Abstract

Glaciers are an important source of fresh water for Central Asia as they release water during the summer months when precipitation is low and water demand highest. Many studies address glacier area changes but only changes in glacier mass can be directly linked to climate and runoff. Despite the importance, investigations of glacier mass changes have been restricted to only a few glaciers in the Tien Shan until now. Geodetic mass balance measurements are suitable to complement and extend existing in-situ measurements. In this study, both area and mass changes of the ~40 km² glacier ice in the Ala Archa Valley, Kyrgyz Tien Shan, were investigated using 1964 and 1971 stereo Corona, 2012 stereo ASTER, the SRTM digital terrain model and other optical data such as Landsat ETM+ or Rapid Eye. In addition, ice thickness was modeled taking the basal shear stress and the glacier surface topography into account. The results indicate an area loss of 18.3±5.0% from 1964 until 2010 with continuous shrinkage in all investigated periods. The glacier’s mass balance was −0.45±0.27 m w.e. a−1 for the period 1964–1999 and −0.42±0.66 m w.e. a−1 for 1999–2012. Golubin Glacier showed a possible slight mass gain for 1964– 1971 and a decelerated mass loss for the 1999–2012 period. This is in good agreement with existing in-situ measurements exiting from 1962 until 1994 and since 2010. The overall ice volume was estimated to be 1.56±0.47 km³ of ice in the year 2000. Hence, the entire ice would be lost by 2100 if the mass loss would continue at the same rate

Highlights

  • IntroductionThe Tien Shan and its cryosphere is the origin of the large rivers Amu-Darya, Syr-Darya, Chu, Ili or Tarim which contribute to huge endorheic lakes like Aral Sea or Lake Balkhash or terminate in the steppe or desert

  • The Tien Shan and its cryosphere is the origin of the large rivers Amu-Darya, Syr-Darya, Chu, Ili or Tarim which contribute to huge endorheic lakes like Aral Sea or Lake Balkhash or terminate in the steppe or desert. These rivers are the artery for the region and, in addition, many large cities like Urum chi/Xinjiang, China, Tahskent/Uzbekistan, Almaty/ Kazakhstan or Bishkek, the capital of Kyrgyzstan are located on the foothills of this mountain range and directly depend on the runoff from nearby moun tains

  • Runoff from glaciers is especially important in summer and early autumn when the water demand is high and the seasonal snow of the mountains melted

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Summary

Introduction

The Tien Shan and its cryosphere is the origin of the large rivers Amu-Darya, Syr-Darya, Chu, Ili or Tarim which contribute to huge endorheic lakes like Aral Sea or Lake Balkhash or terminate in the steppe or desert. These rivers are the artery for the region and, in addition, many large cities like Urum chi/Xinjiang, China, Tahskent/Uzbekistan, Almaty/ Kazakhstan or Bishkek, the capital of Kyrgyzstan are located on the foothills of this mountain range and directly depend on the runoff from nearby moun tains. It is of high importance to study the ice storage of the glaciers and their past and possible future evolution

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