Controls on jökulhlaup impact during a period of glacier margin recession, Blautakvísl-Súla river system, south-east Iceland (1996-2010)
Bazeley, Katherine Mary
PublisherUniversity of Newcastle Upon Tyne
MetadataShow full item record
Glacier outburst floods (jokulhlaups) comprise major hazards in Iceland and can have considerable impact on the surrounding environment and infrastructure due to their ability to erode, transport and deposit large volumes of sediment. Greater knowledge of jokulhlaup processes will therefore improve our ability to mitigate their impacts. This investigation aims to determine the controls on jokulhlaup impacts within the Blautakvisl-Sula river system, south-east Iceland. The Blautakvisl-Sula drains the western margin of Skeioararjokull; a surge-type outlet glacier of the Vatnajokull ice cap. The margin of Skeioararjokull has been in recession since its last surge in 1991. A literature-based model of the controls on jokulhlaup impact at a receding glacier margin is developed and tested. Although models of the geomorphological impacts of glacier margin recession on proglacial areas exist, none are specific to jokulhlaups. Therefore this study is important for conceptualising the impacts of jokulhlaups on proximal glacial environments. Glacier margin recession plays both a direct and indirect role in affecting the impacts of jokulhlaups on the Blautakvisl-Sula system. It has resulted in a change in the drainage pattern of the system, with flood waters being routed progressively eastwards since 1996. Ice surface lowering at the snout of the glacier and changes in the drainage mechanism of Graenalon ice-dammed lake have also affected jokulhlaup cyclicity, magnitude, frequency and routing. Geomorphological maps produced as part of this research show that the east of the system has become more heavily impacted by jokulhlaups than the west of the system over the past 15 years, as the ice front lowers and causes ponding of water in the west. Sedimentological data provides evidence as to how recent floods have been of progressively lower magnitude, and have had less impact on the geomorphology of the Blautakvisl-Sula system as a whole than previous episodes in the record. Existing models of the impacts of glacier margin recession on flood systems have suggested that some systems 'decouple' from their feeder system as they recede. This study however, finds that Skeioararjokull shows evidence of being coupled to the sandur, despite the glacier being in recession. This study therefore identifies an additional state of 'coupled recession' as a transitional phase between a 'coupled' and 'lowering' system. The resultant model can potentially be of use for other glacier systems worldwide in conceptualising jokulhlaup impacts on the proximal sandur.