South America: Water deficits to persist in central, eastern Brazil & in Chile

17 February 2017

The Big Picture
The forecast through October 2017, as seen in the 12-month map (below), shows widespread deficits in much of Brazil including a vast extent of exceptional deficits in Brazil’s eastern mid-section. Deficits are also forecast for Venezuela, French Guiana, Bolivia, and Chile.

Surpluses are forecast for central Loreto region in northern Peru and La Pampa, Argentina.

Impacts
The Cedro Reservoir in Ceará, Brazil - with a capacity of 50,000 Olympic swimming pools - lies completely dry, littered with turtle carcasses and fish bones, a sobering symbol of the drought that has gripped the country's northeastern region, known as the Sertao, for the past five years. There has been almost no rain since 2012, leaving reservoirs at around 6 percent capacity or empty. Farmers are de-stocking what few cattle and donkeys remain alive, fetching meager prices. Rural communities rely on government water trucks or expensive private deliveries; those who dig wells find the water too salty to drink.

The level of Lake Araros near Varjota, Ceará has plunged in the last four years, and conditions in the nearby State of Paraíba are no better. Residents of Campina Grande have never seen the Boqueirão Reservoir so low, now at 4 percent of capacity. Nearly 400,000 people depend on the reservoir and after two years of water rationing they are running out of options. "If it does not fill up, the city's water system will collapse by mid-year," says Janiro Costa Rêgo, a water resources expert.

Though their numbers are dwindling, some senior citizens in Ceará can recall being forced into "government corrals," drought concentration camps set up by the government in 1932-33 to prevent mass migration from drought-ravaged rural areas to the city of Fortaleza.

Facing drought and a plague of locusts, Bolivia is looking to the United Nations' Green Climate Fund for US$250 million to help mitigate the impacts of climate change. The worst drought in 25 years led to the declaration of a state of emergency, in place since November, accompanied by water rationing. The 800,000 residents of La Paz are adapting to a world without water. Bolivian hydrologist Edson Ramirez estimates that 37.4 percent of tropical glaciers around LaPaz disappeared between 1980 and 2009.

Meanwhile, a plague of locusts is threatening corn and sorghum harvests in Bolivia's eastern grain belts, affecting around 1,000 hectares (2,470 acres) of crops and 500 producers and forcing the country to import more than 100,000 metric tons (110,230 US tons) of corn worth $21 million in 2016.

Heavy rains in Peru caused flooding that affected over 90,000 people in the northern region of Piura, leaving 2 people dead, 2,450 people displaced, 500 homes destroyed, and 19,000 homes flooded. Flooding was also reported in Lambayeque, with 1 fatality, 1,877 homes destroyed, and over 60,000 people affected.

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

Though the extent of water deficits in South America is expected to shrink overall February through April, severe to exceptional deficits are forecast in central Brazil affecting southern Pará, Tocantins, Mato Grosso, Goiás, Bahia, Minas Gerais, São Paulo; as well as pockets in some western states. Clearly visible on the map is a path of exceptional deficit that traces the São Francisco River in the east.

Deficits in Bolivia are forecast to shrink in extent but severe to exceptional deficits are expected to persist in large pockets. Likewise, though the extent will shrink slightly, much of Chile will remain in deficit conditions ranging from severe to exceptional. Exceptional deficits are forecast along some rivers in southern Argentina. Moderate to severe deficits are forecast in northwest Venezuela and southern Peru, particularly along Peru’s coast.

Surpluses will continue to emerge in central and northeastern Argentina; Rio Grande do Sul, Brazil; northern Peru; and eastern Colombia.

From May through July severe to exceptional deficits will persist in eastern Brazil and severe deficits will emerge in northernmost Pará and will continue to emerge in nearby Amapá. Much of the Amazon Basin will transition to near-normal water conditions. Moderate to severe deficits are expected to emerge in western Colombia and some moderate deficits are expected in Venezuela. Deficits will retreat in Bolivia except for a large central-south area. Deficits along Peru’s coast will increase in intensity, becoming exceptional. Exceptional deficits will persist in northern Chile, creeping further north, while prior deficits in southern Chile are expected to retreat almost entirely.

Surpluses will continue to emerge in central and northeastern Argentina.

The forecast for the latter months – August through October – shows an increase in the extent and severity of water deficits across northern South America along with persisting deficits in eastern Brazil.

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