Hydrodynamic process of Tibetan Plateau lake revealed by grain size: Case study of Pumayum Co

Abstract

Under the background of global warming, some lakes on the Tibetan Plateau (TP) are potentially sensitive to temperature change. With a case study of Pumayum Co, where glacier meltwater is important to supply (we call this a glacier-fed lake hereafter), we analyze the sensitivity of lake sediment grain size to temperature change. This is done by resolving the modern hydrodynamic process, coupled with comparison of paleoclimatic proxies. According to the spatial distributions of parameters, percentage of grain size and the grain size frequency distribution curve, hydrodynamic processes are analyzed. Five clastic sedimentation types are thereby discriminated. In the open lake area, suspended load transport is the main transport agent. Grain Size Trend Analysis (GSTA), a sediment dynamics model, reveals a trend toward eastward transport. This indicates that the largest and glacier-fed river, the Jiaqu River, influences the entire lake (not just the subsurface alluvial fan), and that lake sediment grain size may serve as a temperature indicator. Time series comparison between grain size of a short core from the central lake and meteorological data confirms this temperature indication, which in turn shows reliability of the method discriminating the hydrodynamic process. This case study will improve the ability of paleoclimatic reconstruction using lake sediment in glacier-fed lakes on the Tibetan Plateau.