HR: 0800h
AN: C21A-0067    [Abstracts]
TI: How lake morphometry reflects environmental conditions in the permafrost-dominated Lena Delta
AU: Morgenstern, A
EM: Anne.Morgenstern@awi.de
AF: Alfred Wegener Institute of Polar and Marine Research, Telegrafenberg A43, Potsdam, 14473, Germany
AU: * Grosse, G
EM: ggrosse@gi.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Drive, P.O.Box 757320, Fairbanks, AK 99775-7320, United States
AU: Schirrmeister, L
AF: Alfred Wegener Institute of Polar and Marine Research, Telegrafenberg A43, Potsdam, 14473, Germany
AB: Numerous lakes characterize the landscape of the northeast Siberian Lena Delta, which is situated in the zone of continuous permafrost. We provide a detailed lake inventory of this largest Arctic delta. The inventory is based on Landsat-7 ETM+ image data and spatial analysis in ArcGIS. Several morphometric lake attributes were determined from the resulting data set and statistically analysed regarding the lakes' association with one of the three geomorphological main units of the Lena delta. Significant differences in the morphometric lake characteristics allowed the distinction of a mean lake type for each main unit. The lake types reflect the special lithological and cryolithological conditions and geomorphologic processes prevailing on each terrace. The first main unit, which represents the modern active delta, is characterized by small lakes of irregular shape, like meander scrolls and oxbow lakes. Large oriented lakes dominate on the second terrace that consists of Late Pleistocene to Early Holocene sands. On the third terrace, which is represented by relics of a Late Pleistocene accumulation plain with fine-grained and ice-rich deposits, typical thermokarst lakes with regular, circular shorelines prevail. Most studied lakes are thermokarst lakes by their nature, as they have been or still are expanding by thermoabrasion of shore banks and deepening of the lake basin. However, a distinction between primary and secondary thermokarst lakes can be made. Primary lakes are those initially formed by thaw subsidence, i.e. the third terrace lakes. Secondary thermokarst lakes are typically formed by other processes, e.g. the change of the fluvial channel network on the first terrace. The role of lakes on the second terrace is still debated. They appear to be typical thermokarst lakes by morphometry, but their primary initiation might have been related to inter-dune or old fluvial water bodies.
DE: 0702 Permafrost (0475)
DE: 0708 Thermokarst
DE: 0746 Lakes (9345)
DE: 0758 Remote sensing
SC: Cryosphere [C]
MN: 2007 Fall Meeting