Occupation of APPs on the banks of rivers and streams doubled between 1985 and 2020

Despite this, more than 70% of these areas are still preserved

According to the Forest Code, the strips along the banks of rivers, streams and springs are permanent preservation areas (APPs). Their extent is determined by the characteristics of the water courses, such as their width, with the minimum being 30 meters for the narrowest rivers and up to 500 meters for the widest rivers. To find out how much these APPs are (or are not) conserved in urban environments, MapBiomas analyzed satellite images between 1985 and 2020. The results show that in this period the urbanized area in this strip, which by law must follow specific regulations for its 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 worrying fact in itself, since the proximity of buildings and urban infrastructure can compromise the quality and increase the flow of water, contributing to flooding in the rainy season," recalls Julio Cesar Pedrassoli, coordinator of the urban infrastructure team of MapBiomas and who participated in the preparation 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," adds Edimilson Rodrigues, one of the authors of the study.

The 30-m marginal strips of urban water bodies occupy 422 thousand hectares in Brazil. Of this total, 71% were not urbanized in 2020. These remaining 300.2 thousand hectares of vegetation, or not covered by built-up areas, can still be preserved. Currently, this task falls to the municipalities that, since the end of December last year, have received the power to regulate the restriction zones along rivers, streams, lakes and ponds within their urban limits. This attribution is a result of the amendment to the Forest Code by Law 14.285, of 2021, which allows the regularization of buildings on the margins of water courses and bodies of water in urban areas.

Almost one fifth (19.8%) of the urbanized areas within 30 m around urban rivers and streams are concentrated in only 20 municipalities. "This means that a more rigorous action by these municipalities can preserve or even recover these APPs, increasing the resilience of the urban environment to flooding and improving people's living conditions," explains Julio. Of these 20 municipalities, 11 are capital cities, including the leaders in 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 largest urban occupation around rivers and lakes. Three states of the Southeast 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 of them have registered dramatic flooding episodes with huge human and financial losses, which reinforces the importance of the recovery and preservation of the water PPAs," reinforces Júlio.

The MapBiomas technical note evaluated the Permanent Preservation Areas in the 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 universe, the results are more favorable: in it, 82% of the urban water APPs are not occupied by constructions or infrastructure, which represents 48,924 ha covered by vegetation or water in 2020. In other words, even cities with dense urban occupation still have vegetation cover in water APPs. The rate of vegetation cover in hydric APPs in areas of dense urbanization 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%). At the other extreme, 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: of the 27 Brazilian states, only six have less area covered by buildings and infrastructure than the preserved areas within the 30-m margin around rivers and lakes. They are: Roraima (0.12 thousand ha of urbanized area vs. 0.29 thousand ha of areas not covered by buildings and infrastructure), Mato Grosso do Sul (0.38 thousand ha vs. 0.50 thousand ha), Goiás (1.15 thousand ha vs. 1.16 thousand ha), Paraná (2.25 thousand ha vs. 2.78 thousand ha), Rio Grande do Sul (3.11 thousand ha vs. 3.18 thousand ha) and Espírito Santo (3.89 thousand ha vs. 4.08 thousand ha).

"When the states as a whole are analyzed, the situation gets milder. This is because it is in specific municipalities, such as São Paulo, Manaus, Rio de Janeiro, and the other capitals, that the occupation problem is more serious", explains Edimilson.