According to the Water Framework Directive (WFD), the good ecological status of all aquatic environments should be achieved by 2015. This status is evaluated largely using biological parameters, which are controlled by the physico-chemical and hydromorphological conditions of water bodies. To achieve the objectives of the WFD, assessing the physical condition of the hydrographic network appears to be a prerequisite, yet this issue still requires research of a fundamental nature. This stage in the basin of the Rhône raises a number of scientific issues which it is necessary to answer before considering practical application. In fact, knowledge of geomorphology and hydrology is now sufficient at a local scale and we can envisage applying this information at a regional scale. However, the change of scale results in important methodological constraints linked in particular to the great heterogeneity of environments.This thesis has two objectives. The first one is to implement geomatic tools to obtain an overall and homogeneous characterisation of the physical network. We propose to develop a methodology to extract information. Second, these tools and methodology will be tested and applied to the Rhône River system to evaluate their effectiveness and to provide reliable evidence for the characterization of large-scale physical conditions.
