Spatial analyses of thermokarst lakes and basins in Yedoma landscapes of the Lena Delta
Abstract. Distinctive periglacial landscapes have formed in late-Pleistocene ice-rich permafrost deposits (Ice Complex) of northern Yakutia, Siberia. Thermokarst lakes and thermokarst basins alternate with ice-rich Yedoma uplands. We investigate different thermokarst stages in Ice Complex deposits of the Lena River Delta using remote sensing and geoinformation techniques. The morphometry and spatial distribution of thermokarst lakes on Yedoma uplands, thermokarst lakes in basins, and thermokarst basins are analyzed, and possible dependence upon relief position and cryolithological context is considered. Of these thermokarst stages, developing thermokarst lakes on Yedoma uplands alter ice-rich permafrost the most, but occupy only 2.2% of the study area compared to 20.0% occupied by thermokarst basins. The future potential for developing large areas of thermokarst on Yedoma uplands is limited due to shrinking distances to degradational features and delta channels that foster lake drainage. Further thermokarst development in existing basins is restricted to underlying deposits that have already undergone thaw, compaction, and old carbon mobilization, and to deposits formed after initial lake drainage. Future thermokarst lake expansion is similarly limited in most of Siberia's Yedoma regions covering about 106 km2, which has to be considered for water, energy, and carbon balances under warming climate scenarios.