South America: Water surpluses will increase in N Amazon Basin

17 August 2021

THE BIG PICTURE
The 12-month forecast through April 2022 indicates exceptional water deficits across northern Colombia and Venezuela and many regions of Chile, deficits of generally lesser intensity in central and southern Brazil and Peru, and large pockets of surplus in the continent’s north.

Deficits will be exceptional from Colombia’s northern Pacific Coast through the northern Orinoco River Watershed in Venezuela. Moderate to exceptional deficits are forecast in southern Colombia.

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Surpluses are expected in northern Ecuador, east of Cali in Colombia, southern Venezuela, eastern Venezuela including the Orinoco Delta, northern Guyana and spanning its border with Suriname, and at the intersection of the Negro and Branco Rivers in the northern Amazon Basin of Brazil where anomalies will be exceptional.

While many other regions in Brazil north of the Amazon and in the nation’s east can expect relatively normal water conditions, deficits of varying intensity are forecast in parts of the west and in the central and southeastern states. Exceptional anomalies will be especially prevalent in pockets of southern Amazonas and southern Pará. Severe to exceptional deficits will be widespread in Mato Grosso do Sul and São Paulo States.

Much of central Peru will experience moderate deficits, more intense near the Brazilian border. Central Bolivia can expect intense deficits between La Paz and Sucre. Nearly all of Chile will experience deficits, with exceptional deficits dominating the nation from La Serena through Valparaiso and Santiago to the Gulf of Corcovado. Deficits in southern Patagonia will extend across the border, eventually downgrading as they reach through Argentina. However, deficits will be intense in Tierra del Fuego and the Falklands. Elsewhere in Argentina, deficits are forecast north of the Salado River in Buenos Aires Province, severe to extreme in the metropolis of Buenos Aires; moderate deficits in the province’s southeastern region and in northeastern Argentina; and moderate surpluses in La Pampa Province.

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

The forecast through October indicates widespread deficits in Brazil south of the Amazon and surpluses north. Deficits will be exceptional in many areas including the Purus River Watershed in the west, and in large pockets of Pará, Mato Grosso, Mato Grosso do Sul, and São Paulo States. Surpluses north of the Amazon will increase and will be severe to exceptional in the central Amazon. Deficits from northern Colombia through northwestern Venezuela will shrink but remain widespread in the western Orinoco River Watershed and will include exceptional anomalies, notably around Merida, Venezuela and northeast of Bogotá, Colombia. Surpluses will increase from eastern Venezuela through northern Guyana and in Venezuela’s southern tip, and will persist from Quito, Ecuador into southwestern Colombia and will include extreme anomalies.

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Severe deficits are forecast for central Peru and deficits in the south near Arequipa will intensify, becoming exceptional. Surpluses will persist in the south around Huancayo and from Lake Titicaca through Cusco and across the border into Bolivia. Anomalies will be exceptional in Cusco. Deficits are expected in many other regions of Bolivia and eastern Paraguay with exceptional deficits on the Paraguay River through its namesake. In Uruguay, moderate to severe deficits will emerge in the north.

Deficits of varying intensity are expected throughout much of Chile, severe in Santiago and exceptional in Biobío Province. In Argentina, deficits will be moderate along the northern Paraná River, becoming severe on its approach to the Rio de la Plata. Between the Paraná and Salado Rivers in Buenos Aires Province deficits will be severe to extreme, while moderate deficits are expected in southeastern Buenos Aires Province. Deficits of varying intensity are forecast in Patagonia, and exceptional deficits will persist in Tierra del Fuego and the Falklands. Widespread, severe surpluses will continue in La Pampa Province, and pockets of surplus will linger in San Luis Province.

From November 2021 through January 2022, moderate surpluses are forecast in northeastern Venezuela and deficits near Caracas in the north. A few pockets of moderate surplus are expected in the central Brazilian Amazon north of Manaus, and moderate deficits will span the nation’s southern border into Uruguay. Severe deficits are forecast for Ecuador’s southern corner, and pockets of moderate to severe deficit in central and southern Peru reaching past Lake Titicaca into Bolivia. Deficits are expected throughout most of Chile, moderate overall but more intense near Concepción in central Chile and along the Argentine border. Some moderate deficits are forecast in eastern Argentina and along rivers in the south, but deficits will be more intense in western Patagonia, Tierra del Fuego, and the Falklands.

The final quarter – February through April 2022 – indicates surpluses in northeastern Venezuela, Brazil’s northeastern tip, and pockets in Ecuador and in Córdoba Province, Argentina. Moderate deficits are forecast for north-central Venezuela, and mild to moderate deficits in much of Chile with exceptional pockets spanning the northern border and in Concepción. Deficits of varying intensity are expected for western Argentine Patagonia; deficits will downgrade in Tierra del Fuego; and surpluses will increase in the Patagonian Icefields.

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

IMPACTS
Chile plans to bring a shuttered coal power plant back into service to help address hydropower shortages created by the country’s drought. Completion of some renewable generators will be fast-tracked as well to join the grid according to the energy minister.

An unusually hot July and snow drought in the Andes have compounded conditions generated by a decade of drought, leaving the nation parched. The central region, the most populous and the country’s breadbasket, has been especially hard-hit, including the capital, Santiago. One weather station in the recorded 78mm (3 inches) of rainfall this year compared to the average of 252mm (9.9 inches).

Argentina's National Meteorological Service reports that 75 percent of the Paraná River Basin is in moderate to exceptional drought, affecting around 70 million hectares (173 million acres). Shallow water on the river itself, a major grain-shipping artery, has reduced cargos by 18 to 25 percent. The federal government plans to shift $300 million in funding received from the Inter-American Development Bank to address drought impacts on the river.

Agricultural experts have revised their estimates of Brazil’s total corn production as drought continues to take a toll, reducing it by about 7 percent from previous projections and 15 percent from last year’s output.

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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