川江中坝遗址自然地层与文化层测年、粒度分析及其与长江沿岸现代洪积物粒度分析对比研究表明,中坝遗址自然沉积层为多期洪水泛滥成因。文化层中大量破碎陶罐、瓦片以及窑址的发现,结合实地调查表明当时遗址区主要以制盐为主。一定数量未燃尽的段木的发现,表明人们为制盐或烧制陶器而砍伐树木,导致水土流失与生态恶化,水土流失导致河床淤积,储水量减少,从而加重洪灾程度、加剧河床演变。频繁的洪水泛滥使研究区河床发生较大变化,使遗址从河岸孤立出去,成为河中心的一个孤岛。

Field investigation was performed on Zhongba site, the Chuanjiang River, and at the same time, sampling for grain size analysis and ¹⁴C dating were also collected for the research of flood events and its possible influences on the human activities in the study region. For exact determination of the flood sediments of Zhongba site, modern flood sediments along the Changjiang River were taken for comparison research. Grain size analysis is performed on these samples along the bank of the Changjiang River for determining the sedimentary environment. Research results indicate that the grain size characteristics of the modern flood sediments along the Changjiang River are similar when compared to those samples from the natural layers of the Zhongba site, which means that the natural layers of Zhongba site were the results of flood events in different periods. Geomorphological investigation in the study region also provides evidences for this viewpoint. On-the-spot investigation of the site indicates that natural layers characterized by flooding alluvium interrupted the cultural layers. It can be said that floods of different periods exert great influences on human activities, interrupting the sequence of the sedimentation of the section. The main phenomenon is the cultural hiatus of the site section. Large amount of broken keramics and utensils for salt producing and the large kiln were excavated near the site indicating that the salt production was the main economic activities. Large amount of burned trees were found in the natural layers. People here destroyed forest for making keramics and utensils or for salt production, which leaded to the great loss of loss and water and resulted in deterioration of ecological environment in the study region, which in turn leaded to the deteriorating and more serious flood disasters. That is the main reason for the phenomenon that the natural layers were interrupted by the natural layers (flood alluvium layer). Frequently occurred flood inundation caused fast evolutions of the riverbed. Floods and evolution of the river channel cut the site off from the riverbank, making the site the geographically isolated island. Therefore, the human economic activities along the bank of the Changjiang River are receiving tremendous impacts from the floods. And at the same time, improper human activities exert negative influences on ecological environment. In the near future, under the influences of the global warming, stress should be put on the research of the influences from the occurrence of the flood events and riverbed evolution on the local human social economic activities.