São Paulo's relationship with water

A study conducted by University of São Paulo shows that the problems of water scarcity and flash flooding have similar historical roots.

By Karina Toledo

Agência FAPESP – Two apparently opposite problems that affect the São Paulo Metropolitan region – water scarcity and flooding – have similar historical roots: misguided public policies, which often cater to private interests, and an appropriation process that excludes water resources and capital floodplain areas.

This analysis, made by geographer Vanderli Custódio, professor at the Universidade de São Paulo’s Brazilian Studies Institute (IEB-USP), is presented in a book recently released by Editora Humanitas (Escassez de Água e Inundações na Região Metropolitana de São Paulo).

The work, published with funding from FAPESP, brings together texts produced during Custódio’s masters and doctoral programs, both at USP’s Geography Department.

The first three chapters outline the urbanization process that created both water scarcity and flooding problems.

“There was an iniquitous and exclusive appropriation of water resources from the basin of the upper Tietê, from the source of the river in Salesópolis to the dam in Pirapora do Bom Jesus. This allocation  prioritized power generation, as if there was not a metropolis that depended on this water for its supply,” affirms the researcher.

Custódio is referring to the concession given to the São Paulo Tramway, Light and Power Company (known as Light) at the beginning of the 20th century to exploit the region’s water resources for power generation for 90 years.

The measure helped to broaden the industrial park and transform São Paulo into “the locomotive of Brazil.” However, this growth was not accompanied by an evaluation of environmental concerns. The pollution generated by industrial processes and increasing population density made the water useless for anything other than power generation.

“The rivers became too silted up for transportation. They are not suitable for fishing, leisure or recreation. They became channels of sewage, basically. But this polluted water once generated energy, development and progress,” she comments.

The effects of this policy began to be noticed at the end of the 1980s, when the Metropolitan Region faced its first supply crisis. The situation worsened in the following decade and today remains in a fragile balance.

“With all its systems working at maximum capacity, the São Paulo State water company Sabesp can produce approximately 67 cubic meters of water per second. The Tietê’s flow rate when it crosses the Metropolitan Region is 82 cubic meters per second.  It is enough to supply everyone and have surplus water,” says Custódio.

Light also had a decisive role in the flooding issue, which is a more delicate and difficult matter to resolve, according to Custódio. The company was responsible for restoring the Pinheiros River. The Tietê was restored by the São Paulo State government. The two projects, according to the author, were inadequate.

“The rivers ended up narrow and subdimensioned. Light appropriated the floodplains, which were appreciating in value, and sold them to the real estate market,” explains Custódio.

The project to build riverside expressways was another major mistake of public management. To make room for the roads, the space for the rivers was reduced. The soil was made impermeable,” she says.

Custódio also cites another important cause of flooding: the methods used during roadway construction and the opening of lots for housing.

“You have an elevation in the South, which is the Serra do Mar mountain range. To the North, we have the Cantareira range. When there is any land movement, the residue goes to the bottom of the basin, which is the Tietê River. It is more expensive to do it right, so consideration of the appropriate construction to avoid run-off receives secondary priority,” she explains.

These problems, coupled with the lack of adequate maintenance of storm sewers and the tendency for strong downpours in the summer, led the researcher to believe that the capital will continue to suffer from flooding for many years to come. “I am pessimistic. I don’t see a definitive or a short-term solution,” she said.