Changes in the hydrodynamic intensity of Bosten Lake and its impact on early human settlement in the northeastern Tarim Basin, Arid Central Asia

Abstract

The climate of arid central Asia (ACA) is extremely dry and early human settlement in the region were dependent upon an unstable water supply. Thus, knowledge of the hydrological fluctuation history is essential for understanding the relationship between humans and the environment in the region. Here we present a record of Holocene lake hydrodynamic intensity based on the grain size of suspended lacustrine silt isolated from the sediments of Bosten Lake, which feeds a river flowing to the northeastern Tarim Basin. The results show that lake hydrodynamic intensity was very weak during the early Holocene (12.0–8.2 ka); and then increased with two distinct centennial-millennial-scale intervals of weak intensity during 4.7–3.7 ka and 1.2–0.5 ka. Notably, increases in lake hydrodynamic intensity occurred 2.2 kyr prior to an increase in local precipitation. We speculate that this was a consequence of relatively high early summer temperatures during 8.2–6.0 ka that resulted in an increased water supply from melting snow and ice in mountainous areas of the catchment. Thus, we conclude that the changes of the Holocene hydrodynamic intensity of Bosten Lake were mainly controlled by temperature or precipitation at different times. The variations in the hydrodynamic intensity of Bosten Lake also influenced water availability for the human population that occupied the downstream area of the northeastern Tarim Basin. A drastic decrease in hydrodynamic intensity of Bosten Lake occurred around 400 and 700 CE likely has caused the emigration of the inhabitants and cultural collapse of Loulan Kingdom.