Landscape Reorganization Caused by Cascading Arctic Lake Drainage
Abstract
Drained lake basins in the Arctic are often the dominant geomorphic expression in lowland permafrost regions across the circumpolar north. Despite the well-recognized importance of lake drainage and post-drainage evolution of the landscape, direct observations of lake drainage remain scant. Here, we document a cascading Arctic lake drainage event at Bugeye Lakes, a complex of four lakes on the Arctic Coastal Plain of northern AK. Lower Bugeye Lake drained into the Alaktak River in June 2020 when the lake was still more than 90% ice covered. This lake drainage occurred earlier in the season than had been observed in remote sensing imagery of other lake drainage events in the region, and we speculate that it resulted from the underground erosion of ice wedges along thermal contraction cracks that had formed during the prior winter. We anticipated that drainage of the Lower Bugeye Lake may trigger cascading lake drainages from adjacent lakes because of landscape reorganization following the catastrophic event. Middle Bugeye Lake drained the following year (2021) in early July. Direct measurements from a pressure transducer deployed in Middle Bugeye Lake showed that drainage occurred in one day, and that its waters flooded the drained lake basin of Lower Bugeye Lake. This triggered further erosion of the Lower Bugeye Lake outlet. The cause of drainage of the Middle Bugeye Lake was also inferred to result from underground erosion since the lake level did not rise above the bank before drainage. Drainage of Upper Bugeye Lake South occurred during the fall of 2021 and the drainage mechanism was inferred to be bank overtopping following a period of heavy rain. Finally, partial drainage of the Upper Bugeye Lake East occurred in early July 2022 in less than 24 hours. Direct observations of the drainage site in the first few days following the drainage revealed underground erosion and ice wedge tunneling as the drainage mechanism. Thus, the drainage of Lower Bugeye Lake in June 2020 triggered the drainage of three other lakes over the convening two-year period. Our observations demonstrate the potential for landscape reorganization through cascading lake drainage due to underground erosion of ice wedges in lake and drained lake basin systems in lowland Arctic permafrost regions.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.C52D0390J