South America: Intense water deficits to persist in Amazonas & Chile

17 December 2018

The 12-month forecast through August 2019 indicates water deficits of varying intensity in the western Amazon Basin of Brazil reaching into neighboring nations to the north and west. Exceptional deficits are expected to trace a path along the continent’s Pacific coast from northern Peru past Santiago, Chile, and deficits of similar intensity are forecast for southwestern Bolivia beginning near Cochabamba.

Surpluses are forecast in parts of the continent’s mid-section, and anomalies will be extreme to exceptional in central Paraguay. Primarily moderate surpluses will extend from eastern Paraguay through Brazilian states to the northeast and south into Argentina, trailing along the Paraná River to Buenos Aires. Surpluses are also forecast for: northern Bolivia; northern Rio Grande do Sul, Brazil; Neuquén Province, Argentina; and, Patagonia surrounding O’Higgins/San Martín Lake and along Río Santa Cruz.

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

The extent of exceptional deficits in the region will diminish considerably over the next several months. However, through February exceptional deficits are forecast for: southern Amazonas, central Mato Grosso, and northern Tocantins, Brazil; southeastern and northwestern Venezuela; northern Chile; and southwestern Bolivia in an arc from La Paz to the southern border. Deficits of lesser intensity are forecast in Peru, Colombia, Venezuela, Guyana, Suriname, and western French Guiana.

Amapá, Brazil will transition from deficit to moderate surplus, as will western Ecuador. Moderate surpluses will also emerge in Pará, Brazil along the Xingu and Iriri Rivers and pockets of central Brazil. Surpluses will moderate but increase in extent from southern Mato Grosso through western Minas Gerais, and will also increase in northern Rio Grande do Sul. In Bolivia, surpluses in the north will downgrade but increase in extent. Surpluses will downgrade somewhat in central Paraguay but remain intense, and moderate surpluses will emerge across the border into Argentina along the Paraná River to Buenos Aires. Regions of prior surplus in Uruguay and the Argentine Pampas are expected to normalize.

The forecast for March through May indicates primarily moderate deficits in the Amazon Basin and mild deficits in eastern Brazil. Deficits will shrink and downgrade in Brazil’s northern neighbors, though severe deficits are forecast for Suriname and extreme deficits in pockets of northwestern Colombia. Exceptional deficits will persist and increase in Chile’s northern half. Deficits of equal intensity will emerge along most of coastal Peru, and severe deficits are forecast for southern Peru. In Bolivia, surpluses in the north will shrink and deficits in the southwest, though downgrading from exceptional, will be extreme. Surpluses will increase from central Peru into northeastern Argentina and Brazil’s southernmost states – while conditions normalize in Mato Grosso – and will emerge in eastern Uruguay. Anomalies are expected to be moderate overall but may be extreme in central Paraguay.

In the final quarter – June through August – deficits will increase across Brazil’s northern breadth, intensifying in the east, as well as in Suriname, French Guiana, and Peru. Surpluses will persist in Paraguay and increase in Brazilian states to the east through São Paulo.

(It should be noted that forecast skill declines with longer lead times.)

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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Many analyses reported in ISciences-authored blog posts are based on data generated by the ISciences Water Security Indicator Model (WSIM). Other sources, if used, are referenced in footnotes accompanying individual posts. WSIM is a validated capability that produces monthly reports on current and forecast global freshwater surpluses and deficits with lead times of 1-9 months at 0.5°x0.5° resolution. This capability has been in continuous operation since April 2011 and has proven to provide reliable forecasts of emerging water security concerns in that time-frame. WSIM has the ability to assess the impacts of water anomalies on people, agriculture, and electricity generation. Detailed data, customized visualizations, and reports are available for purchase.

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