Multi-agent modeling of urban growth distribution in systems of cities

A strong regularity in urban systems has long been identified : the hierarchical distribution of city sizes. Moreover, a closer observation of the evolution of this distribution shows that in the majority of city systems, there is a trend towards a more and more unequal distribution of city sizes. Why does the majority of urban systems show those strong regularities? What are the common growth processes involved? Several dynamic growth models have been proposed but no consensus has yet been reached because of the under-determination of models by those empirical laws. In this presentation we describe a new method of agent-based parsimonious modeling that we think can contribute to the identification of the common urban growth processes. This modeling method is based  on  intensive model exploration for quantitative evaluation of implemented mechanisms. The exploration tools were first developed for the evaluation of SimpopLocal, a model of the organization of urban systems when cities first emerged. The use of those exploration tools was then generalized into a modeling method that was applied for the first time with the construction of the MARIUS family of models which aims at reproducing the evolution of Soviet urbanisation between 1959 and 1989. Those two examples show how this new modeling method can help the construction of urban theories by helping the evaluation of assumptions made on urban processes.

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Communication at the seminar Quanturb, ISC-PIF (Paris), November 19th.

Clara Schmitt and Paul Chapron

Complex Systems and Geography

GeoDiverCity Team was active at presenting their work to a diverse and large audience at the inauguration of the Complex Systems Institute in Paris.

Here are some documents we presented :

> A selection of visual results in geographical modeling

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Paul Chapron, Clémentine Cottineau, Robin Cura, César Ducruet, Julie Fen-Chong, Sébastien Haule, Marion Le Texier, Nora Marei and Clara Schmitt

Picture Refs : 1. C. Cottineau, 2. D. Holten & J. W. Jarke, 3. R. Cura, 4.5. C. Ducruet, 6. M. Le Texier, 7. C. Cottineau, 8. P. Chapron, 9.10. C. Schmitt

> Netlogo models of systems of cities

  • SimpopNet

Clara Schmitt

 

  • MARIUS : Modeling of Agglomerations of Imperial Russia and the Soviet Union

Clémentine Cottineau and Paul Chapron

 

> A poster about a method to conceive, build and evaluate models at the intersection of generic systems of cities and the specific case of post-Soviet cities

Clémentine Cottineau, Paul Chapron, Denise Pumain and Romain Reuillon

 

> Accessing the European Grid computing power

Mathieu Leclaire and Romain Reuillon

 

Is there a system of Russian cities? Generic properties and specificities in the description and modeling of Russian cities’ interactions

In the context of GeoDiverCity, generic properties of city systems are looked for as stylized facts that apply to these particular objects over the world and over time. Examples of those properties lay in the hierarchy of city sizes (expressed by Zipf’s law), or the process of urban growth (as described by Gibrat in 1931). Using those regular patterns, modeling of the co-evolution of cities becomes possible and useful.

Russian cities oppose several obstacles to the observation of such regularities. The spatial limits of the system varies over time, which complicates  the choice of urban definition, and the collection of reliable data. Moreover, the historical object of Russia and the Soviet Union exhibits strong specificities related to its (supposed absolute) control over urban definition, development, interactions and inner organization. Our work aims at distinguishing the specific from the generic behavior of the Russian system of cities from the urban transition up to now, in order to model its evolution and propose possible projections with the help of Multi-Agent Models.

This project 1 begins with the harmonization of urban definitions. Theoretical and data collection constraints led us to consider agglomerations of 10.000 inhabitants and more between 1840 and 2010. Agglomerations have been composed of administrative units which take part in the same built-up area in 2010. Since the boundary of the system is not obvious over the XIX and XXth centuries, its larger extension (the Former Soviet Union) is tested along with its present configuration (the Russian Federation).

Generic models (Zipf, Gibrat) are tested and compared with the results obtained in other geographical contexts. Europe, North America, South Africa, India, China and Brazil are represented in the research fields of GeoDiverCity, sharing the same principles of data harmonization, which helps us in the process of comparison. Other tools are used to explore and explain the specificities of the system of Russian cities (analysis of urban trajectories and financial links between cities with the ORBIS Database produced by Bureau van Dijk, 2010 and augmented by C. Rozenblat).

The characteristics of the Russian system learned from these studies, coupled with the experience accumulated within Géographie-Cités and GeoDiverCity will help modeling the system and simulating its possible futures.

Clémentine Cottineau

Notes:

  1. PhD project of Clémentine Cottineau, under the supervision of Denise Pumain (founded by University Paris 1 Panthéon-Sorbonne)