine fisherman and hunter from a river island community in Charigue, some 300 kilometers (186 miles) upriver from the Argentine capital Buenos Aires, lamenting the impact on fish stocks and fresh water.

“When everything dries up, the water rots.”

The Parana’s crisis is among the multitude of woes arising worldwide associated with global climate change linked to the burning of fossil fuels and the resulting greenhouse gas emissions. World leaders are set to meet at the United Nations Climate Change Conference, or COP26, starting on Oct. 31 in Glasgow, Scotland amid warnings from a U.N. panel about climate-related disruptions for decades, if not centuries, to come.

The Parana, meaning “like the sea” in Tupi-Guarani language, is born from the convergence of two great rivers in Brazil, the Rio Grande and the Paranaiba. It fills with water in southern Brazil before its long journey to the River Plate estuary in Buenos Aires. But these areas upriver have seen rainfall levels decline steadily over the last decade.

An analysis of thousands of precipitation data points over three decades showed that combined average rainfall in Goias, Minas Gerais, Sao Paulo and Mato Grosso do Sul - key states where the river fills - was at its lowest level since at least the early 1990s.

In the four states, which surround the top of the Parana, combined daily precipitation, averaged over 12-months, fell from a high of 160 millimeters three decades ago to just half that amount now, with the biggest drop-off in the last ten years.

“This past year will stand out compared to anything else from the past any way you measure it,” said Isaac Hankes, Refinitiv senior weather research analyst.

Agronomist and climate expert Eduardo Sierra, “Many dams had been built in the La Plata basin, wetlands have been removed to make waterways, to generate electricity, and they haven’t taken care that this all impacts the river’s ability to regulate itself.”

The Itaipu Hydroelectric dam is one the world's largest operational electricity generators and is facing an energy crunch as low river levels hit electricity production. Cesar Olmedo/Reuters

Weather experts have said the Parana’s decline could last at least into next year. October rains have given some respite but the longer-term forecast is not encouraging, with only average or below average water levels predicted into 2022.

“We need a period of rapid recharge of the river,” said Lucas Chamorro, head of hydrology at the Yacyreta hydroelectric plant, adding that human activity such as cattle ranching, burning lands and soybean farming is impacting the wider Pantanal wetland area as well as the Amazon.

The two-year average depth of the river at the Argentine inland grains port Rosario is the second lowest on record behind the historic drought of 1944-45. The river level there, measured with yard sticks giving an index of the depth, hit -0.33 meters in August.

It has recovered slightly since then, but is set to recede again at least until December before the arrival of the rainy season. The official National Water Institute’s (INA) intermediate projection is for -0.39 meters by mid-December.

The low water mark is at 2.4 meters at Rosario.

“In more than 40 years that I have been in this job, I have never seen it reach 33 centimeters below zero. I had never seen that,” said Guillermo Wade, manager of Argentina’s Chamber of Port and Maritime Activities.

A ship is loaded with grain in Rosario, Argentina on the Parana River. Ships have had to reduce their normal cargo weights by thousands of tonnes to avoid hitting the bottom of the river due to low water levels. Agustin Marcarian/Reuters

Wade explained that the lower level meant that ships were cutting grains cargoes currently by around 20% versus normal levels and would get worse if river levels dropped as expected.

Cargo ships have to cut between 1,600-2,175 tonnes of grain to save a foot of draft - the distance from the waterline to the boat’s bottom - Wade said. Boats were currently leaving Rosario with a draft of 30-feet versus the normal 34-feet.

The difference in water levels in the Parana were captured by satellite imagery between July 2019 and July 2020, and shows a dramatic decline. The combination of shortwave infrared and visible light helps to distinguish between land and water. Lower water levels have had a dramatic impact in recent years and In 2020, dryness led to a huge spike in wildfires that could be seen for miles around burning the carbon-rich soil.

In 2020, dryness led to a huge spike in wildfires throughout the Parana Delta. Agustin Marcarian/Reuters

The arid weather driving the Parana’s decline is in-part driven by a long-term natural cycle of weather patterns, exacerbated by global warming, the burning of wetlands and the construction of dams upriver, said agronomist and climate expert Eduardo Sierra.

“It is a twice in a century event,” said Sierra, who is an advisor to the Buenos Aires grains exchange, adding that a long-term weather cycle had converged with a double hit from the La Niña phenomenon which lowers precipitation.

“Then we have a human cause which is global warming, which is accentuating all the variations in the climate.”

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