Workshop on Land Accounts and urban morphology, ETC-CE, 12 july 2006 A classification of European urban areas on a double scale of compactness Marianne Guérois Université Paris 12, C.R.E.T.E.I.L. Associated to UMR Géographie-cités, Paris

Ph-D in 2003 : How to characterise the compactness level of European agglomerations in a comparative way ? > A unique model of « compact city » VS diversity of urban shapes throughout Europe ? CLC well-suited to staging comparisons often impeded by heterogeneous nature of source of information

What are the main determinants of areal extent contrasts ? Built-up surface = an elementary and relevant estimate of the absolute degree of sprawl Urban areas > 200000 inh. in 1990

How does areal extent vary when population size increases? Strong correlation with population size, even within a cross-national frame Linear fit : +1,5 km² per 10 000 inh. Residual values highlight trends towards sprawling or compact extensions

Tendencies to compactness, tendencies to sprawl On a European scale, a south-to-north gradient Predilection for urban values inherited from Latin culture? Spatial diffusion process of peri-urbanisation? National determinants : Dutch agglomerations A careful link to national planning features Local « perturbations » Influence of topography but not only…

A second dimension of morphological compactness : The urban « footprint » To complete areal extent and population density approach, a comparison of built-up global design (> 500 000 inhab. in 1990) Three significant features : Elongation Digitation Indentation How to convert qualitative descript° into numeric expressions ?

How to quantify shape variations ? A selection of indices > Ratios between elementary parameters (area, perimeter, Longest axis …) > Values range from 0 (linear or digited shape) to 1 (circular shape) Limits ? > Circle as an absolute reference > Some measures remain ambiguous

The need for a combinaison of indices A test on schematic shapes Results of the multivariate analysis (PCA) : > Axis 1 (79%) = global distance to the circle feature > Axis 2 (16%) = linear VS digital shapes => Each specific pattern can be identified by a set of indices

Extreme positions of agglomerations for each index

A typology of agglomerations extension patterns Cluster analysis 6 relevant types of shape No regional consistency Strong influence of topography, but also…

2 dimensions of compactness

2 dimensions of compactness No correlation between those two dimensions of compactness Must be crossed

CONCLUSION Crossing these two dimensions of morphological compactness provides original framework to compare the shape of European agglomerations CORINE Land cover potential regarding urban analysis at this scale … A careful link between morphological features and normative discourses about sustainable cities … what description for suburban extents ? … The need for a state of the art about classification of European cities shapes