Anne Bretagnolle

A New Database for the Cities of Europe? Exploration of the Urban Morphological Zones (CLC2000) from Three National Database Comparisons (Denmark, France, Sweden)

Urban sprawl is one of the main factors underpinning the changes observed in European landscapes and environment. The analysis of a phenomenon of this sort is conditioned in large part by the availability of documented urban databases, validated by experts and regularly updated. From this point of view the Urban Morphological Zones (UMZs) produced by the European Environment Agency form an important prospect for the future. However, it is essential to set the results of this highly automated approach against the already well-documented national databases. In this paper we investigate the validity of the UMZs for reflecting urban entities, through comparisons with Danish, French, and Swedish national databases for year 2000. We propose a method based on a matching protocol between UMZs and national agglomerations which is based on conceptual and technical choices, in order to take account of the complexity of urban objects. Two main results are pinpointed. On a global level the UMZ database is fully adequate for comparing levels of urbanisation among states. There is no systematic bias in the delineation of urban areas by the UMZs and total urban populations differ only by 5% to 8%. Conclusions should be more cautious when the scale of observation is the town or city itself. In France, mean differences are as small as in Denmark and in Sweden, but certain large agglomerations display marked divergences that depend partly on local urbanisation patterns. We propose a typology of deviations which could be useful for the majority of states that do not have a national morphological urban database, in particular in Eastern Europe.

Multilevel comparison of large urban systems

For the first time the systems of cities in seven countries or regions among the largest in the world (China, India, Brazil, Europe, the Former Soviet Union (FSU), the United States and South Africa) are made comparable through the building of spatio-temporal standardised statistical databases. We first explain the concept of a generic evolutionary urban unit (“city”) and its necessary adaptations to the information provided by each national statistical system. Second, the hierarchical structure and the urban growth process are compared at macro-scale for the seven countries with reference to Zipf’s and Gibrat’s model: in agreement with an evolutionary theory of urban systems, large similarities shape the hierarchical structure and growth processes in BRICS countries as well as in Europe and United States, despite their positions at different stages in the urban transition that explain some structural peculiarities. Third, the individual trajectories of some 10,000 cities are mapped at micro-scale following a cluster analysis of their evolution over the last fifty years. A few common principles extracted from the evolutionary theory of urban systems can explain the diversity of these trajectories, including a specific pattern in their geographical repartition in the Chinese case. We conclude that the observations at macro-level when summarized as stylised facts can help in designing simulation models of urban systems whereas the urban trajectories identified at micro-level are consistent enough for constituting the basis of plausible future population projections.

Urbanization of the United States over two centuries: an approach based on a long-term database 1790–2010

This paper presents an original methodology for the construction of a harmonized database for urban areas in the United States from 1790 to 2010 (a period with a census every 10 years, amounting to 23 dates). Upstream, this method is based on a theoretical choice, the use of a spatio-temporal reference frame to construct urban areas over the long term, defined by a maximum range of one hour’s travel for each period. We used an automatic aggregation from a Reilly model. Urban measures (growth, concentration) derived from this harmonized database are then presented, providing a unified picture of urbanization in the United States over more than two centuries. They are compared with results derived from more classical databases established using the official figures from the Census Bureau, or from other constructions differing from the present system. The results diverge considerably in some instances, which confirms the impact of the method of delineation of geographical areas in measures of growth.

Emergence of an integrated city-system in France (XVIIth–XIXth centuries): Evidence from toolset in graph theory

ABSTRACT In this article, the authors discuss the emergence of an integrated city-system in France one century before the Industrial Revolution, starting from two different databases, the postal roads relays and the cities and towns populations, between 1632 and 1833. They first model historical distances, weighted by elevation and connectivity (measured as a conductance). A major transformation of inter-urban exchange space is then enlightened, with new roads systematically privileged in the northern part of France and the largest cities, but avoiding mountains. They then study territorial integration processes on two different scales: the national, with the diffusion of hubs (characterized by a high betweenness centrality) all over French territory, and the regional, with the emergence of regional city-systems (modeled by a Reilly equation) in the northern part of France. The role of medium-sized cities as necessary links for connecting local and national scales is emphasized in most results.

La ville à l’échelle de l’Europe - Apports du couplage et de l’expertise de bases de données issues de l’imagerie satellitale

Plusieurs bases de donnees, recemment construites sur les villes europeennes sont analysees et comparees au moyen d’une demarche d’integration des specifications. Nous nous focalisons ensuite sur l’une d’entre elle, la base Urban Morphological Zones produite par l’Agence europeenne de l’environnement. Nous developpons des methodes generiques pour l’enrichir, valider son utilisation et mieux comprendre l’image qu’elle renvoie de la realite urbaine en Europe. Nous proposons enfin plusieurs explorations thematiques de cette base selon une approche multi-niveaux : nous montrons ainsi que la densite d’une ville n’est pas correlee avec sa forme, que nous caracterisons par un indice de distance moyenne entre les habitants ; a l’echelon de l’Europe, nous proposons une modelisation de la repartition des densites au moyen d’une regression multiple.

The US Urban System

This chapter documents the historical evolution of the US urban system. From a handful of port cities in the colonial period, there was a sustained urban growth from 1830 to the twentieth century. While the initial rise is associated with a transportation revolution and early industrialization, regional shocks associated with immigration, Second Industrial Revolution, gold and oil discoveries, and land speculation give special character to US urban development. The rank-size analysis of city sizes shows that there were three periods of urban hierarchy, largely coinciding with functional evolutions of cities: first, as regional mercantile centers; second, as national, industrial-mercantile, densely built cities; and, third, as postindustrial, service-oriented, metropolitan, suburban places. A more detailed analysis of postindustrial cities shows that innovations in services such as finance, insurance, and real estate contribute significantly to the concentration of few large metropolitan areas, whereas manufacturing and retail tend toward medium and smaller cities. The larger cities were considerably more economically diverse than smaller cities, and a spatial analysis indicates that cities tend to coevolve as they compete to grow. The chapter concludes with an analysis of the impact of political institutions on urban development. In contrast to developments in Latin America and Canada, American federalism that grants significant political authority to state and localities has significantly impacted US urban and rural development.