Study highlights factors associated with the risk of flooding in Heliópolis, São Paulo’s largest favela

Booklet summarizes the results of a survey conducted by groups from the Center for Favela Studies and the Laboratory of Urban and Regional Studies and Projects of the Federal University of ABC; the material was presented to the community at a workshop held in February.

Agência FAPESP – The interventions carried out by the public authorities to address the problems caused by excessive rainfall in Heliópolis, the largest favela in the city of São Paulo, did not cover all the areas that suffer from flooding in the community, nor did they consider smaller-scale measures that could reduce the number of areas affected by heavy rainfall. In addition, no project was developed to occupy the banks of the Independência stream, resulting in the rebuilding of small, unhealthy houses on the banks and the reoccurrence of flooding in some areas.

These are the main results of a study carried out between 2023 and 2024 by a group of scientists associated with the Laboratory for Urban and Regional Studies and Projects of the Federal University of ABC (LEPUR-UFABC) and the Center for Favela Studies (CEFAVELA), a FAPESP Research, Innovation and Dissemination Center (RIDC). The study is part of a larger project entitled “Urbanized Favelas in São Paulo: the built environment and post-construction appropriation,” coordinated by Rosana Denaldi and Luciana Nicolau Ferrara, deputy director and associate researcher of CEFAVELA, respectively.

The conclusions are included in the booklet Águas na Quebrada (which translates as “waters in the hood”) and were presented to the Heliópolis community by CEFAVELA and LEPUR researchers at a workshop held last February at the headquarters of the Union of Nuclei, Associations of Residents of Heliópolis and Region (UNAS), a partner organization in the research. Participants included representatives from various Heliópolis centers, as well as young people from the Observatório De Olho na Quebrada (“Eyes Upon the Hood Observatory”), a UNAS project, and the organization’s director, Manoel Otaviano da Silva.

“Our goal in conducting the study is to provide data to discuss environmental quality and how drainage works and interventions in streams affect housing, public areas and community life,” says Ferrara. According to data from the 2022 Demographic Census, Heliópolis is home to 20,205 households with 55,583 inhabitants. Of these, an estimated 31,183 residents, spread across 13,346 households, are registered with CadÚnico, the federal government’s system for registering and enrolling low-income families in social assistance programs.

The researchers from CEFAVELA and LEPUR complemented the analysis of the flooding problems in Heliópolis with the collaborative mapping carried out by the De Olho na Quebrada observatory. The residents’ own initiative to do this mapping came about because they realized that the official government sources, such as the Climate Emergency Management Center, the São Paulo Flood Alert System and GeoSampa, are incomplete and do not cover various areas of the favela that flood. The results of this mapping were presented in January 2024.

The findings

During the technical evaluation of the collaborative mapping of flood points carried out by the De Olho na Quebrada observatory, the researchers noted that the Mina and Lagoa nuclei have already undergone urbanization interventions, but part of the territory was not covered by the projects of the federal government’s Growth Acceleration Program – Urbanization of Precarious Settlements (PAC-UAP).

The omission of part of the region has led to a more precarious situation in some alleys (vielas) where there is a high density of buildings and population. The situation is not isolated and is even more serious because these alleys are located at lower points and, due to the lack of an adequate drainage system, they become areas of flooding during rainy periods, as the water enters the alleys and has nowhere to go.

Adding to the problem is the compromise of existing infrastructure and the lack of adequate maintenance and cleaning. “Residents reported that they organize themselves to pay a person to clean the self-built drainage boxes when they become blocked,” the researchers say in the study. “There is therefore a situation of internal socio-environmental inequality. This problem is structural to the organization of space in Heliópolis, and its solution would depend on new urbanization and infrastructure interventions,” the research points out.

Another critical issue identified in the study and discussed in the workshop is garbage. Heliópolis has regular daily collection, except on Sundays. Nevertheless, the amount of waste is high. For their part, the residents put the garbage out at inappropriate times. When it rains, the waste clogs the surface drainage system. The research suggests that community awareness should be improved and recommends the installation of garbage cans and other waste disposal strategies.

Critical analysis of the PAC-UAP

Another part of the study analyzed the interventions carried out by the PAC-UAP in the Independência stream, located in the Redondinhos/João Lanhoso Nucleus of Heliópolis. In order to carry out the macro-drainage works, it was necessary to remove houses, in a process mediated by UNAS and started in 2005. Between 2008 and 2016, the alleys were urbanized and the stream was channeled, as is usual in macro-drainage projects, but nothing was planned for the unoccupied banks, which could have had a green area and spaces for common use.

In Viela Sabesp, for example, the residents have respected the common decision not to use the now vacant space around the stream for housing, but have built other types of structures that complement the space of the houses. In Viela Gaivotas, where the Independência stream flows into the Meninos creek, there has been reoccupation, which has resulted in the channel being walled off. Residents report recurrent flooding along this stretch. “Therefore, an intervention aimed at the environmental qualification of the stream area, removing dwellings from risk areas, has not been completed and has created new precarious and risky situations in some sections,” the research points out. The PAC project did not take into account the high demand for space in Heliópolis, which is densely populated, and did not propose ways of using and occupying the land that would guarantee the quality of housing and common spaces.

Scientific basis for the community’s struggle

The workshop to present the Águas na Quebrada booklet was coordinated by Ferrara, with researchers from the team as facilitators. In addition to presenting the data from the study, they worked with the participants on environmental and geographic concepts. They also gave general advice on what to do in case of flooding. The participants were also able to start a discussion about the problems and possible solutions based on the data and guidelines in the booklet.

The workshop was held in two parts. In the first, some of the concepts related to the problem of flooding were presented, such as the watershed and the difference between flooding, inundation and submergence, among others. In the second part, the results of another study of the CEFAVELA-LEPUR group on the quality of housing were presented.

Denaldi handed over to Antonia Cleide Alves, president of UNAS, a complete study with all the data on Heliópolis from the 2022 Census already available from the Brazilian Institute of Geography and Statistics (IBGE).

“Holding the workshop is part of our extension activities because it’s important to give this feedback to the community. Our principle is always to work in partnership, to give a voice to those who live in the area and to produce results that help them in their daily lives,” says Denaldi.

According to the researcher, the aim of disseminating the results is to support the community when it is the target of interventions in the area, both by public authorities and the private sector. “By sharing the knowledge we’ve produced, we help them to think about and discuss solutions to their problems and challenges, based on their knowledge and life experience, as well as technical and scientific data.”

The Águas na Quebrada booklet is available at: cefavela.ufabc.edu.br/wp-content/uploads/2025/02/cartilha-aguas-na-quebrada.pdf.

* With information from CEFAVELA