TWO MILLENNIAL WATER LEVEL FLUCTUATIONS FOR LAKE POYANG IN SOUTHERN CHINA AND THE IMPACT ON HISTORICAL SETTLEMENTS

Lake Poyang, the largest freshwater lake in China, has played important ecological and social roles ever since its formation, including the development and distribution of historical settlements. The reconstruction of its past lake water level changes is essential both for our understanding of the environmental impact on ancient settlements and for the exploration of new archeological sites in the region. Here we established a continuous high-resolution lake water level variation record for Lake Poyang during the past two millennial based on microbial glycerol dialkyl glycerol tetraether (GDGT) distributions and ¹⁴C dating of drill core sediments. Our GDGT-based lake water level reconstruction showed that the lake is approximately 2,000 years old, and the water level exhibits a rising trend since its formation, mainly due to changes in the lake outlet drainage conditions. A comparison with the distribution of documented ancient cities and towns, our lake water level record suggested that restricted water areas allowed ancient settlements to establish along riparian zones close to the current lake center regions during the first millennia AD. During high lake water periods, ancient settlements moved away to occupy then lakeshore areas with different lifestyles. The rising water level of Lake Poyang, as well as the increasing groundwater tables, played a crucial role in protecting the underground cultural relics in Lake Poyang region, including the preservation of spectacular artifacts in the renowned Han Dynasty Marquis of Haihun tomb that was recently unearthed. This study marks the first attempt to reconstruct lake water level using the GDGT-based proxy for geoarchaeological analysis and illustrates the potential of applying biomarkers for the exploration and preservation of historical settlements.