South America: Water deficits will shrink overall

21 November 2020

THE BIG PICTURE
The 12-month forecast through July 2021 indicates intense water deficits in a vast region of west-central Brazil, and in northern Venezuela, Colombia’s southern corners, pockets throughout much of Chile, and straddling Argentina’s northern provinces of Chaco and Corrientes.

In Brazil, deficits will be widespread from Rondônia through Mato Grosso, Tocantins, and Mato Grosso do Sul. Anomalies will be exceptional in many areas of Mato Grosso. Deficits of varying intensity are expected in the western state of Acre, the state of São Paulo on the Atlantic Coast, and the southern states. Surpluses are forecast in the northeastern Amazon Basin with transitional conditions directly south.

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Coastal regions of Guyana, Suriname, and French Guiana can expect moderate surpluses. Surpluses are also forecast for the Orinoco Delta in Venezuela, but exceptional deficits will form a wide band north of the Apure and Orinoco Rivers. Deficits are forecast in northern Colombia and in its southern corners, as previously mentioned. Generally moderate deficits are forecast for Ecuador and through the Andes in Peru and the Cordillera Orientales in Bolivia. Northern and eastern Peru can expect a few pockets of surplus. Surpluses are also forecast in central Bolivia near Santa Cruz and into northern Paraguay.

Intense deficits are expected in many regions of Chile including exceptional anomalies on the Bío-Bío River in south-central Chile and extreme deficits near Valparaiso and Santiago. Northeastern Argentina and the northern Pampas can expect deficits. Scattered, isolated surpluses will pock western Argentina, but deficits are forecast near the Chilean border. In the south, severe deficits are forecast along the Chico River in Chubut Province and in Tierra del Fuego, and deficits in the Falkland Islands will reach exceptional intensity.

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

The forecast through January 2021 indicates that deficits will shrink and downgrade significantly, but many areas can expect anomalies. Deficits of varying intensity are forecast in an arc from western Venezuela into Peru. Deficits in southern Guyana will intensify but moderate surpluses will emerge in its coastal north and surpluses will increase across the border in northeastern Venezuela. Surpluses are also expected in coastal French Guiana. In Brazil, moderate surpluses will emerge in pockets of the northern Amazon Basin, particularly in northern Pará, and smaller pockets in Brazil’s easternmost tip and Minas Gerais in the southeast. Deficits are forecast in the south from São Paulo State through Rio Grande do Sul and anomalies will be intense north of the metropolis of São Paulo, in Santa Catarina State, and along the Uruguay River as it flows through Brazil, Uruguay, and Argentina. Deficits are also forecast in some pockets of central and western Brazil.

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Surpluses in south-central Bolivia will shrink and downgrade and moderate deficits are forecast through the Cordillera Oriental Range. Nearly normal conditions are expected in Paraguay with some moderate deficits in the south leading into moderate to severe deficits in northeastern Argentina. Deficits will blanket Uruguay but will be primarily moderate. In Chile, moderate deficits are forecast in central Chile and extreme to exceptional deficits in much of the south, crossing the border into Argentina. Deficits will be intense in Tierra del Fuego and the Falklands.

From February through April 2021, normal water conditions will return to many regions of the continent with deficits persisting primarily in pockets of western Venezuela, Bolivia’s southern tip, and southern Chile. Widespread surpluses will emerge from the northern Amazon Basin into Colombia, Venezuela, northern Guyana, Suriname, and French Guiana. Surpluses will be exceptional in the Lower Amazon until it reaches the Trombetas River, a northern tributary. Moderate surpluses will increase in eastern Bolivia reaching into Paraguay, and will emerge in pockets of western Colombia, from north-central Peru into Bolivia, and in San Luis Province in central Argentina.

In the final quarter – May through July 2021 – surpluses in the north will shrink considerably. Some small pockets of exceptional deficit will persist in Bolivia’s southern tip and along the northern border shared by Chile and Argentina.

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

IMPACTS
Persistent drought has affected many regions of South America, the second most intense drought on the continent since 2002, according to NASA. In mid-October, the Paraguay River dropped to its lowest level in 50 years, delaying cargoes and increasing shipping costs.

Estimates for Chile’s 2020 wine production are running 13 percent behind last year, with drought suppressing grape yields.

Commodity forecasters predict that Argentina’s 2020-2021 corn crop will be down 8.7 percent. Drought forced many farmers to forgo early season crop planting, September-October, for late season planting, December-January.

Just as northeastern Brazil is approaching its drought season, several states, including Bahia and Pernambuco, have been advised by authorities that federally-managed water tank deliveries will cease as of 1 November due to budgetary constraints. Many families rely on these deliveries for their drinking water.

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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