Estimation of glacier mass loss and its contribution to river runoff in the source region of the Yangtze River during 2000–2018

With rapid climatic warming, glaciers in the source region of the Yangtze River (SRYR) generally experienced apparent terminus retreats over the past several decades. However, the influence of glacier melting in the river runoff of the SRYR remains poorly known due to lack of glacier mass balance measurements. In this study, we derived the glacier mass changes of the SRYR in 2000–2018 by comparing the digital elevation models (DEMs) produced from ZiYuan-3 tri-stereo scenes with the SRTM DEM. Glacier mass balances were spatially heterogeneous (range from −0.55 ± 0.12 to −0.14 ± 0.05 m w.e. yr⁻¹) in the SRYR, which may be mainly attributed to the spatial difference in snowfall variation. Overall, the glacier mass loss of −0.343 ± 0.055 Gt yr⁻¹ was estimated for the entire SRYR. By using the hydrological data recorded by the Zhimenda station, we calculated the annual runoff of 17.84 Gt yr⁻¹ between 2000 and 2018. Therefore, the contribution of glacier mass loss to the river runoff of the SRYR was only 1.9 ± 0.3% in 2000–2018. Our results reveal that glacier melting was not the major water resource in the SRYR during recent decades.