Geomorphic Features and Origin of the Valley Bottom Troughs at the Site of Three Gorges Dam

  • 1. Department of Urban and Resources Sciences, Nanjing University, Nanjing 210093, China;
    2. Exploration Bureau, Hydraulics Committee of the Changjiang River, Wuhan 430010, China

Received date: 2001-11-25

  Revised date: 2002-06-28

  Online published: 2002-09-25

Supported by

Fund by the Exploration Corporation of the Three Gorges Project; The "985 project" construction project of physical geography for Nanjing University


This paper describes valley bottom troughs of the Changjiang River and infers the geomorphological development of troughs. Based on the morphology of the troughs, the following conclusions are drawn. (1) The deep troughs on the Three Gorges valley bottom are formed by river downcutting along the structurally zones on the background of regional tectonic uplift. The data of 14C dating indicate that the downcutting of the troughs occurred at about 40-30 ka BP. (2) When river downcutting occurred in the river bed of Changjiang, the jets current with a large number of pebbles, ground and eroded the valley bottom, resulting in trough formation and deepening. Meanwhile, water currents with gravels and pebbles eroded the bank and the left wall of No.76 trough as well as the right wall of No.77 trough by striking, scouring, horizontal and vertical grinding. The left wall of No.77 trough was developed after trough deepening, when the pressure-released fracture formed on trough bank and hence induced collapse of the wall under the water. (3) The trend of the troughs is controlled by longitudinal structural fissures. The deepest points of the troughs are normally located at the intersection of the longitudinal fissures with the transverse ones. The depth of the trough is mainly determined by the intensity of the water current and the consistency of bedrock against erosion, of which the trough is composed, and is not controlled by the altitude of the sea level as the base level.

Cite this article

YANG Dayuan1, LI Xusheng, KE Xiankun, ZHOU Lufu, CHEN Deji,YANG Tianmin, XUE Guofu . Geomorphic Features and Origin of the Valley Bottom Troughs at the Site of Three Gorges Dam[J]. Acta Geographica Sinica, 2002 , 57(5) : 547 -552 . DOI: 10.11821/xb200205006


[1] Yang Dayuan. Study on the origin of the deep troughs at the Three Gorges reaches of the Changjiang River. Mountain Research, 1992, 10(3): 141-147.
[杨达源. 试论长江三峡河段深槽的成因. 山地研究, 1992, 10(3):141-147.]

[2] Shen Yuchang. Valley Landforms of the Upper Reaches of the Changjiang River. Beijing: Science Press, 1965.
[沈玉昌. 长江上游河谷地貌. 北京: 科学出版社, 1965.]

[3] Yang Dayuan. Study on the Three Gorges terrace of the Changjiang River. Journal of Nanjing University (Geography), 1988, (9):32-43.
[杨达源. 长江三峡阶地的研究(II). 南京大学学报(地理学), 1988, (9): 32-43.]

[4] Shi Yafeng, Liu Xiaodong, Li Bingyuan et al. Extreme strong event of the summer monsoon and its relation to precession periods in the Qinghai-Xizang Plateau 40-30ka BP. Science Bulletin, 1999, 44: 1475-1480.
[施雅风, 刘晓东, 李炳元 等. 距今40-30ka青藏高原特强夏季风事件及其与岁差周期关系. 科学通报, 1999, 44: 1475-1480.]

[5] Liu Shixing. The Quaternary System of the Sichuan Basin. Chengdu: Sichuan Science & Technology Press, 1983.
[刘兴诗. 四川盆地的第四系. 成都:四川科学技术出版社, 1983.]