Extensive responses of lake dynamics to climate change on northeastern Tibetan Plateau

Abstract

The lakes on the Qinghai–Tibetan Plateau have undergone substantial changes. As intensive cryospheric components change, the response of the lake dynamics to climatic factors, glacier-snow melting, and permafrost thawing has been complex. Based on Landsat images, meteorological data, and glacier and permafrost data, the spatial-temporal changes in the lake area on the northeastern Tibetan Plateau between 1988 and 2019 were analyzed and the driving factors behind the lake changes were further explored. The results suggest that the regional lake area increased from 1988 to 2019 at rates of 0.01–16.03 km2/yr. It decreased during 1988–2000, quickly increased during 2000–2012, and rapidly increased during 2012–2019. The most significant lake expansion occurred in sub-region I, which is the source region of the Yangtze River Basin. There was a sharper increase during 2012–2019 than during 2000–2012 in sub-region II (the source region of the Yellow River Basin and the Qinghai Lake Basin) and sub-region III (the Qaidam Basin). The significant lake expansion occurred about 12 years earlier in sub-region I than in sub-regions II and III. This dramatic change in the lake area was closely associated with the annual precipitation, and precipitation was the primary driving factor. Although serious glacier retreat occurred, most of the lakes in the sub-regions were non-glacier-fed lakes. The correlation between glacier ablation and the change in the lake area was poor, which suggests that glacial meltwater was not the replenishment source of most of the lakes in this region. A more accelerated increase in the active layer thickness occurred (1.90 cm/yr), which was consistent with the more rapid lake expansion, and the permafrost degradation further intensified the lake expansion.

Characteristics Analysis and Prediction of Land Use Evolution in the Source Region of the Yangtze River and Yellow River Based on Improved FLUS Model

“…From the point of view of land use patterns, the obvious changes are, respectively, the expansion of waters in the west leading to the remarkable braided river channel, the extensive spread of high-coverage grassland in the southeastern Zoige area, and the expansion of the urban land in the SRYE. Some studies have shown that in the past three decades, the area of the Geladandong Glacier has decreased by 16.4%, ice reserves have decreased by 29.5% [63], and that the loss of glacier mass in the SRYA is about 0.343 Gt/yr [64]; in addition, Gao et al [65] have confirmed that glacier meltwater is an important source of recharge for the lakes in the SRYA, which leads to a clear increase in the area of these lakes [66]. In the last three decades, the area of lakes in the SRYA has increased by 29% [67], and the external expansion of lake shorelines in some relatively independent lakes has led to the formation of new rivers that connect to the water system; this has resulted in the extensive development of braided channels, which are very likely to form a large braided river group.…”