汉江旬阳至白河段万年尺度洪水流量恢复比较研究

Comparative study on flood discharge restoration at 10000-years time scale in Xunyang-Baihe section of Hanjiang River

对汉江上游旬阳至白河段基岩峡谷进行了详细的野外调查,在全新世黄土地层中发现了古洪水滞流沉积层。综合野外宏观特征和粒度分析,并与现代洪水滞流沉积物的对比,判定是典型的古洪水滞流沉积物。通过全新世地层关系对比和光释光(OSL)测年表明,古洪水事件发生年代距今为1800~1700 a(A.D.200-300)。汉江上游旬阳至白河段万年尺度流量恢复比较发现,由古洪水SWD厚度与含沙量关系法恢复的洪水水位和流量更为合理。这些成果为汉江上游水资源开发与重大水利工程的安全校核提供了重要的科学依据。

Detailed field investigations were carried out along the bedrock gorges of the Xunyang-Baihe section in the upper Reach of Hanjiang River and Palaeoflood slackwater deposits(SWD) were discovered in the Holocane loess stratum.Through field observation,particle size distribution analysis and comparison with modern flood SWD,it was judged to be typical palaeoflood SWD.Through Holocene stratigraphic correlation and OSL dating,it is shown that the palaeoflood occurred before 1800-1700 years.Comparative study on flood discharge restoration at10000-year time scale for the Xunyang-Baihe section in the upper reach of Hanjiang River show that,the peak discharge of the palaeoflood obtained from SWD thickness and bulk of suspended sediment load of the floodwater is more reliable.These results provide an important scientific basis for water resources development and safety check of major hydrolic projects in upper reach of Hanjiang River.