| Cote: |
989 |
| Auteur: |
RUTTIMANN Sébastien |
| Année: |
Janvier 2016 |
| Titre: |
Subglacial channel characterisation using high-resolution remote-sensing methods and modelling on the Haut Glacier d’Arolla, Switzerland |
| Sous la direction de: |
Prof. Stuart Lane et Dr James Irving |
| Type: |
Mémoire de master en géographie |
| Pages: |
53 |
| Complément: |
10 pages d'annexes paginées (complément sur le géoradar et bibliographie) |
| Fichier PDF: |
 Mémoire [28 Mo]
|
| Mots-clés: |
Glacier hydrology / subglacial drainage / ground-penetrating radar / sensors and software pulseEkko Pro / digital drone photogrammetry / orthoimagery / digital elevation model (DEM) |
| Résumé: |
Glaciers have a major impact on mountain catchment hydrology by storing water in cold periods and releasing it during warm periods, as well as transporting considerable amounts of eroded material. Understanding how meltwater flows through glaciers is key to understanding glacier dynamics and its results in effects such as speedup events and bed lubrication. The primary objective of this study was to use high-resolution ground-penetrating radar to detect subglacial channels on the Haut Glacier d’Arolla. The key question is whether or not ground-penetrating radar techniques can be used to identify and to estimate the geometry of a subglacial channel and to what extent; and what the data obtained tell us about subglacial flow and sediment transport processes. The results have provided insight into the characteristics of a major near-snout subglacial channel. The channel was followed for 20 m upglacier and evidence suggested that the conduit was significantly larger than expected and rapidly became smaller as the overlying ice thickens. Flow modelling revealed that the channel could never be full of water as compared with discharge records, confirming other field reports of near-snout atmospheric channel flow (e.g. Hooke, 1984). Evidence from ground-penetrating radar, drone photogrammetry, and flow and sediment modelling suggested a combination of sediment clogging and flushing mechanics coupled with bed and ice-wall concentrated erosion to be the driving factors of observed channel dimensions. Sediment clogging and flushing could be of great influence for water pressure dynamics and glacier speedup events, leading to new research questions in relation to subglacial hydrology. |