Abstract
The riverbed evolution of upper part of Yangtze estuary, Chengtong reach, is analyzed by comparison of 6 sets of bathymetry data during 1977~2011. The significant changes of water depth profiles along 6 representative cross-sections indicate the reach is still in the process of development. In order to get a better understanding of the effect of river discharge at upstream on the riverbed evolution of Chengtong reach, a series of numerical experiments are implemented by specifying different river discharge conditions at the upper boundary. The corresponding discharge ratio at main sub-reaches is compared to reveal the response of the riverbed evolution to the hydrodynamic changes at upstream. The results show that with the increase of river discharge, the discharge ratio in the main channels of Fujiangsha sub-reach and Rugaosha sub-reach increases, but it changes to decrease when the upstream river discharge becomes very large; however, the discharge ratio in the main channel of Tongzhousha sub-reach always decreases with the increase of river discharge at upstream.
Highlights
Yangtze River is the longest river in China and the third longest river in the world
A lot of research on the riverbed evolution of the Yangtze Estuary has been done in the past (e.g. Wang et al, 2008; Jiang et al, 2011), but most of the work focused on the field data analysis and presented the qualitative trend of riverbed evolution only
Fujiangsha sub-reach, Rugaosha sub-reach and Tongzhousha sub-reach under those upstream discharge conditions are shown in Fig.5, Fig.6 and Fig. 7, respectively
Summary
Yangtze River is the longest river in China and the third longest river in the world. The estuary of Yangtze River starts from Ebizui of Jiangsu Province and reaches the East China Sea by the city of Shanghai. The riverbed of Yangtze estuary has exhibited significant changes under the effects of natural evolution and anthropogenic works (Yang et al, 2006; Liu et al, 2007). Wang et al, 2008; Jiang et al, 2011), but most of the work focused on the field data analysis and presented the qualitative trend of riverbed evolution only. The study area for this paper is the Chengtong reach, which is located at the upper part of the Yangtze Estuary, starting from Ebizui and ending at Xulijing, with the total length of about 90km.
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