A study of intra-urban configurational development in Porto Alegre - Brazil

Abstract

This study is concerned with local scale description of urban form and forecast of urban form development, within a systems approach. Urban intervention of various scales - ranging from lhe replacement of a single building to implementation or re-structuring of entire districts - as well as urban regulations of the type generally used in Brazillan cities, are taken as design issues whose outcomes are spatial configuration alternatives that can be predicted and assessed in their performances. A two-step development is devised for the research; the first one looks for definition and measurement of morphological properties which, being based on essenllally spatial variables, are able to consistently correlate patterns of morphological configuration to olher aspects of the urban system. Identification of common ground between certain spatial configurations and their corresponding social activity system is proposed, as a means to provide purposeful basis for urban form performance assessment. A series of descriptive models, based on graph theory are formulated; thelr ability to assess morphological performance is tested by correlating their output with independently measured elements of the urban spatial structure, by using real data from Porto Alegre city. The second step explores the spatial background for morphological change. ln this way, the actual spatial configuration is taken as the basis for the modelling of future changes. A new set of models are proposed and tested, for simulation of past and future development. These models, which incorporate potential, as well as vintage features, simulate the distribution of further development by considering the capital gains implied by lhe production of such development in alternative locations. The properties of different locations are defined by using the morphological measurements obtained in the first stage of the study. The outcome of the research is an articulated procedure to, first, describe morphological properties of an urban system, and second predict its further development for lhe case of altenative design proposals or urban policies. By describing those properties and modelling future development, the study helps to understand the logic and dynamics of local morphological change. It also allows design proposals to be assessed both in thelr abillty to generate desired patterns of social appropriation and to sustain or change them, according to design goals.