Glacier Volume Calculation from Ice-Thickness Data for Mountain Glaciers—A Case Study of Glacier No. 4 of Sigong River over Mt. Bogda, Eastern Tianshan, Central Asia

The determination of total glacial volume is important for the observation of climatic change and its consequences such as global sea-level rise. The tongue area of Glacier No. 4 of Sigong River over Mt. Bogda, eastern Tianshan was surveyed by ground-penetrating radar（GPR） and real time kinematic（RTK）-global positioning system（GPS） during the summer campaign 2009. In order to calculate the glacier volume, both co-kriging algorithm and estimation based on the theory of perfectly plastic material were employed. Results indicated that the ice-thickness distribution of the investigated glacier ranges from 0 to 105.0 m, with the mean thickness of 27.6 m in 2009. The corresponding ice volume was;.076 km3（;.068 km3 water equivalent）. The bedrock topography shows more undulating than the glacier surface. The difference of the calculated ice volume in this study and the estimated value from the empirical formula is large. Therefore, it is urgent to validate the applicability of the existing empirical formula.