South America: Water deficits will shrink overall

24 March 2020

THE BIG PICTURE
The 12-month forecast through November indicates deficit conditions in many areas throughout the region. Though eastern Brazil will be largely spared, deficits of varying intensity are forecast for much of the remainder of the country and will include severe deficits along the Amazon River and deficits reaching exceptional intensity in Amapá in the north; Mato Grosso, Pará, Tocantins, Goías, and Mato Grosso do Sul in central Brazil; Rondônia in the west; and Rio Grande do Sul in the south.

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In the east, pockets of surplus are forecast in Pernambuco and Minas Gerais. Moderate deficits are expected in southern Bahia and deficits somewhat more intense farther south in São Paulo State.

Across the northern arc of the continent, exceptional deficits are expected in French Guiana; moderate to exceptional anomalies in Suriname, Guyana, southern and northwestern Venezuela, and eastern Colombia; and moderate anomalies in southern Colombia and small pockets of Ecuador. Surpluses are forecast for the Orinoco Delta in northeastern Venezuela.

Deficits of varying intensity are forecast in many areas of Peru and in eastern and southern Bolivia, and surpluses are expected along their shared border as well as several pockets in northern and central Peru.

The forecast for Chile indicates deficits throughout much of the nation which will be intense in many regions including Santiago. Conditions in Paraguay will be relatively normal though extreme deficits will trace a path along the Paraguay River through the center of the country, downgrading slightly to severe intensity as it meets the Paraná River through Argentina.

Moderate to severe deficits are forecast for Buenos Aires Province in the Argentine Pampas. Some areas of exceptional deficit are forecast in northern and western Argentina, and surpluses in the northwestern provinces of La Rioja and Catamarca. Moderate deficits are expected in southern Uruguay.

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 the extent of deficits in the region will shrink considerably overall. Intense deficits are forecast, however, for French Guiana and Suriname; southern Venezuela and northern Amazonas (Brazil); Piura (northwestern Peru); southernmost Bolivia; Mato Grosso do Sul, Rio Grande do Sul, and the border of São Paulo State and Paraná (Brazil); and the Gulf of Corcovado (Chile). Deficits ranging from moderate to severe are forecast for the western Amazon Basin and Mato Grosso (Brazil); northwestern Venezuela; southern Colombia; pockets in Peru and in Bolivia’s southern half; the Paraguay River through Paraguay and pockets in the east; northern Argentina and the Pampas; and northern and central Chile.

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Surpluses will emerge in a large block of southeastern Brazil including Minas Gerais and nearby regions of neighboring states east and west, and a few pockets in eastern Brazil, particularly Pernambuco. Surpluses elsewhere include the Orinoco Delta in northeastern Venezuela, Argentina’s northwestern provinces, and some lingering, though shrunken, pockets in Ecuador and Peru.

From June through August, conditions in many parts of the continent will normalize. Intense deficits will persist in Mato Grosso do Sul, Brazil; in pockets of Bolivia’s southern tip and across the border into northern Chile; and along the northern border of Chile and Argentina. Small pockets of intense deficit will emerge in western Ecuador and in a spotted path through the Cordillera Occidental Mountains in western Peru. Severe deficits are forecast for Buenos Aires Province in Argentina, and generally moderate deficits in southern Colombia, eastern Ecuador, much of Peru, the southern Amazon Basin in Brazil, and some areas of Bolivia and Chile. Surpluses will shrink but persist around Minas Gerais, Brazil and Pernambuco, and in northwestern Argentina.

In the final quarter – September through November – generally moderate deficits are forecast for scattered pockets in western nations, with a few more intense areas, and surpluses will persist in northwestern Argentina.

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

IMPACTS
In a blunt statement last month, Chile’s agricultural minister acknowledged that the government lacks the resources needed to address “a drought of this magnitude,” referring to widespread, persistent dry conditions much of the country has been facing.

The DGA (Dirección General de Aguas), the state agency responsible for water rmanagement, reports that 12 of the nation’s 19 most important rivers have flows below the historical minimum.

Vichuquén, a community in the Maule region of central Chile, instituted water rationing in mid-February in a move the mayor hopes will help preserve the town’s tourism economy. Residents of Nirivilo, a rural village also in Maule, have restricted access to water as well - three hours in the morning and three hours in the afternoon.

As many Chilean communities face water shortages in the midst of the global coronavirus pandemic, even the simple precaution of frequent hand-washing is a life-threatening challenge.

Flooding and landslides in early March killed 24 in Brazil’s southeastern state of São Paulo and displaced 5,000 in the Rio de Janeiro. Flooding from heavy rainfall in mid-February had already claimed several lives in the Greater São Paulo area when the Tiete and Pinheiros rivers broke their banks, with some areas receiving more rain in three hours than the average rainfall for February.

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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