沁河流域全新世特大洪水及其重现期初步研究

Holocene extraordinary flood of Qinhe River and its recurrence interval

沁河流域是黄河三门峡以下主要的洪水来源之一。由于沁河流域的实测水文记录时间较短,可以考证的历史洪水记录的时间尺度仅有百年左右,因此,如何延长古洪水、历史洪水记录的时间,就成为河口村水库项目设计洪水可靠性的关键问题。以1982年洪水为参照,利用沉积地貌学方法,结合历史洪水调查的成果,对沁河流域全新世以来的特大洪水进行了初步研究。1982年洪水是沁河流域最大的实测洪水;2480±100aBP的洪水是全新世已知的最大古洪水,其洪峰流量达到12900m3/s;沁河流域千年一遇的洪水洪峰流量为5000m3/s左右。

Qinhe River Basin, so-called 'Little Yellow River', is the main source of flood in the downstream of the Yellow River below Sanmen Gorge. The timescale of gauging record in Qinhe River is only more than 40 years and it can be extended to more than 150 years by the investigation of historic floods. Extending the timescale of the extreme floods records in Qinhe River is the key to raise the reliability of design flood of the project of Hekou Village Reservoir. Based on the comparison of fluvial landform and sediments of paleo-flood with that of the flood in 1982 and 2002, Holocene extraordinary paleo-floods in Qinhe River Basin are reconstructed, then their recurrence interval are analysed in this paper. The flood in 1982 is the maximal one of gauging records. The flood of 2480±100 aBP, with the peak discharge of 12900m^(3)/s, is the maximum during Hollence. The peak discharge with return period of 1000 years is about 5000m^(3)/s.