Recent dynamics of alpine lakes on the endorheic Changtang Plateau from multi-mission satellite data

Abstract

Monitoring of the alpine lakes on the endorheic Changtang Plateau is vitally important in understanding climate impacts on hydrological cycle. Existing studies have revealed an accelerated lake expansion on the Changtang Plateau during the 2000s compared with prior decades. However, the partial hiatus of recent Landsat archive affected the continuation of understanding the lake changes in the recent decade. Here we synergistically used imagery from Landsat and Huanjing satellites to enable a detailed monitoring of lake area dynamics on the Changtang Plateau. Our results present that lakes on the Changtang Plateau continued to expand at a rapid rate of 340.79km2yr−1 (1.06% yr−1, p<0.05) from 2009 to 2014. Changes in endorheic (terminal) lakes contribute to 98% of the net expansion, suggesting that monitoring endorheic lake dynamics is of critical importance for understanding climate changes. Meanwhile, changes in saline lakes, which are mostly endorheic, account for 96% of the net expansion, implying that the proportion of freshwater storage on the Changtang Plateau is likely in decline. Rapid expansion occurred in both glacier-fed and non-glacier-fed lakes, with a rate of 224.94km2yr−1 (0.92% yr−1, p<0.05) and 115.85km2yr−1 (1.47% yr−1, p=0.08), respectively, indicating that glacier retreat alone may not fully explain the recent lake expansion. Intra-annual variations of the selected 24 large lakes fluctuated within 0.22–2.46% (in coefficient of variation) for glacier-fed lakes and 0.17–2.36% for non-glacier-fed lakes. Most of these lakes expanded during the unfrozen period (from May/June to October) and reached to their maximum extents in September or October. By spatially associating our revealed lake changes with climate variables, we observed that the recent lake expansion is more related to precipitation than to temperature, although future efforts are needed for a more comprehensive picture of the lake changing mechanisms.