POST-DRAINAGE ICE DAM RESPONSE AT LAKE MERZBACHER, INYLCHEK GLACIER, KYRGYZSTAN

The Inylchek glacier system in Central Tian Shan, Kyrgyzstan, comprises a large glacier‐dammed lake which usually drains once a year through a subglacial drainage system. Detailed GPS measurements on the ice dam and the analysis of Aster scenes from several subsequent years provide insight into the post‐drainage dam response and the changed ice dynamic conditions. We demonstrate that during high water levels in the lake a large part of the ice dam is afloat, lifting the ice surface up to almost 20 m in the central dam region. During this phase of extensive flotation strong calving is facilitated, which is supported by the high density of ice debris in the lake. In general, surface ice velocities are about 1.5‐2 times higher during summer than winter. Closer to the lake, however, ice velocities increase considerably after the drainage event, showing values more than three times the annual mean. The increased mass flux during the phase of high lake level needs to be compensated by replenishment of the lost ice from the dam. Therefore the ice velocities show compressive flow during the remaining part of the year. These results show that Southern Inylchek glacier is strongly influenced by the existence of the lake.