However, more than 70% of these areas are still preserved.
According to the Forest Code, the strips along rivers, streams, and springs are permanent preservation areas (APPs). Their extension is determined by the characteristics of watercourses, such as their width, with a minimum of 30 meters for narrower rivers and up to 500 meters for wider rivers. To understand how these APPs are (or are not) preserved in urban environments, MapBiomas analyzed satellite images between 1985 and 2020. The results show that during this period, the urbanized area in these strips, which by law must comply with specific regulations for their occupation, doubled. The areas covered by buildings and infrastructure at least 30 meters from water bodies (such as rivers and streams) within cities increased from 61.6 thousand hectares in 1985 to 121 thousand hectares in 2020.
"This is a concerning fact in itself, as the proximity of buildings and urban infrastructure can compromise water quality and increase water flow, contributing to flooding during the rainy season," recalls Julio Cesar Pedrassoli, coordinator of the urban infrastructure team at MapBiomas, who participated in the development of the Technical note "Analysis of urban occupation around water bodies in Brazil”. "With the worsening of the climate crisis, which is affecting the regularity and volume of rainfall, the preservation of areas without constructions around water bodies becomes critical for people's safety and environmental quality," concludes Edimilson Rodrigues, one of the authors of the study.
The 30-meter marginal strips of urban water bodies occupy 422,000 hectares in Brazil. Of this total, 71% were still not urbanized in 2020. These remaining 300,200 hectares of vegetation, or areas not covered by built-up areas, can still be preserved. Currently, this task falls to the municipalities, which, since the end of December last year, have been empowered to regulate the restriction strips along rivers, streams, lakes, and lagoons within their urban limits. This assignment stems from the amendment to the Forest Code by Law 14,285 of 2021, allows for the regularization of buildings along watercourses and bodies of water in urban areas.
Nearly one-fifth (19.8%) of the urbanized areas within 30 meters of urban rivers and streams are concentrated in just 20 municipalities. "This means that a more stringent action by these city governments can preserve or even restore these APPs, increasing urban resilience to floods and improving people's living conditions," explains Julio. Of these 20 municipalities, 11 are capitals, including the leaders of this ranking: São Paulo (3.73 thousand ha), Rio de Janeiro (3.40 thousand ha), Fortaleza (1.41 thousand ha), Manaus (1.38 thousand ha), and Curitiba (1.27 thousand ha).
MapBiomas also calculated the states with the highest urban occupation around rivers and lakes. Three Southeastern states are among the top five: São Paulo (12.94 thousand ha), Rio de Janeiro (7.28 thousand ha), Minas Gerais (6.68 thousand ha), Santa Catarina (4.94 thousand ha), and Ceará (4.19 thousand ha). "All have experienced dramatic episodes of flooding with huge human and financial losses, which reinforces the importance of recovering and preserving water APPs," emphasizes Julio.
The MapBiomas technical note assessed Permanent Preservation Areas within urban perimeters, delving into a set of 17 municipalities in the Legal Amazon (Rio Branco/AC, Cuiabá/MT, Belém/PA, Boa Vista/RR, Palmas/TO, and Manaus/AM) and in the Paraná Basin (Brasília/DF, Campinas/SP, Campo Grande/MS, Curitiba/PR, Goiânia/GO, Londrina/PR, Ribeirão Preto/SP, Santo André/SP, São Bernardo do Campo/SP, São Paulo/SP, and Sorocaba/SP).
In this scenario, the results are more favorable: 82% of urban water preservation areas (APPs) are not occupied by buildings or infrastructure, representing 48,924 hectares covered by vegetation or water in 2020. Thus, even cities with dense urbanization still have vegetation cover in water preservation areas. The vegetation cover rate in water preservation areas in densely urbanized areas in this set of 17 municipalities is led by Goiânia (74.93%), Campo Grande (65.43%), Belém (52.77%), Curitiba (52.25%), and Cuiabá (51.26%). On the other hand, the lowest rates were found in São Bernardo do Campo (13.06%), Manaus (16.48%), Santo André (17.01%), Boa Vista (17.28%), and Campinas (22.37%).
However, when the analysis looks at the states as a whole, the situation is different: out of the 27 Brazilian states, only six have areas covered by buildings and infrastructure that are less than the preserved areas within the 30-meter margin around rivers and lakes. They are: Roraima (0.12 thousand hectares of urbanized area vs. 0.29 thousand hectares of areas not covered by buildings and infrastructure), Mato Grosso do Sul (0.38 thousand hectares vs. 0.50 thousand hectares), Goiás (1.15 thousand hectares vs. 1.16 thousand hectares), Paraná (2.25 thousand hectares vs. 2.78 thousand hectares), Rio Grande do Sul (3.11 thousand hectares vs. 3.18 thousand hectares), and Espírito Santo (3.89 thousand hectares vs. 4.08 thousand hectares).
"When states as a whole are analyzed, the situation becomes more moderate. This is because it is in specific municipalities, such as São Paulo, Manaus, Rio de Janeiro, and the other capitals, where the issue of occupation is more serious," explains Edimilson.