Identifying urban diffusion in compact cities through a comparative multivariate procedure

A multivariate approach integrated with spatial analysis using morphological indicators was illustrated in the present study with the aim to analyze the recent urban expansion in compact cities. The approach incorporates a Principal Component Analysis, a k-means cluster analysis and a Discriminant Analysis, and it was applied to three case studies in Southern Europe (Lisbon, Rome and Athens) using enumeration districts as the spatial scale of analysis. Six clusters describing a range from hyper-compact to low-density, dispersed settlements have been identified in the three cities together with the indicators accounting for the highest discrimination among clusters. Low-density and dispersed settlements were more diffused in fragmented (Lisbon) and moderately polycentric (Rome) cities than in mono-centric cities (Athens). Such a classification may prove useful when calibrating measures to contain sprawl in compact urban regions.