Ice thickness, volume and subglacial relief of Ashuu-Tor, Bordu, Kara-Batkak and Golubina glaciers (Central-Asia) derived from GPR measurements and different approaching methods

Abstract

<p>Glaciers in the Tien Shan (Central-Asia) mountains contribute a considerable part of the freshwater used for irrigation and households in the dry lowland areas of Kyrgyzstan and its neighbouring countries. Since the Little Ice Age, the total ice mass in this mountain range has been decreasing significantly. However, accurate measurements of the current ice volume and ice thickness distribution in the Tien Shan remain scarce, and accurate data is largely lacking at the local scale. In 2016, 2017 and 2019, we organized 1-month field campaigns in Central-Asia to sound the ice thickness of four different glaciers in the Tien Shan using a Narod ground penetrating radar (GPR) system.</p><p>Here, we present and discuss our in-situ ice thickness measurements of the four glaciers. We performed in total more than 1000 GPR soundings. We found a maximum ice thickness of 200 meters in the central part of the southern facing Ashuu-Tor glacier. On both Bordu and Golubina, we measured ice thicknesses up to 140 meters. Kara-Batkak was found to have the thinnest ice which is in agreement to the large average slope of this glacier. We extended all the ice thickness measurements to the entire glacier surfaces using three different methods based on the assumption of plastic flow (method 1) and the principle of mass conservation (method 2 & 3) and assessed their differences.</p><p>In this research, we show a detailed ice thickness distribution of Ashuu-Tor, Bordu, Golubina and Kara-Batkak glaciers. This can be used for glaciological modelling and assessing ice and water storage. We also point out the locations of potential lake formation in bedrock overdeepenings as a succession of glacier retreat.</p>