Contrasting evolution patterns between glacier-fed and non-glacier-fed lakes in the Tanggula Mountains and climate cause analysis

摘要

High-altitude lakes in the Tibetan Plateau (TP) showed strong spatio-temporal variability during past decades. The lake dynamics could be associated with several important factors including lake type, supply of glacial meltwater, local climate variations. It is important to differentiate these factors when analyzing the driving forces of lakes dynamics. With a focus on lakes over the Tanggula Mountains of the central TP, this study investigates the temporal evolution patterns of lake area and water level of different types: glacier-fed closed lake, non-glacier-fed closed lake and upstream lake (draining into closed lakes). We collected all available Landsat archive data and quantified the inter-annual variability of lake extents. Results reveal accelerated expansions of both glacier-fed and non-glacier-fed lakes during 1970s-2013, and different temporal patterns of the two types of lakes: the non-glacier-fed lakes displayed a batch-wise growth pattern, with obvious growth in 2002, 2005 and 2011 and slight changes in other years, while glacier-fed lakes showed steady expanding tendency. The contrasting patterns are confirmed by distinct lake level changes between the two groups derived from satellite altimetry during 2003-2013. The upstream lakes remained basically stable due to natural drainage regulation. The intermittent expansions for non-glacier-fed lakes are found to be related to excessive precipitation events and positive "precipitation-evaporation". In contrast, glacier-fed lake changes showed weak correlations with precipitation variations, which implies a joint contribution from glacial meltwater to water budgets. Our study suggests that glacial meltwater supply may have an equivalent influence on lake growth with precipitation/evaporation in the study area.