South America: Widespread water surplus ahead in N Amazon

19 November 2021

THE BIG PICTURE
The 12-month forecast through July 2022 indicates exceptional water deficits across northern Colombia and Venezuela throughout the northern Orinoco River watershed. Deficits will also be intense in Colombia’s southern tip.

Brazil can expect surpluses in the northern and eastern Amazon River Basin, mild to moderate overall but reaching exceptional intensity in a pocket northwest of Manaus. Surpluses are also forecast in some pockets in eastern Brazil and in southern Venezuela, the Orinoco Delta, and northern regions of the Guianas.

Severe deficits are forecast for western Amazonas, becoming exceptional in Acre. Deficits are also forecast in Brazil’s Central West, Southeast, and South regions and will reach exceptional intensity in Mato Grosso and severe to extreme intensity in Paraná and São Paulo States.

Nearly all of Chile will experience deficits and exceptional anomalies will dominate the nation from La Serena through Valparaiso and Santiago to the Gulf of Corcovado. Deficits in Patagonia will extend across the border into Argentina, eventually downgrading though remaining intense along several southern rivers in Argentina. Deficits will also be intense in Tierra del Fuego and the Falklands. Elsewhere in Argentina, moderate to extreme deficits are forecast in Corrientes Province in the northeast, and moderate deficits in Buenos Aires Province north of the Salado River. Moderate surpluses are expected in the central provinces of San Luis and Córdoba.

Deficits are forecast in pockets of Peru, intense near the Brazilian border, and moderate surpluses are expected north of Lake Titicaca. Bolivia can expect severe deficits surrounding Tarija in the south and moderate deficits east of La Paz. Moderate deficits are also forecast in northeastern Uruguay.

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

The forecast through January 2022 indicates that widespread deficits observed in the prior three months will shrink considerably. However, intense deficits will persist in the northern Orinoco River Watershed of Colombia and Venezuela. Surpluses will persist in the Orinoco Delta and will increase in southern Venezuela. The Guianas, too, will experience surpluses, particularly French Guiana and Suriname. Widespread surpluses will emerge in the northern portion of the Brazilian Amazon with severe to extreme anomalies in Pará, and moderate surpluses will emerge in Brazil’s southeastern states of Bahia, Minas Gerais, Espírito Santo and Rio de Janeiro. In Brazil’s far west and south, deficits are forecast in western Amazonas and Rio Grande do Sul. Moderate deficits in the south will extend through Uruguay.

Mixed conditions are forecast in Ecuador and Peru, including surpluses in a pocket near Quito (Ecuador) and north of Lake Titicaca (Peru), and deficits in the Marañón River Watershed of Peru. In the center of the continent, moderate surpluses are expected to emerge in central Paraguay and pockets in northern and eastern Bolivia, while moderate deficits will linger southern Bolivia.

Chile can expect deficits, exceptional in the south where anomalies will bleed into Argentina, moderating as they reach through to the Atlantic Coast. Intense deficits will persist in Tierra del Fuego and the Falklands, and deficits of varying intensity in northeastern Argentina and north of the Salado River in Buenos Aires Province where anomalies will be severe in its eponymous metropolitan area.

From February through April 2022, deficits will continue to shrink and downgrade, persisting primarily in the northern Orinoco Watershed where anomalies will be exceptional near Merida, Venezuela, and in southern Chile where anomalies, while shrinking, will remain intense, crossing the border into Argentina. Surpluses on the continent will shrink but moderate anomalies will continue to be widespread in the northern Amazon Basin in Brazil and pockets will emerge in western Brazil. Surpluses in the Orinoco Delta, southern Venezuela, and the Guianas will downgrade. Pockets of moderate surplus will increase in the Cordillera Orientales in Ecuador and into Peru, and surpluses will increase in San Luis and Córdoba Provinces in the Argentine Pampas.

The final quarter – May through July 2022 – indicates moderate surpluses in northern Guyana, pockets of northern and eastern Peru, and the Argentine Pampas. Mild to moderate deficits are expected in Chile but pockets of exceptional deficit along with surpluses are expected skirting the northern border regions.

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

IMPACTS
A late October landslide triggered by heavy rain killed 11 people in Nariño Province, Colombia and blocked the Junín-Pedregal highway, hindering rescue.

At the same time, flash flooding struck Jaén, a city of over 80,000 residents in Cajamarca Region in northern Peru. One death was reported and roads, buildings, and water infrastructure were damaged. Images posted of the local hospital show a flooded waiting room.

Flash flooding in mid-November left seven people dead in western Bolivia after heavy precipitation caused several rivers to overflow. The Mercke and Mapiri Rivers in Larecaja Province breached their banks, with the Mapiri River rising by over three meters (9.8 feet). Naval personnel were deployed in search and rescue operations.

The recent heavy rainfall has, however, proved beneficial to Brazil’s hydroelectric output which had reached crisis levels due to prolonged drought. The national grid operator is projecting improved conditions, but the water shortage tariff that has Brazilian’s paying more for electricity will likely remain in place through April of next near.

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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