Prevention

The search for solutions to the problems created by the urbanization model imposed on the city's complex geomorphological site is also part of our history. Prevention processes and actions always come in the wake of episodes, catastrophic or not, that beset the city. Even the landfill and river channeling processes had this connotation at some point in the urbanization. Coexisting with mangroves, marshes, wetlands, lagoons, torrential rains, and hillside landslides was and still is, after all, a historic challenge to occupation, and solutions were provided according to the beliefs and technology of the time.

A historic landmark in the risk-prevention processes in the City of Rio de Janeiro is the creation of GeoRio (Fundação Instituto de Geotécnica do Município do Rio de Janeiro), in 1966, in response to the major rain event that brought down hillsides in the neighborhood of Santa Teresa, leaving a few dozen dead. This was undoubtedly a positive response from City Hall, creating a foundation responsible for geological-geotechnical studies, risk mapping, and the recommendation of containment works. Golden years of the 1970s and 1980s, when major works were carried out and many hillsides were cleared of the risk they posed. Even today, the agency's skilled technicians, supported by several universities that developed their own geotechnical study centers, ensure the safety of many of our hillsides.

Once again, in response to catastrophic episodes, in this case the 1996 landslides, GeoRio created the "Alerta Rio" Warning System, with an extensive network of rain gauges, monitoring precipitation input over the city in real time, with measurements every 15 minutes and allowing alerts to be issued to the entire population of Rio. In the beginning, it already started to exist in the form of a website, on the nascent Brazilian internet, and today it is available on mobile phone systems. Expertise in geotechnology and geoprocessing was essential for building a warning and risk-area mapping system. It created a database on the hillsides and areas prone to disasters, using satellite imagery, radar, and field surveys, which allowed for greater precision in identifying critical locations. The Alerta Rio System was upgraded, expanding the city's forecasting and response capacity. The system, which involves 33 weather stations and sensors spread across the city, carries out real-time monitoring of weather conditions and provides forecasts on rain and storms. This monitoring network began providing detailed, advance information, not only about rainfall intensity but also about the probability of landslides in high-risk areas. Alerta Rio became an essential tool for authorities and for citizens themselves, who began receiving timely notifications, enabling more efficient evacuations and preventive actions.

After the 2010 accidents, the Rio Operations Center was created, now renamed the Operations and Resilience Center (COR), which centralized the coordination of emergency actions in the city. COR integrates various areas of the municipal administration, including Civil Defense, the Municipal Guard, and the Fire Department, allowing for a faster and more coordinated response in risk situations. Through an integrated monitoring system, COR is able to issue real-time alerts about areas affected by heavy rains, landslides, and flooding, as well as coordinate the mobilization of resources to the most impacted regions. As the institutional text itself states: "COR has a unique and unprecedented dynamic. Before its creation, rains and other events would catch the public administration and Rio residents by surprise. After COR, solutions are anticipated, alerting the responsible sectors about the risks and the urgent measures that must be taken in cases of crisis."

These joint actions, which combine cutting-edge technology with an emergency response structure, reflect the Rio City Hall's effort to prevent natural disasters and minimize damage to the most vulnerable communities. However, despite these advances, the challenge remains the occupation and growth driven by the logic of the real estate market, which sees the city as a business opportunity rather than a place for good living. Of course, beyond emergency measures, the city requires a more robust and sustainable urban restructuring. Integrating monitoring technologies with public management is an important step, but it is still necessary to deepen responsible urbanization policies to prevent tragedies from happening again.

Over the past few decades, the City of Rio de Janeiro has carried out several projects aimed at mitigating the impacts of flooding, especially in low-lying areas with poor drainage. Among the main initiatives are the construction of stormwater retention basins (piscinões) and the modernization of drainage systems, which seek to increase the capacity for rainwater runoff and reduce urban flooding.

One of the highlights of the anti-flooding works was the Piscinão da Praça da Bandeira, built in the Zona Norte, a region historically affected by flooding due to its proximity to the Rio Maracanã and the area's topography. The project serves to increase the neighborhood's drainage capacity and reduce flooding in the surrounding areas. This piscinão temporarily stores rainwater, helping to relieve the region's drainage systems, which previously could not handle the volume of rainfall.

These works are part of a series of infrastructure initiatives aimed at flood control in the municipality, alongside the improvement of drainage networks, the construction of storm drains, and the development of monitoring and alert systems, such as Alerta Rio. However, they act on the effect, meaning they work to correct historical errors in the city's construction process, but they do not prevent new areas from continuing to be developed under the same patterns of urbanization. Therefore, in the future we will have to act on the effect once again, increasing public spending on alert systems and monumental works.

Image description: The image is an informative graphic about investments in landslide prevention during the Summer Plan (Plano Verão). On the left, there is textual information about investments and interventions on hillsides. In the center, there is a map with blue circles distributed across different regions, representing areas where interventions were carried out. On the right, there is a comparative chart of hillside interventions between the periods 2018-2020 and 2021-2023. The colors are predominantly blue, green, and white.

Rio de Janeiro city government's official website with the main actions for rain prevention, updated every summer.

Image description: The image is an informational poster about the Rainy Season Action Plan. It is divided into three main sections, each with a title and corresponding images. From left to right, the first section, "Technology," shows a weather antenna in a clear blue sky, with trees in the background. The second section, "Prevention," features an excavator in a construction area with vegetation. The third section, "Response," shows workers on a street, wearing safety equipment. Each section has a title in blue and explanatory text below.

Main technologies and prevention actions featured on the Rio City Hall website

Image description: The image is a rainfall report for May 2025. It is laid out in a table with three main columns: station number, station name, and rainfall values. The first column lists numbers from 1 to 25, representing different weather stations. The second column shows the names of these stations. The third column displays rainfall values in millimeters for each station. The table colors are light blue and white, with black lines separating the cells.

Presentation of rainfall data provided by the Rio de Janeiro city hall's Alerta Rio website

Image description: The image is a rainfall map updated at 4:13 PM on 06/01/2025. The spatial layout begins on the left, with protected areas and highways, moving through cities such as Queimados and Nova Iguaçu, until reaching the central region with green markers indicating rainfall points. On the right, Guanabara Bay and the city of São Gonçalo stand out. The colors are predominantly green and blue, representing natural areas and water, respectively.

Map of the rainfall gauge stations of the Alerta Rio system of the Rio City Hall

Image description: The image is a map showing the probability of landslides in different areas of Guanabara Bay. On the left, there is a detailed map with areas marked in green, representing areas of low landslide probability. On the right, there is a table with information about the current situation of the mentioned areas. The last update was at 09:00 on 06/01/2025.

Landslide risk map based on incoming rainfall, updated every 15 minutes by the City of Rio's Alerta Rio System