Abstract: Changes of glacier in the source region of Changjiang (also known as Yangtze) River reveal the climate change trends in the Qinghai-Xizang (Tibetan) Plateau. Subglacial topography is crucial for understanding glacier development and movement processes, and is, furthermore, of guiding importance for the soil and water conservation and freshwater resource reserves in the source region of Changjiang River. Based on a decade of scientific expedition and research on the source region, the Changjiang River Scientific Research Institute accurately measured the glacier thickness on the main peak of Geladandong in 2022 and 2023 by employing ground-penetrating radar (GPR). We also conducted investigations on the upper limit of permafrost thickness in the Chatan Wetland. In association with numerical simulations of GPR wave field by multiple glacier and permafrost geological models, we have enhanced the effectiveness and accuracy of GPR in detecting glacier and permafrost in the source region. The findings manifest that both the glacier thickness on the main peak of Geladandong and the upper limit of permafrost in the Chatan Wetland have experienced varying degrees of decline. Long-term observations of glacier thickness and permafrost upper limits are essential and must be continued in order to accumulate more data and analyze trends, thus estimating ice reserves in the detection area and investigating the impacts of climate change on glaciers.

Key words: source region of Changjiang River, Ground Penetrating Radar (GPR), glacier, frozen soil, climate change, soil and water conservation, freshwater resource reserve