Antoine Peris (p), Willem Jan Faber, Evert Meijers, Maarten van Ham

Marion Maisonobe

When studying the organisation of systems of cities, most research builds on the movement of people, goods and capital. Only few studies have analysed the exchanges of information, which is surprising because information plays a crucial role in organising the complex pattern of networks and flows connecting cities. Only recently has information regained attention with studies employing data derived from social media, phone calls or scientific collaborations. In a way this is a return to the start of research on systems of cities, as in the early days information flows received a lot of attention. For instance, researchers used newspapers to analyse the circulation of news, because it was one of the only ways to develop a relational approach of cities. But because of the cost of the data collection, these studies were limited to a small number of cities, and very short periods of time.
Today, thanks to the effort of digitalization of historical newspapers, and developments in data science, it is now possible to go back in time and map the circulation of information with a high spatial resolution. While researchers have shown that these massive digital archives can be used to identify macroscopic trends related to cultural change, very few studies have looked systematically at the geographical dimension of these archives. In this paper, we use Delpher, the digital archive of historical newspapers of the Royal Library of the Netherlands. We look at the spatial diffusion of information between the Dutch cities with a corpus of 35 local newspapers published in 29 different cities. These newspapers have published around 48 million of news-items between 1869 and 1939.
As local newspapers had a limited area of diffusion, we were able to build origin-destination matrices of information flows from 317 cities and towns to the 25 cities for which we have digitalized newspapers. This operation allowed us to map the information field of these 25 cities and its evolution through history. Because of the challenges of mapping this data with such a high spatial and temporal resolution, the visualisation of ‘information fields’ is complemented with the application of a cross-temporal gravity model used to measure the evolution of the distance decay coefficient across the 70 years that our dataset covers. Obviously, pioneering this method is of importance to apply it to more contemporary resources.

Melanie Krause (p), Sebastian Kripfganz

Marion Maisonobe

Commuters spend a substantial portion of their income in a different place from where they earn it, thereby constituting an important channel for cross-regional economic dependencies. In this paper, we analyze their role for economic convergence. Commuter flows are inherently asymmetric which implies a stronger shock propagation from large economic centers to rural regions than in the opposite
direction. This is in contrast to the symmetric network structure implied by the conventional geographic weights in spatial econometric models that are based on contiguity or geographical distance measures. Motivated on the grounds of the neoclassical growth model, extended for spatial spillover effects, we use German county-level data from 2002 to 2014 to estimate a panel data model that is dynamic both across time and space. We find that the speed of convergence is substantially overestimated when ignoring spatial spillover effects, irrespective of the choice of the spatial weights matrix. The estimates of the spillover effects themselves are
smaller using commuter weights than geographical measures due to the restricted feedback to large economic centers.

Alain L'hostis (p)

Marion Maisonobe

Closer cities and distant space: a new geographical time-space map of Europe

Alain L’Hostis, LVMT, UMR-T 9403, École des Ponts, IFSTTAR, UPEM, Champs-sur-Marne, France

Abstract for the ERSA 2019 conference session S29 “Mapping flows, movements and cities networks at a European
level”

We propose a geographical time-space model extending time-space relief cartography introduced by L'Hostis and Mathis (Mathis, Polombo, et L’Hostis 1993; L’Hostis 1996, 2009). The novelty of the model resides in the use of cones to describe the terrestrial surface instead of graph faces, and in the use of curves instead of broken segments for edges. The approach lies a the intersection of two domains involving graphic representation: cartography, and three dimensional computer graphics.
We implement the model on the European space. The European geographical time-space of the reference year 2014 is produced by the combination and the confrontation of the fast air transport system and of the 7.5 times slower road transport system. Slower, short range flights are represented as curved lines above the earth surface with longer length than the geodesic, in order to account for a slower speed. The very steep slope of cones expresses the relative difficulty of accessing terrestrial time-space, as well as the comparably extreme efficiency of long-range flights for moving between cities. Finally, the whole image proposes a coherent representation of the geographical time-space where fast city to city transport is combined with terrestrial transport systems that allow to reach any location but at a much slower speed.

Françoise Bahoken (p), Emna Chikhaoui, Étienne Duperron, Laurent Jégou, MarionMaisonobe (p)

Marion Maisonobe

Choosing the appropriate scale of analysis is a well-known problem in regional studies. Changing the level of quantitative spatial studies is not trivial and can have many substantial effects on the indicators, their representation and their interpretation, especially if the original data is spatially diverse and at a fine granularity. One cannot regroup spatial data points automatically without consequences. As geographical datasets are becoming increasingly available, and with a finer resolution, we want to provide some pointers and use-cases scenarios from a geography standpoint, to present and analyse this issue. What definitions can be used to delineate the idea of a city, an urban area or an agglomeration? At what size, population density, volume of urban activity or surface are we observing a city? We consider this issue especially in a comparative purpose taking the example of analysing networks of European cities.

In this proposal, we provide a comparative analysis of spatial clustering methods or aggregation procedures with an interactive web-based application designed to explain and visualize their effects on different results: volume of urban activity (discrete values) and rankings, on the one hand, spatial configurations, sizes and relational flows (links) of the aggregated values, on the other hand. We will use the themes of demographics and the geography of scientific activity, at the city scale in their spatial and relational dimensions.