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Fractal dimension, spatial dynamic and urban fragmentation patters of medium-sized cities of São paulo state

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Author(s):
Gracieli Trentin
Total Authors: 1
Document type: Doctoral Thesis
Press: Campinas, SP.
Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Geociências
Defense date:
Examining board members:
Marcos César Ferreira; Carlos Roberto de Souza Filho; Claudia Maria de Almeida; Lindon Fonseca Matias; Reinaldo Paul Perez Machado
Advisor: Marcos César Ferreira
Abstract

Most of the conventional methodologies employed in urban studies do not consider the level of perimeter irregularity and the morphological complexity of cities, because they tend to approximate the urban form to the Euclidean geometry. However, the urban phenomenon can also be studied in its real form, based on the fractal geometry. In this case, the urban grade fill and fragmentation can be estimated by fractal dimension (D), contributing to the analysis of the spatial and temporal dynamics of urban forms. The aim of this work was to analyze the urban sprawl dynamic of a set medium-sized cities, based on fractal dimension to identify possible grow patterns associated to urban fragmentation. We chose 14 cities with population between 100.000 and 500.000 inhabitants, which represents a sample of the total medium-sized cities in Sao Paulo state. According to the proposed space-time analysis at a regional scale and the availability of cartographic material, four dates were defined to analyze the spatial dynamic of urban forms: 1938, 1985, 1995 and 2005. Firstly, the urban sprawl was mapped and related to the Sao Paulo urbanization process, highlighting the influence of the road network on the urban configuration. Afterwards, the fractal dimension was estimated by three methods: perimeter-resolution (PRE), perimeterarea (PAR) and occupation density (DOC). The analysis of the results showed great spatial and temporal dynamic in these cities, mainly between 1938 and 1985 - a phase of greater intensity in the urbanization process. Furthermore, the road network was determinant in the direction and definition of the main axes of urban sprawl. These characteristics were reflected in the estimated D values, which characterized the cities as regards irregularity, complexity and urban fragmentation. The temporal changes in the fractal dimension were related to shape index, which enabled the association of urban forms to elongated or circular formats. Based on the D values for the DOC method - which presented greater variation in the period - groups of cities to each date of analysis and for the dynamic of the entire period (1938-2005) were delimited. From this grouping, the following urban fragmentation patterns were defined: fragmented forms; fragmented forms by environment and physical constraints; and forms with more regularity. The characterization of groups of cities was based on population, area, perimeter and physical-geographical factors of urban sites. This allowed to observe differences concerning the fill and fragmentation of forms a long time. The spatial and temporal behavior of each pattern suggests continuity in the urban growth, with a great influence from the most recent period, which demonstrates the existence of temporal autocorrelation in the fragmentation process. In conclusion, the fractal dimension used as a category for spatial analysis proved its efficiency as a dynamic mapping and monitoring method for complex and irregular forms, those observed in urban environments (AU)