GIS for SUSTAINABLE DEVELOPMENT - PART 3A

Part III-A Learning from Practice: GIS as a Tool in Planning Sustainable Development Urban Dynamics © 2006 by Taylor & Francis Group, LLC 18 Urban Multilevel Geographical Information Satellite Generation Sébastien Gadal CONTENTS 18.1 Introduction..................................................................................................313 18.2 Contribution of Data Satellites for Urban Geographic Information System (UGIS): Accuracies of Socioeconomic and Demographic Statistical Information...........................................................314 18.3 Interests of Remote Sensing Data for Geographical and Statistical Databases Generation...................................................................................316 18.4 Space Imagery, Urban Dynamics, and UGIS..............................................317 18.5 An Approach of Urban Dynamics by UGIS Satellite Data Generation ...........................................................................................318 18.5.1 The Morocco Atlantic Metropolitan Area Example: The Available and Interoperable UGIS Question............................318 18.5.2 A Multidimensional Approach.........................................................318 18.6 Technical and Operational Problems: The Information Paradigm Question .......................................................................................................319 18.7 Conclusion....................................................................................................325 References..............................................................................................................326 18.1 INTRODUCTION The exploitation of satellite data in urban land planning is sometimes unpredictable because of the specific needs of these practices compared to others. In common practice, morphological, environmental, and social aspects are needed to describe the characteristics of urban zones. However, remote sensing image processing meth-odologies, generating social and environmental information from satellite data as multispectral classification and textural filters, give a zone description of the urban environment mostly limited to the land use [1], the land cover, or the build densities zone’s description [2]. Furthermore, the socio-environmental level generated is dependent on the spatial resolution of satellite imagery. This inadequacy limits the use of remote sensing data for multilevel urban and socioeconomic database infor-mation systems development. New methodologies based on geometrical, logical set 313 © 2006 by Taylor & Francis Group, LLC 314 GIS for Sustainable Development filters, and thermal imagery characteristics have been developed and utilized to generate and integrate socio-environmental and economical information databases at three different spatial levels [3]. The settlement level (the interface between imagery, society, and social characteristic of territories) deals with information on urban form, economical and social functions, levels of life, and equipment [4]. The meso-metropolitan level deals with demographic information (urban and human densities, human development indicators, the types of social or economical zone activities, and water pollution). The global level concerns the environmental infor-mation, global densities and localizations of populations [5], land cover and land use [6], spatial structures, and urban form dynamics [7,8]. The first method requires morphological operators and symbolic recognition (description of the geometrical properties such as the surface, the compactness, etc.). The objective of this method is to automatically generate a vectorial map of every build elements-settlements and a descriptive geometrical database for the geographical objects. From this descriptive geometrical database, a classification processing is then used to extract the different urban forms and built elements settlements typology. The second methodology uses logical set theory and textural filters to separate and identify functions of build elements at settlement level; it allows recognition of spatial structures and urban forms at a global level. Thirdly, a set of methodologies based on interpretation of urban thermal gradient permits characterization of social domains and production of demographical indicators. All these methodologies generate environmen-tal and social urban databases which may be useful in supporting territorial control and urban planning, as it will be shown with reference to a case study developed for the Morocco Atlantic Metropolitan (MAM) Area (Kenitra-Rabat-Casablanca). Production, update, and availability of multilevel urban geographic databases are some of the main problems many land-planning agencies and local governments from the Maghreb have to face in daily practice. While socio-demographic census data exist, like in Morocco, and can be used and implemented at two different spatial levels (prefectures and districts), the accuracy, pertinence, and efficiency are not properly exploited yet for the MAM’s territorial control and urban planning. For these reasons, the use of satellite data has been chosen and tested as the basis for the socio-environmental multilevel information system implementation. The use of satellite imagery for the socio-environmental and multilevel GIS implementation constitutes an advantage, because it makes it possible to produce, to associate, to merge, and to generate several types of socio-spatial information, as shown in the remainder of this chapter. 18.2 CONTRIBUTION OF DATA SATELLITES FOR URBAN GEOGRAPHIC INFORMATION SYSTEM (UGIS): ACCURACIES OF SOCIOECONOMIC AND DEMOGRAPHIC STATISTICAL INFORMATION The accuracy of socioeconomic and demographic statistical databases is dependent on the special context, which varies for different countries. In general, three sets can be distinguished. © 2006 by Taylor & Francis Group, LLC Urban Multilevel Geographical Information Satellite Generation 315 · The information collections based on exhaustive censuses are generally produced or updated every 8 to 10 years. They are usually based on administrative spatial units [9]. The spatial units generally serve as a base for annual samplings updating. This mode of information collection rep-resents the majority of the cases in the world. Generally, the studies on the urban processes based on the demographic and socioeconomic statis-tics show social practices of the populations, their dynamics, and their distributions on the territory. They also allow approaching the economic dimension of the urban territory. They give a social, human, and economic representation of urban territories, describing them geographically by highlighting the territorial organizations. The plurality of the data, indi-cators, and statistical variables allows encircling the variety of the human facts and describing the urbanization dynamics. The statistical relation-ships of economical and human variables and the preparatory statistical methods verify the aptness of UGIS information. They examine the sig-nificance of the practices and the socioeconomic dynamics while charac-terizing them. They have descriptive and heuristic characters. As economic and socio-anthropological measure, the statistical data get at the same moment the driving elements and the actors of these geographic dynamics. Therefore, they offer the geographer a means to encircle the explanatory factors. However, they face difficulties so that it is often necessary to look for socio-anthropological and cultural factors. Hence, questions arise about the geographic scale aptness to report urban processes such as their choice in the studies concerning this geographic process. The interest in this descriptive statistical analytical method and this structuring informa-tion mode should take into account a very high number of variables. It allows refining the measure of the urban state process of the geographic space portion under study. The fitted multilevels method links the urban levels in various geographic scales and allows understanding of whether the urban process is at a stage of development that is only local or embraces the whole region or country. Thus, it can be defined as an indicator of geographic and urban spatial distribution. The normalization of the statistical measure extrapolated at the national or regional level reports, certainly, the urban level tendency and the average level of territory at that scale. It does not represent, however, the differential character of the urban process in its full character. Thus, issues arise about the administrative spatial unity choice and the most relevant geographic scale. · Other “conventional” data are produced from the administrative registers such as the registry office or statutory: building permission, cadastre, etc. While they often refer to the same concepts, these data often have different semantic meanings and refer to different spatial units [10]. · The data produced from the spatial remote sensing imageries. Remote sensing data give a physical description of the urban territory, from which it is possible to extract environmental and social indicators. © 2006 by Taylor & Francis Group, LLC 316 GIS for Sustainable Development 18.3 INTERESTS OF REMOTE SENSING DATA FOR GEOGRAPHICAL AND STATISTICAL DATABASES GENERATION Satellite imagery does not succeed in reporting all the above aspects per se. It describes, it measures the visible physical aspects — by remote sensing — of the consequences that result from geographic processes. Unlike studies made with socioeconomic data, urban studies using satellite data nevertheless show the influ-ence of the geographical context which relates the urban processes through the situation, the localization, the neighborhood, the spatial differentiation, etc. Indeed, the use of demographic and socioeconomic statistical data in the UGIS supplies an aspatial representation of the urban territory. They can be geo-referenced, but they are not necessarily spatial in essence. The cartographic transcription of urban pro-cesses, a posteriori, remains constrained by their membership in an area with boundaries that may be the result of a statistical sampling technique or an admin-istrative one: the municipality, the region, etc. Satellite data are not affected by this limit. In some other rare cases, on the other hand, the studies based on ground observations present the inconvenience to be too punctual to give a systematic description. A monograph is indeed often too local to allow more that a confirmation or a local analysis of an aspect of the urban processes. Nevertheless, if conceived as a separate element becoming integrated into the processing line, the field studies based and planned as sampling technique for statistical methods can be an indispensable aid to the expert to validate or invalidate his results or identify unrecognized geographic objects. These methods can help in understanding elements of social and cultural dynamics difficult to recognize by only image processing or data analysis [11,12]. Urban econometric and demographic analyses supply evident advantages, but they also present a certain number of deficiencies: failing to properly deal with the spatial dimension, and in the integration of physical, social, and human environment with cultural urban characteristics. Available statistical data are often inadequate when adapted to the problem at hand. Often, geographers or urban planners have to adapt the method and the geographic level of interest within the research focus or the urban planning project to the available statistical data, and not the opposite. The question is then how to construct geographies with information sources which are not made for the geographer or the urban planner? In the past, geographers and urban planners coped, like it or not, with this established limit, restricting the access to a part of the geographical reality. Paradoxically, the problem is less important for geographers or urban planners in developing countries, where information is poorest, ill assorted, or still unavail-able. Hence, the geographer or the urban planner has to create his own information for its work. This fact gives place to the experimentation with a number of spa-tiotemporal information production methodologies in developing countries. The result of these research efforts is that these “African methods” are nowadays begin-ning to replace classical urban spatial sampling techniques even in Western countries [6,13]. “African” sampling technique methods have the advantage of being less expensive, easier to implement from an administrative point of view, and often more © 2006 by Taylor & Francis Group, LLC ... - tailieumienphi.vn