The Cantareira water system, largest of the six reservoirs that provide water to 20 million people living in the metropolitan area of Sao Paulo, Brazil is at 5.6% (as of January 20) of its capacity of one trillion liters (264 billion gallons), as reported by the water utility Sabesp. During the first two weeks of January 2015 rainfall totaled 7.1 centimeters (2.9 inches), well below the average 27.1 centimeters (10.7 inches). This comes as a result of the worst drought Brazil has faced in 84 years.
In all, the reservoir has lost 1.6 percentage points of the stored volume of water from the first day of the year.
Reservoirs and rivers that provide water to millions have received less rainfall than hoped for during the first weeks of the wet season, also seen by the state in other five water systems: Alto Tiete is at 11 percent of capacity, Rio Claro 25 percent, Alto Cotia 30 percent, Guarapiranga 40 percent and Rio Grande 70 percent.
In 1960, the São Paulo state government decided to enhance the water supply of the Metropolitan Region of São Paulo by constructing several reservoirs in the headwaters of Piracicaba River basin, creating the Cantareira System.
Number of days without rain. Image credit: INPE/CPTEC
Brazilian mega cities along the east coast like São Paulo and Rio de Janeiro are home to 80% of Brazilians, they rely on their own river basins and thanks to their rapid growth and development they find themselves water stressed. The estimates are that the regions that supply 73% of the country’s water needs could face shortages over the next decade. Brazil is the world’s leading exporter of soybeans, coffee, orange juice, sugar and beef, so these water stresses can also have a marked impact on the global food market.
São Paulo climate graph in metric units. Image credit: Sao Paolo Climatemps
Deforestation of the Amazon could interfere with the forest’s function as a giant water pump. Trees lift vast amounts of moisture up into the air, which then circulates west and south, falling as rain to irrigate Brazil’s central and southern regions.
“Destroying the Amazon to advance the agricultural frontier is like shooting yourself in the foot. The Amazon is a gigantic hydrological pump that brings the humidity of the Atlantic Ocean into the continent and guarantees the irrigation of the region. Of course, we need agriculture. But without trees there would be no water, and without water there is no food.” Said Antonio Nobre, a leading climate scientist at INPE.
Tree cover loss in South America from August 2012 to present. Image credit: Global Forrest Watch
Featured image: Aerial view of Sao Paolo, Brazil. Credit: chensiyuan/Wikimedia