Diversification in urban functions as a measure of metropolitan complexity

Newly emerging relationships between form and function reveal the increasingly complex nature of metropolitan regions. The present study investigates spatial diversification in settlement forms and socioeconomic functions in metropolitan Attica (the administrative region including Athens, the capital of Greece), with the aim of implementing a holistic framework assessing urban complexity in contemporary cities. Taken as key components of urban complexity, morphological and functional diversity have been analysed using multi-domain indicators that describe settlement characteristics (land-use, soil sealing, building use, vertical profile of buildings, building age, construction materials) and socioeconomic functions (economic base, working classes, education levels, population age structure, composition of non-native population by citizenship, distribution of personal incomes), thus providing a comprehensive description of local-scale diversification in urban structures. A correlation analysis was used to verify the spatial coherency between individual dimensions of urban diversification. Analysis of global Moran's spatial autocorrelation index reveals specific gradients of urban diversification that discriminate morphological attributes from socioeconomic functions. Municipalities were profiled on the basis of Pielou's evenness indexes for each urban dimension: a factor analysis indicates latent patterns characterizing areas with high and low diversification in metropolitan functions. Urban and rural municipalities were, respectively, characterized as the most and least diversified in the study area, with peri-urban municipalities ranking in-between, evidencing a diversification gradient correlated with the distance from downtown Athens. A multidimensional analysis of the most relevant dimensions of metropolitan complexity has proved to be a promising tool for monitoring urban gradients, polycentric development and (latent) socioeconomic transformations in contemporary cities.