Applications in Fluvial Geomorphology : a Multi-Scale Perspective.

English Abstract:

Fluvial geomorphology is providing critical knowledge and tools for improving river management, restoration or conservation because river managers recently widened their scope in term of spatial and temporal scales, following in Europe for example the implementation of the Water Framework Directive and the wish to promote sustainable solutions. As a consequence, scientific feedbacks for improving or designing management strategies can be expected at different spatial scales according to stake-holder expectations. Top-down approaches usually promoted by regional or national decision-makers for planning and targeting actions can capitalize on conceptual development (reference, valuiing process versus form, assessing success of policies) as well as on efforts to highlight riverscape organisation and provide tools to target actions (so-called “geomorphic regionalisation”). Bottom-up approaches, promoted at a local scale on reaches of several 10^th of km or smaller basins (e.g., 1000 to 2000 km2), usually performed to identify sustainable solutions in term of ecological benefits or natural hasard assessment can be nourished by geomorphic diagnosis and retrospective analysis, experiment, modelling and risk analysis allowing to set the river trajectory and identify objectives for river improvement or conservation. A few examples will be introduced to highlight the different approaches and open the debate on the implication of the discipline in practices. The geomorphologist as actor of social arenes has also to be considered, as such context influences the knowledge production and question the scientific independence and the way of doing research.