South America: Widespread water deficits in Brazil

19 May 2021

THE BIG PICTURE
The 12-month forecast through January 2022 indicates water deficits in much of Brazil south of the Amazon River. Deficits will be exceptional in many states including southern Amazonas, Pará, Mato Grosso, Mato Grosso do Sul, and São Paulo. Exceptional deficits are also forecast along the Paraguay River through its namesake and along the Paraná River through Brazil, Paraguay, and Argentina.

South_America_Composite_Adjusted_202102-202201_12mo_twitter.png

Across the northern arc of the continent, intense deficits are expected in a path from Colombia’s northern Pacific Coast through Medellin and into northwestern Venezuela. Deficits will also be intense in Colombia’s southeastern corner reaching into Brazil, and in southern Bolívar State in Venezuela. Severe deficits are predicted for Venezuela’s central coast, and surpluses for a pocket in the nation’s south and near the mouth of the Orinoco River. Deficits are expected in Guyana’s southeastern corner and in French Guiana.

Much of central Peru will be dominated by deficits and anomalies will be exceptional in the middle portion of the Ucayali River Watershed. Moderate deficits are expected in the nation’s southern corner. Surpluses are forecast for a pocket in the central Peruvian Andes and from Cusco in the southeast into Bolivia. Central and eastern Bolivia can expect deficits of varying intensity. Deficits of varying intensity are also forecast in nearly all of Chile with exceptional anomalies in pockets of the north and around the Gulf of Corcovado in the south reaching into Argentina. Near Santiago and Valparaiso deficits will be severe to exceptional.

In Argentina, deficits are forecast in pockets of the Chaco in the north, in Buenos Aires Province north of the Salado River, and in Tierra del Fuego and the Falklands. Surpluses are forecast in northern San Luis Province and northern La Pampa Province. Moderate deficits are expected in western Uruguay.

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

The forecast through July indicates that deficits of varying intensity will remain widespread in Brazil south of the Amazon while the region to the north normalizes. Deficits will be exceptional in many pockets but will be especially widespread in the Purus River Watershed in the west, Mato Grosso, Mato Grosso do Sul, Goiás, and São Paulo States. Notably, exceptional deficits are also forecast along the Paraguay River through its namesake and along the Paraná River through Brazil, Paraguay, and Argentina. Deficits across the northern arc of the continent will shrink though intense anomalies will persist from Colombia’s northwestern coast through Medellin and into Venezuela, and in a pocket of southeastern Colombia. Moderate deficits will persist on Venezuela’s central coast. Surpluses are forecast for southern and eastern Venezuela, the northern reaches of the Guianas, and a few pockets in western Colombia and Ecuador.

South_America_Composite_Adjusted_202102-202201_3mo_twitter.png

Surpluses will nearly disappear from Loreto in northern Peru but will increase from Huancayo past Cusco into Bolivia. Deficits will continue to dominate central Peru though the extent of exceptional anomalies will shrink, and deficits will persist in many regions of Bolivia. Likewise, deficits are expected throughout much of Chile, moderate overall in the north, mild in central Chile, and exceptional near the Gulf of Corcovado in the south. In Argentina, deficits will remain intense in the northeast and in northern Buenos Aires Province. Surpluses will increase somewhat in the Andes of northwestern Argentina and in pockets in the center of the country, intensifying in La Pampa Province. While shrinking and downgrading, deficits will remain intense in Tierra del Fuego and the Falklands.

From August through October, deficits will remain widespread in Brazil south of the Amazon, downgrading overall though exceptional deficits will persist, especially in the Purus Watershed, Mato Grosso, Mato Grosso do Sul, and São Paulo States. Conditions in much of the continent’s northern third will normalize with pockets of moderate deficit in southern Columbia and the northern portion of the Guianas and severe deficits on Venezuela’s central coast. Deficits in central Peru will shrink and moderate and surpluses from Huancayo into Bolivia will shrink somewhat. Elsewhere in Bolivia, many pockets of deficit will persist, moderate overall but more intense in the center of the nation. Deficits will retreat from the Paraná River but will be extreme to exceptional on the Paraguay River through Paraguay. Deficits will persist in northeastern Argentina and northern Buenos Aires Province and surpluses in the country will shrink and downgrade slightly. Mild deficits are expected in Chile’s southern half and more intense pockets in the north.

In the final quarter – November 2021 through January 2022 – mild to moderate deficits are forecast throughout most of Chile but pockets of exceptional deficit are expected across its northern border into Argentina and Bolivia. Moderate deficits are also forecast for southern Brazil and deficits will persist on Venezuela’s central coast. Surpluses are forecast for a pocket in northern Pará, Brazil, and southeast of Cusco, Peru.

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

IMPACTS
Nearly 400,000 people in Amazonas, Brazil have been affected by flooding after unusually heavy rainfall. In Manaus, the state capital where the Amazon River branches into the Rios Negro and Solimões, the central market was underwater as the Negro began to rise in mid-May and many smaller villages nearby have flooded, forcing evacuations.

Late April brought flooding to several regions of Venezuela as well including the capital, Caracas, disrupting traffic as water flowed through city streets. The San Pedro River burst its banks after a week of intense precipitation in the state of Mérida in the nation’s northwest, damaging 100 buildings and affecting 400 families.

Many Brazilian states south of the Amazon are in various stages of drought, limiting the nation’s hydroelectric production. Federal authorities have approved increased imports of natural gas to increase thermal power production and have postponed maintenance to bring thermal plants to full capacity. November through March rainfall, Brazil’s rainy season, was the lowest in 20 years according to the national grid operator. Brazil normally generates three-quarters of its electricity from hydropower.

One farming community in the Peruvian Andes is refurbishing an ancient, traditional canal system to preserve water. The 1,400-year old system, known as “amunas,” reroutes water to permeable soil, replenishing aquifers and emerging in down-mountain springs. The system helps feed rivers that eventually provide water to the capital, Lima.

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.

Subscribe to our monthly Water Watch List

Search blog categories

Search blog tags