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Application of Landsat-7 remote sensing data and GIS for the quantification of Holocene thermokarst effects in the Lena-Anabar coastal area of the Laptev Sea, NE Siberia

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Citation:
Grosse, G. , Malthus, T. J. , Schirrmeister, L. and Hubberten, H. W. (2004): Application of Landsat-7 remote sensing data and GIS for the quantification of Holocene thermokarst effects in the Lena-Anabar coastal area of the Laptev Sea, NE Siberia , 1st Göttingen GIS & Remote Sensing Days (GGRS 2004), 7-8 Oct., Göttingen, Germany. .
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Abstract:

During the Last Glacial Maximum, the global sea level was 120-140 m below the present one and the shore line of the Laptev Sea was situated several 100 km further north. Remains of the former periglacial shelf landscape are preserved in the recent Laptev Sea coastal lowlands and the New Siberian Islands. This is also the case for the region near Mamontovy Klyk in the Lena-Anabar coastal area. In that region, ice super-saturated permafrost deposits, so-called Ice Complexes (IC), are found widely distributed. During the Late Pleistocene, when the IC has formed, NE-Siberia was dominated by strong continental climate and no extent glaciations occurred. According to various analyses, the ICs in the coastal lowlands are assumed to be products of mainly nival-eolian processes in nearby mountains and hills.The ice content of these deposits up to 160 weight-% (compared to dry mass) makes it very sensible for regional and global climatic changes. With the beginning of the Holocene, the IC was influenced by thermokarst. Thermokarst expresses as expansive surface subsidence due to ground ice thawing. Additionally, thermo-erosion evolves due to action of running water, occurring at coastal, river or valley sites during the warm season. Both processes lead to fast rearrangement of sediments and are an important factor in periglacial relief generation and landscape evolution. Connected to the process of thermokarst and thermo-erosion is the release of organic carbon into the ocean or the atmosphere, stored in formerly frozen and recently thawing paleo-soil deposits as well as fast coastal erosion of ice-rich shores.Nowadays, a complex tundra landscape exists in the investigation area, composed of Late Pleistocene accumulation structures and Holocene thermokarst and thermo-erosional features.Remote sensing is an important instrument for up-scaling our field data. Our attempt is, to quantify periglacial landscape units in the investigated area in NE Siberia using Landsat-7 satellite data from 2000. A classification of these periglacial landscape units is possible, mainly because of differences in vegetation, soil moisture and relief position, determined in the field and from digital elevation models.The spatial distribution of thermokarst can be analysed within a GIS and calculations regarding spatial coverage can be done. Using digital elevation models, it is possible to calculate the volumes of the investigated features. The results of this research are estimations of quality, quantity and distribution of extensive thermokarst and thermo-erosional processes for the investigated region at the Laptev Sea coast.

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