Lake outbursts of the eastern part of the Larsemann Hills, East Antarctica, through snow and ice dams

Abstract

Abstract. The Antarctic oasis Larsemann Hills is characterized by a developed drainage system. It includes several lakes of different genesis. However, besides the state of knowledge of this region and regular expeditions, which are conducted nowadays, the lakes of this oasis have not been studied comprehensively yet. In general, international and Russian research is dedicated to the monitoring of the ecological state of the water bodies, inferring climate change signals from the lake deposits. At the same time, works related to determination of the bathymetry and morphology of water bodies do not virtually exist or are hidden in scientific-technical reports of the Antarctic Programs of different countries. Interest in the investigation of the oasis lakes has increased sharply after the formation of a vast depression on on Dålk Glacier (Larsemann Hills, East Antarctica) on 30 January 2017 caused by the outburst of intraglacial reservoir. Field research in 2017/18 revealed that sudden destructions of impound dams and the generation of breakthrough floods are indicative for many lakes of the oasis. Thus, the present work aims at the application of mathematical modeling methods to shed light on the processes that lead to dam destruction and the outburst of lakes temporarily impounded by natural firn-ice and glacial dams. Such discharges are comparable to jökulhlaups and can be calculated using the adapted model of Yu.B. Vinogradov. As main objects of this research we select among the lakes located close to Russian and foreign Antarctic stations and field bases those, for which destructions of ice-snow bridges are detected. According to the modelling results, the following characteristics were identified for every outburst: the distribution of the discharges over time, the volume and transmission time of the flood. Moreover, its catastrophic risk and fracture force was assessed. The data obtained will form a basis for studying the formation of temporary ice hydrographic networks in Antarctica and the analogous processes occurring under the Arctic glaciers.