South America: Intense water deficits will persist in Mato Grosso do Sul

25 March 2021

THE BIG PICTURE
The 12-month forecast through November 2021 indicates water deficits in much of Brazil south of the Amazon River from Rondônia in the west through the nation’s eastern tip, and from Amapá in the north through Rio Grande do Sul. Deficits will be exceptional in many areas and along many rivers.

Exceptional deficits are also forecast along the Paraguay River through its namesake and along the Paraná River through Brazil, Paraguay, and Argentina.

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Across the northern arc of the continent, intense deficits are expected in a belt from Colombia’s northern Pacific Coast to the Venezuelan border, and in the southeast reaching into Brazil. Deficits will be severe along Venezuela’s central coast, and intense around Merida in the northwest and in southern Bolívar State. Moderate surpluses are forecast in a pocket of southern Venezuela and in the Orinoco Delta. In Guyana, deficits are expected in the southeast; exceptional deficits are forecast for eastern French Guiana.

On the Pacific Coast, moderate to severe deficits are forecast for central Peru, moderating as they reach north into Ecuador but becoming exceptional near the Brazilian border. Surpluses are expected east of Cusco and moderate deficits in the far south. Bolivia, too, will experience deficits, severe in the east and moderate near Sucre. In Chile, deficits will be mild in the north, moderate to severe in central regions including Santiago, and exceptional in the south around the Gulf of Corcovado.

In Argentina, deficits are forecast in the Chaco Austral in the north, in the eastern Pampas, along the border with Chile, and in Tierra del Fuego and the Falklands. Surpluses are forecast in northern San Luis Province. Severe deficits are expected in southwestern Uruguay near the Rio de la Plata.

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 that deficits will shrink and downgrade, persisting primarily in Brazil. While much of central and eastern Brazil can expect mild to moderate deficits, widespread exceptional anomalies will persist in Mato Grosso do Sul and São Paulo State, and small intense pockets in Pará, Maranhão, Tocantins, Piauí, Bahia, Amapá, and western Amazonas into Venezuela. Surpluses, primarily moderate, are forecast for southwestern and eastern Colombia, southern Venezuela and the Orinoco Delta, and pockets in the Guianas and northern Amazon regions. Other areas with a forecast of surplus include north-central Ecuador, southeastern Peru, and San Luis Province, Argentina. Extreme to exceptional deficits are expected on the Paraná River and extreme deficits on the Paraguay River. Deficits elsewhere include the Marañón River Watershed in northern Peru, the Gulf of Corcovado region in Chile, and the Chaco Austral and eastern Pampas of Argentina. Anomalies will be exceptional near the Gulf of Corcovado.

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From June through August, normal water conditions will return to many regions of the continent. However, intense deficits will persist in Mato Grosso do Sul and São Paulo State in Brazil, shrinking somewhat, and deficits will intensify in pockets of central Brazil. Some moderate deficits are forecast for coastal Venezuela, a path through central Colombia, pockets of Ecuador, north-central Peru and the nation’s southern extreme, a few pockets in central Bolivia, northern Chile, and the eastern Argentine Pampas. Exceptional deficits will continue to skirt the shared northern border of Chile and Argentina, reaching into southern Bolivia, along with some surpluses. Surpluses are also forecast for southeastern Peru and San Luis Province in Argentina.

In the final quarter – September through November – deficits will shrink considerably. Pockets of deficit are forecast for northeastern Brazil; near Caracas, Venezuela; and in southern Colombia and northern Chile. Surpluses are forecast in Peru from Cusco to Lake Titicaca, and in northern San Luis Province, Argentina.

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

IMPACTS
Drought in Argentina, particularly in the Pampean region, has suppressed the expected soy output, reducing anticipated yield by 10 percent compared to last year. Argentina, one of the world’s top three soybean producers, stands to lose as much as $2.26 billion in export revenues from soymeal livestock feed and soy oil used for cooking and biofuel.

At the end of February, the volume of water in the Cantareira reservoir system that serves 7.5 million people in the São Paulo metropolitan area of Brazil was nearly 9 percent lower than in February of 2013, the year before the region entered into a water crisis. With lower than average February 2021 rainfall and a forecast that does not indicate sufficient precipitation to recharge the system, the situation has experts concerned.

In late March, a downpour in Cali, Colombia caused flooding and landslides that inundated many roads, including the Autopista Sur de Cali, and knocked out power in the region. The deluge pushed the Cañaveralejo River over its banks. One man was killed by falling debris and residents described a waterfall as floodwaters surged into a market area.

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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