PhD theses that contributed to GeoDiverCity programme


phd-swerts

Swerts E., 2013, The Indian and Chinese Systems of Cities , University Paris I.

Abstract. This thesis compares the urban systems in China and India using dedicated data bases that have been constructed using comparable and harmonized principles, describing the evolution of the population of all urban agglomerations above 10 000 inhabitants, every ten years from the beginning of 20th century for India and 1964 for China. Both very large countries of ancient urbanization are characterized by many small towns and have developed gigantic metropolises during the last decades. Despite their geo-historical specific features, these two systems share with others in the world the same properties of hierarchical differentiation and urban growth processes (Zipf’s law and Gibrat’s model), at country scale as well as for regional subsystems. A regional diversity is linked to former processes of unequal concentration of urban development. The most interesting result is identifying for the first time a reverse trend in the evolution of the Chinese urban hierarchy compared to other countries in the world among which India: despite the very rapid recent urban growth, the inequalities in city sizes are decreasing. This may in part depend of the under-registration of migrant urban populations. It also reveals the power of the political control on China’s urban processes that also appears in the magnitude of spatial concentration of manufacturing cities due to the implantation of Special economic Zones. Comparing the trajectories of Indian and Chinese cities may well improve the prospect of global urbanization that is crucial for the world and the planet.

Key-words. System of cities, Urban hierarchy, Zipf, Gibrat, Urban trajectories, China, India.

Link. HAL-SHS.



PhD Clémentine Cottineau

Cottineau C., 2014, The evolution of cities in the post-Soviet Space. Observation and modellings, University Paris I.

Abstract. The Russian and Soviet urbanisation process happened late and fast, compared to other territories. Many new towns and cities were created by the Soviet regime that officially promoted discourses about the socialist function of the city, rational organisation of space and a planned management of the economy. These urban particularities and the multiple demographic and political events of the 20th century have made cities in the post-Soviet space an interesting case and raised question regarding its ruptures and comparability. This dissertation thesis aims to show that the concept of system of cities and generic methods in urban geography (especially models) are useful in the study of urban evolution over the long term in this space, to eventually better understand past trends and predict future ones. We confronted several statistical models with the observed urban dynamics and concluded that the macro-geographical structure of cities in the post-Soviet space was comparable to that of other systems of cities (hierarchy of sizes, spacing, functional differentiation). We also observed specific trajectories related to the size of the territory, natural resources, the recent demographic shrinkage and the effect of particular political decisions. This knowledge about observed evolutions has been included in an incremental approach of agent-based modeling. Starting from theoretical hypotheses about generative mechanisms, we tried to generate generic and specific stylised facts, with a model as parsimonious as possible. The progressive evaluation of increasingly complex models led to the satisfactory simulation of observed urban evolution and highlighted specific trajectories that “resist” modeling.

Key-words. System of cities, Post-Soviet Space, Soviet Union, Generic/Specific, Simulation, Urban evolution, Urban growth.

Link. HAL-SHS.



PhD Clara Schmitt

Schmitt C., 2014, Modeling settlements systems dynamics : from SimpopLocal to SimpopNet, University Paris I.

Abstract. Is urban growth the result of multiple interactions between cities ? Urban evolutionary theory (Pumain, 2000), based on this postulate, analyses urban growth processes. This thesis, undertaken in an inter-disciplinary context, aims to evaluate the validity of the hypothesis by means of computer simulation. Strong regularities of the urban systems dynamics are extracted from the accumulated scientific knowledge and synthetized into ten major stylized facts. Two simulation models, SimpopLocal and SimpopNet, are then built, documented – thanks to a standardized grid – and systematically explored. They each question a specific aspect of the urban evolutionary theory : the nature of the inter-urban interactions for the first model (i.e. competition for innovation) and their support for the second model (i.e. the role of the communication network structure). The evaluation of the two models required the design and the implementation of two original exploration protocols : an automated calibration method and a sensibility analysis protocol (the Exploration Profile algorithm) which individually evaluates the contribution of each implemented mechanism to the simulated behavior. These two forms of exploration systematically confront the simulation results with current scientific knowledge. They indicate that the two models are able to account for key processes of urban systems dynamics, such as their hierarchical organization, and demonstrate for the first time the need for interurban interaction mechanisms in order to simulate urban evolutions that are close to those observed on real urban systems.

Key-words. System of cities, Urban systems, Simpop, SimpopLocal, SimpopNet, Simulation, Urban evolution, Urban growth.

Link. HAL-SHS.


Phd Ignazzi

Ignazzi C. A., 2015, Coevolution in the Brazilian Urban System, University Paris I.

Abstract. This thesis analyzes the urban system in Brazil adopting an advanced database that have been constructed collecting demographic data in order to examine the evolution of the population of all Brazilian agglomerations since the first Brazilian official census carried out in 1872 until 2010.
The largest country of South America has already completed its urban transition during the last century and is characterized by the contrast between a larger number of small towns throughout the immense territory and enormous Metropolitan areas dominating the system of cities.
Despite its geographical and historical peculiarities, this system shares with others in the world the same properties of hierarchical differentiation and urban growth processes (Zipf’s law and Gibrat’s model).
Economic data have been integrated in the database with the aim of testing the validity of scaling laws for Brazil and performing robust statistical analysis in order to explore the functional differentiation of cities, their economic performances and the spatial autocorrelation processes occurring among them.
The most interesting result is characterizing the Brazilian urban hierarchy over the long period and measuring the increasing inequalities in city sizes. Moreover, the parallel support of demographic and economic data is essential to identify the connection between population and economic growth in one of the most urbanized country of the world.

Key-words. System of cities, Urban systems, Urban hierarchy, Zipf, Gibrat, Urban trajectories, Brazil, Functional differentiation, spatial autocorrelation.

Link. Online.



PhD Rey-Coyrehourcq

Rey-Coyrehourcq S., 2015, An integrated platform for building and evaluating model of simulation in geography, University Paris I.

Abstract. Since 1990’s, Agent Based Modelling are commonly used by geographers to study complex systems like cities.
However, very few technical platforms are advanced by searchers to assist in the construction and evaluation of models of simulation. With the help of ERC program GeoDiverCity and the formation of an expert interdisciplinary team, we try to solve these problematic following two objectives. Relying on the support of OpenMOLE platform developed at the Institute of Complex System Paris-Ile-de-France in order to make it simple the distribution of simulation on distributed computing environments, we identify, use or build new tools and methodology to construct and explore model of simulation. To anchor this work in practice, we use this platform to build and explore a new model of simulation: SimpopLocal. This very practical work is accompanied by an historical and epistemological reading of simulation, and the means of simulation in geography. These contextualisation permits us to examine, and perhaps to anticipate, the historical link between the old problematic of “Validation”, very important to consider for knowledge justification, and the building and exploration of models of simulation.

Key-words. Simulation, Agent Based Modelling, Complex systems, Distributed computing environments, Validation.

Link. Online.



PhD Solène Baffi

Baffi S., 2015, Railways and city in territorialization processes in South Africa : from separation to integration?, University Paris I.

Abstract. First railway network in Africa, the South African Railways constitute a privileged marker of the territorial mutations that have been shaping this country for decades. The radicalism of political systems shows through the persistency of segregative schemes of which the railways, as part of the planning toolbox, are one of the elements. The inertia of this infrastructure questions its re-appropriation and insertion into the various planning projects over the long term. This thesis approaches the long-term dynamics of ‘territorialisation’ in South Africa through the prism of railways. This study focuses on the interaction between cities and the railway network, at both the interurban and the intra-urban levels.
In order to understand this interaction, cities’ location and railways diffusion patterns are analysed, with a specific emphasis on the shape of the network. Indeed, through their pattern, railways express the intentions of actors in charge of planning at the national level. By the flows it supports and the mobilities it enhances, it gives us information on the socioeconomic requirements of society and the power relations it contains. Thus, this thesis relies on a qualitative and quantitative approach aiming to outline the structuring effects of the railways in South Africa over the long term.
Its political use by successive segregationist powers explains partly why nowadays railways keep on marking partition in the post-apartheid urban space and in the practices of city dwellers. However, the recent rail renewal observed in the metropolises, Cape Town in particular, might indicate a possible major inflection in the persistency of inherited dynamics. Indeed, the evolution of the rail offer demonstrates a shift towards a co-construction trend between South African society and urban planning unheard of until now.

Key-words. System of cities, Urban system, South Africa, Railways, Territorialisation, Inclusion/exclusion, Intra-urban mobilities.

Link. HAL-SHS.



PhD Olivier Finance

Finance O., 2016, French cities hosting foreign direct investments: from networked companies to localized establishments, University Paris I.

Abstract. Transnational corporations, which are amongst the major players in the contemporary global economy, integrate and exclude territories at various scales, due to their specific location strategies. These inequalities are well known at an international scale, yet the knowledge of this diverse integration is much more limited regarding urban levels, although cities and metropolises are considered as being the major nodes of the globalized networks. France and the OECD countries certainly appear in central positions in the networks that characterize these corporations, but observations made at the urban level remain very partial due to the lack of localized data. This thesis suggests to both approach and localize conventional data about Foreign Direct Investment (FDI) in the French case by mobilizing data about financial links connecting economic units. The detailed breakdown of transnational corporations affiliation networks has been conducted up to the level of the establishments, which are the real individual economic and geographic cells of these transnational networks. An original database about localized inward FDI stocks has been built and explored to appreciate how far foreign transnational corporations integrate the 355 main cities into the French urban system. These data revealed the diverse integration of French cities, between dependence and attractiveness for the investors. The mobilization of scaling laws, which constituted a major analytical tool in this work, allowed us to identify the major factors explaining the diverse integration of French cities into the whole system of cities, reflected both by inequalities of hierarchical and regional order.

Key-words. System of cities, Urban system, France, Scaling laws, Foreign Direct Investment, Transnational firms.

Link. HAL-SHS.


How to estimate the singularity of (post-)Soviet cities?

Revue d'Economie Regionale et Urbaine - n°1 - 2017 New Article, in RERU – Revue d’Économie Régionale et Urbaine.


Cottineau C., 2017, “How to estimate the singularity of (post-)Soviet cities?”, Revue d’Économie Régionale et Urbaine, n°1-2017.

Abstract. Although the urbanisation of the Former Soviet Union is a unique experience, this article questions the possibility of estimating the share of the generic processes of urban growth, spatial location and economic specialisation, the share of the particular processes of urbanisation linked to the size and political organisation of the country, and the share of the singular processes that cannot be explained without a local knowledge of the events which happened in the cities under study. Using several types of models at different scales, we identify the residual as the element that “resists modelling” and illustrates the singular evolutions of the Soviet Union and its cities. To do so, we built a harmonised urban database and fitted hierarchical, spatial and regression models. We conclude that city size inequality increased in a generic manner compared to other systems of cities, that the spatial distribution of cities resemble that of vast countries (especially with the increased reliance on sub-surface resources), and that there exists a set of singular urban trajectories.

Key-words. System of cities, Soviet Union, Singularity, Models, Urban growth, Urban trajectories, Urbanization.

Link. Revue d’Économie Régionale et Urbaine

Beyond Corroboration: Strengthening Model Validation by Looking for Unexpected Patterns

diversityNew Paper, in PLoS ONE


Chérel G., Cottineau C., Reuillon R., 2015, « Beyond Corroboration: Strengthening Model Validation by Looking for Unexpected Patterns », PLoS ONE 10(9): e0138212. doi:10.1371/journal.pone.0138212

Abstract. Models of emergent phenomena are designed to provide an explanation to global-scale phenomena from local-scale processes. Model validation is commonly done by verifying that the model is able to reproduce the patterns to be explained. We argue that robust validation must not only be based on corroboration, but also on attempting to falsify the model, i.e. making sure that the model behaves soundly for any reasonable input and parameter values. We propose an open-ended evolutionary method based on Novelty Search to look for the diverse patterns a model can produce. The Pattern Space Exploration method was tested on a model of collective motion and compared to three common a priori sampling experiment designs. The method successfully discovered all known qualitatively different kinds of collective motion, and performed much better than the a priori sampling methods. The method was then applied to a case study of city system dynamics to explore the model’s predicted values of city hierarchisation and population growth. This case study showed that the method can provide insights on potential predictive scenarios as well as falsifiers of the model when the simulated dynamics are highly unrealistic.

Key-words. Simulation and Modelling, Evolutionary Algorithm, Population Growth, Space Exploration, Urbanisation, Complex Systems.

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

Cities and Transport relations in South Africa over the long-term

The aim of my study 1 is to understand the role of South African cities in the transport flux and networks, and how cities and transport are interacting, from colonization in the 17thuntil nowadays. If cities and transport interactions are a particularly interesting approach to understand the metropolisation process and the urban system building, the South African context makes it even more relevant. Indeed, South Africa is a young country and national transport networks such as the railway network, have been built while the urban system was formed.

Co-evolution of urban system and railway network in South Africa

The arrival of European settlers in 1652 to the Cape of Good Hope marked the beginning of South African modern history, in particular by initiating the urbanization process. Until then, no city, strictly speaking, existed yet (Coquery-Vidrovitch). The implementation of a settlement engaged the constitution of an urban system well connected with Europe, but not very well between cities (Vacchiani-Marcuzzo).

The discovery of the goldfields and diamond mines in the 1860’s overturned that system. In the heart of the mining region, Johannesburg faced a fast growth to become the biggest metropolis in the country. The emergence of this new centre deeply modified the urban structure by switching the country’s centre of gravity from the coast to the Witwatersrand. Indeed, the British Empire decided to experiment inner-city railways in Cape Town and Durban in the 1860’s. But given the mining revolution, the decision to extend it to the entire country was quickly made in order to dispatch the mining extractions from the Witwatersrand plateau to the shoreline before having them exported to Europe. Hence, in a bit less than 100 years, a 20 000 km railway network has been built.

The implementation of such a network whereas the urban system was formed enables us to talk about a co-evolution of urban system and transport network in South Africa. Citie’s growth has largely been influenced by their position on the railway network. Large cities benefitted from a better accessibility, which reinforced their centrality while small towns had to deal with the simplification of urban hierarchy. As in many other countries, we can notice the strong interaction between cities and transport and its effect on the process of cities selection, particularly reinforced  by the railway network in the South African example.

I started my research by focusing on the railway network given it seemed easier to start with an historical approach at the larger scale. To observe and study this co-evolution we decided to cross two databases created in Geographie-Cités. The first one, built in the research program Harmonie-Cités, gathers data about the evolution of South African cities (of more than 5 000 inhabitants) over almost a century. To create this database, South African censuses have been used. The second one, made up in the frame of Geodivercity research program, contains data about the railway network’s development in South Africa and has been built thanks to the SARH archives. By crossing these databases, we created maps over 60 years which show the concomitant evolution of the urban system and railway network.

Now, I intend to deepen my analysis and enlarge my focus to the implementation of transport in metropolitan areas on one hand, and the position of South Africa in global networks on the other.

Solène Baffi

Notes:

  1. PhD project of Solène Baffi, under the supervision of Anne Bretagnolle, Olivier Ninot, Denise Pumain and Celine Vacchiani-Marcuzzo (founded by ERC GeoDiverCity)

Evolution and urban modeling: a complexity perspective on the Brazilian city system

The project performed in this thesis, aiming at the knowledge of the Brazilian system of cities, sets out to demonstrate, within an historical and legal frame, the peculiarities of the history of urbanization in Brazil, a large and populous developing country that is widely considered to have completed an early urban transition.

Undertaking a research on this topics means, primarily, to handle with a problem of an apparent dearth of literature; even if is possible to find many works on Brazilian urbanization, above all in Portuguese language, only a few of these treats urbanization under the aegis of complex systems, as an adaptation process to changes arising from massive urbanization and from insertion in a global, hierarchized network of cities, in which, each metropolitan area is compelled to adapt its internal structure in response to demographic, economic and technical changes. Brazilian main centers will be considered as nodes of a hierarchized structure extending their influence over other agglomerations and territories.

A complexity perspective can provide a general appropriate context within which to understand the behavior of socio-economic systems, notably urban cities systems; computer based models will be associated to a geographical conception in order to analyze urban systems starting with geographical and historical data and trying to foresee their future dynamics through modeling.

By the means of an analysis of both geographical conception and computer-based conception of cities, we will try to set up a model that simulates the peculiarities and so the dynamics of cities and this will be explicitly done using the software Netlogo in order to realize a simulation of a cities system in Brazil. The testing done with our model will be also used to simulate the possible effects of climate changes on the future evolution of urbanization.

Cosmo Antonio Ignazzi

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)

From SimpopLocal to SimpopClim: Three stages of urban growth dynamics under resource accessibility constraints

  The aim of this series of models 1 is to study growth regimes of systems of cities, which are defined by the nature of the interaction between the cities. Three different stages of urbanisation are considered as resource accessibility, which plays a major role in growth dynamics, takes different forms. For each stage, a set of stylized facts characterizing the state of the system and urban growth dynamics is proposed and defines the structure of an ABM model.

The SimpopLocal model tries to characterise a stylised dynamics of urban emergence.  This first urban regime is defined by the role of local environmental constraints on growth. Central to this model is the notion of landscape carrying capacity. Settlement sizes and their growth are controlled by the amount of resources locally available.  But innovations and their diffusion in the system thanks to interactions between settlements help to overcome those limitations, eventually producing the proto-structure of urban systems.

The SimpopNet model characterise the progressive networking of urban economies. Innovations in communication and transport networks allow the trade and long distance diffusion of goods and techniques which enables cities to overcome, by importing what was lacking, the local constraints and climatic hazards that limited their growth. In this regime, the resource accessibility of each city is defined by its situation in the network. The SimpopNet model simulates the co-evolution of urban systems and transportation networks.

The SimpopClim model will represent a dynamic regime that takes into account the impact of global environmental constraints on urban dynamics.

This PhD is made possible thanks to interdisciplinary work with computer researchers participating in the GeoDiverCity programme, hired after previous collaboration with ISC-PIF (Romain Reuillon and Mathieu Leclaire, http://www.iscpif.fr/) and a PhD in geomatics conducted by Sébastien Rey Coyrehourcq. The SimpopLocal and SimpopNet models are used as case studies for the development of grid exploration procedures and protocols with OpenMole (http://www.openmole.org/). Those explorations and validating tools are designed to meet the validation and reproducibility requirements and to be generic and adapted to the exploration of spatial simulation models.

Clara Schmitt

Notes:

  1. PhD project of Clara Schmitt, under the supervision of Denise Pumain (founded by ADEME, The French Agency for Environment and Energy)

Pre-AGILE joint workshop MECHANICITY VS GEODIVERCITY (ERC)

On Tuesday April 24th 2012, the ERC programs MECHANICITY and GEODIVERCITY met at a pre-AGILE workshop in Avignon.

First part: joint session with Workshop “Complexity modelling for urban structure and dynamics” organised by Bin Jiang  and Itzhak Benenson

Mike Batty and Robin Morphet, “Spatial complexity”

Denise Pumain, “Organizing a variety of agent-based models for solving theoretical problems”

Itzhak Benenson
, “Equations or geosimulation? To understand the phenomenon you need both!”

Bin Jiang
, “Head/tail breaks: A new classification scheme for data with a heavy-tailed distribution”

Second part: MECHANICITY and GEODIVERCITY

Urban Growth, Chair: Denise Pumain

Elsa Arcaute (MECHANICITY), “Looking for scaling in UK Cities”

Clémentine Cottineau (GEODIVERCITY), “A tool for assessing the specificity of the evolutionary path of Russian cities”

 

Urban Boundaries, Chair: Mike Batty

Erez Hatna (MECHANICITY), “Redefining urban boundaries towards scaling”

Elfie Swerts (GEODIVERCITY), “A multi-level analysis of urban growth in the Indian urban system”

Simulating cities, Chair: Arnaud Banos

Mathieu Leclaire and Romain Reuillon (GEODIVERCITY), “Openmole, a generic platform for model experimentation using distributed computing”

Clara Schmitt and Sebastien Rey-Coyrehourcq (GEODIVERCITY), “Simpoplocal, a simulation model for early urban settlements : automated calibration with genetic algorithm”

Erez Hatna (MECHANICITY), “The Schelling model of Segregation: the effect of agents with distributed tolerance thresholds”

Thomas Louail (GEODIVERCITY), “SimpopNano, a model for exploring the effect of networks on urban dynamics”

Conclusion of the day, discussion and perspectives of collaboration