摘要
通过对汉江上游河谷的考察，在旬阳县东段构元-棕溪乡河段发现的典型的全新世古洪水滞流沉积剖面，进行了古洪水沉积学和水文学研究。在野外考察的基础上，对于采集的全新世地层剖面序列样品，进行粒度成分和磁化率等分析测试，从沉积角度揭示了这些沉积层是古洪水在高水位滞流环境中悬移质泥沙的沉积物。通过地层对比分析确定由其记录的古洪水事件分别发生全新世早期9000-8500aB．P.和全新世晚期3200-2800aB．P.。利用古水文学原理恢复其洪峰水位，计算出古洪水洪峰流量介于45630-50220m^3／s之间。结合现代洪水洪痕洪峰计算、洪峰流量与流域面积关系分析多种方法，对古洪水洪峰流量计算结果进行了验证，从而建立了更加可靠的万年尺度洪峰流量与频率关系。本文的研究成果，对汉江上游水资源开发、防洪减灾、水土保持和深入理解汉江上游水文过程对全球变化的响应规律具有重要的科学意义。
Integrative studies of palaeoflood hydrology were carried out in the upper reaches of the Hanjiang River, a major tributary of the Yangtze River. Two sets of palaeoflood slackwater deposits were found in the east Xunyang reach. The very typical flood slackwater deposits were identified in the slope elastic deposit profile. The NGK site in the bedrock gorges was chosen for palaeo-hydrology study. On the basis of field survey, sediment samples were taken for analyzing grain size distribution and magnetic susceptibility. The results of field observation and grain-size and magnetic susceptibility indicate that these slackwater deposits are very typical and that they have been deposited by suspended sediment load in the floodwater of the Hanjiang River. Stratigraphic correlation with ETC profile of Jinghe River basin and JJTZ profile downstream of the NGK site shows that the palaeoflood events occurred at 9000-8500 a BP and 3200-2800 a BP respectively. The flood peak discharges were reconstructed to be 45630-50220 m^3/s. Reconstruction of modem flood （2010.07.18） and comparison with the gauged discharge proved the hydrological method used and its results were reliable. And the relationship between drainage area and flood peak discharge illustrated that the reconstructed discharges were reasonable. A relationship between peak discharge and occurrence frequency at 10000-year time-scale was established. This resuit is very important for flood design in the hydraulic engineering, soil and water conservation and flood control, and for understanding the response of fluvial systems to global climate change.
出处
《地理科学进展》
CSCD
北大核心
2012年第9期1141-1148,共8页
Progress in Geography
基金
国家自然科学基金重点项目(41030637)
国家社科基金重点项目(11AZS009)
中央高校基本科研业务费专项基金项目(GK200901007
GK200902020)
关键词
汉江
古洪水
滞流沉积物
万年尺度
全新世
Hanjiang River
palaeoflood
slackwater deposits
10000-year time-scale
Holocene
