摘要
The Changjiang River Delta is a delta of tremendous scale which is formed under the control of tide and tidal currents. The study on the role of tide and tidal currents in the process of formation and development of the Changjiang River Delta can provide a typical example for the ocean-continent interaction process in the east area of our country. The tide and tidal currents in the Bohai Sea, Yellow Sea and East China Sea at the post-glacial transgression maximum are simulated, the sediment transport field in the Paleo-Changjiang River Estuary(PCRE) and its peripheral area at that time is calculated, and the seabed erosion/accretion pattern is obtained according to the divergence of sediment transport rate. The results show that a distinctive wave belly of standing tidal wave existed at the post-glacial transgression maximum and the wave belly lines protruded seawards from the wave belly point in the mouth of the PCRE. Under the wave belly control tidal currents converge to or diverge from the wave
The Changjiang River Delta is a delta of tremendous scale which is formed under the control of tide and tidal currents. The study on the role of tide and tidal currents in the process of formation and development of the Changjiang River Delta can provide a typical example for the ocean-continent interaction process in the east area of our country. The tide and tidal currents in the Bohai Sea, Yellow Sea and East China Sea at the post-glacial transgression maximum are simulated, the sediment transport field in the Paleo-Changjiang River Estuary(PCRE) and its peripheral area at that time is calculated, and the seabed erosion/accretion pattern is obtained according to the divergence of sediment transport rate. The results show that a distinctive wave belly of standing tidal wave existed at the post-glacial transgression maximum and the wave belly lines protruded seawards from the wave belly point in the mouth of the PCRE. Under the wave belly control tidal currents converge to or diverge from the wave belly point. After a single tidal cycle, sediments started by tidal currents are mainly netly transported into the PCRE in the southeast and east directions, while there is a small amount of sediment to be netly transported to the northeast-southwest area off northern Jiangsu coast. The above sediment transport certainly results in deposition within the PYRE, in the area to the northeast of PCRE, and in the nearshore area between the south bank of the PCRE and the northern one of the Qiantangjiang River Estuary, while erosion occurs in the areas to the east and southeast of PCRE. The seabed erosion/accretion pattern is consistent with the situation of convergence or divergence of sediment transport rate. The Changjiang River Delta developed under the condition that the Changjiang River supplies a large amount of sediment, and the tide and tidal currents in the open sea impel this sediment to deposit as much as possible within the PCRE and its peripheral area. The tide and tidal currents in the open sea provide necessary and favorable dynamic conditions for the development of the Changjiang River Delta When the Changjiang River Delta developed, it was very possible to form small scale sand bodies, which might be the embryonic of the Radial Sand Ridges in the southern Yellow Sea, in the area to the northeast of PCRE. The stretch seawards of the Changjiang River Delta is gradually enlarging the Hangzhou Bay.
