南黄海辐射沙脊群地貌演变的模拟研究

Evolution simulation of radial sand ridges in the southern Yellow Sea

南黄海辐射沙脊群的地貌演变机制是物理海洋和海洋地质学家们近30多年来争议较多的问题.本文设计了两个理想实验,模拟苏北潮流脊在理想地形下的发育过程.通过对比真实地形和两个理想地形下的模型结果,本文探讨了潮流脊的发育条件和古沙坝对沙脊群发育的影响以及沙脊群在理想状态下的演变过程.结果表明,(1)江苏近岸海域辐射状流场不依赖于辐射状地形,局部区域的地形差异不影响大范围的潮波系统和潮流特征;辐射沙脊群区域的辐射状潮流是潮汐与中国东部岸线的必然产物.(2)废黄河口海域不断受到侵蚀,等深线向后退,是辐射状沙脊群发育的重要泥沙来源之一.(3)潮致沉积和侵蚀对20m水深以下且未发育潮流脊的平坦地形影响微弱.

Evolution mechanism of Radial Sand Ridges in the Southern Yellow Sea has been one of the most controversial issues in the field of Physical Oceanography and Geological Oceanography since 1980 s.Two ideal experiments were set up to simulate the evolution of tidal sand ridges in the Southern Yellow Sea.By comparing the results of real model with real bathymetry and ideal model with idealized bathymetry,this paper discussed the essential condition for the growth of tidal sand ridge,as well as the effect of pre-existing giant sand ridge on the growth of tidal sand ridges.The result shows the radial tidal current is independent on the radial topography,and change of local topography doesn＇t make a significant different on the large-scale tidal dynamics.The radial tidal current is the inevitable outcome of large-scale tidal dynamics and coast shape of East China Sea.The result also shows abandoned Yellow River Delta undergoes significant erosion and is one of the most important sediment sources for the growth of radial sand ridges in the Southern Yellow Sea.Additionally,comparison between different scenarios indicates that tidal current has little effect on the erosion and deposition of sediment in area where there is no sand ridge and the depth is larger than 20 m.