末次盛冰期南京长江四桥附近长江古流量估算

利用南京长江四桥的39个地质工程钻孔资料及其它现有资料,已知长江四桥附近约-65～-90m的深槽为末次盛冰期时的长江河槽。根据古河槽断面、形态参数、底部沉积物颗粒级配等,运用河相关系法、泥沙粒径水力学法、地貌水力学法,计算了末次盛冰期时的断面面积、断面平均流速。计算得到末次盛冰期南京长江四桥附近长江古流量约为22000～27000m3/s。初步根据宽深比、悬移质含量、弯曲率等参数值判断末次盛冰期长江四桥附近长江古河型为曲流。

Discharge Estimation of the Yangtze River's Paleovalley near the No.4 Nanjing Yangtze River Bridge in the Last Glacial Maximum

Using 39 geological engineering drilling data and other available data for the No.4 Nanjing Yangtze River Bridge,we can see that the paleovalley is dated to LGM at a depth of-60~-90 m near the No.4 Nanjing Yangtze River Bridge.According to the paleovalley section,shape parameters,particle size grading of sediments in the incised-valley and so on,the cross section area and average velocity of the LGM were calculated by such ways as the hydraulic geometry method,the sediment particle size-hydraulics method and the geomorphology-hydraulics method.At the end,the discharge in the No.4 Nanjing Yangtze River Bridge near the Yangtze River during the LGM has been estimated to be around 22 000~27 000 m3/s.Moreover,the ancient Yangtze River near the No.4 Nanjing Yangtze River Bridge in the LGM was a meander river according to the width-depth ratio,suspended sediment concentrations,and channel curvature.