South America: Intense water deficits to persist in French Guiana

20 August 2020

THE BIG PICTURE
The 12-month forecast through April 2021 indicates nearly normal water conditions in roughly half of the continent’s extent though deficits of varying intensity are forecast in nearly every nation.

Pockets of deficit are forecast across the northern arc and will be exceptional in southwestern Colombia, northern Venezuela, Suriname, and French Guiana.

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Deficits of varying intensity will dominate Brazil’s central and southern states of Mato Grosso, Mato Grosso do Sul, São Paulo, Paraná, and Santa Catarina. Exceptional anomalies will be especially widespread in Mato Grosso, spilling over the border into eastern Bolivia. Moderate to severe deficits are expected in pockets of central Brazil and surpluses in pockets of the eastern states and northern Amazonas. In Bolivia, intense deficits are forecast in the east, as previously mentioned, and in the south; severe surpluses are expected in the center of the nation. The bulk of central Peru will see deficits of varying intensity with exceptional anomalies in the east from Ucayali into Acre in western Brazil.

In the southern portion of the continent, deficits are forecast throughout much of Chile north of Santiago, reaching across the northern border into Argentina. Anomalies will be severe in Valparaiso and Santiago. The forecast for Argentina includes surpluses in the northwestern province of La Rioja, northern La Pampa Province, southern Buenos Aires Provinces, and the Southern Patagonian Ice Fields. Moderate deficits are expected in the Gran Chaco area of northeastern Argentina and in Santa Fe Province. The continent’s southernmost tip will see some intense deficits.

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 that, though deficits will shrink, many areas of significant deficit are expected. Nearly normal conditions will return to some areas in the northern nations, the northern Brazilian Amazon, southern Brazil, Uruguay, and Chile’s southern half. In Brazil, intense deficits are expected in the eastern Amazon Basin, moderating through central Brazil, then intensifying again in the far western and southern reaches of the Basin. Moderate to severe deficits are expected from Mato Grosso through São Paulo. Surpluses will shrink but persist in eastern Brazil and some pockets of exceptional deficit will emerge in the northeast.

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Across the northern arc of the continent, deficits are expected in Ecuador, southern Colombia, northeastern Venezuela, Guyana, Suriname, and French Guiana, and will include exceptional deficits. Much of Peru will be in deficit with exceptional deficits emerging in the central Cordillera Occidental Range and some surpluses persisting in the southeast. Surpluses are also forecast in central Bolivia with deficits of varying intensity in much of the remainder of the nation. Intense deficits are forecast in Chile’s northern half and along the Paraguay River through the center of its namesake. Argentina can expect moderate to severe deficits in the northeast and some pockets of surplus in the Pampas.

From November 2020 through January 2021, water conditions will normalize on much of the continent, most notably in Brazil. Some pockets of surplus will persist in Brazil’s eastern tip and will emerge in Rio Grande do Sul. Intense deficits will persist in southern Guyana and southern Suriname. Deficits will downgrade in northwestern Venezuela and southern Colombia, and will shrink considerably in Ecuador and Peru, becoming generally mild. Deficits will downgrade in Chile and nearly disappear in remaining central and southern nations. Moderate surpluses are forecast for central Bolivia and southern Buenos Aires Province in Argentina.

In the final quarter – February through April 2021 – normal conditions are forecast for much of the continent with some deficits persisting in northwestern Venezuela and northern Chile. Surpluses will nearly disappear in Brazil’s eastern tip, but mild anomalies will emerge in scattered pockets elsewhere, and some surpluses are forecast in Bolivia, Paraguay, and Argentina.

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

IMPACTS
In Venezuela’s northwestern state of Lara, drought has left the Dos Cerritos reservoir in El Tocuyo at critical level, bringing the threat of water rationing to surrounding communities.

Residents of Venezuela’s capital, Caracas, are refilling drums of bottled water more frequently as drought diminishes piped water supply and water trucks arrive less frequently. The need for clean water has increased due to the COVID 19 pandemic.

Drought conditions in Argentina are fueling fires raging through the nation’s famed wetlands in the Paraná Delta. The water level in the Paraná River at the port of Rosario measured just 80 centimetres in early August, 20 to 25 percent of normal. Believed to have been started by ranchers burning land to clear it, the fires encompass 90,000 hectares, an area about four times the size of the metropolis of Bueos Aires. The fires have prompted consideration of a national wetlands protection law as well as a Supreme Court lawsuit.

With drought affecting Argentina’s farm lands, the wheat harvest is not likely to reach earlier projections of 21 million tonnes.

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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