Recently, participation emerged as an appropriate tool to enhance natural resource management. Despite official recognition, there is no consensus on the practical meaning of participation. In this work, we consider the participation as a process through which stakeholders influence and share control over development initiatives and the decision and resources affecting them. The aim of this research is to answer to the participation's issues : who should participate? when? and how? The main contribution of this reserach work is to propose a methodology that allows to introduce the participation for large projects having impacts on the landscape. The result of this methodology is a system of participation. This system is composed of elements (project, stakeholders, techniques and levels of participation) and processes (identification, characterisation and structuration of the stakeholders, identification of the participation level, choice of the participation techniques, application and evaluation of the participation) in interaction. This system of participation is general and can be used for others projects. Howewer, the chronological order of the processes is iterative and is project specific. For each of the process used in the participation system, techniques were adapted, deveopped and tested. Stakeholders identification followed the adapatation of the Mason and Mitroff technique. Stakeholders structuration was made using cluster analysis. Identification of the level of participation followed the modifications of the Daniels et al and Vroom models. Relevent identification and assessment of participation techniques were made with the help of tables. All these thechniques yield results readily and pratically usable. The way stakeholders perceive the landscape and its dynamics are also studied in this research. This study allows to analyze the type and the effects of the information presented on the participative process and on the stakeholders. Based on our results, we advise to present landscape dynamics in a participative context. We recommand the use of simple landscape metrics such as the area doubled with the spatialization of the transition matrix. The stakeholders landscape preference allows to identify criteria such as the attitude towards the changes that would help in the elaboration of the future project. The originalities of this study can be found at various levels. In a general way, we can list the globality of the proposed methodology, the overlap of the social and technical sciences and the application of the methodology to the third Rhone correction project. In a more specific way, we can mention technical developments such as the application of original experiments concerning the identification of stakeholders landscape preferences. The system of participation proposed provides a conceptual framework that can be applied to others participative projects such as agenda 21 or the development of any projects having impacts on the landscape.