Fractal geometry can be used for determining the morphological boundaries of metropolitan areas. A two-step method is proposed here: (1) Minkowski's dilation is applied to detect any multiscale spatial discontinuity and (2) a distance threshold is located on the dilation curve corresponding to a major change in its behavior. We therefore measure the maximum curvature of the dilation curve. The method is tested on theoretical urban patterns and on several European cities to identify their morphological boundaries and to track boundary changes over space and time. Results obtained show that cities characterized by comparable global densities may exhibit different distance thresholds. The less the distances separating buildings differ between an urban agglomeration and its surrounding built landscape, the greater the distance threshold. The fewer the buildings that are connected across scales, the greater the distance threshold.
International audienceIn this paper we extract the morphological boundaries of urban agglomerations and characterize boundary shapes using eight fractal and nonfractal spatial indexes. Analyses were first performed on six archetypal theoretical cities, and then on Belgium's 18 largest towns. The results show that: (1) the relationship between the shape of the urban boundary (fractal dimension, dendricity, and compactness) and the built morphology within the urban agglomeration (fractal dimension, proportion of buildings close to the urban boundary) is not straightforward; (2) each city is a unique combination of the morphological characteristics considered here; (3) due to their different morphological characteristics, the planning potential of Flemish and Walloon cities seems to be very different
International audienceThe impacts of urban growth on biodiversity vary according to the form and the intensity of urbanisation.However, there is a lack of knowledge about the consequences of the type of urban structure (e.g. mono-centric vs polycentric), the shape of urban boundaries, the local density of residential development, on the habitats of wildlife species. In this context, this paper focuses on the relationship between forms ofurbanisation and functional connectivity of ecological habitats. In the urban region of Besanc¸ on (easternFrance), three emblematic protected species were selected to represent forest mammals. From the initialstate describing current land cover, five prospective residential development scenarios were simulated,corresponding to the form currently most commonly found (e.g. compact development, transit-orienteddevelopment, polycentric development). For each scenario, we also simulate the volume of traffic on theroad network to allow for the barrier effect of roads on habitat connectivity. Then, for each developmentscenario, we model the functional connectivity of habitats of the various target species using landscapegraphs. Results show that compact city maintains more functional connectivity for all the species con-sidered whereas urban sprawl leads to much more marked impacts. Moderately compact and regulatedperiurban scenarios have intermediate levels of impact. The transit-oriented development scenario pro-duces specific impact values according to the species. An interesting point is that the decline in functionalconnectivity of forest habitats is more due to increased traffic than residential development proper. Thisoutlines the relevance of integrated models for simulating both land use and transport at a fine scale
International audienceThis paper addresses the relationship between anthropogenic forest habitat fragmentation and the form of urban patterns. Using a two-step methodology we first generate 40 theoretical residential development scenarios following a repeatable procedure; the simulated urban forms are either moderately compact or fractal. Then, we compare the scenarios according to the functional connectivity of the remaining forest habitat using a graph-based approach. The methodology is applied to the urban region of Besançon (France), where forest surfaces are considered as a generic habitat for several animal species. Results obtained show that fractal scenarios of residential development are almost equivalent to moderately compact scenarios regarding the connectivity of forest habitat when the residential development is weak. In the case of a more intense residential development, fractal scenarios are superior to nonfractal scenarios when low dispersal distances of animals are concerned
Case studies in geography are strongly dependent on the size of the spatial units used for the analysis. This has been expressed as the Modifiable Areal Unit Problem (MAUP): whatever the phenomenon under consideration, it is impossible to identify a single spatial partition that would be most appropriate to analyze it. In this respect, multifractal analysis may be an interesting tool for geographers. It integrates not just a series of nested spatial resolutions, as fractal analysis does, but also a series of points of view about the quantity of information contained in each spatial unit. In this article, we first expose the mathematical bases of multifractal analysis and we describe how it applies to geographical analyses. We insist on the mathematical notion of dimension, which allows us to describe how multifractal parameters can be used to quantify the MAUP. Then, we use the method to characterize the spatial distribution of population density in France. The main result is a typology map of population density that uses the MAUP as a descriptive tool. This map allows the joint identification of several phenomena: the main cities, the rural settlement patterns, and several types of periurban settlement patterns.
International audienceIn this paper, we propose a conceptual framework for the design of multifractal urban or regional development plans that adhere to five planning principles: hierarchical polycentric urban development; transit-oriented development; locally dense residential development; penetration of green areas into built-up areas across several nested scales; preservation of interconnected networks of natural and green areas having various sizes. This conceptual planning framework is based on multifractal spatial modelling, which is intrinsically multiscalar. The GIS-based software application Fractalopolis (current version 1.0) is used to apply this conceptual framework to real-world case studies. Fractalopolis helps to define where to create new housing units and new facilities in accordance with the planning principles set out above. We use Fractalopolis to create a multifractal development plan for a medium-sized French metropolitan area, namely Besançon, for the year 2026. This plan allows a realistic “soft” transformation the Besançon metropolitan area in keeping with the five planning principles set out above and makes the region more multifractal
One of the challenges of urban planning and design is to formulate an optimal urban form that meets all the environmental, social, and economic expectations of sustainable urban development. In this perspective, some scholars have taken an interest in fractal urban forms. Our objective is to evaluate the benefit of a fractal urban form in terms of spatial accessibility to local urban (shops and services) and rural (open spaces) amenities. To do this, we propose a multiscale fractal simulation system named MUP-City for simulating various residential development scenarios based on an existing urban pattern. Using MUP-City over a single study area, we generate fifty fractal and nonfractal urbanization scenarios and then compare them in terms of spatial accessibility to local amenities. Compared with nonfractal urbanization scenarios, fractal scenarios involve travelling shorter distances to reach various types of open space, but greater distances to visit various types of shops and services. Access to shops and services in fractal scenarios can be improved by altering the location of shops and services, whereas access to open spaces in nonfractal scenarios cannot be improved without changing the built form of reference.
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