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Teshebaeva K.,German Research Center for Geosciences | Teshebaeva K.,University of Potsdam | Roessner S.,German Research Center for Geosciences | Echtler H.,German Research Center for Geosciences | And 4 more authors.
Remote Sensing | Year: 2015

This study focuses on evaluating the potential of ALOS/PALSAR time-series data to analyze the activation of deep-seated landslides in the foothill zone of the high mountain Alai range in the southern Tien Shan (Kyrgyzstan). Most previous field-based landslide investigations have revealed that many landslides have indicators for ongoing slow movements in the form of migrating and newly developing cracks. L-band ALOS/PALSAR data for the period between 2007 and 2010 are available for the 484 km2 area in this study. We analyzed these data using the Small Baseline Subset (SBAS) time-series technique to assess the surface deformation related to the activation of landslides. We observed up to ±17 mm/year of LOS velocity deformation rates, which were projected along the local steepest slope and resulted in velocity rates of up to -63 mm/year. The obtained rates indicate very slow movement of the deep-seated landslides during the observation time. We also compared these movements with precipitation and earthquake records. The results suggest that the deformation peaks correlate with rainfall in the 3 preceding months and with an earthquake event. Overall, the results of this study indicated the great potential of L-band InSAR time series analysis for efficient spatiotemporal identification and monitoring of slope activations in this region of high landslide activity in Southern Kyrgyzstan. © 2015 by the authors.

Unger-Shayesteh K.,German Research Center for Geosciences | Vorogushyn S.,German Research Center for Geosciences | Farinotti D.,German Research Center for Geosciences | Farinotti D.,ETH Zurich | And 4 more authors.
Global and Planetary Change | Year: 2013

We have reviewed about 100 studies on past changes in climate, snow cover, glaciers and runoff in Central Asian headwater catchments, which have been published in the past 20. years. We included studies published by Central Asian researchers in Russian language, which are usually not easily accessible to international researchers. Most studies agreed on general warming trends in Central Asia with acceleration since the 1970s, but varied with regard to seasonal changes and the magnitude of the warming. Most studies also confirmed that glaciers in the Tien Shan and the Pamir continue to retreat and to shrink, though only little is known about mass and volume changes. Only few studies investigated changes in seasonal snow cover, and they suggested a decrease in maximum snow depth and a reduction in snow cover duration. The studies on runoff trends in the high mountain areas of Central Asia indicated a complex response of catchments to changes in climate. It appears that catchments with a higher fraction of glacierized area showed mainly increasing runoff trends in the past, while river basins with less or no glacierization exhibited large variations in the observed runoff changes.We conclude that our knowledge is still incomplete in particular with regard to the magnitude and the spatio-temporal patterns of changes in the water cycle of Central Asian headwater catchments. The limitations in our knowledge are due to (1) the scarcity of reliable and appropriate data sets especially for the glacio-nival zone; (2) methodological limitations of trend analysis; (3) the heterogeneity in both spatial and temporal extent of the available analyses, hampering the synthesis to a regional picture; and (4) the insufficiently understood interactions between changes in highly-variable climate parameters, the cryosphere, and the hydrological response of individual headwater catchments.Finally, there is a need for sound attribution studies linking the observed hydrological changes in individual catchments to particular processes triggered by climatic and cryospheric changes. This research gap needs urgently to be closed as projections of future hydrological changes are of vital importance for water management in Central Asia. © 2013 .

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