| Cote: | 946 |
| Auteur: | BRUGHELLI Mattia |
| Année: | Janvier 2015 |
| Titre: | Seasonal Variations of glacial Abrasion: testing a new approach to infer Sediment Production and Provenance. Franz Josef glacier, New Zealand |
| Sous la direction de: | Prof. Frédéric Herman et Prof. Stuart Lane |
| Type: | Mémoire de master en géographie |
| Pages: | 91 |
| Complément: | 10 pages d'annexes paginées (complément de texte) |
| Mots-clés: | Glacier / Erosion / Abrasion / Suspended Sediment / Subglacial Hydrology / Ice Motion / Manual Sampling / Subglacial Drainage Syste / Hydrological Forcing / Raman Spectroscopy on Carbonaceous Materials / Spatio-Temporal pattern of erosion / Sediment Provenance / Franz Josef glacier / New Zealand |
| Résumé: | The twenty-first century is characterized by an increasing anxiety about climate changes. In this context, glaciers are considered as one of the key indicators by the Intergovernmental Panel on Climate Change [Houghton, 1996]. Even if it seems obvious that glaciers transport and depose sediments, the massive retreat to which glacier will be submitted in the future may mobilize a considerable quantity of materials which may cause a multitude of troubles, especially in high populated countries as Switzerland. Important efforts have been made in order to create a reliable glacial model which will permit to make accurate forecast for the future landscape evolution. However, some relations are still poorly understood and many of the needed parameters are still constrained to theories. The main objective of this thesis is to define if it exist a relation between glacial erosion and ice velocities. We provide a reliable estimation of the abrasion rate of an alpine temperate glacier and we quantify the provenance of subglacial sediments during a melt season. Couple sediments provenance and ice velocities patterns may permit to establish a relation of proportionality between erosion and ice velocities. To reach this goal, we have adopted a triple methodology. First, we measure hydrological parameters such as water discharge and suspended sediment concentration in a glacial stream, to define the total suspended sediment load, thus abrasion. Second, we use Raman Spectroscopy on Carbonaceous Materials to define the spatial and temporal variations of abrasion. Third, we compare the observed abrasion patterns to ice velocities distributions to detect the eventual similarity. We hope that our research will lead to clarify the relation between glacial erosion and ice sliding and will contribute to the development of a reliable model describing glacial environment. |