South America: Widespread, intense water deficits in much of Brazil

22 August 2017

The Big Picture
Water deficits are forecast for much of Brazil north of Rio and are expected to be exceptional in many regions. Deficits reaching exceptional severity are also forecast for: northwest and southern Venezuela; French Guiana; Cochabamba, Bolivia; northern Chile; Bío-Bío in central Chile and across the border into Argentina; and the Chubut River in Argentina.

Exceptional surpluses are expected in central Mendoza Province, La Pampa Province, and along the Salado River in Buenos Aries Province in Argentina. Surpluses of lesser severity are forecast for the border area between Argentina, Paraguay and Brazil, and in a band across central Bolivia.

Impacts
Heavy rains in early August caused flooding on major rivers in Venezuela, including the Orinoco and Caroní, affecting 40,000 people in the states of Bolívar, Delta Amacuro, Amazonas, Sucre, Mérida and Miranda. Floodgates of the Guri hydroelectric dam in Bolívar were opened to lower the water levels of the dam, though local politicians claimed that this exacerbated problems in downstream communities.

In the wake of devastating floods that hit Peru earlier this year, the government plans to award US$6.15 billion in reconstruction projects through 2021, starting with US$600 million this year and US$2.2 billion in 2018. Flooding in March killed 100 and caused US$4 billion in infrastructure damage, about 2 percent of GDP.

Flooding continues in central provinces of Argentina, including Córdoba, Buenos Aires, and La Pampa. Water crossed Route 8 in Arias in southeast Córdoba, preventing the movement of an estimated 10,000 trucks of soy and corn. The city of Bolívar in Buenos Aires province is surrounded by water, and pastureland in the region is flooded creating losses for cattle producers. The National Institute of Agricultural Technology reports that 200,00 hectares (494,211 acres) in La Pampa remained under water as of the end of July. Officials estimate that 50,000 hectares (123,553 acres) of peanuts have been lost due to flooding, primarily in southeast Córdoba, northwest La Pampa, and northwest Buenos Aires, and that harvestable crop remained in fields as inundated road networks prevented truck access.

Brazilian farm operator, SLC Agricola, cited water stress in Brazil's drought-prone northeast in its decision to reduce to 23 percent cultivation of land holdings in Piauí and Bahia states, down from 34 percent four years ago, working just 95,436 hectares (235,828 acres).

INMET, Brazil's National Institute of Meteorology, reported at the end of July that the Federal District of Brasília had not received any rainfall for 65 days and warned of potential health risks associated with low humidity.

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

Though a slight reduction in the extent of exceptional deficits is expected, the forecast for the next three months indicates a basic pattern of water conditions similar to observed conditions in the prior three months which includes widespread, intense deficits in most of Brazil north of Rio de Janeiro and surpluses in La Pampa Province, Argentina. Exceptional deficits will continue to emerge in northern Chile, and will persist in Bío-Bío, and along the Chubut River in Argentina. In addition, the August through October forecast indicates a transition from surplus to deficit in Brazilian states south of Rio and in eastern Paraguay. Prior surpluses in northern Peru, Ecuador, central Colombia, northeast Venezuela, and northern Guyana are forecast to recede considerably. The extent of exceptional surpluses in La Pampa, Argentina will shrink somewhat, and the intensity of surpluses in nearby Buenos Aires Province – including along the Río Salado – will diminish.

Widespread deficits across northern South America are forecast to shrink considerably November 2017 through January 2018, though severe to occasionally exceptional deficits remain in the forecast for northern Brazil, Suriname, and French Guiana. Surpluses in La Pampa, Argentina will diminish, but moderate to extreme surpluses will continue to emerge in nearby Buenos Aires Province. Primarily moderate surpluses will emerge in the Iberá Wetlands of northeastern Argentina, across the border into northern Rio Grande do Sul, Brazil, and along the Rios Uruguay and Paraná.

The forecast for the final months – February through April – indicates deficits in northeastern Brazil and in Chile, and the emergence of moderate surpluses in the northern Amazon Basin.

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

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