Characterizing thermo-erosional landforms in Siberian ice-rich permafrost - Morphometric investigations using high resolution satellite imagery and digital elevation models


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Samuel.Stettner [ at ] awi.de

Abstract

This study aims at understanding the patterns of thermo-erosional valleys and identifying the key drivers for their distribution in an ice-rich permafrost landscape in the central Lena Delta, Siberia. The spatial extent of thermo-erosional processes and related landforms (e.g. water tracks, gullies, valleys) and their impact on the degradation of permafrost is still not well quantified. Although degradation processes related to thermokarst and the resulting landscape features are well studied in ice-rich permafrost regions, only a few studies with detailed investigations of thermo-erosional processes and resulting features and their relevance for permafrost degradation exist. These processes and features are important indicators of climate change in the Arctic. The Arctic is a substantial and very sensitive element in earth’s climatic system that is undergoing extensive and rapid changes. Permafrost degradation affects the climatic system through carbon release and changes the living conditions for arctic communities. We use high resolution remote sensing data and digital elevation models (DEMs) to derive and analyse geomorphometric relief characteristics to understand periglacial landscape dynamics. However, geometric correction of remote sensing data, and generation of DEMs in arctic lowlands, is challenging due to low relief and surface contrast gradients and often scarce reference data. Therefore, high quality and high-resolution DEMs are rarely available, especially in Siberia. To address these difficulties, this study is using a multi-sensor and multi-temporal satellite data approach for a detailed inventory and 2D/3D morphometric analysis of thermo-erosional valleys on Kurungnakh Island. A high resolution DEM with 5m spatial resolution and a RMSE of 3.8 m was generated from ALOS PRISM stereo-datasets acquired in 2006 and 2009 and validated against extensive ground measurements taken during an expedition in July 2013. Mapping of 1214 stream segments related to thermo-erosional processes with a total length of 336 km was performed using a time-series of orthorectified GeoEye-1 and RapidEye datasets. We measured 32 longitudinal and transversal profiles of thermo-erosional valleys at three key sites, each representing different stages of valley evolution. We used additional profiles extracted from the DEM to characterize different valley types on Kurungnakh Island. We present a detailed inventory and characterization of thermo-erosional features on Kurungnakh Island. Our findings show a strong dependence of thermo-erosional processes to the prior degradation of ice-rich permafrost through thermokarst activity. Since the stream network of Kurungnakh Island is poorly developed, accelerated permafrost thawing due to an arctic warming could promote the degradation of ice-rich permafrost by thermo-erosional processes and alter the hydrologic regime as well as the sediment and carbon fluxes. Our dataset provides a new level of accuracy for the Lena Delta region.



Item Type
Conference (Poster)
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Primary Division
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Peer revision
Not peer-reviewed
Publication Status
Published
Event Details
Arctic Change 2014, 08 Dec 2014 - 12 Dec 2014, Ottawa, Canada.
Eprint ID
37569
Cite as
Stettner, S. , Morgenstern, A. , Günther, F. , Fedorova, I. , Chetverova, A. and Rost, T. (2014): Characterizing thermo-erosional landforms in Siberian ice-rich permafrost - Morphometric investigations using high resolution satellite imagery and digital elevation models , Arctic Change 2014, Ottawa, Canada, 8 December 2014 - 12 December 2014 .


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