• Highlights

• Disaggregation by Hydrographic Macroregion: IBGE organizes environmental and population data based on the 12 Hydrographic Macroregions, gathering physical, biotic, and resident population information.
• Population distribution: The Hydrographic Macroregions of Paraná and Southeast Atlantic concentrate almost half of Brazil's population, while larger macroregions, such as the Amazon and Tocantins-Araguaia, have lower population density.
• Land use: Between 2000 and 2020, there was an increase in agricultural areas, pastures, and forestry over natural vegetation areas, with the biggest change in the Amazon and Tocantins-Araguaia macroregions.
• Susceptibility to landslides: The change in relief and geological structure is associated with differences in susceptibility, with higher proportions in the Southeast Atlantic and South Atlantic macroregions.

A portrait of the country based on the 12 Hydrographic Macroregions is the proposal of the publication Territory and Environment – Statistics by Hydrographic Macroregions launched today (08) by the IBGE. The territorial division is adopted as an alternative to traditional administrative divisions for the dissemination of statistics, and integrates data on Geology, Geomorphology, Soils, Vegetation, Land Cover and Use, and Susceptibility to Landslides, as well as information on the extent of Biomes and the resident population of each Hydrographic Macroregion.

"With this publication, IBGE contributes with the perspective of looking at environmental, demographic, and land use data in an integrated way, based on a spatial delimitation defined by the country's hydrographic dynamics," explains Ivone Batista, Manager of Accounts and Environmental Statistics at the Institute.

The study highlights the importance of hydrographic territorial units as a fundamental geographic framework for environmental analysis and planning, as a complement to the political-administrative divisions traditionally used to generate statistics.

Fernando Dias, Environmental and Geography Manager at the IBGE Superintendence in Santa Catarina, explains that "the dissemination of demographic and environmental data in different divisions from the usual ones allows the identification of new territorial and temporal dynamics."

The 12 Hydrographic Regions (MacroRHs) show significant differences in terms of territorial extent. The Amazon, Tocantins-Araguaia, and Paraná regions make up the largest areas, accounting for 45.02%, 11.01%, and 10.32% of the national territory, respectively—almost two-thirds of Brazil combined. On the other hand, the smallest regions are the South Atlantic and Uruguay basins, each covering about 2% of the country's area. However, population distribution does not follow this territorial coverage, and despite the vast size of some MacroRHs, settlement has historically remained concentrated in other regions.

From a demographic perspective, all Hydrographic Macroregions are predominantly urban, with Paraná and Southeast Atlantic standing out, where more than 93% of the population lives in cities. These two regions have more than 96 million residents, which is equivalent to 47.35% of the total Brazilian population. The macroregions with the smallest populations are the Paraguay and Uruguay, with just over 2.4 million and 4.2 million residents, respectively, both characterized by strong urbanization. In the other regions – Amazon, East Atlantic, Northwest Northeast Atlantic, South Atlantic, São Francisco, and Tocantins-Araguaia – about 35% of Brazilians are distributed, revealing the persistent spatial inequality in the occupation of the territory.

Biomes and Hydrographic Macroregions reveal mosaics of the Brazilian landscape

The analysis of the distribution of Brazilian biomes across Hydrographic Macroregions reveals different occupation and transition patterns. The Amazon biome is predominant in the Amazon Hydrographic Macroregion, covering 96.31% of the area, and extends to other ones, such as the Western Northeast Atlantic (54.27%), Tocantins-Araguaia (35.93%), and Paraguay (9.49%). The Cerrado, due to its vast extent and central location in the territory, is the most frequent biome, found in 9 of the 12 Hydrographic Macroregion with highlights in Tocantins-Araguaia (64.07%) and Parnaíba (59.37%).

The Atlantic Forest is another relevant biome, being  predominant in the Southeast Atlantic (99.75%) and occupying significant proportions in Paraná (50.55%), East Atlantic (49.82%), Uruguay (49.30%), and South Atlantic (46.61%) Hydrographic Macroregions. The Caatinga, characteristic of the northeastern hinterland, covers 87.88% of the Eastern Northeast Atlantic and appears in São Francisco (50.87%), Parnaíba (40.62%), and East Atlantic (39.91%) Hydrographic Macroregions. More spatially restricted biomes, such as the Pantanal and Pampa, occur in specific regions: the Pantanal occupies 41.77% of the Paraguay Hydrographic Macroregion, while the Pampa is present in the South Atlantic (53.15%) and Uruguay (50.67%).

“Except for the Amazon and Southeast Atlantic Hydrographic Macroregions, dominated by a single biome, all the others have at least two formations, showing complex environmental mosaics. São Francisco, Paraguay, and East Atlantic concentrate the greatest diversity, integrating the Caatinga, Cerrado, Atlantic Forest, and Pantanal. The centrality of the Cerrado, present in most macro-regions, contrasts with the more concentrated distribution of biomes such as Pantanal and Pampa. This scenario reinforces the heterogeneity of Brazil's natural landscapes to be considered in the management of our water resources,” Fernando explains.

Diversidade de ecossistemas e mudanças no território revelam desafios para gestão ambiental

A diversidade fisiográfica do Brasil, refletindo a pluralidade de rochas, relevo, solos e vegetação, também influencia em grande medida na ocupação humana, assim como no uso da terra.

Cada MacroRH apresenta uma combinação singular de províncias estruturais, tipos de relevo, de solos e de vegetação. Na Amazônica, por exemplo, predominam Patamares (35,69%) e Depressões (28,71%), com Argissolos (40,21%) e Florestas Ombrófilas Densas (44,51%).

Na MacroRH Paraná, sob a província homônima, destacam-se Planaltos (68,98%) e Latossolos (52,91%), cobertos por Savanas (35,25%) e Florestas Estacionais Semideciduais (27,05%).

Na Atlântico Sudeste, Serras (33,45%) e declividades acentuadas sustentam Florestas Estacionais Semideciduais (51,56%) e Florestas Ombrófilas Densas (32,60%). É nessa MacroRH que se concentram as áreas de maior suscetibilidade a deslizamentos, somando 61,51% do território na classe Muito Alta, devido, principalmente, à predominância de relevos serranos. Esse aspecto também é percebido em menor extensão na Atlântico Sul (18,35%) e Atlântico Leste (15,56%).

Observando-se o mesmo aspecto, as MacroRHs Paraguai, Parnaíba e São Francisco apresentam baixa suscetibilidade, associada a formas de relevo mais planas, com 47,94%, 45,77% e 43,30%, respectivamente, de suas terras tipificadas na classe Muito Baixa.

No que diz respeito à dinâmica territorial, entre os anos 2000 e 2020, todas as MacroRHs estiveram sujeitas a alterações de cobertura e de uso da terra pelas atividades humanas, com um avanço das áreas consideradas antropizadas sobre aquelas consideradas naturais florestais e naturais não florestais.

Em termos proporcionais, o maior incremento de áreas antropizadas ocorreu na MacroRH Amazônica, as quais passaram de 264.896 km², em 2000, para 478.882 km², em 2020, o que representa um aumento de 80,78%. O menor avanço ocorreu na Atlântico Sudeste (1,61%), com suas áreas antropizadas passando de 164.964 km² para 167.627 km².

As maiores perdas, em termos proporcionais, de áreas naturais florestais e naturais não florestais ocorreram, respectivamente, nas MacroRHs do Tocantins-Araguaia e Paraná. Na primeira, a redução foi 28,67% (78.027 km²), enquanto na segunda, 27,75% (22.607 km²).

“Essa compreensão integrada de informações é essencial para reforçar a importância de considerar a pluralidade dos ecossistemas brasileiros, tanto para o planejamento territorial, quanto para a gestão de recursos hídricos e para a avaliação de riscos ambientais. As informações reunidas pelo IBGE oferecem subsídios técnicos valiosos para políticas ambientais e para o fortalecimento da contabilidade e estatística ambiental no Brasil”, conclui Ivone.

Além dos dados estatísticos, os usuários também podem consultar e baixar o recorte geográfico de Macrorregião Hidrográfica na página do Quadro Geográfico e na Plataforma Geográfica Interativa (PGI).