Éléments méthodologiques de diagnostic paysager utilisant les systèmes d'information géographique

Although landscape is not a recent notion, its place in environmental management is now of major concern. Unprecedented land transformations have become a source of worry in terms of impacts on the landscape. The dynamics are still poorly understood and need to be studied in detail to be able to design consistent planning strategies. Today's policy is largely reactive and calls for prospective, as well as participative, methods and tools at different scales. Information Technologies (IT) and more particularly Geographic Information Systems (GIS) are fast-expanding domains proposing more and more better-suited solutions for problems concerning our environment. They generally provide means to capitalize on the different land data sources, whether they are spatial or not. Though their use is still limited in the context of landscape analysis, they have a huge potential that needs to be developed. Therefore, the current study is concerned with landscape research as well as GIS development. The contribution of GIS is assessed with respect to landscape management and both methodological and technological adaptations are proposed in return. One of the most important question concerns the integration of the qualitative dimension of landscape evaluation in fundamentally quantitative systems. The Jura mountains and more specifically the Marchairuz region in the higher part of the Jura vaudois constitute the study region. The main result of the work consists in the proposal of a participative and multiscale landscape assessment method, relying on the specific use of information technologies. Landscape is considered to be the visible part of the land, that the local community perceive and consider. Different forms of appreciation are modelled within a system of spatial indicators. It is used on a small scale to identify and locate landscape impacts coming from land transformations, in order to compare them with public perception. On a larger scale, indicators are used to translate social preferences in space, from the definition of landscape representation models. The assessment method relies on visibility analysis functions, improved with visual correction factors and content analysis operators. Finally, the method proposes an objective way to put together subjective landscape perceptions and thus offers an interesting basis for negotiation. The relevant approach is defined by examining its integration potential in existing management processes. Additionally, the pros and cons of the method and the tools developed here are described and some final perspectives are drawn.