Monitoring recent lake variations under climate change around the Altai Mountains using multimission satellite data

Estimating lake dynamics is vital for the accurate evaluation of climate change and water resources monitoring. However, it remains a challenge to estimate the lake mass budget due to extremely scarce in situ data, especially for alpine regions. In this article, multimission remote sensing observations were blended to examine recent lake variations and their responses to climate change around the Altai Mountains during 2001–2009 and 2010–1018. First, the multitemporal Landsat images were used to enable the detailed monitoring of the surface extent of 43 lakes (> 5 km 2 ) around the Altai Mountains from 2001 to 2018. The results presented that the total lake surface extent shrunk from 9835 km 2 in 2001 to a minimum of 9652 km 2 in 2009, while subsequently rose to 9714 km 2 in 2018. By combining the lake area with the water level derived from the ICESat and CryoSat-2 altimetry data, the water storage of seven lakes covering ∼84% of the overall lake area in the region was obtained. The total water storage was detected with a decrease of 4.86 ± 1.17 km 3 from 2003 to 2009 and a decrease of 3.65 ± 1.16 km 3 from 2010 to 2018, respectively. Although most of the glaciers in this region had a significant mass loss in the past decades, the factor analysis indicated that most of the lakes had maintained a steady or slightly changing tendency because the glacial melting water was counteracted by the negative impact of high evapotranspiration amount. For the lakes with a few glacier melting supplies, e.g., the Uvs lake and Hyargas lake, the significant water budget loss was caused by the increasing evapotranspiration, decreased precipitation, and developed animal husbandry, which mainly dominated the overall decreasing trend of lake water storage in the Altai Mountains