Scaling of urban heat island and nitrogen dioxide with urban population: a meta-analysis

Scientific Conference (2021, June 10)

Radial Urban Forms: Lessons from Land Profile Scaling Analyses & Spatial-Explicit Models

Scientific Conference (2020, November 25)

We definitely live in an increasingly urban World for half of humanity now lives in cities. Cities provide wealth but also negatively impact the environment and the health of citizens. Arguably the benefits and costs of cities relate to both their size, in population terms, and their internal structure, in terms of the relative spatial arrangement of built-up and natural land. Much of urban research focusses on very large cities and urban cores. Yet 3 urban human out of 4 live in cities of less than 4 million inhabitants (according to the global GHSL dataset). Similarly, 3 out of 4 in a typical (European) city do not live in its core but beyond (using a 7-8km radius to define core for a city like London or Paris). To address urban sustainability issues and design adaptation policies, these 75% certainly count and, we can argue, also deserve specific attention because of the relative proximity between urban and non-urban (natural) use that smaller cities and suburban (non-core) areas may permit. In this respect, it is key to understand how the internal structure of cities, in particular the form and density of built-up areas and the interwoven green space emerge out of the core up until the fringe. It is also key to understand whether the form of cities, especially density gradients and the share of urbanised/non-urbanised land change with city size. In this talk we draw lessons from 2 research approaches to urban forms: one theoretical that uses spatial micro-economic simulations, and one empirical that uses spatially detailed land use datasets. Our theoretical simulations relate individual behaviour to urban forms while our empirics relate urban forms to city size. Both have in common a radial perspective to cities, i.e. explicitly or implicitly assuming that the accessibility trade-off to a given centre is a key determinant of locations and land uses. In both cases, we look at urbanisation and green space structures and at pollution exposure as an example of impact.

A Spatially explicit ABM of Central Place Foraging Theory and its explanatory power for hunter-gatherers settlement patterns formation processes

in Adaptive Behavior (2020)

The behavioural ecological approach to anthropology states that the density and distribution of resources determine optimal patterns of resource use and also sets its constraints to grouping, mobility and settlement choice. Central Place Foraging (CPF) models have been used for analysing foraging behaviours of hunter-gatherers and to draw a causal link from the volume of available resources in the environment to the mobility decisions of hunter-gatherers. In this study we propose a spatially explicit agent-based CPF mode. We explore its potential for explaining formation of settlement patterns and test its robustness to the configuration of space. Building on a model assuming homogeneous energy distributions we had to add several new parameters and an adaptation mechanism for foragers to predict the length of their stay, together with a heterogeneous environment configuration. The validation of the model shows that the spatially explicit CPF is generally robust to spatial configuration of energy resources. The total volume of energy has a significant effect on constraining sedentism as predicted by aspatial model and thus can be used on different environmental conditions. Still the spatial autocorrelation of resource distribution has a linear effect on optimal mobility decisions and needs to be considered in predictive models. The effect on settlement choice is not substantial and is more determined by other characteristics of settlement location. This limits the CPF models in analysing settlement pattern formation processes.

Central place foraging and hunter-gatherer settlement patterns: how resource depletion influences population concentration

Scientific Conference (2019, September 09)

Settlement patterns are one of the main products of the Stone Age archaeological research. Their emergence processes can be explained by different models of settlement and mobility choices done by past inhabitants. In current study we explore central place foraging (CPF) model of huntergatherers as a tool for exploring formation of settlement patterns. CFP model is used for describing mobility choices of hunter-gatherer groups. It implies the groups settle at a central location and make logistic forays to surrounding areas foraging for required resources. The central location is chosen by it’s optimal position in relation to those resources and the group is willing to leave the current base location if a better alternative arises. We introduce a spatially explicit Agent-Based Model (ABM) of the CPF and explore how heterogeneous environment influences the settlement pattern formation. The motivation to move in CFP comes from changes in the environment. An important part of the change is the depletion of existing resources by the hunter-gatherers themselves. We are using the ABM model to explore how depletion process influences the dispersal of huntergatherer groups in the environment and which conditions and strategies will result in higher concentration and clustering of the population.

Unravelling the border-facade of France : a multi-level modelling of cross-border commuting

in Caruso, Geoffrey; Gerber, Philippe; Jones, Catherine; Klein, Olivier; Perchoux, Camille (Eds.) 21st European Colloquium on Theoretical and Quantitative Geography (ECTQG), Book of Abstracts, Mondorf-las-Bains, 5-9 septembre 2019 (2019, September 09)

Given its central position in Western Europe, France is the European country where cross-border commuting is most intense. Over 350000 residents cross the national border everyday to go to work. Cross-border commuting raises a lot of concerns for planners on both side of each border, especially for provisioning transport infrastructure and local public services but also because it impacts land and housing markets, especially when salary differentials are high. While there is a lot of research about the daily functioning of specific borders (e.g. France-Switzerland or France-Luxembourg), generalization is lacking and spatial heterogeneities impede our understanding of the very determinants of cross-border commuting, such as the role of benefits differentials, transport costs and distance, or the relative availability of jobs at residential places and across the border. Further, these effects are most likely mediated differently by the socio-demographic characteristics of workers, their employment sector, and the quality of their residential environment at large. This suggests that an individual approach and a spatially detailed approach is needed, which contrasts sharply with the fact that most European-wide studies of cross-border commuting are conducted at very aggregated spatial scales (NUTS 2 or 3).

How does the relative spatial pattern of green within cities impact carbon uptake? A European scale analysis

Scientific Conference (2019, September 06)

Cities constitute the main source of CO2 emissions into the atmosphere. Urban areas exhibit a variety of land use profiles and carbon metabolisms. Yet it is important to assess to what extent they can cope with their own emissions. We address this issue by examining how the internal spatial organization of cities can impact the flow of anthropogenic CO2 between their major sources - human activities - ; and their main storage infrastructures, with a focus here on urban green spaces and forests. Is it better to have a dense core with a peripheric green belt? Large green patches within the core centre? Or small and fragmented green spaces? The objective of the present work is to tests whether the internal spatial organization of urban areas - in terms of green infrastructure characteristics and land use types - matters for evaluating carbon sequestration potentials within urban areas. Or whether they can simply be considered as single objects with a quantity of carbon emissions and a carbon sink capacity derived directly from aggregated land use data. We present a spatially explicit urban carbon flow model. Using land use data, an emission inventory and sequestration potentials from the vegetation we allocate a carbon budget to each spatial unit within the urban systems. Anthropogenic CO2 emissions are accounted from different land use categories using the TNO CAMS dataset. The potential of carbon sequestration by the urban forest is set using estimates from the literature. Urban carbon flows are then simulated for all Functional Urban Areas (FUAs) of European cities using the Urban Atlas 2012 database. Most studies on carbon dioxide uptake into vegetation at city or metropolitan scales estimate carbon stocks or aggregated carbon flows, while spatially explicit urban carbon flow analyses are made on spatially limited areas - i.e. neighbourhood level. Also, the homogenous land use data and emissions inventory at the continental level allows for a comparison of the different urban areas. We then compare the aggregated budget of the areas of study – commonly done in budget approaches from micro to global scale – to the spatially explicit budget. It allows us to estimate the real contribution of the urban forest to the uptake of anthropogenic emissions within the same urban ecosystem. The analysis then investigates the level of efficiency of CO2 uptake for different typology of urban areas for different carbon profiles. The efficiency is defined as the share of local emissions captured within the urban boundaries. In the future, the model will be validated using eddy covariance empirical data.

Urban densities and patterns: stylized facts and generic abstract tools

Conference given outside the academic context (2019)

21st European Colloquium on Theoretical and Quantitative Geography: Book of abstracts

Book published by LISER (2019)

Walking, trip purpose, and exposure to multiple environments: A case study of older adults in Luxembourg

in Journal of Transport and Health (2019), 13

Purpose: Understanding the geographical and environmental triggers for active transport among older adults is crucial to promote healthy and independent lifestyles. While transportation research has long considered trip purpose as a major determinant of transport mode choices, “place and health” research has paid little attention to it, and even less in connection with environmental determinants. To avoid an oversimplification of how neighborhood built environments influence utilitarian walking, it is critical to account simultaneously for trip purposes, the locations of visited places, and the related exposure to surrounding environments. Methods: Based on a cohort of 471 older adults in Luxembourg, this study examines the influence of trip purposes on utilitarian walking, and the potential interaction effects with characteristics of multiple geographic environments and distance to the place of residence. Information related to demographics, health status, and regularly visited destinations was collected in 2015 and 2016. Associations between trip purpose, environment, distance, and walking were analyzed using multilevel logistic regressions, accounting for demographics, neighborhood self-selection, and health status. Results: After accounting for environmental attributes, distance, and confounding factors, trip purpose remained a strong correlate of walking among older adults. Associations between distance and walking strongly differed by trip purpose (Wald Chi 2 test p < 0.001). Access to amenities, public transport stops, and street connectivity were associated with walking, although no interaction with trip purpose was observed. Conclusion: Trip purposes based on free-time activities–including visits to family and friends, and restaurants and cafés–seem to be less influenced by the barrier effect of distance on walking. While place and health studies increasingly address both the “where” and “when” of travel behaviors, the current study additionally stresses the importance of the trip purpose to emphasize “why” and “for what” people walk. © 2019

The provision of urban green space and its accessibility: Spatial data effects in Brussels

in PLoS ONE (2018), 13(10), 0204684

Urban green space (UGS) has many environmental and social benefits. UGS provision and access are increasingly considered in urban policies and must rely on data and indicators that can capture variations in the distribution of UGS within cities. There is no consensus about how UGS, and their provision and access, must be defined from different land use data types. Here we identify four spatial dimensions of UGS and critically examine how different data sources affect these dimensions and our understanding of their variation within a city region (Brussels). We compare UGS indicators measured from an imagery source (NDVI from Landsat), an official cadastre-based map, and the voluntary geographical information provided by OpenStreetMap (OSM). We compare aggregate values of provision and access to UGS as well as their spatial distribution along a centrality gradient and at neighbourhood scale. We find that there are strong differences in the value of indicators when using the different datasets, especially due to their ability to capture private and public green space. However we find that the interpretation of intra-urban spatial variations is not affected by changes in data source. Centrality in particular is a strong determinant of the relative values of UGS availability, fragmentation and accessibility, irrespective of datasets.

Conceptual framework of assessing the influence of cultural complexity to settlement pattern formation

Scientific Conference (2018, September)

Settlement patterns are one of the main products of prehistorical archaeological research and are used as spatial projections of past societies. In current paper we study how geographical locational data can reveal information about cultural complexity. The formation of the patterns is influenced by multiple factors from human-environment interactions to complex processes within society. We analyse the forces behind formation of settlement patterns from an agent based modelling perspective. For the purpose we construct a spatial discrete choice model and formulate it using random utility theory. We argue that agent decisions in the models can be decomposed into different rulesets. Those rules are mostly determined by attraction to natural affordances and sociocultural behaviours. Paleoecological and geological data can be used to extract information about human attraction to natural affordances. Analysing the resulting empirical data can reveal the significance of environment as determining settlement choice which we argue is declining with growing cultural complexity.

Transferring knowledge from locational predictive models into spatial Agent Based Models: generilizing human perception of environment

Scientific Conference (2018, March 22)

Predictive models have been used for finding potential archaeological site locations already for more than 40 years. In addition to their extensively used application in cultural heritage management they can also offer insights into past human behaviour in relation to environment. The proposed paper discusses how the information gathered from predictive modelling of archeological settlements, especially the revealed from location determinants, can be transferred to spatial Agent Based Models. We argue that spatial simulation models, especially those based on agents behaviour, above all aim to build theory and create generalisable knowledge. They therefore need to free themselves form local contexts and particular spatial heterogeneities, and automatically test the effect of agents behaviour on a wider range of spatial configurations. In cultural heritage management, models are usually created using geographical variables of existing settlement patterns (eg. water access and land formations). For finding archaeological sites the model needs to be calibrated for specific accuracy and precision. In this paper we focus on defining the potential residential space – an area that could be considered by people of the past as suitable for habitation or specific economic activities. We develop a framework that links geographical variables and behaviour as extracted from empirical studies to the development of a theoretical spatial agent-based model.

Aggregate and disaggregate dynamic spatial interaction approaches to modelling coins diffusion

in Thill, Jean-Claude (Ed.) Spatial Analysis and Location Modeling in Urban and Regional Systems (2018)

With the 2002 introduction of the euro as a common currency in Europe,the possibility has emerged to assess international mobility using this new tracer, given that every coin bears a specific national side. Using a simple two-country framework, four dynamic modeling strategies were designed in order to simulate the diffusion of coins and to understand how this diffusion is affected by population size, mobility rates and coin exchange processes. Methodological implications are raised with respect to aggregation, synchronicity and stochasticity issues. Although each model converges to an equilibrium, the time to reach this end stage and the level of coin mixing in each country strongly varies with the modeling strategy. Calibration is undertaken with French data, using mobility rates as adjustment variables. The experiment shows that convergence to a perfect mix of coins can only be obtained if reciprocal exchanges are modeled, with a time horizon around 2064 - while non-reciprocal models indicate an imperfect mix converging in the year 2020 at the latest.

Agent-based modeling as an interdisciplinary bridge in spatial humanities. Designing the modeling framework for simulation of Mesolithic settlement patterns

Scientific Conference (2018)

Settlement patterns have been one of the central products of Stone Age archaeological research. Because of long time spans and very scarce information, scientific explanations of the patterns are usually limited to just defining the areas of the phenomena of interest. Any further deductions about past communities tend to be without additional proof and thus presented as hypotheses in scientific literature. In this paper we introduce a study that seeks to create a general framework for modeling the emergence of settlement patterns. The central concept for modeling is the human / social perception of the environment and how it is related to potential residential space – places that can be used for human habitation. We hypothesize that the human perception can be used to simulate the processes of emergence of immigration and seasonal mobility. The first goal of the research is to identify possible knowledge sources (eg. paleoecology, geography, geology, anthropology) that give information about residential mobility of pre-agricultural societies. The second goal is to translate selected knowledge to algorithmic representation and evaluate its usability for modeling. The purpose of which is to find the determining factors in the emergence of the settlement patterns and to distinguish between emerging and irreducibly complex phenomena.

Spatial sorting, attitudes and the use of green space in Brussels

in Urban Forestry and Urban Greening (2018), 31

Extensive evidence exists on the benefits provided by urban green space (UGS) but evidence is lacking about whether and how socio-economic benefits accrue to all residents or disproportionally depending on their socio-economic status or residential location. We model joint effects of socio-economic and locational attributes on attitudes and use of UGS in Brussels (BE). The analysis is based on a survey conducted along an urban-suburban continuum with respondents sampled across non-park public space. Patterns of use are depicted by the frequency and the distance travelled to the most used UGS. Attitudes are analysed along three dimensions: willingness to (i) pay for UGS, (ii) trade-off housing for green space and (iii) substitute private for public green. Our results stress the importance of separating effects of attitudes from socio-economic and locational effects to quantify UGS use, and suggest endogenous effects of green space with residential sorting.

City delineation in European applications of LUTI models: review and tests

in Transport Reviews (2018), 38(1), 6-32

This paper stresses the lack of attention paid to the geographical definitions of cities in LUTI models as one key detrimental aspect to transferring and generalising LUTI results. First, the argumentation develops from a meta-analysis of peer-reviewed publications about LUTI applications in European cities. We show that most authors do not assess findings against potential geographical biases. Second, theoretical simulations are conducted with UrbanSim applied to a synthetic urban area. By varying the geographical limits of the system and population endowments, our simulations confirm that the absence of control on city delineation weakens the results. Finally, the paper suggests methodological guidelines to improve the comparability of LUTI applications and push forward their theoretical agenda.

The homothetic scaling of urban land and density profiles: evidence from Europe

Scientific Conference (2017, November)

Evidence for the homothetic scaling of urban forms

Scientific Conference (2017, September)

Measuring urban forms from inter-building distances: Combining MST graphs with a Local Index of Spatial Association

in Landscape & Urban Planning (2017), 163

A new method is proposed for characterising local urban patterns at the scale of a large urban region. The approach overcomes the difficulties of surface-based representations of built-up morphologies and provides an efficient way to account for the proximity of built and non-built land. The strength of the approach resides in the direct use of the coordinates of each building, a very parsimonious input of external parameters, and a local spatial statistical perspective. The method consists in, first, constructing and clumping the Minimum Spanning Tree (MST) that links each building to its neighbours in order to obtain connected urban and suburban graph subsets, and second, measuring a Local Index of Spatial Association (LISA) on inter-building distances in order to characterise patterns. The method differentiates heterogeneous settlements from statistically significant homogeneous clusters with either long or short connections between buildings. The method is applied to the Southern periphery of Brussels (Belgium).

Localisation résidentielle de la population étrangère selon la nationalité et la structure urbaine au Luxembourg

E-print/Working paper (2017)

The number of foreigners living in Luxembourg is still rising and represents today about 48% of the inhabitants. This study focuses on the description and mapping of the place of residence for the different nationalities living in Luxembourg. It seeks to underline differences through indicators built from the 2011 census data. We focus on the territorial distribution of the different nationalities by taking into account the urban structure and distance to jobs. If differences according to nationalities in the residential behavior of households can be empirically identified they may raise issues of spatial equity and (un)equal accessibility to job market. We analyse whether the geographic location of different nationalities in Luxembourg is linked to urbanisation level, the distance to the “poles d´emploi” or general accessibility to jobs.

Framing and reviewing a green mismatch hypothesis

Scientific Conference (2017, April 08)

Scaling evidence of the homothetic nature of cities

E-print/Working paper (2017)

In this paper we analyse the profile of land use and population density with respect to the distance to the city centre for the European city. In addition to providing the radial population density and soil-sealing profiles for a large set of cities, we demonstrate a remarkable constancy of the profiles across city size. Our analysis combines the GMES/Copernicus Urban Atlas 2006 land use database at 5m resolu- tion for 300 European cities with more than 100.000 inhabitants and the Geostat population grid at 1km resolution. Population is allocated proportionally to surface and weighted by soil sealing and density classes of the Urban Atlas. We analyse the profile of each artificial land use and population with distance to the town hall. In line with earlier literature, we confirm the strong monocentricity of the European city and the negative exponential curve for population density. Moreover, we find that land use curves, in particular the share of housing and roads, scale along the two horizontal dimensions with the square root of city population, while population curves scale in three dimensions with the cubic root of city population. In short, European cities of different sizes are homothetic in terms of land use and population density. While earlier literature documented the scaling of average densities (total surface and population) with city size, we document the scaling of the whole radial distance profile with city size, thus liaising intra-urban radial analysis and systems of cities. In addition to providing a new empirical view of the European city, our scaling offers a set of practical and coherent definitions of a city, independent of its population, from which we can re-question urban scaling laws and Zipf’s law for cities.

Equilibrium and first-best city with endogenous exposure to local air pollution from traffic

in Regional Science and Urban Economics (2017), 62

Exposure to urban traffic-induced air pollution is a major health concern of cities. This paper analyzes the urban structure when localized pollution exposure arises from commuting traffic and investigates the feedback effect of endogenous pollution on residential choices. The presence of stronger traffic-induced air pollution exposure reduces the geographical extent and the population of cities. Land rents fall with distance from the city center while population densities may be non-monotonic. Cleaner vehicle technologies reduce pollution exposure everywhere, increase population and density everywhere and do not affect the spatial extent of the city. The paper compares the urban equilibrium with the first-best. The first-best structure is a less expanded city with higher densities at the center and lower densities at the fringe.

Bee Species Richness in Europe

Cartographic material (2017)

This map portfolio compares maps of bee species richness in Europe automatically aggregated per country from the IUCN Red List with national numbers obtained from various other sources.

An agent-based model to simulate the feedback effect between traffic-induced air pollution and urban structure

Scientific Conference (2016, September 22)

A spatial complexity currently of increasing concern is the relation between the internal structure of urban areas and traffic‐induced air pollution. Urban air pollution has severe impacts on the environment and on human health with traffic being its major source. Air pollution from traffic varies locally within the city depending on traffic patterns that arise from the spatial arrangement of land uses and subsequent travel demand across time. In this paper, we contribute a dynamic agent‐based residential model (ABM) applied to 2D theoretical space based on micro‐economic principles with local exposure and pollution externalities arising from car commuting traffic and an endogenous road network. We analyse the effects of households’ aversion to generating and being exposed to local traffic pollution on emerging land use patterns and pollution distribution. The focus is thereby set on endogenising local health but also global environmental concerns of traffic‐induced air pollution in location choice. The ABM framework allows discussing the spatial interactions against the background of pollution‐related (e.g., pollutant diffusion, cold‐start emissions, additional emissions through traffic congestion) and preference‐related (e.g., exposure during the commute versus at the residential location, size of the impact neighbourhood) framework conditions and planning approaches (localized lump‐sum taxes, cordon tolls, flat taxes). We discuss the stability and performance criteria of the resulting cities, which are on the one hand city aggregates (e.g., total emissions, total exposure, spatial extent of the urban area), but on the other hand and more importantly location‐dependent disaggregates (local patterns of land rents, exposure, green spaces, design of the road network). Thus, our paper interlinks pollution‐related concerns and urban structures from a health and environmental perspective, which take place at different spatial scales (different radii of interaction) and thereby ties in with the compaction‐sprawl debate in the literature.

Land use and density in the European city: monocentric analysis and scaling

Scientific Conference (2016, August)

In this work we study the evolution of land use and population density in European cities with respect to the distance to the city centre, and how land use and density curves scale with city population. The principal aim of this research is to provide stylized facts and generic formulas for the calibration of monocentric urban economic models to European cities. We use the GMES Urban Atlas database, providing a precise description of land use in the 305 major European larger urban zones (LUZ), which have more than 100.000 inhabitants. For the population density we use the Geostat population grid, which covers the whole of European Union (EU) with a 1km$^2$ grid dataset. We combine the land use and population datasets by attributing the population of the Geostat grid to the geographic units of the (much more precise) land use dataset. This attribution is proportional to the surface of each unit and weighted thanks to the nomenclature of the GMES Urban Atlas, which gives classes of soil sealing and density of urban fabric. Then we analyse the evolution with distance to the city centre, which we define for convenience as the location of the city hall, of population density and of the share of land used for different purposes: housing, roads, railways, urban green, water, agriculture, forest. To this end, we define concentric rings of fixed width around the city centre, in which we average land use and population. In order to compare results between different cities and to obtain a global picture ("average" or "standard" European city), we study simple scaling relationships for the obtained monocentric land use shares and density curves. We choose to study the scaling of these curves with respect to the city population, as has been done in the literature for different parameters (like income or road space). In our case city population is taken as the population of the LUZ, computed thanks to the population grid. It turns out that land use curves, in particular housing or roads shares, tend to scale like the square root of city population. Population curves have roughly exponential shapes, as widely modelled in the literature, and tend to scale like the city population to a power close to $1/3$. These results allow us to propose a simple monocentric description of land use shares and population curves in a representative European city, whose size can be chosen based on the scaling relationships we obtain. This result is especially interesting, and of practical use, for the purpose of calibration of monocentric urban models.

Land use and density in the European city: monocentric analysis and scaling

Scientific Conference (2016, July)

Land use and density in the European city: monocentric analysis and scaling

Scientific Conference (2016, May)

In this work we study the profile of land use and population density in European cities with respect to the distance to the city centre. More specifically we address the scaling of land use and density curves with respect to city population and rely on fine grained land use data. Our main objective is to retrieve generic laws that can support the calibration of monocentric urban economic models for European cities. We use the GMES Urban Atlas database, providing a precise description of land use at 5m resolution in the 305 major European urban areas (more than 100.000 inhabitants). We combine this dataset with population density from the Geostat population grid, which covers the whole of European Union (EU) with a 1km2 resolution. Population is allocated proportionally to surface and weighted by soil sealing and density classes of the GMES data. We analyse the evolution with distance to the city centre, which we define for convenience as the location of the city hall, of population density and of the share of land used for different purposes: housing, roads, railways, urban green, water, agriculture, forest. To this end, we define concentric rings of fixed width around the city centre, in which we average each land use and population. In order to compare different cities and to identify a global picture, i.e. a standard representative European city, we study scaling relationships for the ob- tained monocentric land use shares and density curves. We analyse the scaling of these curves with respect to city population, following similar approaches con- ducted in the literature for different parameters (such as income or road space). The total population for each city is computed from the population grid. We find that land use curves, in particular housing and roads shares, tend to scale like the square root of city population. Population curves have roughly exponential shapes, as it has been widely modelled in the literature, although usually not based on land use and soil sealing data. Population curves tend to scale like the city population to a power close to 1/3. These results allow us to propose a simple monocentric description of land use shares and population curves in a representative European city, whose size can be chosen based on the scaling relationships we obtain. This result is especially interesting, and of practical use, for the purpose of calibration and validation of monocentric urban models, that can differentiate (or not) housing from land and include interactions between non-developed and developed land.

Formes Urbaines et Aménités Vertes

Conference given outside the academic context (2016)

La ville est insensible aux formes idéales

Conference given outside the academic context (2015)

L’urbanisme, c’est bien plus qu’une simple affaire de dessin en plan. Un dessin en plan, si régulier soit-il sur le plan géométrique/géométral, ne donnera en fait jamais dans la réalité deux villes identiques quant à leur fonctionnement. La vie d’une ville se passe dans le temps, ses occupants et ses activités produisent des strates qui se cumulent et produisent un espace hétérogène. Cette « dépendance de chemin » contraint fortement les activités et les flux, au point de les rendre insensibles à des impositions, même fortes, mais elle crée aussi des opportunités de reconversion, des quartiers attractifs, uniques voire sympathiques. Les villes wallonnes n’y échappent pas, jouons-en !

Monocentric urban simulation models: getting closer to fractal properties and landscape representation

Scientific Conference (2015, November)

Urban growth generates spatial patterns that in many cases demonstrate fractal properties. Geocomputational models, particularly cellular automata and spatial agent-based simulation models have been used over the last 20 years to generate urbanisation patterns with the aim to replicate at best observed expansion footprints, including matching observed and simulated fractal dimensions. In applied cases, with the addition of constraints at multiple scales (land constraints, threshold per zones, etc.) simulation models seem to perform rather well and obtain sound urban fractal dimensions. Models that are more parsimonious in parameters however do not seem to perform as well. Exceptions are those models directly inspired from physics such as DLA (Diffusion Limited Aggregation) or DBM (Dielectric Breakdown Models) but these are frustrating when it comes to behavioural or economic interpretation. Models with explicit micro-economic component in a monocentric setting also seem to lag behind in terms of fractal performance: unless exogenous spatial heterogeneity is provided, the spatial outcome of these models is too homogenous to resemble real cities, despite agglomeration and dispersion processes at neighbourhood scale and despite the self-emergence of road networks and subsequent open land lock-ins. Rather than resolving to exogenous polycentric setting or exogenous stochasticity that would provide better looking outcomes, we investigate this insatisfaction by exploring the results of an augmented micro-economic simulation model on a theoretical monocentric space. The innovations are brought along three rationales: Firstly, an assumption is made that the length of the infrastructure network should feed back into households budget. Cities cannot expand too quickly not only because of unitary commuting costs but also infrastructure costs. We therefore implement an infrastructure tax that should lead to agglomeration or a more efficient generation of roads from the city perspective. Secondly, we assume that the infill of undeveloped spaces by new residents is limited by residents who settled earlier in the city and refuse important utility losses in terms of open green space. This leads to relaxing the assumption of a dynamic adaptation of rents and building stock trough time. Free entry and placement is somehow limited by a public authority that keeps utility at its higher possible state at each time step. Thirdly, we abandon the assumption that neighbourhood quality is related to the density of available activities or the density of green space within a given neighbourhood, but replace this with the access to a diversity of urban and green opportunities depending on their use frequency (daily walk, playground, hiking in forest,…). This is a very important change in geocomputational terms since simple focal functions can no longer be used to represent externalities in simulation models. The gradual construction of roads and houses change gradually the nature of the landscape and the value taken out of it, typically by dividing green patches into parts, creating detours to access bigger parks, shadowing effects, etc. In addition, this requires that landscape objects are represented as vectors, not cells, which is a second important change in geocomputational terms. To some extent this brings urban simulation models closer to landscape ecology and graph-based approaches. In this paper we explore and contrast the effects of the three mechanisms mentioned above on the resulting urban morphology.

A perspective on urban economics and geographical agent-based models. (Keynote Speech)

Scientific Conference (2015, September)

In this presentation, we will argue that there are many benefits to further liaise urban economic models and geographically -aware agent-based simulation models for further understanding the structure and dynamics of cities, especially at the scale of city regions but also, eventually, for contributing micro understanding of changes in a system of cities. At first sight it appears that these two fields of urban research are very separated: urban economics relies mostly on mathematical proofs, a parsimonious set of interactions, static equilibria and a rather homogeneous space and set of agents; while geographical agent-based models emphasize the dynamics and complexity of cities, the heterogeneity of agents and space, and rely solely on computational methods. The presentation will showcase a series of theoretical and applied research to stress the idea that the two can fruitfully be combined and that results are then palatable to both urban economists and geographers and can therefore participate to consolidating a wider and formalised urban theory. The geographical turn towards agent-based approaches, compared to more aggregate models and behaviourally-blind geocomputational methods, is actually a chance for geographers to formalise market as well as non-market interactions in a manner that is consistent with urban economic theory and enhance the treatment of space in this theory. Relying on a formal description of agents utility permits to discuss normative instruments where environmental and welfare impacts can be traded-off by policy makers. Furthermore,, land or housing market outcomes of the models and the analytical efforts actually help to reduce parametric space and calibrate or validate models against independent data.

Dielectric breakdown and urban growth: Morphological similarities or conceptual links?

Scientific Conference (2015, September)

Urban dynamics generate sprawl patterns that reveals in many cases fractal-like properties. This is the reason why a couple of research projects focused on how to simulate the growth of such patterns while respecting their fractal features. It is well-known that cellular automata can be used for generating random fractal structures. This holds e.g. for certain models developed in physics like DLA (Diffusion Limited Aggregation) or DBM (Dielectric Breakdown Models) and thus such models inspired urban growth simulation models. However in physics these models are based on a transcription of the underlying physical laws, combining electrodynamics and thermodynamics. Hence DLA and DBM are not just morpho-descriptive, but refer to explanatory approaches. However it seems difficult to establish a direct causal link between these approaches and urban growth. The goal of several recent models was to introduce a more explanatory approach for simulating the emergence of urban patterns by means of cellular automata. Following this objective, micro-economic reasoning has been used for describing households’ residential choice behaviour and constituting the driving force of cellular automata. These models assume that households settle down subsequently in the vicinity of a preexisting CBD where jobs are localized. Households have preferences for social and green amenities in their neighbourhood. Even if these approaches can explain some properties of urban growth processes, like leapfrogging, the patterns generated do not really show fractal properties, even if some morphological analogies with DBM have been identified. Moreover in the enunciated models, the dynamics is driven only by the evaluation of households who to want to settle down in the already existing city region. The City Administration is supposed to construct new road segments without consequences for the budget of the households. This is questionable. Here we introduce a model that starts from a pre-existing cross-like street network with a CBD at the crossing point where all kinds of services, shopping amenities and jobs are concentrated. However we introduce a series of new mechanisms. First, new arriving households use the utility of already located households as a reference. Second a tax per household is introduced for maintaining the existing street network and the infrastructures of the pre-existing centre. New households can improve the utility of urban population by contributing to these fixed costs. However if a well evaluated site needs to be connected by a new road segment to the existing street network, this will increase the costs for total maintenance of the street network and thus the tax. Third, each household wants to benefit from green amenities for different use (daily walks, playground, hiking…) but the construction of side branches of the road network can impede direct accesses to open landscapes and can generate supplementary travel costs thus impacting the budget of households. This “shadowing effect” reminds some mechanisms of the DBM-models. The model thus combines different aspects acting positively or negatively on the households’ utility and budget. According to the expected changes to their indirect utility function, the households who have settled down earlier in the city will not be in favour of accepting new households. This paper focuses on the conceptualization of the model and on the morphological properties of the emerging patterns. It is illustrated by several simulation results.

Land Use and Transport Interaction Models - Where is the limit?

Scientific Conference (2015, July 08)

Land Use and Transport Interaction (LUTI) models are precious tools to integrating the many impacts and feedbacks of the location of activities on transport infrastructures and vice versa. In that sense, applying LUTI models is key to delivering regulation and planning options for urban and transport sustainability. For they have been used in practice to guide urban planners and help transport policy since the 1960’s and the pioneering work of Lowry (1964). The effectiveness of LUTI models as decision support tools is generally well accepted by transport and planning researchers and by practitioners, despite sailing through troubled waters between consultancy secrets, politically led options, data problems, rule of thumb calibration, and model openness and transparency. At the turn of the millennium, LUTI models have developed from aggregate zone-based models to micro representation of space and disaggregated representation of agents, following increased computing capacity and availability of better GIS and individual data. As demonstrated by Wegener (2011) this modeling shift however goes with costs that impede empirical validation and further adoption in planning. LUTI modelers have long recognized that the different processes within LUTI models act and interface at different speeds (Wegener, 1986). The further granularity accompanying disaggregation then leads to dynamics that are trickier to handle. As argued by Anas (2013), LUTI models need clearer definitions and a stricter use of urban economics concepts. Likewise, we argue in this paper that LUTI models also need to take better care of geographical knowledge and spatial biases. They require the analysis of the robustness of model outcomes to the choice of spatial units and MAUP, which is analyzed by Jones et al. (2013) but also the effect of changing urban system boundaries, which is under focus here. Defining the limits of a coherent study area for modeling is actually questioning the delimitation of a city or urban region. This is obviously not a new question to geographers and economists but it impacts deeply on how inner stocks (population, firms, …) and external flows (traffic, labor,…) are modeled in LUTI models and therefore on their outcome. From intuition and practice, we hypothesize that there is strong inertia in LUTI models outcomes because the many parameters and variables that are present in these models are eventually strongly constrained by the geographical structure considered (monocentric, polycentric, including exurbs or not, etc.). Where the outer limit of a model is traced not only impacts the internal components of the city but also questions the problem of the limits between two cities, which is not trivial. First, we perform a meta-analysis of recent LUTI applications in European contexts based on 19 peer-reviewed articles. The lack of definition of the study area is striking. Interestingly in the first LUTI implementation, Lowry (1964) explicitly mentioned the use of an estimate of the commutershed of Pittsburgh for the next 20 years. The lack of explicit choice in later literature with models of increased complexity, stresses the need for guidelines that could improve practice in order to improve the comparability of applications and the generalization of results where possible. Second, we perform simulations on a synthetic city system using UrbanSim (Waddell et al., 2003). We gradually vary the spatial limits of the system from an inner center monocentric system to a polycentric city region. We also vary population and employment endowments, hence commuting patterns. Our simulations show that LUTI results are highly impacted by the change of limits and therefore suggest a reason why LUTI models are sensitive to large parametric shocks only. Our paper confirms that the absence of a strict theoretical rationale for city delineation weakens the effectiveness of LUTI models. References Anas, A. 2013. A response to the guest editorial: economics as the science for urban modeling. Environment and Planning B, 40 (6), 955 – 958 Jones, J., Peeters, D and Thomas, I. 2013. On the Influence of Scale on Urban Planning Evaluations by LUTI models. ASRDLF Congress 2013. Lowry, I.S. 1964. A model of metropolis. Memorandum RM 4035 Rand Corporation, Santa-Monica. 136p Waddell, P., Borning, A., Noth, M., Freier, N., Becke, M. and Ulfarsson, G. 2003. Microsimulation of Urban Development and Location Choices: Design and Implementation of UrbanSim. Networks and Spatial Economics, 3 (1), 43-67 Wegener, M., Gnad, F., Vannahme, M. 1986. The time scale of urban change. In Hutchinson, B and Batty, M. (Eds), Advances in Urban Systems Modelling. North-Holland, Amsterdam, 145–197. Wegener, M. 2011. From macro to micro - how much micro is too much? Transport Reviews, 31, 161–177

Emergence of leapfrogging from residential choice with endogenous green space: analytical results

in Journal of Regional Science (2015), 55(3), 491-512

Leapfrog development is a typical form of sprawl. This paper aims at analyzing the existence, size, and persistence of leapfrogging in a dynamic urban economic model with endogenous green amenities. We analyze whether incoming households choose to settle at the fringe of the city or to jump further away depending on their preferences and the structure of the city. We first provide an analytical treatment of the conditions and characteristics under which a first leapfrog occurs and show how the optimal choice is affected by the size of the city, income, commuting costs, as well as the size of the area where green amenities are considered. We then study how further leapfrogging and multiple urban rings may appear and be maintained in the long-run equilibrium, and how infill processes take place through time.

Editorial: Challenges, specificities and commonalities of transport research and policy within the BENELUX countries–the case of Luxembourg

in European Journal of Transport and Infrastructure Research (2015), 15(4), 501-505

In the recent years, the Grand Duchy of Luxembourg has emerged as a new player in research as part of a strategy to foster its knowledge for both economical and societal developments. In the transport research field, the University of Luxembourg (created in 2003) with its Geography and Spatial Planning Institute (created in 2007) and its Transport Engineering group (created in 2012) joined forces with the public research institution LISER (previously CEPS-INSTEAD) to organize the 2013 Transport Research Day of the BIVEC. Looking backward to the event while preparing this editorial, we can see it actually played a kick-off role for the international diffusion of Luxembourg research on transport and related land-use issues, and was a good occasion to shed lights on Luxembourg specificities and commonalities within the Benelux, which we like to stress in this editorial.

Housing land transaction data and structural econometric estimation of preference parameters for urban economic simulation models

in Data in Brief (2015), 5

This paper describes a dataset of 6284 land transactions prices and plot surfaces in 3 medium-sized cities in France (Besançon, Dijon and Brest). The dataset includes road accessibility as obtained from a minimization algorithm, and the amount of green space available to households in the neighborhood of the transactions, as evaluated from a land cover dataset. Further to the data presentation, the paper describes how these variables can be used to estimate the non-observable parameters of a residential choice function explicitly derived from a microeconomic model. The estimates are used by Caruso et al. (2015) to run a calibrated microeconomic urban growth simulation model where households are assumed to trade-off accessibility and local green space amenities.

Mapping uncertainty from multi-criteria analysis of land development suitability, the case of Howth, Dublin

in Journal of Maps (2014)

This paper presents a method for determining and mapping suitable locations for development using Multi Criteria Analysis and the Analytical Hierarchy Process and considering uncertainties in the process. The method is applied to the case study of Howth (Dublin), where development suitability is assessed against specific protection and conservation areas as well as ground water vulnerability. Uncertainty is incorporated using a Monte Carlo simulation into the Analytical Hierarchy Process calculations to determine criteria weightings. A map is derived, which includes, for all locations, both site suitability for development and the level of uncertainty attached to this suitability. The map combines a double categorization of suitability and uncertainty. The method allows for increased transparency in decision making regarding site suitability for development, as well as increased confidence in decision making to allow for reduced risk in terms of the potential impact of development.

Spatial Analysis of internal migration in Luxembourg

Presentation (2014, September 08)

The aims of this paper are to look at the spatial patterns and to model internal migration in Luxembourg. Between 2010 and 2011, 17344 people or 3.7% of the total population moved from one municipality (commune) to another within Luxembourg, showing a very dynamic migratory system. Luxembourg City is a net migration looser in terms of internal migration: 3128 people moved out of Luxembourg and 1428 people moved in to the capital in the same period. This paper presents an innovative migration flow map while attempting to explain, for the first time in Luxembourg, the driving forces of migratory moves at a fine geographical scale, most of the literature being focussed on the strong international migration, thus hiding local residential processes. The data analysed refer to the migration flows between the 116 local authorities (communes) in Luxembourg and the 12-months migration question. We present models for out-migration, in-migration and migration flows. For the latter, we fit unconstrained gravity models using Poisson, and Negative Binomial (NB) regressions, and their Zero Inflated variants in order to account for overdispersion and the large number of zero flows. The empirical results are very interesting and show processes that differ from other countries. It appears that cultural and urban planning factors rather than labour force factors affect the decision to migrate within Luxembourg, which is plausible given the location, the size and the ethnic background of the population residing in Luxembourg.

Spatial implications of endogenous pollution externalities in a residential location model

Scientific Conference (2014, August)

Exposure to traffic-induced air pollution is acknowledged to cause harmful effects on the environment and human health. Citizens are increasingly concerned as reflected in the willingness of citizens to pay for living in less polluted urban environments. Air quality is an amenity progressively considered in location choice . While residents might seek to remove oneself from traffic as source of emissions and favour low density environments, urban planners often argue towards urban densification in order to limit the generation of emissions by reducing distances between activities and, thus, distances travelled . The potential ease of citizens’ satisfaction in such densified areas with reduced green space amenities and concentration of development and traffic is, however, often omitted . This contradiction triggers the debate about the role of urban structure and, in particular, residential preferences on mitigating not only environmental, but also health and social impacts caused by urban air pollution. To shed further light on this debate, we contribute a spatial economics model focussing on residential choice and explicitly including traffic-induced exposure to air pollution as residential disamenity. Economic literature introducing air pollution on an urban scale into economic models to assess its impact on urban structure comprises equilibrium models with aggregate pollution from industrial sources ; however, only few with (disaggregate) pollution from transport and an explicit treatment of space . A general link between environmental and traffic congestion externalities has been mathematically formalized but not yet explicitly so in the context of residential exposure. This research builds on the standard urban economics model and explicitly formulates exposure disamenities in residents’ utility perception. The paper focuses on deriving analytical properties from the model with pollution exposure from traffic, while the literature is predominantly numerical so far. Analytical comparative statics grant insights into spatial implications, residents’ utility and health impacts. Thereby, also the impact of, for instance, environmental awareness, technological improvements and the severity of health damage are analysed. Despite vast critiques on sprawl, with regard to air pollution dispersed urban structures resulting from exposure aversion might yet reflect beneficial trade-offs between commuting distance and prevention of exposure; thus, between environmental and social concerns.

Die Bevölkerung der Großregion SaarLorLux

E-print/Working paper (2014)

This contribution is an excerpt from the report on the economic and social situation of the Greater Region 2013/2014 for the Economic and Social Committee of the Greater Region (IBA/OIE, 2014, pp. 3-10). The maps show the population density in the Greater Region as of 1 January 2013, the working-age population as of 1 January 2012 and the population development from 2000 to 2013 (Lorraine: zones d'emploi 1999-2011), calculated by the Interregional Labour Market Observatory IBA. The population density of the Greater Region in 2013 was almost 175 inhabitants per square kilometre, although the distribution varies widely from regionally: from more than 2,000 inhabitants per square kilometre in Mainz and Ludwigshafen to the sparsely populated areas of Verdun and Commercy with less than 30 inhabitants per square kilometre. This is where important economic priorities lie and influences from the large conurbations of neighboring federal states have an impact. Densely populated areas are also located in the northern part of Wallonia, particularly in the economic centres of Charleroi and Liège. In addition, the population of the Greater Region concentrates primarily on a transnational core area, which encompasses all sub-regions and important economic priorities.

Morphogenèse et maîtrise de l'étalement urbain: des noyaux d'habitat pour accompagner le choix résidentiel?

Conference given outside the academic context (2013)

Réussir une politique de maîtrise de l'étalement urbain qui, en apparence au moins, contrecarre les désirs des ménages est assurément une gageure sur laquelle plus d'une ville s'est cassé les dents. Le concept de noyaux d'habitat enrichit la perspective normative en apportant une dimension locale trop absente du discours sur la ville compacte et la densification des villes. A la lumière de travaux théoriques et empiriques reliant l'émergence de formes urbaines aux contraintes de mobilité des ménages et à leur goût pour des biens publics locaux, il apparaît que c'est peut-être moins la localisa;on intrinsèque des noyaux d'habitat que la qualité de leur aménagement et leur connexion aux espaces verts et biens publics qui permettra de réconcilier les enjeux communs d'une urbanisa;on durable et les choix individuels.

Effects of residential preferences and structures on population exposure to air pollution

Presentation (2013)

On MAUP, neighbourhood definitions and the measure of urban sprawl

Scientific Conference (2013)

Das Brauwesen in der Großregion SaarLorLux

E-print/Working paper (2013)

The beginnings of beer go back to the time of Roman rule. However, beer only gained in importance through the medieval monasteries of the Greater Region, but was exposed to strong competition from wine. It was not until the political and economic upheaval following the French Revolution that the brewery industry spread.

Emergence of scattered and leapfrog urban development from analytical results to complex simulation outputs with realistic calibration

Scientific Conference (2013)

Effects of periurban structure on air pollution: coupling CA models to understand the link between urban structure and air pollution

in Pinto N, Dourado J (Ed.) Proceedings of the Symposium on Cellular Automata Models of Urban and Spatial Systems (2012)

Air quality is a major concern in urban areas worldwide not only because of its severe health impacts but also due to its influence on living quality and residential behaviour. The subsequent increasing demand for residential areas in the greener fringes of urban agglomerations fuels the discussion about sustainability in future cities. As traffic emissions are acknowledged to be the major source of pollutants in an urban environment this residential trend has triggered research to further understand the influence of urban structure on air quality. In order to meet sustainable growth, many researchers argue that in a global perspective a compact city is the desirable urban form due to less traffic distance, just in contrast to the trend towards urban sprawl. However, quantifying the link between urban structure and air pollution has only been the aim of few research studies so far. Thus, our objective is to deepen the understanding of this link by coupling a micro-economic CA urban growth model with a traffic emission model and a CA air pollution model while focussing on the impact on residential population.

From land use scenarios to sustainable mobility: Luxembourg case study in the MOEBIUS Project

Scientific Conference (2012)

Die Keramikerzeugung in der Großregion SaarLorLux

E-print/Working paper (2012)

Bestehend aus vier Einheiten, Regionen oder Staaten, im Herzen Europas gelegen, wird die Großregion seit Langem als ein Territorium mit einer reichen industriellen Vergangenheit von großer Dynamik angesehen. Unter den zahlreichen Aktivitätszweigen gibt es einen, der lange Zeit ein Aushängeschild ihres Könnens war: die Keramik. Der Begriff „Keramik“ umfasst eine gewisse Anzahl an sehr unterschiedlichen Produkten, was ihr Aussehen und ihre Eigenschaften betrifft, alle hergestellt aus gebranntem Ton. Im Laufe der Zeit haben sich die Herstellungstechniken weiter entwickelt und immer weniger poröse und feinere Ausführungen hervorgebracht. Die Anwendungen dieses Materials haben sich damit beachtlich ausgeweitet. Das Arbeiten mit Ton stellt in dieser Region eine althergebrachte Tradition dar, da die ersten an archäologischen Fundstellen entdeckten Keramiken 7 000 Jahre alt sind. Jahrtausende lang stellten also Töpfer Gegenstände aus gebranntem Ton her.

Kirchenbau im 20. Jahrhundert in der Großregion SaarLorLux

E-print/Working paper (2012)

Im Gebiet der Großregion SaarLorLux entstanden im 20. Jh. schätzungsweise mehr als 1 000 neue Kirchenbauten oder vollständige Umbauten älterer Kirchen. Starkes, schubweises Bevölkerungswachstum im Zuge der Industrialisierung; Zerstörungen in beiden Kriegen sowie durch die Kriege bedingte Bevölkerungsverschiebungen schlugen sich auch im Kirchenbau nieder. Für die Gestalt der Kirchenbauten spielen auch innerkirchliche Entwicklungen eine Rolle, insbesondere die seit dem frühen 20. Jh. einsetzende Liturgiediskussion, die als Reform im 2. Vatikanischen Konzil gipfelte und in den verschiedenen Regionen unterschiedlich starke Auswirkung hatte. Mit dieser Karte wollen die Autoren das interdisziplinär zwischen Architektur- und Kunstgeschichte, Städtebau und allgemeiner Kulturgeschichte aufgefasste Thema des Kirchenbaus im 20. Jh. erstmalig flächendeckend sondieren.

Das grenzübergreifende Angebot im Einzelhandel in der Großregion SaarLorLux

E-print/Working paper (2012)

Die Karte zeigt die kommerziellen Ballungszentren in den Grenzregionen der Großregion auf der Grundlage eigener Erhebungen. Sie ermöglicht, das kommerzielle Angebot nach der Größe und Zusammensetzung der kommerziellen Zentren zu quantifizieren und zu typisieren. Das abgedeckte Gebiet setzt sich zusammen aus dem Großherzogtum Luxemburg und den belgischen, deutschen und französischen Ballungsräumen, die in der Isochrone einer zwanzigminütigen Autofahrt ab der luxemburgischen Grenze liegen. In dieser Isochrone liegen folgende Städte und ihre Ballungsräume: Trier und Bitburg in Rheinland-Pfalz, Saarbrücken im Saarland, Metz, Thionville und Longwy in Lothringen sowie Arlon und Bastogne in Wallonien. Ein einziges Zentrum wurde außerhalb dieser Zone lokalisiert: The Style Outlets in Zweibrücken. Es erscheint in der Datenbank aufgrund seines ausgedehnten Einzugsgebietes, das bis ins Großherzogtum Luxemburg reicht. Im Rahmen dieser Studie wurden nur die Zentren berücksichtigt, die eine ungefähre Größe von 10 000 m² überschreiten.

Spatial quantile regression analysis of residential land prices in Luxembourg

Presentation (2011, September)

A micro-economic based residential choice simulation model for Luxembourg

Scientific Conference (2011)

Towards an ESPON thesaurus? Some preliminary considerations for the thematic structuring of the ESPON database

Report (2011)

Mapping textual data by keyword co-occurrence to determine subject-matter domains in geographical statistics

Scientific Conference (2011)

Formes paysagères dans les modèles théoriques d’économie et de géographie urbaine

in Oueslati, Walid (Ed.) Analyses Economiques du Paysage (2011)

Atypische Grenzgänger in der Großregion SaarLorLux

E-print/Working paper (2011)

Die Großregion kennzeichnet sich durch einzigartige Arbeitsmarktverflechtungen zwischen ihren Teilgebieten. Das grenzüberschreitende Pendeln über nationale Grenzen wurde durch den Europäischen Einigungsprozess spürbar erleichtert, in dessen Zuge der Status des Grenzgängers unter sozial- und steuerrechtlichen Gesichtspunkten definiert wurde. Diese Definition unterscheidet jedoch nicht zwischen Grenzgängern, die aus ihrer ‚angestammten Region’ ins benachbarte Ausland pendeln und solchen, die aus dem benachbarten Ausland in die ‚angestammte Region’ an ihren Arbeitsplatz kommen. Das letztgenannte atypische Grenzgängerwesen gewinnt in der Großregion jedoch zunehmend an Bedeutung. Im Kontext der grenzüberscheitenden Wohnort- und atypischen Arbeitnehmermobilität werden in diesem Beitrag die Motive der atypischen Grenzgänger sowie Fragen der räumlichen Organisation von Alltagspraktiken im Zuge des Wohnortwechsels untersucht. Ferner werden Aspekte des sozialen Zusammenlebens am Wohnort beleuchtet und die subjektive Bewertung der Wohnsitzverlagerung dargelegt. Die Betrachtung dieser Teilaspekte erfolgt vergleichend am Beispiel der atypischen Pendelbewegungen an der saarländisch-lothringischen und luxemburgischen Grenze.

Das UNESCO Weltkulturerbe der Großregion SaarLorLux

E-print/Working paper (2011)

In der Großregion gibt es heute nicht weniger als dreizehn UNESCO-Welterbestätten. Sie stehen für die reiche Geschichte und die außergewöhnliche kulturelle Vielfalt der Großregion, sie repräsentieren unterschiedliche Epochen und Kategorien. Bau- und Industriedenkmäler gehören ebenso dazu, wie Platz- und Altstadtensembles, Festungsanlagen und ganze Kulturlandschaften. Jede Welterbestätte bringt ihre eigene Geschichte mit sich, ihr eigenes räumliches, kulturelles, gesellschaftliches Koordinatensystem.

Die Autoindustrie in der Großregion SaarLorLux 2011 - aktuelle Entwicklungen, Herausforderungen und Lösungsansätze

E-print/Working paper (2011)

Mit rund 150 000 Beschäftigten und mehr als 600 Unternehmen zählt die Automobilindustrie zu den wichtigsten Wirtschaftszweigen in der Großregion. In der jüngeren Vergangenheit haben allerdings die Globalisierung, technologischer Wandel und vor allem die globale Wirtschafts- und Finanzkrise die Branche stark beeinflusst und vor große Herausforderungen gestellt. Der Beitrag versucht, diese Entwicklungen nachzuzeichnen und mögliche Strategien und Maßnahmen zu diskutieren, mit denen auf die Herausforderungen reagiert werden kann. Dieser Beitrag ergänzt den vor der Wirtschaftskrise von 2008 geschriebenen Beitrag Autoindustrie 2007 von C. Schulz, P. Dörrenbächer und H. Pansch. Die beiden Karten zeigen die Betriebe der Autohersteller und ihrer Zulieferer mit mindestens 500 Arbeitsplätzen in den Jahren 2007 (C. Schulz/P. Dörrenbächer/H. Pansch) und 2011 (C.K. Hahn) im Vergleich, also kurz vor bzw. nach der 2008 ausgebrochenen Finanzkrise.

Der frühmittelalterliche Leihe- und Schenkungsbesitz der Klöster Gorze und Weißenburg (661 - ca. 860)

E-print/Working paper (2011)

In der mittelalterlichen Welt kommen dem Kloster vielfältige Bedeutungen zu. An erster Stelle war es ein Ort geistlichen Lebens, wo die Klostergemeinschaft nach den strengen Idealen der Regel – im Frühmittelalter zumeist nach der Regel des hl. Benedikt von Nursia – lebte, betete und arbeitete. Schulen, Bibliotheken und Skriptorien, in denen Handschriften kopiert und teilweise kunstvoll bemalt wurden, machten es aber auch zu einem Zentrum von Bildung und Wissenstradierung. Weiterhin waren die Klöster einer der größten Grundherren des Mittelalters und ihre Äbte nicht bloß Vorsteher religiöser Gemeinschaften, sondern auch Leiter großer Wirtschaftsbetriebe. Umfangreichen Besitz erhielten die Klöster durch die Gründungsausstattung sowie durch Schenkungen des Königtums oder des Adels. Dieser Besitz war keineswegs eine zusammenhängende Masse, die in der Nähe des Klosters lag, sondern verteilte sich über große Entfernungen. Die Klöster Weißenburg und Gorze sind aufgrund der erhaltenen Urkundenbücher geeignet, die Klosterökonomie genauer zu untersuchen.

Morphological similarities between DBM and a microeconomic model of sprawl

in Journal of Geographical Systems (2011), 13(1), 31-48

We present a model that simulates the growth of a metropolitan area on a 2D lattice. The model is dynamic and based on microeconomics. Households show preferences for nearby open-spaces and neighbourhood density. They compete on the land market. They travel along a road network to access the CBD. A planner ensures the connectedness and maintenance of the road network. The spatial pattern of houses, green-spaces and road network self-organises, emerging from agents individualistic decisions. We perform several simulations and vary residential preferences. Our results show morphologies and transition phases that are similar to Dieletric Breakdown Models (DBM). Such similarities were observed earlier by other authors, but we show here that it can be deducted from the functionning of the land market and thus explicitly connected to urban economic theory.

Data mining in geographical contexts and texts

Presentation (2010)

An increasing number of institutions, acting at different scales and within different sectors, create in-house geographical information systems, e.g. for regional statistics, for land and transport management, for local urban planning, etc. In addition, with the advent of new technologies, such as GPS's or web-mapping facilities, the use of such geographical data is being more and more popular and data is made more easily accessible (sometimes even contributed by the end-users). Geographers find themselves in rather data rich environments today (irrespective of homogeneity and quality). Also geographical objects require specific visualization and statistical methods. The application and adaptation of data mining approaches in geographical contexts is an increasingly important research topic. In this lecture we will start from theoretical considerations on data mining in geography, particularly emphasizing what is special with exploratory spatial data analysis. We will then refer to ongoing research related to geographical data mining undertaken at the University of Luxembourg in collaboration with colleagues from other institutions. A first example will refer to a large and homogeneous dataset of all dwellings within a Belgian province. Using graph theory and local spatial statistics, the data is used to identify and categorize urbanisation patterns across scales in an iterative way. A second example will depict an application of 'self-organizing maps' to understand patterns of 'territorial cohesion' in Europe using a rather small and lacunary dataset. The third example will be dedicated to a text-mining application to a rather large corpus of documents related to spatial development in Europe. This work funded under the ESPON (European Spatial Observatory Network) aims at producing a relevant thematic structure to the online regional statistics database of the ESPON network.

Text mining methods and visualization tools as means to support the thematic structuring of the ESPON 2013 DB

Report (2010)

Grenzgänger in der Großregion SaarLorLux (1998-2008)

E-print/Working paper (2010)

Die Karte zeigt die Grenzgängerströme zwischen den Teilräumen der Großregion. Dabei sind besonders ausgeprägte Einpendelbewegungen an der luxemburgischen Staatsgrenze zu beobachten und viele Grenzgänger, die aus Lothringen in das benachbarte Wallonien, Großherzogtum und Saarland auspendeln. Seit der Jahrtausendwende kommen auch aus den deutschen Bundesländern immer mehr Menschen nach Luxemburg an ihren Arbeitsplatz.

Tourismus in der Großregion SaarLorLux

E-print/Working paper (2010)

Die touristische Struktur der Großregion ist sehr heterogen und lässt sich nicht als eine gemeinsame Destination beschreiben. Vielmehr besteht sie aus verschiedenen Destinationen, die in diesem Artikel, unabhängig von Grenzverläufen und ausschließlich an den landschaftlichen Gegebenheiten ausgerichtet, vorgestellt werden.

Die Wahrnehmung der Großregion SaarLorLux in den Medien

E-print/Working paper (2010)

Wie wird die Großregion jenseits der Grenzen von den Medien wahrgenommen? Am Beispiel der wichtigsten regionalen Tageszeitungen wird untersucht: Was sind für die Medien Nachrichten-Zentren, was informationelle Peripherien in den Nachbarregionen? Welche Themen sind dabei dominant?

Die Großsporteinrichtungen in der Großregion SaarLorLux

E-print/Working paper (2010)

Schon in der Antike entstanden die ersten Großsporteinrichtungen, ihre auffällige Verbreitung im 19. Jh. blieb allerdings den wohlhabenden sozialen Schichten vorbehalten. Erst im 20. Jh. führten die Demokratisierung und der zunehmende Wohlstand der Bevölkerung, verstärkt durch politischen Voluntarismus dazu, dass die Großsporteinrichtungen einen Aufschwung erlebten, der seither nicht mehr nachgelassen hat. Verschiedene dieser Sporteinrichtungen wurden immer größer und einigen wurden neben ihrer sportlichen Bestimmung andere Aufgaben zugedacht, kultureller (Konzerte, …), rekreativer (Geschäfte, …) oder berufsorientierter Art (Seminare, …). Die Grenzen zwischen diesen Zielen werden immer durchlässiger. So entsteht aus den Großsporteinrichtungen eine Kategorie geographischer Objekte, die es bis dato nicht gab und denen eine bedeutende Rolle bei der Raumentwicklung Aufbau zukommt.

Grenzänderungen in der Großregion SaarLorLux vom Wiener Kongress bis heute

E-print/Working paper (2010)

Untersucht werden die Grenzänderungen, die in der Großregion SaarLorLux im Verlauf der letzten 200 Jahre stattgefunden haben. Als Anfangsdatum wurde der Wiener Kongress, der die Neuord-nung in Europa zum Ziel hatte, genommen. Als vorläufiges Ende wurde das Jahr 2006 herangezo-gen. Die Geschichte dieser Region, die sich aus unterschiedlichen Ländern zusammensetzt, soll anhand der Entwicklung der Grenzen beschrieben werden.

Geographical Modelling with Cellular-Automata

Presentation (2009)

Grenzüberschreitender öffentlicher Personennahverkehr in der Großregion SaarLorLux

E-print/Working paper (2009)

Die Karte zeigt die grenzüberschreitenden Verbindungen des öffentlichen Personennahverkehrs in der Großregion SaarLorLux mit Bus und Bahn. Die Binnenverbindungen sind nicht dargestellt. Der grenzüberschreitende Personennahverkehr reflektiert vor allem die internationalen Pendelbeziehungen zwischen den einzelnen Teilarbeitsmärkten der Großregion. Von den rund 196 000 Pendlern (2008) benutzen inzwischen etwa 15% den grenzüberschreitenden öffentlichen Nahverkehr, der in den letzten Jahren imnmer weiter ausgebaut wurde. 85% nutzen weiterhin den Pkw, der bei den oft weiten Pendelentfernungen insbesondere gegenüber Umsteigeverbindungen des ÖPNV Zeitvorteile bietet.

Die Tranchot-Müffling-Karte (1801-1828)

E-print/Working paper (2009)

Die Tranchot-Müffling-Karte deckt als historische topographische Karte aus dem frühen 19. Jahrhundert den deutschen Teil der Großregion SaarLorLux ab. Gemeinsam mit der Cassini-Karte für den französischen Bereich sowie der Ferraris-Karte für den wallonischen Teil sowie das Großherzogtum Luxemburg kann so die Situation fast der gesamten Großregion SaarLorLux vor den umwälzenden Veränderungen durch die industrielle Revolution dargestellt werden.

Exploring EU Territorial Cohesion with Self-Organising Maps (SOM)

Scientific Conference (2009)

Das Klima der Großregion SaarLorLux

E-print/Working paper (2009)

Die beiden Klimakarten der Großregion, die hier beschrieben werden, zeigen die Jahresmitteltemperaturen und das Jahresmittel der Niederschläge für den Zeitraum von 1971 bis 2000.

Transition phases and leapfrogging in urban sprawl patterns: a simulation and analytical approach with SGHOST

Scientific Conference (2009)

Morphological similarities between DBM and an economic geography model of city growth

in Zhou, Jie (Ed.) Complex Sciences (2009)

An urban microeconomic model of households evolving in a 2D cellular automata allows to simulate the growth of a metropolitan area where land is devoted to housing, road network and agricultural/green areas. This system is self-organised: based on individualistic decisions of economic agents who compete on the land market, the model generates a metropolitan area with houses, roads, and agriculture. Several simulation are performed. The results show strong similarities with physical Dieletric breakdown models (DBM). In particular, phase transitions in the urban morphology occur when a control parameter reaches critical values. Population density in our model and the electric potential in DBM play similar roles, which can explain these resemblances.

ESPON Database 2013: objectives and structures

Scientific Conference (2008)

Calibration of households preference for open-spaces from an urban cellular automata model: method and application to Dijon

in Foltête, Jean-Christophe (Ed.) Actes des Huitièmes Rencontres de Théo Quant (2008)

We propose a calibration method for a residential growth model that is grounded on a microeconomic cellular automaton. This model can be seen as a spatial and dynamic representation of an urban economic model with neighbourhood externalities. A 2D spatial equilibrium of residential locations is obtained stepwise through time instead of being a one-shot instantaneous equilibrium. Previous research work showed that the model can produce more or less dense and fragmented urban patterns depending on the preference of households for open space. We propose here a method for calibrating those preferences from simulations of the model and land rents observed within the Dijon urban area. More precisely, equilibrium properties of the model are used to derive the elasticity of open-space preferences. Then simulations are used to estimate the neighbourhood distance to which open-space are valued by households. Our first results tend to support our residential behaviour assumptions and tend to be in accordance with results obtained with more classic methods. Further methodological improvements are however needed.

Aufschwung und Niedergang des Steinkohlenbergbaus in der Großregion SaarLorLux

E-print/Working paper (2008)

Die Karte zeigt die Verbreitung der ehemaligen Steinkohlengruben der Großregion in der wallonischen und der saarländisch-lothringischen Lagerstätte von etwa 1800 bis heute. Nach der Schließung des letzten wallonischen Bergwerks Sainte Catherine du Roton 1984 und des letzten Lothringer Bergwerks La Houve 2004 endete 2012 mit der Stilllegung des Bergwerks Saar in Ensdorf der Steinkohlenbergbau in der Großregion SaarLorLux endgültig. Insgesamt wurden in den wallonischen Revieren über die Jahrhunderte rund 2 Mrd. t Kohle gefördert, im Saarland 1,5 Mrd. t und in Lothringen 800 Mio. t.

Glas- und Kristallerzeugung in der Großregion SaarLor-Lux

E-print/Working paper (2008)

Die Kunst des Glasmachens gehört seit dem Beginn des 15. Jahrhunderts zu den wichtigsten und erfolgreichsten Industriezweigen der Großregion. Die für die Glasherstellung benötigten Rohstoffe waren im Überfluss vorhanden, die jeweiligen Landesherren förderten die Ansiedlung der Glasmacher. Von Südlothringen aus verbreitete sich die Kunst des Glasmachens in Richtung Norden, an die Saar und nach Wallonien. Eine besondere Herausforderung für Regierende, Unternehmer (Investoren) und Arbeiter bedeutet(e) die geopolitische Lage der Glashütten im Herzen Europas, zwischen deutschem und französischem Einflussbereich. Trotz der durch zahlreiche Kriege und Grenzverschiebungen erschwerten Bedingungen entstanden am Westrand der Vogesen, im Bitscher Land, an der Saar und in Wallonien ab dem 18. Jahrhundert einige der wichtigsten, größten und innovativsten Glas- und Kristallglashütten Europas. Einige von ihnen setzen bis heute weltweit Qualitätsmaßstäbe in Handwerk und Design.

Space-time patterns of urban sprawl, a 1D cellular automata and microeconomic approach

E-print/Working paper (2008)

We present a theoretical model of residential growth that emphasizes the path-dependent nature of urban sprawl patterns. The model is founded on the monocentric urban economic model and uses a cellular automata (CA) approach to introduce endogenous neighbourhood effects. Households are assumed to both like and dislike the density of their neighbourhood, and trade-off this density with housing space consumption and commuting costs. Discontinuous spatial patterns emerge from that trade-off, with the size of suburban clusters varying with time and distance to the centre. We use space-time diagrams inspired from 1D elementary CA to visualize changes in spatial patterns through time and space, and undertake sensitivity analyses to show how the pattern and timing of sprawl are affected by neighbourhood preferences, income level, commuting costs or by imposing a green belt.

S-GHOST city: Self-Generating Housing, Open Space and Transportation in the city

Scientific Conference (2008)

Naturräumliche Gliederung der Großregion SaarLorLux

E-print/Working paper (2007)

The paper shows and explains the natural classification of the Greater Region SaarLorLux, following a consistent concept. The natural regions, their main groups as well as the natural space units, were created according to the concept of Meynen & Schmithüsen (1953-1962).

Autoindustrie in der Großregion SaarLorLux 2007 - Produktion, Forschung, Ausbildung

E-print/Working paper (2007)

Die Automobilindustrie gilt in der Großregion als wichtiger Pfeiler des wirtschaftlichen Strukturwandels. Eine Vielzahl teils hoch spezialisierter Zulieferer und Dienstleister prägt heute die Unternehmenslandschaft und stellt einen Großteil der industriellen Arbeitsplätze. Die Karte zeigt alle Betriebe des Sektors ab 500 Beschäftigten im Jahr 2007. Aufgrund der durch die Allgemeine Wirtschaftskrise ab 2008 aufgetretenen tief greifenden Veränderungen der Branche wurde dieser Beitrag durch einen zweiten, ausführlicheren Beitrag zur Autoindustrie der Großregion 2011 (C.K. Hahn, GR-Atlas Vol. 27) ergänzt.

SOLUTIONS Micro-scale modelling: method and initial results

E-print/Working paper (2005)

Un modèle cellulaire et dynamique de dispersion et ségrégation spatiale périurbaine

in XXXIX ème Colloque de l’Association de Science Régionale de Langue Française (2003)

Cette contribution propose d’explorer les processus de dispersion des ménages et de ségrégation par le revenu au sein d’un espace périurbain. La méthode consiste à simuler un modèle économique urbain avec deux types d’externalités de voisinage sur un espace cellulaire. Il permet la mise en place de processus dynamiques locaux endogènes et offre un éclairage sur la relation qui unit la morphologie des espaces périurbains et les caractéristiques des agents économiques qui s’y localisent. Des structures spatiales diverses sont générées sur deux configurations données des lots fonciers. Les équilibres présentent des structures concentriques constituées de multiples anneaux mais aussi, au cours des étapes de la croissance de la ville, des processus de dégradation cumulée ou des structures plus indépendantes de la distance.

Periurbanisation, the situation in Europe: a bibliographical note and survey of studies in the Netherlands, Belgium, Great Britain, Germany, Italy and the Nordic Countries

Report (2001)

In this report the extent of "peri-urbanisation" in Europe is analysed. The aim is to give an insight into the ways in which "peri-urban" processes are described in different European countries. The work has been undertaken for DATAR (Délégation à l'Aménagement du Territoire et à l'Action Régionale, France) as part of their ongoing study of "peri-urbanisation" in France. Urban development is one of the major concerns for the future of rural areas and ecological zones. This work contributes to the "peri-urban" debate by taking a European perspective that complements local or national case studies. The focus is on the spatial aspects of peri-urbanisation and on its recent demographic trends. The report is divided into three parts : The first part consists of a general discussion about the diversity of concepts used to analyse peri-urban processes, and provides an overview of urbanisation typologies and global trends in the EU. In the second the spatial extent and the description of peri- urban processes is discussed for different countries: The Netherlands, Belgium, Great Britain, Germany and Italy. Some bibliographical references are also given for the Nordic countries. The third part summarises the main spatial and demographic trends and identifies some of the similarities and differences between the countries considered. A bibliography is provided at the end of the report and includes references on some additional countries. It is shown how diverse can be the tools used to assess peri-urbanisation. Nevertheless, there is a clear diffusion of population towards commuting and rural areas of Europe. A growing share of national territories and population are concerned with this process. Changes in the urban-rural interface are driven by similar behaviour throughout Europe, but slight differences can be observed. Local geographic and demographic specificities, regional economic dynamism, historic settlements as well as spatial policies differentiate the evolution and morphology of European peri-urban areas today.