South America: Water deficits to increase in Peru

24 July 2020

THE BIG PICTURE
The 12-month forecast through March 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, Santa Catarina, and Rio Grande do Sul. Exceptional anomalies will be especially widespread in Mato Grosso - spilling over the border into eastern Bolivia - and in Mato Grosso do Sul. Moderate 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, reaching across the border into Argentina in many areas. Anomalies will be severe in Valparaiso and Santiago, Chile. The forecast for Argentina also includes surpluses in the northwestern province of La Rioja, northern La Pampa Province, and the Southern Patagonian Ice Fields. Moderate to severe deficits are expected in the Gran Chaco area of northeastern Argentina and in Córdoba and Santa Fe Provinces in the Pampas.

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

The forecast through September 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, Paraguay, Uruguay, and Chile’s southern two-thirds. Vast areas of deficit are forecast, however, throughout much of Peru, in the western and southern Amazon Basin in Brazil and the states of Mato Grosso and Mato Grosso do Sul, and northern Chile. Anomalies will be severe to exceptional in many of these regions. Surpluses will persist in eastern Brazil but diminish in the center of the country as widespread, primarily mild to moderate deficits emerge.

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Intense deficits are also forecast for western Ecuador, northwestern Venezuela, Suriname, French Guiana, and along the Paraguay River through its namesake. Deficits in northern Argentina will downgrade. Surpluses will increase in central Bolivia, persist in the central Argentine Pampas and the country’s northwestern provinces, and emerge in southern Buenos Aires Province and in coastal Uruguay.

From October through December, water conditions will normalize on much of the continent. Intense deficits are forecast, however, for Suriname, French Guiana, and nearby Amapá in Brazil, as well as pockets of northern Chile and Bolivia’s southern tip. Deficits of lesser intensity are predicted for north-central Venezuela, southern Colombia, pockets of Ecuador and Peru, Acre (Brazil), Cochabamba (Bolivia), and central Chile. Some surpluses will persist in Brazil’s eastern tip and surpluses are also forecast for a pocket in southern Peru, central Bolivia, northwestern Argentina, and southern Buenos Aires Province.

In the final quarter – January through March 2021 – normal conditions are forecast for much of the continent. Intense deficits will persist in southern Bolivia, moderate deficits in pockets of Chile and in northwestern Venezuela. Surpluses will nearly disappear in Brazil’s eastern tip but will emerge in scattered, small pockets in the north and south, and elsewhere on the continent.

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

IMPACTS
Fires in the Brazilian Amazon spiked to a 13-year high for the month of June, rising by nearly 20 percent over June 2019, an ominous start to a fire season that typically sees its greatest increases from July through September.

Though Chile saw its rainiest June in 14 years, the precipitation isn’t enough to offset long-term deficits say meteorologists. Anticipating La Niña conditions toward the end of the year, indicating less rain, experts predict that Chile will not reach annual normal rainfall of 340 mm during 2020. The “megadrought” that has plagued central Chile for a decade is likely a once-in-a-1000-years occurrence according to paleontologists who use tree rings to study climate history.

Chile recently completed work on a US $250 million desalination plant in the Atacama region and has begun construction of a US $136 million reservoir to provide water to the Petorca Valley in the Valparaíso region. Fog nets are being used to harvest water in the Coquimbo region north of Santiago.

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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