| Résumé: |
Flow abstraction and diversion to water storage systems is a common element of Alpine hydro-electric power schemes. However, such systems require a particular kind of sediment management, resulting from sediment accumulation at points of offtake. Such sediment is commonly released as a pulse, leading to an increase of sedimentation rate and intense morphological responses in the rivers. The importance of these schemes aside, few studies have investigated these impacts over longer time scales. Throught the development of appropriate remote sensing methods, this paper aims to quantify these adjusments on a long term basis for the Arolla valley, in the south-western Swiss Alps. The complementarity of archival photogrammetry and terrestrial laser scanning (lidar) allows us to present results at scales ranging from individual sediment releases to over 50 years. The longer timescale measurements suggest the organisation of sediment releases into valley forced sediment waves. The event scale measurements help understand why and how these waves develop. |
Mémoire [27 Mo]