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Drought in the Metropolis

São Paulo has had other droughts in the past, almost always related to the increase in population

The Bispo Creek dam, part of the old Cantareira Supply system in 1893

SABESP archivesThe Bispo Creek dam, part of the old Cantareira Supply system in 1893SABESP archives

Experts are familiar with water scarcity cycles.  Even São Paulo, far from Brazil’s semiarid regions, experiences periods of drought that are sometimes prolonged.  The problem becomes acute when the lack of rain occurs at the same time as a major increase in demand.  Looking at past droughts in the Metropolitan Region of São Paulo (MRSP), it is easy to perceive that relationship.  “We always remember the population boom of the 1950s and 1960s, but forget about the drastic increase in population between the end of the 19th century and the 1940s,” says Ricardo Toledo Silva, professor at the School of Architecture and Urban Studies at the University of São Paulo (FAU/USP), who is researching the integrated management of urban water infrastructure and sanitation.  Records indicate that the impact of the two factors—drought plus population growth—has brought about previous water shortages in the region.

“Between 1874 and 1900, the state capital saw its population increase approximately tenfold (from 23,253 to 239,820 people).  When calculated from 1857 to 1940, it became 57 times larger (from 23,253 to 1,326,261),” Toledo reports.  “That’s a very big jump.  There were fewer people than there are today, but everyone lived in small areas.”  The uncontrolled growth of urban units is degrading the environment, making the soil less permeable, creating islands of heat, occupying riverside zones, and affecting the volume of rainfall.

Laying the water mains in the Tatuapé neighborhood to supply the Belenzinho reservoir in São Paulo (undated photo)

SABESP archivesLaying the water mains in the Tatuapé neighborhood to supply the Belenzinho reservoir in São Paulo (undated photo)SABESP archives

The great drought of 1924 and 1925 led The São Paulo Tramway, Light and Power Company, known popularly simply as “Light” and responsible for supplying electricity to the city of São Paulo, to publish an announcement in the newspapers on February 24, 1925, listing actions it would take so it would not have to completely suspend the supply of electric power.  Light would start using the steam-driven power plant that it already owned, install new generators and turbines, complete a plant then under construction, and build a new hydroelectric facility.  It would also start buying electricity from the electric company in Campinas.

Another serious drought occurred between 1951 and 1956.  The worst year was 1953.  The water shortage of 1969 was also covered intensely by the press, because of the severity of the rationing.  Now, in the 21st century, according to Toledo, the most notorious drought in the region occurred in 2003 in the area served by Cantareira, the biggest metropolitan reservoir system.  The current drought, in 2014, promises to be the worst of any since 1930, when authorities began recording measurements in the MRSP.

“The population suffers from two types of water shortage: scarcity at the source, and scarcity in the distribution network,” explains the researcher, who is also a technical advisor to the São Paulo state government’s Special Advisory Board for Strategic Affairs.  These days, water shortages caused by problems in the distribution network are merely episodic, occurring because of some accident.  “But in the São Paulo of the 1920s to the 1970s, both situations often occurred simultaneously.”

Construction of the Rio Claro Reservoir System, built in Salesópolis in 1936 to increase the water supply

SABESP archivesConstruction of the Rio Claro Reservoir System, built in Salesópolis in 1936 to increase the water supplySABESP archives

The water supply became a serious social problem in the São Paulo capital city in the final 30 years of the 19th century.  The solution in 1877 was to establish the Companhia Cantareira de Água e Esgoto—taken over by the state in 1892.  In the 20th century, reservoir systems were built to increase the supply, and included such projects as the Rio Claro (in the 1930s and 1940s), the Alto Tietê, and the new Cantareira (both from the 1970s).

“To prevent a water shortage, long-term structural steps are needed, such as rezoning of both the urban and regional territory, starting with the construction of additional water infrastructure,” says Toledo.  Previously limited to the little province of 19th century São Paulo, planning now must involve the entire São Paulo Macrometropolis, which encompasses 180 municipalities—including the capital city—and is home to 31 million people.  A Master Plan for Use of the Hydric Resources was adopted for the São Paulo Macrometropolis and the final reports were ready in October 2013.  The study points out the need to develop new water capture systems and reservoirs, better control water losses, encourage rational use of water, and find ways to reuse it.