South America: Exceptional water deficits in Brazil forecast to retreat to the north after September

24 July 2017

The Big Picture
Water deficits are forecast for much of Brazil in the 12-month forecast through March 2018, with scattered pockets of exceptional deficits. Deficits reaching exceptional severity are also forecast for: northwest and southern Venezuela; Suriname; French Guiana; northern Chile; near the Gulf of Corcovado; and the Chubut River in Argentina.

Exceptional surpluses are expected in Mendoza, La Pampa, and Buenos Aries Provinces in Argentina; and surpluses of slightly lesser severity are forecast for the border area between Argentina, Paraguay and Brazil.

Impacts
Brazil's Ministry of National Integration (Ministério da Integração Nacional) has declared an emergency in 19 municipalities due to drought, floods, and storms, enabling the communities to request national support.

In response to drought in the northeast, the National Water Agency (ANA - Agência Nacional de Águas) has reduced the minimum water release on the São Francisco River to the reservoirs of Sobradinho in Bahia and Xingó on the border of the states of Alagoas and Sergipe. The new minimum, 550 cubic meters per second, is the lowest since 2012 and is in effect until November 30 to preserve water stocks in the basin for energy production and other uses until the rainy season.

Guyana is looking to its neighbor, Brazil, for emergency supplies and technical support as flooding has taken a toll on many parts of the nation since mid-May, inundating major roadways and leaving communities cut off from normal supply routes. Villages in the Rupunini region in the southwest are under eight feet of water, most of the cassava crop is beyond salvage, and authorities announced an early end of the school term to prevent children from contracting water-borne diseases.

Heavy rainfall also produced flooding in Guyana's densely populated coastland, where farmland was inundated and livestock were abandoned or moved. Several new pumping stations are planned for the area at a cost of GYD$600 million (US$2.9 million) but won't be completed until December at the earliest. Floodwaters in Potari-Siparaum in central Guyana were 15 feet high, washing away 10 houses and leaving 20 under water. Over 1,000 residents have been affected.

Peru has modified its 1993 constitution to make access to water a constitutional right, giving rural communities more leverage in dealing with extractive industries and paving the way for additional financing of water and sewage projects in both urban and rural areas.

The National Forest and Wildlife Service of Peru reports that thousands of trees are beginning to grow in the desert in Piura, part of a massive reforestation project in the region where devastating floods killed 18 people and destroyed 14,000 homes in March.

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

The forecast map for July through September shows the persistence of widespread deficits across Brazil though the extent of exceptional deficits is expected to decrease slightly. Severe to exceptional deficits are forecast for: Guyana, Suriname, French Guiana, pockets of northwestern and southern Venezuela, a path from western Peru down through Chile, from Cochabamba southward in Bolivia, and pockets in Tierra del Fuego.

Surplus conditions in eastern Paraguay, southern Brazil, and northern Uruguay will transition to near-normal conditions during this period. Exceptional surpluses are forecast to persist in La Pampa and Buenos Aires Provinces in Argentina, and a pocket of extreme surpluses will persist in northern Argentina near Paraguay.

In general, conditions are forecast to return to near normal from October through March. Exceptional drought in Brazil is forecast to recede from south to north, and most regions with exceptional surpluses will improve to moderate surpluses. From October through December, however, exceptional deficit conditions will persist in: Amapá and northern Pará, Brazil; French Guiana; scattered along the northern coast of Brazil; and, northern Chile. Deficits ranging from severe to exceptional are forecast in Roraima, Brazil and Suriname from October through December. (It should be noted that forecast skill declines with longer lead times.)

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