South America: Water surplus to persist in N Amazon

21 March 2022

THE BIG PICTURE
The 12-month forecast through November indicates widespread water deficits from southern Brazil into Paraguay and Argentina, in Peru’s northern half, and throughout much of Chile. Areas of significant surplus include the eastern Amazon River Basin, Brazil’s large northeastern states, and western Bolivia.

Deficits will be severe to exceptional in the southern Brazilian states of Mato Grosso do Sul, São Paulo, Paraná, Santa Catarina, and Rio Grande do Sul. In Brazil’s far northeast and far west, moderate deficits are predicted. Surpluses, generally moderate, are forecast in the eastern Brazilian Amazon but anomalies will be exceptional in eastern Amazonas. Surpluses are also expected in western Pará, southern Maranhão, Bahia, and Minas Gerais.

Across the northern arc of the continent, intense deficits are forecast from Bogota, Colombia nearly to Caracas, Venezuela; in a pocket of south-central Venezuela; and in Suriname. Surpluses are expected in the Orinoco Delta and Venezuela’s southern tip.

Intense deficits will be widespread in much of Peru’s northern half and will be exceptional in the middle reaches of the Ucayali River Watershed. Moderate deficits are forecast for western Ecuador. Southwestern Bolivia can expect surpluses, severe around La Paz and extreme to exceptional southeast of Lake Poopó near the source of the Pilcomayo River. Deficits are forecast in pockets elsewhere in the nation, particularly in the east.

Deficits in Paraguay’s eastern two-thirds will reach well into northern Argentina. Anomalies will be extreme to exceptional on the Paraná River and exceptional around the Itaipu Dam reservoir and also in the Iberá Wetlands of northeastern Argentina. Moderate deficits will skirt the eastern Pampas region, but a pocket of moderate surplus is forecast in the central Pampas.

Deficits are forecast throughout Chile with exceptional deficits in a vast path from La Serena in the north through most of the nation’s southern extent. Deficits in Chilean Patagonia will cross the border into Argentina. Exceptional deficits are forecast in Tierra del Fuego and extreme deficits in the Falklands.

FORECAST BREAKDOWN
The 3-month maps (below) for the same 12-month period show the evolving conditions in greater detail.

The forecast through May indicates widespread surpluses in the northern Amazon Basin, Guianas, southern and eastern Venezuela, and several regions in Colombia. Exceptional deficits are expected in southern French Guiana and deficits will linger in northern Venezuela. Severe to exceptional deficits will persist in Mato Grosso do Sul, São Paulo, and Paraná, Brazil, downgrading further south. Widespread deficits in central Peru will downgrade. In Bolivia, surpluses in the southwest will moderate; deficits are forecast in the east and south. Moderate to severe deficits are expected in eastern Paraguay, northeastern Argentina, and on the Paraná River. Surpluses will linger in the central Pampas and moderate deficits in eastern Buenos Aires Province. Intense deficits are forecast in southern Chile, Tierra del Fuego, and the Falklands.

From June through August, anomalies in the north will shrink, leaving moderate surpluses primarily in central and eastern Venezuela. Deficits will persist in south-central Brazil, downgrading somewhat, but exceptional anomalies will emerge in Goías and deficits will increase in Mato Grosso and Tocantins. Pockets of surplus are expected in Bahia and Alagoas in the east. In central Peru, deficits will moderate, reaching into Brazil. Surpluses will shrink in Bolivia; deficits will emerge in the north and persist in the east. Moderate deficits will linger in northeastern Argentina and on the Paraná River, and deficits in eastern Buenos Aires Province will intensify. Mild to moderate deficits are expected in Chile and surpluses will emerge in the Southern Patagonian Icefield.

The final quarter – September through November – indicates moderate deficits in large pockets throughout the continent’s northern half, including along the Amazon River, and in southern Brazil, Chile, and central Patagonia. Areas of surplus include Minas Gerais, Brazil, and southwestern Bolivia.

Please note that WSIM forecast skill declines with longer lead times.

IMPACTS
La Niña brought dry conditions to Brazil’s southern states, creating drought that has reduced the nation’s projected soy production. Estimates for the states of Paraná and Rio Grande do Sul are down by 34.4 and 33.9 respectively compared to last year. Argentina, the world leader in soybean oil and meal exports, anticipates a 7 percent drop while Paraguay’s harvest could plummet by 50 percent.

Drought has also decimated Argentina’s yerba mate crop, particularly in the northeastern province of Corrientes where agricultural leaders say that 60 percent of this year’s planting has died. The leaves of the yerba mate are used in an infused drink popular worldwide. Crop loss translates into income loss for farm laborers dependent on the harvest. Total economic losses are estimated at four billion Argentine pesos (about US $35 million).

Dry conditions in Corrientes have fueled wildfires in the region since December scorching 12 percent of the province, over 2.5 million acres. So far, economic losses total 70 billion pesos (US $645.7 million), largely due to agricultural losses. The fire area includes Iberá National Park, the second-largest wetland in the world, posing a threat to thousands of species. Smoke and ash from the conflagration reached Paraguay’s capital, Asunción, creating a blanket of smog.

Heavy rainfall in Ecuador’s Cotopaxi Province, about 50 kilometers (31 miles) south of Quito in the Andes Mountains, produced flooding that damaged 8 bridges leaving 15,000 people isolated. Many homes were destroyed and water infrastructure in the region was compromised, limiting the drinking water supply. It is the second time this year that the Quindigua River has overflowed its banks. Farther south, flooding and landslides were reported in Azuay Province.

NOTE ON ADMINISTRATIVE BOUNDARIES
There are numerous regions around the world where country borders are contested. ISciences depicts country boundaries on these maps solely to provide some geographic context. The boundaries are nominal, not legal, descriptions of each entity. The use of these boundaries does not imply any judgement on the legal status of any territory, or any endorsement or acceptance of disputed boundaries on the part of ISciences or our data providers.

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