桂圆桥文化—秦汉时期成都平原农业社会对地形和水文的适应OA

The relationship between prehistoric human activity and the natural environment has long been a central focus of archaeology.Uncovering the dynamic adaptation mechanisms of prehistoric agricultural societies under different topographical and hydrological conditions is of great scientific and practical importance.It deepens our understanding of past human-land interactions and provides insights for addressing rapid future climatic and environmental changes.As a key agricultural center in southwestern China,the Chengdu Plain,with its rich archaeological record spanning the Neolithic Guiyuanqiao Culture to the Qin-Han period,serves as an excellent case study for this research.This study investigated the spatiotemporal evolution of agricultural settlement patterns and their adaptation to topographical and hydrological conditions on the Chengdu Plain from the Guiyuanqiao Culture to the Qin-Han period.By integrating data from 223 archaeological sites with high-resolution digital elevation models(DEMs)and river vector data,we employed GIS-based spatial analysis and statistical methods.The key topographical(slope and elevation)and hydrological variables(distance to the nearest river and difference in elevation from the river)were extracted for each site.Statistical analyses,including probability cumulative distribution and period-wise comparative assessments,were conducted to analyze human preferences for settlement locations.Furthermore,to infer demographic trends,a regional radiocarbon(14C)probability density curve was used as a proxy for relative population changes and correlated with settlement patterns and agricultural information revealed by archaeobotanical evidence.The study revealed a phased settlement distribution pattern:initial occupation of peripheral uplands during the Guiyuanqiao period,southward expansion into the low-lying core plain during the Baodun period,northward contraction to the Yazi River Basin during the Sanxingdui period,renewed southward expansion during the Shierqiao period,and a more dispersed layout during the Qin-Han period.These shifts are closely associated with population pressure,flood risks,and migration events.Statistical results indicated that>80%of the sites were located within 1,000 m of a river,and 74.7%had slopes<3°,reflecting an overall preference for flat,river-proximate environments conducive to rice agriculture.However,significant variations were observed across these periods.Sites from the Guiyuanqiao Culture,linked to dryland farming populations migrating from the arid northwest,were predominantly located on higher-elevation slopes(average slope:3.3°;average elevation:516.3 m)and at greater distances from rivers(average distance:1,221.7 m),indicating a strategy to avoid overly humid conditions.The Baodun period witnessed a surge in site numbers and expansion onto flatter terrain(average slope:2.5°)alongside the dominance of rice cultivation to support population growth.However,this aggregation in low-lying areas increased vulnerability to floods from the Min River tributaries,likely prompting a northward relocation to the better-drained Yazi River Basin during the subsequent Sanxingdui period.Correspondingly,sites during this period showed a slight increase in the average slope and an increase in the proportion of dry crops(22.4%).The Shierqiao period saw renewed southward expansion and increased reliance on rice(82.7%)and renewed flood threats.During the Qin-Han period,the influx of northern migrants revitalized dry farming traditions,leading to settlement expansion on steeper slopes(average slope:3.4°)and an increase in dry crop cultivation(22.3%).Rice agriculture persisted in the lowland plains and was supported by mature pond-field irrigation systems.