Evaluation of Climate Change in the Qinghai Lake Basin since Last Glacial Maximum with a Coupled Catchment-Lake Model

摘要

The linkage between past climate and hydrology offers a basis for evaluating the effects of climate change on hydrology in the past and in the future. Qinghai Lake, the largest inland lake in China, is a hydrologically closed basin lake and has continuously recorded climate changes since the last glacial maximum (LGM). The sedimentary and geochemical studies on the Qinghai Lake reveal the variations of Holocene Asian monsoon. Previous studies show that precipitation variability is the most important index for the monsoon intensity. It is critical quantitatively to extract precipitation from paleolake records for understanding the Asian monsoon evolution. In this study, a coupled catchment-lake hydrologic model is implemented to evaluate how the hydrology responds to climate changes (mean annual temperature and mean annual precipitation) in the Qinghai Lake basin since the LGM. The model includes three major components: basin module, catchment hydrology module, and Lake Module. The basin module is used to derive basin geometry from the digital elevation model (DEM). The catchment hydrology module includes surface and subsurface flow processes and their interactions with lakes. The lake module, an energy and water balance model, is used to compute water budget of the lake. The model has been calibrated with modern observation data. The 1 km DEM and simulated results with a regional climate model that is based on boundary conditions provided by the global circulation model are used to drive the catchment-lake model. Simulated results compare well with the results from previous studies through macrofossil, sedimentary, and geochemical records