South America: Intense water deficits in C Brazil, Peru, Chile

25 May 2022

THE BIG PICTURE
The 12-month forecast through January 2023 indicates widespread water deficits of varying intensity in Brazil’s Central West region through the Southeast and South, as well as pockets of deficit elsewhere. Deficits will be moderate overall but more intense in several areas including exceptional deficits in Mato Grosso, Mato Grosso do Sul, and São Paulo State. Exceptional deficits are also expected on the Paraná River from the Ilha Solteira Reservoir through the Itaipu Reservoir. Some pockets of deficit are expected in the Northeast region, particularly in Piauí, along with pockets of surplus in Rio Grande do Norte and central Bahia.

Surpluses are forecast in the northern Amazon Basin of Brazil, moderate overall but exceptional in the central reaches of the Madeira River, a southern tributary of the Amazon. Surpluses in the northern basin will reach into Venezuela’s southern tip and into Columbia.

Across the northern arc of the continent, deficits, including exceptional anomalies, are forecast in a pocket north of Bogota, Colombia; from Merida, Venezuela past Caracas; in a belt between the Ventuari and Upper Orinoco Rivers in southern Venezuela; and in French Guiana. Surpluses are forecast in a pocket north of Quito, Ecuador.

In Peru, exceptional deficits are forecast in the middle reaches of the Ucayali River Watershed, and deficits of varying intensity in much of central Peru. Areas of surpluses include the region surrounding Huancayo in the central Peruvian Andes and from Lake Titicaca in the south through La Paz, Bolivia where anomalies will be severe. Surpluses will also be severe in the Upper Pilcomayo and Upper Grande River regions of southwestern Bolivia. Deficits are forecast in pockets elsewhere in Bolivia, exceptional in the east and extreme south.

Deficits are forecast in Paraguay and in northern Argentina where anomalies will be exceptional in pockets of the Chaco region and in the Iberá Wetlands. Deficits will be severe on the Paraná River as it flows to the Atlantic. The northern and eastern Pampas can also expect deficits, and a pocket of moderate surplus is forecast in the central Pampas. Exceptional surpluses are forecast in coastal Chubut Province in Patagonia.

Mixed conditions are predicted for northern Chile and exceptional deficits in a vast path from La Serena through most of the nation’s southern extent. Deficits in Chilean Patagonia will cross into Argentina. Exceptional deficits are forecast in Tierra del Fuego and severe deficits in the Falklands.

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

FORECAST BREAKDOWN
The forecast through July indicates widespread deficits across central Brazil including exceptional deficits, particularly in Tocantins, Mato Grosso, and Goiás. Surpluses are forecast in the northwestern Amazon Basin of Brazil and into Colombia and northeastern Peru. Surpluses are also forecast from just north of Quito, Ecuador through western Colombia and in pockets of coastal Guyana and French Guiana. Deficits will persist in a pocket surrounding Merida, Venezuela. Widespread deficits are forecast in central Peru, exceptional in the Department of Ucayali in the Amazon rainforest. Surpluses will persist near Huancayo. Bolivia can expect surpluses in the southwest that will be intense in La Paz, and deficits in many other regions. Deficits are forecast throughout much of Chile with intense anomalies dominating much of the nation south of Santiago. In Argentina, deficits of varying intensity are forecast in the Gran Chaco in the north, the northern and eastern Pampas, several rivers in southern Patagonia, and Tierra del Fuego. Surpluses are forecast in the Andes in the northwest, a pocket in the central Pampas, and coastal Chubut.

From August through October, anomalies will shrink and downgrade. In Brazil, generally moderate deficits are forecast for Mato Grosso do Sul, São Paulo, and Paraná, but anomalies will be more intense in some pockets of central Brazil and in Acre in the west. Moderate surpluses will persist in eastern Amazonas and surpluses will increase in central Bahia between the São Francisco and Contas (de Contas) Rivers. Some pockets of deficit, primarily moderate, are forecast in Colombia, Venezuela, the Guianas, and Amapá in Brazil. Deficits will remain intense in Ucayali, Peru, moderating through central Peru. Southwestern Bolivia will continue to see surpluses. Deficits in Bolivia will shrink as will those in Argentina. However, deficits will persist with increased intensity north of the Salado River in Buenos Aires Province. Deficits in Chile will downgrade overall but intensify in a pocket north of Copiapo.

The final quarter – November through January – indicates deficits, primarily moderate, in Mato Grosso do Sul, São Paulo, and Paraná, Brazil; Chile and Patagonian Argentina; and pockets in the coastal Guianas. Surpluses are forecast in pockets of eastern Brazil and from Cusco, Peru past La Paz, Bolivia.

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

IMPACTS
Argentina’s official declaration of emergency on the Paraná River that began in July of last year has been extended for another 180 days due to continued rainfall deficits. The river is the major transport conduit for the nation’s grain exports and provides drinking and water and sewage services for the region’s population. The declaration permits special protections such as tariffs.

In early May, the Negro River in the Brazilian Amazon region passed severe flood stage at Manaus in Amazonas, prompting officials to build walkways above the floodwaters and to disinfect the city’s flooded areas. The Jurua, Purus, Madeira, Solimoes, and Amazon Rivers are also flooding. By the latter part of May, 35 municipalities had declared flood emergencies with over 300,000 people affected. Food security is a concern as rich, riverside agricultural land becomes inundated.

Farther south, the Brazilian state of Mato Grosso experienced a rainfall deficit in April estimated at 70 percent below the ten-year average, its driest April in 17 years. The drought in Mato Grosso, the nation’s top grain producer, will likely suppress the second corn crop, a shortfall that will reverberate through already tight global markets.

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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