Study of Landslide Risk Areas in Rio de Janeiro, Brazil

Rio de Janeiro, RJ, Brazil

By Mariana Barros
landslide, environmental risk, vulnerability, inequality

This project consists of mapping landslide risk areas consequent from heavy rainfalls in Rio de Janeiro and understanding the residents’ profile

The city of Rio de Janeiro is located in the Southeast coast of the Brazilian territory facing the Atlantic Ocean and surrounded by the Atlantic Forest. The climatic condition is Tropical, dry in the winter and very humid during summer months, when the rain hits stronger. The city is known by its beautiful beaches and mountainous landscape but also presents an outstanding scenario of social inequality. In the late 1800s and early 1900s a migration wave started to happen from the interior of Rio de Janeiro and other states. People moved to the city looking for better work conditions and opportunities. It was during this period that the favelas emerged.

The favelas are settlements of informal housing located in irregular land areas. Many times, lacking in urban infrastructure and essential public services such as water supply, basic sanitation, electricity and waste management. The residents are low-income families who usually have underemployment for want of better opportunities. During the 60s, the government applied a public housing program targeting the elimination of the favelas that leaded to displacement of many people. However, since then, these communities have not stopped growing and facing risks.

This introduction is important to understand the social inequality scenario and living conditions of part of the population in the city. As you can see in the income map, wealthiest neighborhoods are located closer to the beach in the South Zone and West Zone of the city.

The city center and job hub are situated in the east side closer to the Guanabara Bay narrow entrance; those are the areas with better accessibility to public transportation (subway stations and bus stops). Such as any other metropolis, the traffic in Rio de Janeiro is chaotic particularly during rush hours. Some commuters take up to 2 hours to get home after work. Therefore, it is comprehensible that some favela residents aim to live close to their jobs.

Rocinha is the major example of informal community in the South Zone of Rio, it is also the largest favela in Brazil housing over one hundred thousand people. The neighborhood occupies part of one mountain from the Tijuca Massif, and border with an Environmental Protection Area. Unfortunately, in this case, irregular urbanization and deforestation exist alongside. The lack of vegetation facilitates soil erosion and allow landslide to happen more often, especially with the incentive of rain. Therefore, the favelas situated on hills are the ones that suffer the most with heavy rain, mass movement, landslides and flash floods, resulting in natural disasters. Not only because of the geolocation but also because of the lack of urban infrastructure, governmental policies and architectural support.

The Brazilian National Center for Monitoring and Early Warning of Natural Disasters (Cemaden) is a federal public institution created in 2011 after a major catastrophe which resulted in chaotic scenarios with records humanity loss in the state of Rio de Janeiro and other regions of the country. The major role is to respond to disasters and also take prevention action. This agency monitors over 870 municipalities in Brazil and in 2013 they could develop a Statistical Basis of Risk Areas for the territory, called BATER. The document maps the risk areas and presents the characteristics of vulnerable population to natural disasters.

One notable characteristic of this data is the separation of “Subnormal Agglomerates” defined as “assortment of, at least, 51 low income residents, distributed in a disordered and/or dense way, most of them lacking in essential public services”, in other words, the favelas.

During the past decade, the frequency and amount of rainfall has increased. As presented before, the period with most occurrence of rain is the summer and early spring, from December until April. The median amount of rain for these months is 130mm (5.12 in) but it has happened to reach over 300mm in few days. Alerta Rio (Rio Warning) is a municipal organization who monitors rainfalls in the city since the 90s. They have 33 stations across the neighborhoods measuring and collecting information about the amount of rainfall. In the following map is possible to see the volume of rain registered by each station for the months of December, January, February, March and April since 2010.

All these strong precipitations can cause landslide and flash flood in different regions of the cities, mainly to the vulnerable and risk areas. These catastrophes lead to chaotic scenarios with records humanitarian losses. During state of emergency, citizens reunite to help families who lost their houses and belongings and do all they can by donating from food, hygiene material, clothes, furniture, etc. Many private agencies and institutions collaborate with locations for donation drop off and deliver it to the community. The interactive map shows some of the donation drop-off locations in the city. By clicking on the pin is possible to check the institution name and address. Because it is a volunteer work and we hope it is temporary, this list of agencies and address can each time a different disaster occurs; also, the main resource for these locations is through word of mouth and social media sharing. For that reason, there is a form (in Portuguese) available in the legend box for those who want to help summitting updates about the drop-off locations. Through the form people can suggest new collection places in the city as well as letting us know about an institution that is no longer available for it.

Though this project it was possible to bring awareness to regular landslide disasters derived from heavy rainfalls in summer and early spring months in the favelas in Rio de Janeiro. It would be ideal to continue the work by updating the maps according to future events and increase community engagement facing emergency victims.