Characteristics of variation of lake water area in Yamzho-Yumco Basin since 1972

Abstract

[Objective] The mass inland lakes were distributed on the Xizang Plateau, and both the regional climate change and lake evolution trends could be indicated by changes of lake water area. The trend and characteristics of lake water area change in the Yamzho-Yumco basin was analyzed in the period of 1972—2023. [Methods] These Landsat satellite images were used to extract on the water area of Yamzho-Yumco, Bajiu Co, Kongmu Co, Chen Co, Duo Co, and Puma Yumco, based on the normalized difference water index method. The variation series of daily and annual lake water area were reconstructed in the past 50 years. The GPS measured data were applied to evaluate on the overall error of lake water boundaries. These driving factors of lake water area change were discussed on the data of meteorological stations near the basin, based on linear trend analysis. [Results] In the period of 1972—2023, the lake water area of Yamzho-Yumco, Kongmu Co, Chen Co and Bajiu Co were shrinking. In the meantime, the lake water area of Puma Yumco and Duo Co were expanding. The expansion on the western boundary of Puma Yumco was more obvious. Compared with the average annual water area in 1972, the average annual water areas of Yamzho-Yumco, Kongmu Co, Bajiu Co and Chen Co had shrunk by 82.72 km², 2.2 km², 2.0 km², 0.9 km² in 2023, respectively. The average annual water areas of Puma Yumco and Duo Co had expanded by 8.3 km² and 0.4 km², respectively. [Conclusion] According to the linear analysis, the meteorological element data of the station showed that the average annual temperature and annual precipitation had an increasing tend from 1972 to 2023, but the annual precipitation did not increase significantly. At the same time, the relative humidity and annual evaporation had a decreasing tend, but the relative humidity did not decrease significantly. Overall, the regional climate in Yamzho-Yumco basin was in the warm and humid state, and the mechanism of lake water surface evaporation and glacial-snow meltwater could not be ignored in the process of lake water area change.

Keywords

satellite remote sensing / lake water area / spatial analysis / uncertainty / time-varying series / spatial-temporal distribution / precipitation / climate change / influencing factors