Unveiling the Mid-Holocene coastal hydrological changes and their impacts on Neolithic cultures along the South Hangzhou Bay of eastern China

The Ningfeng Plain on the South Hangzhou Bay in eastern China has long been recognized as a critical location for understanding the complex relationship between paleoenvironmental changes and human activities. Despite frequent hydrological alterations, the development of Neolithic cultures in this region offers a valuable opportunity to comprehend how ancient societies adapted to environmental transformations in the coastal zone. In this study, the authors analyzed a recently obtained sediment core (LJQ) from the Lujiaqiao archaeological site in order to reconstruct the coastal evolution of the study area over the Holocene. The foraminifera assemblage in core LJQ indicates that the study area was located in a coastal-littoral environment approximately 8.1–7.5 cal kyr BP, which gradually transitioned to an estuary receiving significant input from the open marine around 7.5–7.2 cal kyr BP. Magnetic parameters of the core then reveal the formation of a tidal brackish marsh during a period of marine regression around 7.2–5.5 cal kyr BP. The authors identified at least three episodes of elevated groundwater, likely caused by minor sea-level fluctuations. After 5.5 cal kyr BP, the influence of seawater diminished while freshwater influx increased, resulting in land formation and the development of a freshwater wetland. The Hemudu Culture first appeared in the hinterland of the Ningfeng Plain around 6.5–6.0 cal kyr BP. However, the instability of groundwater hydrological conditions would have hindered the development of Neolithic culture until the formation of the freshwater wetland at 5.5 cal kyr BP, yet the subsequent emmigration of the Liangzhu Culture was not related to any discernible environmental degradation. This study sheds new light on the complexity of the dynamic interplay between humans and their environment over time.