Large-scale bedforms in the vicinity of Serwy Lake (NE Poland): their morphometry and links to the high-energy glaciofluvial environment

Abstract

The Suwałki Glacial Megaflood Landsystem documented in NE Poland led to further morphological analysis of bedforms that originated from glacial lake-outburst floods (GLOFs) in the central and eastern parts of the Augustów Plain. This article focuses on (1) the recognition of large-scale subaqueous dunes in the vicinity of Serwy Lake, (2) the creation of a database consisting of relevant morphometric parameters (lengths, heights and gradients of stoss and lee slopes) and indexes (steepness and asymmetry ratios) and (3) comparison with other landforms that undoubtably indicate glacial floods (e.g., Missoula, Altai, British Columbia, Wigry Lake). The remote identification and measurement of the megadunes’ morphometry based on LiDAR data and digital elevation model with resolution 1×1 m (using hillshade and geomorphons) yielded data characterising 254 bedforms. These represent two-dimensional large-scale subaqueous dunes, which have lengths varying between 23.6 and 241.8 m and average heights of 0.6–5.4 m. Moreover, their morphometric variation creates a continuum typical of subaqueous dunes and has similarities to prominent examples linked to GLOFs. The study is especially crucial due to the lack of a wide range of information about megadune development under unconfined settings during the Weichselian glaciation.