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In Brazil’s agricultural heartland, rivers run dry as monoculture advances

Reginaldo Oliveira.

Reginaldo Oliveira, the manager in charge of Várzeas do Rio Ivinhema State Park in Brazil’s Mato Grosso do Sul state, stands by a stream inside the reserve. The park has been hit by a historic drought. Image by Ana Ionova for Mongabay.

  • The Paraná River Basin has suffered an unprecedented drought since 2021, affecting hydropower generation, river-borne food shipments, and freshwater supplies for 40 million people across Brazil, Argentina and Paraguay.
  • In Brazil, the prolonged drought has hit some of the region’s most important reserves, including Várzeas do Rio Ivinhema State Park, which houses one of the last slices of forest in Mato Grosso do Sul state and acts as a refuge for hundreds of species.
  • The drought has drained lagoons in the park, made parts of the reserve more prone to wildfires, and disrupted the breeding cycles of native birds.
  • Environmentalists blame the advance of large-scale monoculture in the region, which has cleared most of the forests and ushered in changes in rain patterns and droughts.

NAVIRAÍ, Brazil — The red earth is dusty and cracked, parched from weeks without rain. Fields planted with neat rows of corn stretch for miles across this part of Mato Grosso do Sul state, Brazil’s agricultural heartland. Tucked amid the cornstalks swaying in the wind, a sign points the way to the Várzeas do Rio Ivinhema, a sprawling reserve that’s home to one of the region’s last slices of forest.

The reserve spans 73,000 hectares (180,000 acres), straddling the municipalities of Naviraí, Taquarussu and Jateí. In the middle of the park, manager Reginaldo Oliveira stands knee-deep in a grassy patch of land and tugs at the vegetation. Squinting in the burning mid-morning sun, he looks out at a swamp drying up in the distance.

“This here is normally all flooded,” says Oliveira, who has managed the park for the past nine years. “In the last two years, we’ve been able to reach places we could never reach before. The lagoons have retreated, some by more than 10 meters [33 feet].”

Várzeas do Rio Ivinhema State Park, nestled in the Paraná River Basin, was established more than two decades ago, in a bid to preserve a maze of lagoons, marshlands and submerged forests that has mostly disappeared from this corner of Mato Grosso do Sul. The reserve is a refuge for wildlife, home to hundreds of species, some of which, like the jaguar (Panthera onca) and the Pantanal deer (Blastocerus dichotomus), are threatened with extinction in other regions.

But this lush oasis is now on the frontlines of a historic drought that has ravaged the region since 2021. The Paraná River, the second-longest river in South America and the source of freshwater for 40 million people in Brazil, Argentina and Paraguay, is at the center of the crisis: its water levels have plummeted to their lowest in nearly 80 years, pressuring water supplies, slashing hydropower generation, and disrupting food freight transported by ship.

A sign in the corn fields just outside Várzeas do Rio Ivinhema State Park.
Corn fields just outside Várzeas do Rio Ivinhema State Park in Mato Grosso do Sul state, Brazil. A prolonged drought has dealt a blow to the region, with many environmentalists blaming the advance of monoculture in the region. Image by Ana Ionova for Mongabay.
Reginaldo Oliveira.
Reginaldo Oliveira, the manager in charge of Várzeas do Rio Ivinhema State Park in Brazil’s Mato Grosso do Sul state, stands by a stream inside the reserve. The park has been hit by a historic drought. Image by Ana Ionova for Mongabay.

Inside the Várzeas do Rio Ivinhema park, the knock-on effects of the drought have been stark. The Ivinhema River, a tributary of the Paraná River that snakes some 100 kilometers (62 miles) through the reserve, has been largely depleted. Oliveira and his team have been forced to step back from monitoring some 60 km (37 mi) of the river for signs of illegal fishing, as dwindling water levels have made vast stretches impossible to navigate by boat.

“There are huge rocks jutting out, which we couldn’t see before,” he says later as our motorboat hurtles toward the point where the Ivinhema meets the Paraná, passing a family of capybaras sliding into the water one by one. “We risk crashing the boat if we go into these shallow areas.”

The lingering drought has also dealt a blow to wildlife and triggered wildfires in areas once shielded from the flames that plague the rest of the region, Oliveira says. “This type of forest never caught fire before, precisely because it was swamp underneath.”

But earlier this year, he says, fires engulfed the edge of this once-flooded forest, fueled by the parched vegetation. “It’s so dry that, when the winds blew, the flames flared up. And it spread out of control.”

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Advance of agriculture

The Várzeas do Rio Ivinhema park was established in part to offset the environmental damage caused by the Porto Primavera hydroelectric dam. The behemoth construction project flooded an area of 225,000 hectares (556,000 acres) and enlarged the Paraná riverbed to nine times its natural size. Since it began churning out electricity, the dam has curbed water flows, displaced wildlife and reshaped the landscape of the region.

“This human interference caused profound changes in the water cycles,” says Leonardo Palmas, who manages Mato Grosso do Sul’s conservation units as part of Imasul, the state’s environmental agency. “The region’s characteristics began to change — it became more prone to fires.”

The Paraná River Basin has been hit further by the rapid advance of large-scale agriculture, which environmentalists blame for ushering in a new era of erratic rain patterns and more intense droughts across the region.

“At first, the most important economic activity here was cattle [ranching], but now this land is all being converted to grain production,” Palmas says. “And we have seen the buffer region around the park converted from forest to plantations, with the marshlands drained to make that happen.”

Mato Grosso do Sul is home to Brazil’s largest stretch of Atlantic Forest, the country’s most threatened biome. Here, it covers some 6.3 million hectares (15.6 million acres). But the forest has been rapidly giving way to sprawling monoculture plantations over the past five decades. Today, Mato Grosso do Sul is Brazil’s third-largest producer of corn, as well as a major hub for soy, wheat and barley.

This land once belonged to the Guarani-Kaiowá Indigenous people, who depended on the dense forest to hunt and fish. But as colonizers swept through the region, they forced the Guarani-Kaiowá off their traditional lands and confined them to a handful of reserves created by the Brazilian state at the turn of the 20th century. Over the past two decades, the Guarani-Kaiowá have fought to reclaim slices of their ancestral lands, which are now mostly occupied by monoculture plantations.

The Ivinhema River.
The Ivinhema River, in Várzeas do Rio Ivinhema State Park in Brazil’s Mato Grosso do Sul state. The sprawling reserve houses one of the region’s last slices of forest, but has been hit by a historic drought. Image by Ana Ionova for Mongabay.
Two menbers of the Guarani-Kaiowá Indigenous community.
This land once belonged to the Guarani-Kaiowá Indigenous people, who depended on the dense forest to hunt and fish. But as colonizers swept through the region, they forced the Guarani-Kaiowá off their traditional lands and confined them to a handful of reserves created at the turn of the 20th century. Image by Ana Ionova for Mongabay.

The Indigenous village of Kurupi sits on a plot of red dirt, just a few meters away from a busy highway where a steady flow of trucks carrying commodities rumble past on their way to Naviraí. A few wooden huts are scattered amid the last remaining trees, and a blue container brims with rainwater, sparingly used by the few dozen residents to wash and cook. Just beyond the village, corn and sugarcane plantations stretch for hundreds of hectares.

The Guarani-Kaiowá recently reclaimed a part of this sprawling monoculture farm, which they say belonged to their ancestors. But they’re struggling to find a way to survive from the now-barren soil that can no longer yield subsistence crops, according to Valdir Martins, the Indigenous chief, or cacique, of the village.

“The forest is being destroyed and the rain is going away. It’s a weak land and it’s already lifeless,” Martins says. “Because water is life. Because when there’s destruction, the water dries up, it disappears.”

Medicinal herbs central to the Guarani-Kaiowá culture have also vanished as the forest has been replaced by plantations, he adds. “Everything has become a crop, everything has become a sugarcane field here. Our forest is gone.”

A few hours away, in the municipality of Itaquiraí, small-scale farmer Luiz Carlos Prudente, who grows limes and bananas on about 6 hectares (15 acres), says he also feels the impacts of the drought. Each banana tree normally soaks up 20 to 30 liters (5 to 8 gallons) per day, he says, but the prolonged dry spell has stunted their growth, yielding smaller bananas.

Luiz Carlos Prudente next to bananas.
Luiz Carlos Prudente, a small-scale farmer in Brazil’s Mato Grosso do Sul state, grows limes and bananas on about 6 hectares (15 acres). Each banana tree normally soaks up 20 to 30 liters (5 to 8 gallons) of water per day, he says, but the prolonged dry spell has stunted their growth, yielding smaller bananas. Image by Ana Ionova for Mongabay.

“This here is a banana that’s lacking water,” he says as he leads Mongabay through rows of banana trees. “It hasn’t filled out, it hasn’t rounded out, because of the drought … The banana isn’t good quality anymore because of the drought. You can see it’s struggling.”

After two months without rain, Prudente recently dug a well and installed an irrigation system in a bid to offset the damage to his banana trees. As rains have become more unpredictable, he’s also started growing hydroponic lettuce in a greenhouse, hoping to shield his livelihood from drought.

“We are working with a climate problem,” says Prudente, who leads a local association of banana growers. “The weather today is a very serious problem for us and the biggest challenge we have in family farming.”

Like climate scientists, Prudente also blames large-scale monoculture operations for the shifting rain patterns battering his crops and for polluting the soil with pesticides, which he says they often spray from planes that swoop low over the region.

“These large farms that invest in soy, in corn — they clear all the forest,” he says. “But we, the family farmers, know that the biggest problem nowadays is deforestation. This is what’s leading to our struggles.”

Luiz Carlos Prudente with lettuce.
Luiz Carlos Prudente, a small-scale farmer in Brazil’s Mato Grosso do Sul state, says he’s feeling the impacts of drought. As rains have become more unpredictable, he’s begun growing hydroponic lettuce in a greenhouse, hoping to shield his livelihood from drought. Image by Ana Ionova for Mongabay.
Agricultural fields in Mato Grosso do Sul state.
Agricultural fields in Mato Grosso do Sul state, Brazil. This region has been struck by intense drought over the past two years, with environmentalists blaming the advanced of large-scale monoculture. Image by Ana Ionova for Mongabay.

A changing climate

The drought ravaging the Paraná River Basin is part of a broader climate crisis playing out across Brazil’s other biomes, climate experts say.

As deforestation of the Amazon Rainforest hits 15-year highs, parts of the biome have grown drier. This has diminished rains that have historically nourished other parts of Brazil, according to Marcelo Parentes Henriques, a hydrology researcher at the Mineral Resources Research Company (CPRM), an arm of Brazil’s Ministry of Mines and Energy.

“This rain that is supposed to fall but isn’t falling — it normally comes from the Amazon,” says Henriques, who runs a project monitoring water levels in the Paraguay River, another major waterway that merges with the Paraná.

As moisture evaporates from the lush rainforest vegetation, it forms powerful “flying rivers” that travel and eventually dump heavy rainfall over other regions, like the Pantanal wetlands. But this phenomenon is changing as droughts grow more common and severe, according to Henriques.

“These flying rivers are an essential part of a natural cycle that is now being disrupted,” he says in a phone interview. “And the consequences are far-reaching.”

Cracked, dry land just outside Várzeas do Rio Ivinhema State Park.Limes.A family of capybaras slides into the waters of the Ivinhema River.A greater rhea runs along a road.Plants in a marsh in Várzeas do Rio Ivinhema State Park.A Pantanal deer.

The impacts have been particularly stark in the Pantanal, a labyrinth of flooded marshes and lagoons stretching across Brazil, Bolivia and Paraguay. Much of the region is normally permanently flooded, but searing temperatures and prolonged droughts have fueled unprecedented wildfires since 2019, which have engulfed huge swaths of the Pantanal and killed millions of animals.

In the Várzeas do Rio Ivinhema park, Oliveira says, flames have wiped out wildlife habitat and driven some species out. He blames a changing climate for also driving changes in animal behavior: last year, nearly a third of the parakeets broke with tradition and remained in the park after breeding. This year, he adds, those that migrated began trickling back to the reserve in August, two months earlier than usual.

With time, Oliveira says, species that are more resistant to drought will flock to the park, while those better-adapted to more humid environments may migrate out. Ultimately, he says, the park will remain a refuge for wildlife, although the animals that call it home may change over time.

“We don’t know how long the drought will last — that’s what worries us,” Oliveira says. “But, at the same time, what we see is that the fauna has enormous capacity for resilience and adaptation.”

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