South America: Water deficit will persist in the Pampas

23 September 2022

THE BIG PICTURE
The 12-month forecast through May 2023 indicates exceptional water deficits in Venezuela through the northern watershed of the Orinoco River Watershed. Surpluses are forecast in the Orinoco Delta.

Surpluses will be widespread in central Colombia reaching extreme to exceptional intensity. Moderate to severe surpluses are forecast in a pocket near Quito, Ecuador.

In Brazil’s far west, moderate to severe deficits are expected, becoming more intense spanning the Peruvian border before moderating in Ucayali and southern Loreto, Peru. In Brazil’s Central West and Southeast regions, moderate deficits are forecast with some small pockets of greater intensity, notably extreme anomalies northeast of metropolitan São Paulo. Intense surpluses are expected in central Bahia’s Chapada Diamontina region and in the small states in Brazil’s eastern tip, though deficits will trace coastal Bahia. Moderate deficits are forecast in southern French Guiana and a few pockets of greater intensity in nearby regions of Brazil.

Central Bolivia will see severe surpluses in the Upper Yapacani River region while deficits are expected in the nation’s south, exceptional in the southern Altiplano.

Widespread deficits are forecast in Chile, exceptional from La Serena through Valparaiso and Santiago to the Gulf of Corcovado. In Argentina, widespread deficits are forecast in the eastern Pampas, moderate in Córdoba Province and near Mar del Plata on the Atlantic but severe to exceptional in a broad path approaching Buenos Aires. Exceptional surpluses are forecast in coastal Chubut Province near the Valdes Peninsula and deficits in Patagonia, intense along several rivers and in Tierra del Fuego.

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

The forecast through November indicates that widespread deficits in Brazil will retreat though extreme deficits will persist in Amapá; moderate to severe deficits from southern Roraima through northern Pará (severe on the Trombetas River); and moderate deficits in far western Amazonas through Acre. Surpluses will persist in central Bahia and in the small, easternmost Brazilian states along with transitional conditions (pink/purple) as some deficits emerge. Deficits will remain intense in northwestern Venezuela from Merida to Caracas, and surpluses will continue in the Orinoco Delta. In western French Guiana, deficits on the Maroni River will moderate while anomalies in the east will be extreme. Surpluses in Colombia and northeast of Quito, Ecuador will downgrade.

Moderate deficits are forecast in central Peru, but anomalies will be exceptional in Ucayali Region. In southern Peru, some surpluses are expected north of Lake Titicaca and severe deficits in a pocket near the city of Arequipa. Mixed conditions are forecast in Bolivia and deficits of varying intensity throughout Chile, exceptional in the south from Bío-Bío to the Gulf of Corcovado, and in southern Patagonia and Tierra del Fuego in both Chile and Argentina. Elsewhere in Argentina, deficits will persist in the eastern Pampas, exceptional approaching Buenos Aires but downgrading as they reach into southern Uruguay. Exceptional surpluses are forecast in coastal Chubut Province near the Valdes Peninsula and deficits in the Falklands.

From December 2022 through February 2023, near-normal conditions are expected in many regions, but deficits of varying intensity will persist in northwestern Venezuela and much of Chile. Surpluses will shrink, persisting in pockets near Quito and in far eastern Brazil, central Bolivia, and Chubut, Argentina. Moderate surpluses will emerge in northern Pará and northwestern Roraima in Brazil.

In the final quarter – March through May 2023 – deficits will linger in northern Venezuela and Chile. Surpluses are forecast near Quito and pockets in central Bolivia, northern Argentina, and Chubut.

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

IMPACTS
The president of Colombia is considering a preemptive declaration of “economic emergency” to address a forecast of significantly increased precipitation. The nation’s Institute of Hydrology, Meteorology and Environmental Studies has warned that the rainy season could last longer this year, well into December, and is expected to be of 40 percent greater intensity in the Andean region. Preparations could include updating flood risk maps and planned population relocation.

Precipitation has been ongoing and destructive in Colombia for the past few months, with several flood events and landslides in Antioquia Department and other regions. Heavy rainfall in early September triggered flooding in the Caldas Department, killing three people and damaging homes, bridges, and roads. Flooding also struck the port city of Baranquilla in Atlantico Department, dragging cars down streets that had turned into rivers. In Bolívar Department, 15,000 homes were damaged and flooding impacted access to food and drinking water.

The start of the corn planting season in the Argentine Pampas has been delayed, much like the nation’s spring wheat planting, during what is being described as the the driest conditions in three decades. The grain exchange is adjusting its corn planting estimate down and soy estimates up as corn acreage is being converted to soy. Some wheat farmers have simply given up, abandoning lots to the drought.

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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