South America: Intense water deficits in French Guiana & Mato Grosso

18 May 2020

THE BIG PICTURE
The 12-month forecast through January 2021 indicates deficits of varying intensity and extent in parts of every nation with large pockets of exceptional anomalies in many regions, most notably Brazil, French Guiana, and Chile.

Though eastern Brazil will be largely spared, deficits are forecast for much of the remainder of the country and will include widespread exceptional deficits in Mato Grosso do Sul, southern Mato Grosso, and Rio Grande do Sul. Intense deficits are forecast along many rivers including the Amazon, Purus, Tapajos, and Xingu. In the east, pockets of surplus are forecast in Rio Grande do Norte, central Pernambuco, and central Minas Gerais curving to the coast.

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Across the northern arc of the continent, exceptional deficits are expected in French Guiana, becoming somewhat less intense through Suriname. Severe to exceptional deficits are expected in northwestern and southern Venezuela, Colombia’s eastern and southwestern reaches, and the bulk of central Peru. Moderate surpluses are forecast for southeastern Peru into Bolivia.

In the continent’s center, deficits will be exceptional in eastern Bolivia and along the Paraguay River through its namesake nation and through Argentina as the river makes its way to the Atlantic. Severe deficits are forecast on the Paraná River that forms Paraguay’s eastern border.

Conditions in the Argentine Pampas will be relatively normal with surpluses in northern La Pampa Province. Surpluses are also forecast for Argentina’s northwestern provinces of La Rioja and Catamarca, deficits in the northeast, and deficits in much of Patagonia. The forecast for Chile indicates deficits throughout much of the nation which will be exceptional in many regions including Valparaiso and Santiago.

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 will shrink and downgrade throughout the region, bringing nearly normal conditions to northern regions of Brazil and parts of Colombia and Venezuela. Deficits of varying intensity are forecast in Brazil from southern Amazonas through the West Central Region and southern states. Anomalies are expected to be exceptional in many pockets including central Mato Grosso, eastern Mato Grosso do Sul, and central Rio Grande do Sul. Surpluses will increase in pockets of eastern Brazil and will emerge in south-central Pará State and in the state’s northern corner. Deficits will shrink in French Guiana and Suriname, downgrading slightly from exceptional. Deficits will increase in Peru’s vast central bulk, persist in many parts of Bolivia, shrink in Paraguay while remaining exceptional along the Paraguay River, and will transition to normal water conditions in Uruguay. In Chile, deficits will downgrade, leaving Santiago and Valparaiso with mild anomalies. Surpluses will persist in the central Argentine Pampas and the country’s northwestern provinces; deficits in the north and south will downgrade.

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From August through October, conditions in nations forming the northern arc of the continent will normalize overall though moderate deficits will increase in Colombia. Deficits will increase in Ecuador as well and will be exceptional along the central coast including Guayaquil. In Brazil, deficits will persist in southern Amazonas and in Brazil’s West Central Region but will retreat from southern states. Anomalies will be exceptional in Rondônia, Mato Grosso, and Mato Grosso do Sul. Surpluses will shrink in eastern Brazil persisting primarily in central Pernambuco and central Bahia. Deficits will remain widespread in central Peru. Bolivia can expect mild deficits in the west and more intense anomalies in the east. Exceptional deficits will persist along the northern portion of the Paraguay River in Paraguay but water conditions will normalize on the river through Argentina. Surpluses will persist in Argentina’s northwestern provinces and in a pocket of the central Pampas; deficits will shrink and moderate in the north and south. Moderate deficits are forecast for much of Chile with some exceptional anomalies in the north.

In the final quarter – November through January – moderate deficits are forecast in much of Chile with some exceptional deficits along the northern half of its border. Brazil can also expect moderate deficits in large pockets; small pockets are forecast scattered throughout other nations. Moderate surpluses will follow the Cordillera Oriental Range in southern Peru into western Bolivia, and some surpluses will linger in easternmost Brazil and re-emerge in northern Pará.

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

IMPACTS
The Paraná River, second only to the mighty Amazon among South America’s longest rivers, is at its lowest level in 50 years, threatening water supplies in Brazil, Paraguay, and Argentina. Reduced water flow on the Paraná due to drought has affected hydropower production and brought shipping to a halt, worrisome to Argentina’s grain producers who rely on the waterway to move grain and oilseed harvests. Brazil and Paraguay, joint operators of the massive Itaipu Hydroelectric Dam on the Paraná, agreed to release water from the dam for twelve days beginning on 18 May to raise the water level for shipping.

Flows on the Iguazu River, a tributary of the Paraná, were at 13 percent of normal at the end of April, and since March the 45,000 residents of Puerto Iguazu, Brazil have relied on bottled water provided by authorities. Concern over water availability in the region has been heightened by COVID-19 pandemic hygiene protocols requiring frequent hand-washing. The Iguazu Falls, a World Heritage site and major tourist venue, has been reduced to a modest stream, stripped of its usual majestic splendor.

Agricultural authorities in the Brazilian state of Paraná have reduced their estimate of the winter corn crop to 8 per cent lower than last season. Poor rainfall in April during a key crop development phase was cited as the culprit.

Lack of sufficient rainfall has impacted agricultural endeavors in several nations of South America’s Grand Chaco, the lowland of the Río de la Plata basin. The Paraguayan Chaco experienced its worst drought in 50 years, decimating much of the soybean crop. Drought in southern Bolivia’s Gran Chaco region is likely to create agricultural loss affecting over 80 per cent of the land planted. Livestock losses are also expected due to absence of pasture.

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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