Acta Geographica Sinica ›› 2009, Vol. 64 ›› Issue (3): 331-338.doi: 10.11821/xb200903008

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Characteristics and Runoff Volume of the Yangtze River's Paleovalley at Nanjing Reach in the Last Glacial Maximum

CAO Guangjie1, WANG Jian2, ZHANG Xueqin1, QU Guixian2, BAI Shibiao2, GONG Xiaohui2   

  1. 1. Experiment & Education Technology Center,Linyi Normal University,Linyi 276005,Shandong,China;
    2. School of Geography,Nanjing Normal University,Nanjing 210097,China
  • Received:2008-10-25 Revised:2008-12-01 Online:2009-03-25 Published:2010-08-03
  • Supported by:

    National Basic Research Program of China. No.2003CB415201-8;National Natural Science Foundation of China. No.40871010

Abstract:

Three cross-sections of paleovalley depositional sequences were established with references of hundreds of bore data and documents of the No.3, No.1 and No.4 Nanjing Yangtze River bridges. Through analyzing age results of 14C from samples of four drilling cores near the No.4 Nanjing Yangtze River Bridge (to be built), we can find that the time range of paleovalley is dated LGM at a depth of -60~-90 m near Nanjing. It is also indicated that the deep incised-valley channel was narrow and the river flew swiftly. The ancient Yangtze River deep channel presented partially and deeply incised features near the No.1 Nanjing Yangtze River Bridge. According to previous publications, much research has been done on the main paleochannel of the Yangtze River, but few results have been achieved on discharge estimation. In this paper, the incipient velocity and average velocity of the LGM was calculated with Vcetc., in terms of the river shape, sedimentary grain size and sequences near the No.3 and No.1 Nanjing Yangtze River bridges. Moreover, the discharge in Nanjing reach of the Yangtze River during the LGM has been estimated to be around 12000~16000 m3/s according to the relationship of discharge, velocity of flow and cross-section.

Key words: The Last Glacial Maximum, Nanjing reach of the Yangtze River, paleovalley, velocity of flow, runoff volume