South America: Intense water deficits forecast in central Brazil

23 June 2022

THE BIG PICTURE
The 12-month forecast through February 2023 indicates widespread water deficits of varying intensity in Brazil’s Central West region through the Southeast, as well as pockets of deficit elsewhere. Deficits will be exceptional in several areas including Mato Grosso and Mato Grosso do Sul. Intense deficits are also expected on the Paraná River between the Ilha Solteira Reservoir and the Itaipu Reservoir. Some pockets of deficit are expected in the Northeast region including Piauí as well as pockets of surplus in Rio Grande do Norte, Alagoas, and central Bahia. Surpluses are also forecast in pockets of Amazonas.

Across the northern arc of the continent exceptional deficits are forecast from Merida, Venezuela to Caracas; in a belt between the Ventuari and Upper Orinoco Rivers in southern Venezuela; and in French Guiana, moderating as they reach into nearby regions across the borders. Surpluses are forecast in much of central Colombia and a pocket northeast of Quito, Ecuador.

In Peru, exceptional deficits are forecast in the middle reaches of the Ucayali River Watershed, moderate deficits in Loreto in the north and Arequipa in the south, and deficits of varying intensity in much of central Peru. A pocket of surplus is predicted near Trujillo on the north coast and surrounding Huancayo in the central Peruvian Andes. Surpluses are also forecast from Lake Titicaca through La Paz, Bolivia and in the Upper Pilcomayo and Upper Grande River regions of southwestern Bolivia. Deficits are forecast in several other regions of the nation, particularly in the east where anomalies will be exceptional.

Deficits are forecast through central Paraguay and pockets of the Chaco region in Argentina. The northern and eastern Pampas can also expect deficits, severe to exceptional from the Upper Tercero River to Buenos Aires. Exceptional surpluses are forecast in coastal Chubut Province, but areas of exceptional deficit are also expected in Patagonia including along the Chico River.

Mixed conditions are predicted for northern Chile, but exceptional deficits will reach from La Serena through Valparaiso, Santiago, and most of the nation’s southern extent. Exceptional deficits are forecast in Tierra del Fuego and moderate to severe deficits in the Falklands.

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

The forecast through August indicates widespread, exceptional deficits across central Brazil from Mato Grosso into Minas Gerais and from Tocantins in the north into São Paulo State, downgrading as they reach beyond those regions. A pocket of exceptional surplus is forecast in central Bahia and surpluses of lesser intensity are expected in pockets of Brazil’s eastern tip and in much of Amazonas. Surpluses of varying intensity are expected from Ecuador though much of Colombia, parts of southern and eastern Venezuela, and coastal Guyana. Deficits will be intense surrounding Merida, Venezuela and moderate to severe in French Guiana, moderating through Amapá, Brazil. Mixed conditions are forecast in Peru, including deficits in the center of the country, exceptional from Ucayali into Brazil, and in Arequipa in the south. Areas with a forecast of surplus include central Loreto in the north and Huancayo in the south. Moderate surpluses are forecast from Lake Titicaca past La Paz, Bolivia, and south of Lake Poopó. Deficits are forecast in many other areas of the country.

Severe deficits will trace the path of the Bermejo River in northern Argentina and mixed conditions are expected in the northwest. Severe to exceptional deficits are expected in the northern and eastern Pampas, intense in Buenos Aires but downgrading in southern Uruguay. A pocket of moderate surplus is forecast in the central Pampas. Generally moderate deficits are expected in Patagonian Argentina though intense surpluses are forecast in coastal Chubut. Deficits are forecast throughout much of Chile, moderate in the north but exceptional in the south. Deficits will be intense in Tierra del Fuego and severe in the Falklands.

From September through November, anomalies will shrink and downgrade considerably, leaving nearly normal conditions in many regions, notably Brazil. Moderate to severe deficits are forecast in Roraima and moderate deficits from the Guianas through Amapá. Pockets of deficit are expected in northwestern Venezuela, central and southern Colombia, central Peru into Brazil, and from Arequipa through most of Chile to the Gulf of Corcovado. Some moderate deficits will linger in Bolivia and surpluses in the west. In Argentina, mixed conditions will persist in the northwest, intense deficits in Buenos Aires Province between the Paraná and Salado Rivers, and deficits in pockets of Patagonia. Intense deficits will persist in Tierra del Fuego and the Falklands. Surpluses will emerge west of the South Patagonian Ice Field.

The final quarter – December 2022 through February 2023 – deficits are forecast in the Guianas; Mato Grosso do Sul, São Paulo, and Paraná, Brazil; central Paraguay; Chile; and pockets in eastern and Patagonian Argentina. Surpluses are forecast in pockets of northeastern Brazil, from southern Minas Gerais into Rio De Janeiro, and from Cusco, Peru past La Paz, Bolivia.

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

IMPACTS
Flooding and landslides in northeastern Brazil left 128 dead after torrential rainfall in Pernambuco State. The late-May downpour sent rivers of mud roaring through communities near the city of Recife, burying entire neighborhoods. The state has promised compensation of 1,500 reais (US $315) to each of the 82,000 families who lost homes and property in the disaster.

Multiple flood events occurred in Colombia in June triggered by heavy rainfall. In early June, storms pushed the Cali River in its namesake city over flood stage, inundating 20 homes in Floralia and spawning mudslides in the Siloé area. Heavy precipitation mid-month left eight dead due to a landslide in Cauca Department and affected several hundred people in other regions.

In Rio Negro Province, Argentina one person died after heavy rainfall created a mudslide that hit a hotel in a popular Patagonian tourist area. Across the border in Los Rios Region, Chile, flooding damaged roads and houses.

Drought in Argentina has agricultural forecasters predicting a drop in the nation’s wheat production, expected to be the worst in 12 years, as planting in the Pampas is delayed.

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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