TRACKING THE FUTURE OF CITIES
By: Brian Clark Howard
October 24, 2014 (National Geographic)
Rainfall totals in the region this year are 12 to 16 inches (300 to 400 millimeters) below normal.
According to a poll conducted this week, 60 percent of respondents in São Paulo reported that their water supplies have been restricted at least once in the past 30 days. Three-quarters of those people said the cut lasted at least six hours.
The Landsat 8 images above show Jaguari Reservoir, one of five lakes in the Cantareira System that supply water to roughly half of the 20 million people in the São Paulo metropolitan area. (Another 20 million live in São Paulo state.) The images show the reservoir in August 2013, before the recent drought began, and again in August 2014.
NASA satellite images show Jaguari Reservoir in August 2013, before the drought, and in August 2014.
The water appears as a lighter color in 2014 because it is shallower. In the two months since last August, the reservoir has shrunk from 12 percent of capacity to 4 percent. (See “Aral Sea’s Eastern Basin Is Dry for First Time in 600 Years.”)
Last austral summer (December to February), when the region normally would have been at its wettest, precipitation was only one-third to one-half of the long-term average. Since then, rainfall has been about 40 percent of normal.
Marcos Heil Costa, a climate scientist at the Universidade Federal de Viçosa, told NASA that the drought has been “unprecedented.”
Lack of water has hurt coffee farmers and other growers in the area and may hamper economic growth, state officials warn. On Tuesday, a top government official told city dwellers that they may be headed for more severe shortages.
“If it doesn’t rain, we run the risk that the region will have a collapse like we’ve never seen before,” Vicente Andreu, president of Brazil’s National Water Agency, told state lawmakers.
Some scientists have suggested that the recent uptick in deforestation in Brazil may be partly responsible for the drought, since loss of evapotranspiration from trees is known to reduce cloud formation.