PROGRESS IN GEOGRAPHY ›› 2012, Vol. 31 ›› Issue (9): 1141-1148.doi: 10.11820/dlkxjz.2012.09.004

• Original Articles • Previous Articles     Next Articles

Holocene Palaeofloods Recorded in the East Xunyang Reach in the Upper Hanjiang River

WANG Longsheng, HUANG Chunchang, PANG Jiangli, ZHA Xiaochun, ZHOU Yali, LI Xiaogang, ZHANG Yuzhu   

  1. College of Tourism and Environmental Sciences, Shaanxi Normal University, Xi’an 710062, China
  • Received:2012-02-01 Revised:2012-05-01 Online:2012-09-25 Published:2012-09-25

Abstract: 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 clastic 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 m3/s. Reconstruction of modern 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 result 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.

Key words: 10000-year time-scale, Hanjiang River, Holocene, palaeoflood, slackwater deposits