Lake-level variation of Dali Lake in mid-east of inner Mongolia since the Late Holocene

摘要

In recent years, the area of Dali Lake has shrunk significantly, resulting in extremely serious ecological and environmental problems. Combining records from lake sediments and ancient shorelines is effective for investigating paleolake evolution and predicating the lake life trend. This study explored the lake area evolution of Dali Lake using remote sensing images and optical stimulated luminescence (OSL) dating. The results suggest the following: 1) on the century time scale, there has been a significant linear relationship between age and elevation from ca. 1.8 cal ka BP to the present (R2 = 0.99) and a potential quadratic polynomial relationship since ca. 4.2 cal ka BP (R2 = 0.99). 2) According to the 82H and 818O composition, monthly changes in the lake area, and water balance analysis, the groundwater was the main water source to recharge Dali Lake which originated from an external source, whereby the water may be from the Xar Moron Fault or has been transported by a volcanic conduit. 3) Since ca. 1.3 cal ka BP, the clear differences between lake levels and local precipitation indicated that the changes of the lake level are predominantly determined by groundwater. We conclude that the East Asian summer monsoon intensity and groundwater table variations in this area have jointly controlled the lake level evolution since the late Holocene.