Conception d'un système d'information géographique pour la gestion durable des ressources naturelles et l'aménagement périurbain de la ville de Thiès (Sénégal)

L'extension rapide de l'urbanisation de la ville de Thiès se fait au détriment des surfaces agricoles de la communauté rurale voisine de Fandène. Il en résulte une pression sur les ressources naturelles pour le développement social et économique, et donc de nombreux conflits pour l'utilisation de ce ressources. (suite en annexe

Approche systémique et participative du diagnostic urbain:processus de représentation cognitive du système urbain en vue de l'élaboration d'indicateurs géographiques

Social, economic and environmental phenomena as well as the presence of groups of stakeholders with diverging and contradictory interests highlight the complexity of urban projects. Traditional instruments of urban management are seldom adapted to these challenges, as they are often founded on sector- and expert-based approaches. Furthermore geographical information is paradoxically often available in a very large quantity, but not sufficiently relevant and synthetic for an understanding of urban complexity. In this context the goal of this thesis is to develop a method for the elaboration of relevant indicators systems from different stakeholders' cognitive representations of urban complexity; and thus to reinforce territorial diagnosis in the context of participative decision-making processes. However these differences of representations are often sources for conflicts. Each stakeholder uses his own representation in order to defend his point of view in a debate. The notice of these differences, from the "problem setting" phase of the decision-making process should contribute to a better structured debate and to a better management of the conflicts around a territorial project. This goal can be reached through consideration of all opinions and through an establishment of a discussion-space between different groups of representations. This allows the development of a coherent diagnosis framework which includes different stakeholders' cognition and perception of the territorial context. Our reflection is concretized by the developing of a prototype of interface that help a stakeholder to construct his own representation or urban phenomena, by organizing them in a dialectic (discussions) and didactic (complexity-training) manner. The phenomena-systems created are in the form of a causal model. The interpretation of this model permits to highlight critical phenomena through considering the preferred causal axes in order to output the stakeholder's goals. On this basis the stakeholder can debate and discuss with other stakeholders who also have constructed their own representations. From these individual representations, the question is how these representations can be integrated to form a collective representation of the territory. This process can be made in a deliberative manner. Before that, it is proposed to structure the debate by regrouping individuals models using analytical tools (classification, aggregation). Converging (collective reasons) and diverging elements of the urban complexity understanding are emphasized in the groups of models. The idea is thus to create a discussion-space for debates in order to find solutions. On the basis of different representation-groups, indicators-systems can be proposed. Indicators are selected in order to translate on one hand common representation of the main phenomena identified, on the other hand of causal relationships that result in strong differences. These indicators can contribute to a partial solution of conflicts by adding another, more objective point of view in the territorial context. Indicators are developed using spatio-thematical operators of geographical information systems. A concept of interface is proposed so as to facilitate the communication of systems of geographical indicators. In order to emphasis our approach, we have illustrated and applied the methodology of systemic urban-phenomena-modeling. We have conducted individual interviews with stakeholders who have participated in a diagnosis process in a neighborhood of Geneva and with stakeholders who are implied in suburban problematic in Québec. These discussions have shown the interest in our approach to help these stakeholders to formalize their representation of urban dynamics. In the same way, regrouping methods have proved their capability to reveal differentiated models of representation between groups of stakeholders. The method described presents an interest in participative decision-making and creates an advantageous framework for the interaction between these stakeholders around the representation of urban reality. The indicators-system contributes to this process and connects the representation of the territory and different stakeholders' cognitive representations according to a dynamic learning process. From this more solid and objectified basis the development of a diagnosis can succeed and the decision-making process can continue towards more operational phases

A relational indicatorset model for urban land-use planning and management: Methodological approach and application in two case studies

Urban land-use planning and management are in constant mutation throughout the world. With sustainability as the goal, the use of indicators for land auditing and monitoring is becoming more and more in demand. Classical approaches consider the set of indicators as a whole, following the concepts of systemics, and so highlighting the strengths and weaknesses of the sets

3-D visualization of urban environmental quality indicators: using the city GML standard

In October 2005, a survey to several potential end-users (surveyors, architects, urban planners, environmental and energy specialists, among others) of the City of Geneva (Switzerland) howed a strong interest for the integration of the third dimension in the available GIS data of the City of Geneva, mainly by the integration of new layers of information, here referred to as 3-D urban indicators [1]. In order to extract this type of indicators, different geo-referenced data of excellent quality, such as 2-D cadastral data, aerial images, LiDAR (Light Detection And Ranging) data and a 3-D vector model were used. A main focus was given to the construction of innovative 3-D Urban Environmental Quality (UEQ) indicators, which are highlighted through the 3-D visualization displays proposed here. A simple example is the exploration of the solar potential of building facades and roofs. In this case, the purpose is to evaluate the potential of buildings for the installation of solar panels (photovoltaic and thermal).Peer Reviewe

Solar energy potential assessment on rooftops and facades in large built environments based on LiDAR data, image processing and cloud computing. Methodological background, application and validation in Geneva (solar cadaster)

The paper presents the core methodology for assessing solar radiation and energy production on building rooftops and vertical facades (still rarely considered) of the inner-city. This integrated tool is based on the use of LiDAR, 2D and 3D cadastral data. Together with solar radiation and astronomical models it calculates the global irradiance for a set of points located on roofs, ground and facades. Although the tool takes simultaneously roofs, ground and facades, different methods of shadow casting are applied. Shadow casting on rooftops is based on image processing techniques. On the other hand, the assessment on facade involves first to create and interpolate points along the facades and then to implement a point-by-point shadow casting routine. The paper is structured in five parts: (i) state of the art on the use of 3D GIS and automated processes in assessing solar radiation in the built environment, (ii) overview on the methodological framework used in the paper, (iii) detailed presentation of the method proposed for solar modelling and shadow casting, in particular by introducing an innovative approach for modelling the Sky View Factor (SVF), (iv) demonstration of the solar model introduced in this paper through applications in Geneva’s building roofs (solar cadaster) and facades, (v) validation of the solar model in some Geneva’s spots, focusing especially on two distinct comparisons: solar model versus fisheye catchments on partially inclined surfaces (roof component); solar model versus photovoltaic simulation tool PVSyst on vertical surfaces (facades). Concerning the roof component, validation results emphasize global sensitivity related to the density of light sources on the sky vault to model the SVF. The low dense sky model with 145 light sources gives satisfying results, especially when processing solar cadasters in large urban areas, thus allowing to save computation time. In the case of building facades, introducing weighting factor in SVF calculation leads to outputs close to those obtained by PVSyst. Such good validation results make the proposed model a reliable tool to: (i) automatically process solar cadaster on building rooftops and facades at large urban scales, (ii) support solar energy planning and energy transition policies

Towards the development of legislative framework for solar neighborhoods

The growing implementation of sustainable urban infrastructure, utilizing solar energy for heat and power generation, daylighting, and thermal comfort, has intensified the focus on sustainability standards and guidelines. Nevertheless, a noticeable deficiency persists in regulations that specifically address solar energy access and protection, posing a barrier to the diffusion of solar-centric neighborhoods. This paper examines the traditional urban regulatory frameworks and the state of solar energy regulations and practices within five countries (i.e., Canada, Italy, Norway, Sweden, and Switzerland). The aim of the study is to (i) identify gaps in existing regulations, standards, and codes, (ii) highlight the need for future regulations to protect solar access and rights, and (iii) support the deployment of solar technologies on a large scale. The results underline that climate-related regulations often fall short of specificity tailored to regional and local climates, relying on generalized climate considerations. Solar energy legislation is generally scarce and lacks comprehensive planning. Finally, despite various financial incentives for the installation of active solar strategies, their impact remains limited, impeding the wide spread of solar technology as a primary source of energy production in urban environment

Developing the Geneva solar cadaster ::A decision support tool for sustainable energy management in urban areas

Gilles Desthieux, Associate Professor at the Geneva Institute of Landscape, Engineering and Architecture and a Consultant in Urban Energy Planning with Amstein+Walthert Geneva, leads a team of researchers who have developed the Geneva Solar Cadaster, a tool for modelling solar radiation and energy production from building rooftops and facades. Recent urban studies have shown that our cities play a significant role in environmental issues and, in particular, energy transition. One of the targets of the EU 2030 Framework for climate and energy is to reach a minimum of 27% renewable energy consumption and reduce carbon emission. In order to achieve this target, cities will have to accurately evaluate their renewable energy sources

Urban planning in Swiss cities has been slow to think about climate change ::why and what to do ?

Recent years have been marked by a strong popular and political mobilization around climate change. However, to what extent does this mobilization lead to reduce greenhouse gas emissions or the vulnerability of our society to the effects of climate change? This question is at the heart of the research presented, which sought to identify the barriers and levers to the integration of climate issues into urban planning of Swiss cities. The literature review first situates the integration of climate change in Swiss cities in relation to the evolution of practices at the international level. It emerged that Swiss cities have generally been late in integrating climate issues into their public policies. Practices still focus strongly on energy policies aimed at reducing greenhouse gas emissions, but adaptation measures in urban planning are poorly implemented. In order to better understand the reasons for this slow and late integration of climate change into urban planning of Swiss cities, a survey was conducted among more than 200 professionals. It showed that the evolution of practices is generally driven by “pioneering” actors who are strongly mobilized by personal values and who use specialized and scientific sources of information. Finally, two focus groups with representative professionals were organized in order to deepen the barriers and levers observed and to formulate sound recommendations for integrating the climate issue into urban planning. Two lines of action emerged: prioritization (strengthening legal frameworks and organizational structures) and support (training and involvement of climate experts at all stages of urban planning)