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In the afternoon of 30 January 2017, a catastrophic outburst flood occurred in the Larsemann Hills (Princess Elizabeth Land, East Antarctica). The rapid drainage of both a thin supraglacial layer of water (near Boulder Lake) and Lake Ledyanoe into the englacial Lake Dålk provoked its overfill and outburst. As a result, a depression of 183 m × 220 m was formed in the place where Lake Dålk was located. This study summarises and clarifies the current state of knowledge on the flood that occurred in 2017. We present a phenomenological model of depression formation. We specify the reasons for the outburst of the system of lakes Boulder, Ledyanoe and Dålk. In addition, we carry out mathematical modelling of the outburst of each of the three lakes and estimate the flood severity. Outburst hydrographs, channel diameters, volume and duration of floods were calculated. Particular simulation results were validated with field data. In conclusion, we give an overview of the new outburst cycle of the lake system, which began in 2020 with the drainage of the lakes Boulder and Ledyanoe, and the new formation of Lake Dålk. Further research is required to improve our understanding of the lake system responses to changing external factors.

Broknes Peninsula (the area of the Progress station, Larsemann Hills, Princess Elisabeth Land, East Antarctica) is characterized by the presence of well developed hydrographic network consisting of reservoirs located not only in the bedrock, but also inside the glacier thickness and on its surface. As a rule, most of them are dammed by natural snowice weirs, which are often destroyed during the Antarctic summer. As a result of this process, glacial water outburst may occur. In the course of the summer season of the 63‑th Russian  Antarctic Expedition (RAE) intensive hydrological field observations were carried out for identification and comprehensive investigation of potentially outburstprone reservoirs located in close proximity to Russian and foreign stations and field bases (area of the  Progress station and the field base Law-Racovita). The works included: the organization of temporary pile and depth-stick water gauge stations, mapping positions of the shoreline of lakes (reservoirs), bathymetric surveys of them, as well as field hydro-chemical express analyses. Based on the results of the level measurement, it was found that most of the lakes of the oasis are characterized by a sharp drop in the height of the water surface level associated with the breakthroughs. In particular, the authors witnessed the breakthrough of the Discussion Lake, which occurred on January 22, 2018. This resulted in decrease of the water level by 0.95 m. Based on the data of the bathymetric surveys, the morphometric (hydrometric) characteristics of the lakes were calculated and detailed grids (regular net of rectangular matrices, in the nodes of which some effective values of the mapped values are located) were formed for the following numerical modeling of hypothetical and real breakthroughs of water bodies and construction of estimated hydrographs.

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