[pt] A falta de critérios ambientais na ocupação do território pode trazer danos de longo prazo aos cidadãos e ao patrimônio natural da cidade. O objetivo do trabalho é identificar áreas aptas para ocupação urbana, considerando os aspectos geotécnicos do suporte e aqueles ligados à manutenção dos processos naturais, como base para a gestão e o desenho da cidade. Com o apoio de um sistema geográfico de informação é feita a análise e avaliação dos atributos biofísicos de uma área em processo de expansão urbana, o bairro de Vargem Pequena, na zona oeste da cidade do Rio de Janeiro. No local, uma parte significativa do território é constituída de espaços livres de ocupação. A análise e a avaliação do suporte biofísico estão calcadas em uma proposta metodológica interdisciplinar que reconhece os espaços livres como sistema, com um papel protagonista dentro da estrutura urbana e potencial para ordenar a ocupação do território. O núcleo das informações acerca do suporte biofísico da área é a correlação pedológico-geotécnica feita sobre o levantamento de solos do município. O PEDOGEO contém, além dos dados pedológicos de cada classe de solo, informações gerais sobre as principais características do meio físico. Os elementos definidos para análise são: cobertura; solo; hidrologia; e relevo. As avaliações mostram que a utilização de informações biofísicas é pertinente na caracterização da realidade espacial urbana para os fins propostos, indicando, contudo, ainda pouca disponibilidade de dados, de fontes confiáveis e em escalas adequadas, para este tipo de análise. / [en] This thesis deals with the analysis of the biophysical characteristics of areas in urban expansion process with the support of a geographic information system. We highlight the importance of studying the physical reality of territories for urban development in line with environmental values and sustainability principles. The objective of this work was the development of a synthesis map that can determine‒through gradation values and within established criteria‒suitable areas for occupation that do not conflict with the continuity of the natural processes of the territories. To this end, we propose to analyze and evaluate the biophysical attributes of an area in the City of Rio de Janeiro. In this location, within the urban structure, there are spaces that can be characterized as free of occupation, whether in the form of urban infrastructure, roads or buildings. From available data, the use of geo-processing resources in the characterization of urban space reality will be assessed in order to elaborate a basis for management and design of the city. The growth dynamics of a city like Rio de Janeiro does not often comply with the most well-intentioned plans. When cities grow without any planning, it is very common to observe the occurrence of events that cause direct damage to the population, such as landslides and floods. In other occasions, the plans ignore the basic reality of the territory by not considering in depth the potential impact of their deployment. In both cases, the lack of consistent and accessible information on the physical characteristics of the territory results in failing to apply environmental criteria in the process of occupation. This makes the population vulnerable and can cause long-term damage to the environmental heritage of the city.
Although environmental sustainability issues are related to almost any kind of human activity, it is in the cities where they occur in a more evident way. While these issues have grown in scale in recent decades and their solutions have become more and more urgent, the search for integration and balance between the natural and urban environments has definitely been incorporated to urban thinking. Information processing techniques that have emerged with the development of computational systems led to the development of tools such as the Geographic Information System and the Computer Aided Design, which represent a new milestone in the understanding of the physical world, which is necessary to deal with urban and environmental issues within the scale they are placed nowadays. Authors, who deal with the topic of environmental spatial analysis from several approaches, provide the basis of the theoretical foundation of this work. The urban approach regards concepts linked to ecological urbanism and, in this context, the role of the system of open spaces in the urban structure. Concepts relating to biophysical support are reviewed, in an approach to the elements found in the area of study, especially those related to analysis and evaluation. In the case of geographical information systems, we make a summary of their peculiarities, main functions and foundations, and their application in the analysis of the territory. The analysis and evaluation of biophysical support are based on an interdisciplinary methodological proposal of the System of Open Spaces and the Territorial Project. These recognize the free spaces as systems, with a protagonist role within the urban structure and potentialities for territory restructuring. At the same time, they consider the guidance of a future occupation which does not conflict with the maintenance of natural support processes. In the adaptation of the original methodology for the purposes of this thesis, we considered that some criteria and conditions used for the definition of the areas that must be kept free of occupation, within the concept of open spaces system, could also define, in counterpoint, the spaces with better potential for occupation. In this way, the best evaluated areas in this study, from their biophysical characteristics, would be those whose urban occupation would avoid damage to ecosystems, contributing to the maintenance or recovery of the open spaces system. The area of study is defined by the administrative boundaries of Vargem Pequena neighborhood, located in the west zone of the City of Rio de Janeiro, with a total area of 1,443.83 ha. The neighborhood occupies a stretch of the Baixada de Jacarépaguá plain and part of the southern slope of the Maciço da Pedra Branca, which is an important area of environmental protection. The area can be considered one of the city s growth boundaries, limited by natural and urban environments, threatened by a series of unmanageability in its occupation process. In Vargem Pequena, the occupation is characterized by farms and low density residential urbanization of middle and upper-middle classes, also with the occurrence of irregular settlements and slums. The bucolic surroundings and proximity of nature attracts real estate investments with a trend to slopes occupancy. The open spaces lose their original identity, becoming isolated spaces without an effective participation in urban conformation. They are environmentally protected, but threatened by the urban pressure and a rapid process of dismantling with higher occupation of the plain and slopes. The main source of specific data used in the analysis of biophysical support is the PEDOGEO of Vargem Pequena. It is a geo-referenced digital map containing the classification of soils within the administrative boundaries of the neighborhood. The basis of its contents is the soil survey of the City of Rio de Janeiro, which began in the 1960s, in the former State of Guanabara, and was revised and supplemented up to 2009. Another essential source of information is the work carried out by specialists, dealing with the relationship between pedology and geotechnics. The biophysical attributes analyzed were: vegetation; soil; relief; and hydrology. In the research, we used data available and already converted to the Geographic Information System environment, enabling their immediate application. In the organization of information plans, analysis and generation of maps, we used the ArcGIS Desktop 10, ESRI, application package. In the complementation of planimetric information, we used the AutoCAD 2012, Autodesk, application. The geo-processing followed the current methodology in this environment, consisting basically of two steps: construction of a geo-referenced database; and spatial analyses and evaluations for the objective set. Structure of the geo-referenced database
a) Scale of final product: 1:2000
b) Projection: UTM (Universal Transverse Mercator)
c) Datum: SAD 69
d) Resolution: 1 m
e) Information plans: coverage, soil, declivity, water bodies
Procedures adopted in the construction of the geo-referenced database:
1. Collection of data and materials
2. Data conversion
3. Classification of coverage from images interpretation techniques
4. Creation of the digital terrain model
5. Classification of hillsides and declivity layer generation
Procedures adopted in the analyses and spatial assessments:
1. Definition of the variables values
2. Operation between matrices
3. Final classification
Information plans were created with the cropping of the area defined by the boundaries of the neighborhood. The coverage map was done with image interpretation techniques applied to orthorectified aerial images taken in 2009. The map represents the neighborhood surface through the following layers: vegetation; exposed soil; rocks; and urbanized area. The vegetation is classified on the basis of the criteria for analysis of the elements that constitute the system of open spaces, as a mosaic of ecosystems of different scales, considering their internal relationships and those with the surroundings. The urbanized area is divided into built, paved and public spaces. In the soil map, there is information available in the PEDOGEO regarding the pedological and geotechnical characteristics of each type of soil, in addition to data on the physical environment in which they are inserted. The declivity map, generated from the digital elevation model, and the map of water bodies, derive from the digital cartography of the city. The map records: the quota of altitude of the terrain through isograms every 1 m; and the existing water courses through polylines. Areas situated above 100 m altitude, which are part of the SPECIAL ZONE 1 for the preservation of the city, and areas with declivity greater than 30 per cent, or situated at 30 m from the banks of rivers, which form part of Permanent Protection Areas, protected by federal laws, are classified as areas of legal constraint for occupation. After the variables of each information plan were mapped, they were rasterized and reclassified, assigning the same value for each variable. According to the biophysical criteria set and the help of experts who knew the phenomena and situations assessed, we assigned grades 1 to 10 to each variable, from the smallest to the largest suitability of each area for occupation. We assigned grade zero to not classified areas: due to the lack of information; constituting legal restriction areas; or because they had already been urbanized. The matrices were then combined algebraically, resulting in the evaluation map, whose chromatic gradient reflects the degree of suitability for occupation, according to the criteria defined. The map produced with geo-processing resources shows that the biophysical criteria used are relevant in the characterization of the urban space reality for the management and design of the city. The work scale and the classification process of coverage allowed tracing a considerably updated and accurate picture of the urbanized area and the free spaces existing in the neighborhood. However, the final map has some inconsistencies, in part due to the lack of more precise information. The methodology used is simple and could be improved in future works, for example, by applying a mathematical logic more suited to environmental complexity, as the Weighted Average or Fuzzy logic. At the same time, the field biophysical information would be supplemented with the help of experts.
Although the theoretical framework of ecological urbanism and technical data surveys on the environment have progressed in the last few decades, the objective information available in this area is still restricted. At first, the immediate experience could lead to the conclusion that this lack occurs more sharply in countries with many problems to face in the direction of effective development. However, according to the point of view of current authors in the field of geo-processing, it is possible to observe that worldwide research on the environment is just starting. In countries with environmental heritage‒like for example in Brazil‒there is a great need for appropriate surveys and processing of information about natural environments. It is expected that this work will contribute, albeit to a limited extent, with the practice of environmental analysis as a preliminary step for planning and the elaboration of urban projects. At the same time, it will contribute to the use of the Geographic Information System, at the level of users, as a current tool for professionals in the field, as for example the Computer Aided Design, whose use has been consolidated for a long time.
| Identifer | oai:union.ndltd.org:puc-rio.br/oai:MAXWELL.puc-rio.br:55560 |
| Date | 29 October 2021 |
| Contributors | LUIZ FELIPE GUANAES REGO |
| Publisher | MAXWELL |
| Source Sets | PUC Rio |
| Language | Portuguese |
| Detected Language | English |
| Type | TEXTO |
Page generated in 0.0035 seconds