【摘要】 通过对黄河中游晋陕峡谷段的考察,在多个地点发现全新世古洪水滞流沉积层。选择壶口段左岸岩棚内典型的古洪水滞流沉积剖面进行沉积学和水文学研究。对于采集的全新世地层剖面序列样品,进行粒度成分、磁化率、烧失量、CaCO3含量等分析,从沉积学角度证明了研究剖面所夹洪水沉积物为典型的古洪水滞流沉积物,记录了全新世两个时期的特大洪水事件。通过地层学对比分析和OSL测年,确定其分别发生在全新世早期—中期转折阶段,和中期—晚期转折阶段。利用沉积学和水文学原理恢复古洪水水位,计算出第一组古洪水洪峰流量为27490m3/s、27830m3/s、28570m3/s,第二组为40920m3/s。本文的研究发现全新世特大洪水事件,并且恢复了其水文特征数据,对于揭示黄河水文过程对于全球变化的响应规律具有重要的科学意义,对于水利工程建设具有重要的现实意义。更多还原

【Abstract】 Palaeoflood hydrological studies were carried out in the middle reach gorges of the Yellow River.Palaeoflood slackwater deposit was found at the MFT site in the Hukou gorges of the mainstream of the river.Analysis of the grain-size distribution indicates that these SWD consist of sandy silt,sourced from the suspended sediment load of the floodwater.The low magnetic susceptibility indicates they are fresh deposit without weathering and pedogenic alteration.Stratigraphic correlation with the chronological framework established in the middle reaches of the Yellow River and OSL dating shows that these extreme floods occurred in two periods,that is,at the turn from early to middle Holocene,and at the end of the mid-Holocene Climatic Optimum.The reconstructed peak discharges of the palaeoflood range from 27,490 m 3/s to 40,920 m 3/s which is much larger than those of gauged floods.These results were further tested and proved to be reliable in reconstruction of the modern floods at the same reach.This research is of great importance to hydrological engineering and flood mitigation.And it is also very important in the establishment of the relationships between extreme flood events and global climate change.更多还原