琼州海峡及其南岸岬角型线性浅滩形成与演变的动力机制研究

The Qiongzhou Strait is located between Hainan Island and Leizhou Peninsula,with a minimum width of 18km and a maximum water depth of more than 100m.Previous studies on the Qiongzhou Strait have been mainly focused on its geology,geomorphology,dynamic environment and chronology, and few study on its evolution since the Holocene has been conducted. Based on the EFDC (Environmental Fluid Dynamics Code) model, this study will develop a long-term dynamic-sedimentation-morphology model on the timescale of thousands of years. The paleo-bathymetry and paleo-tidal dynamics will be reconstructed. The formation and evolution processes of the Qiongzhou Strait since the highstand of sealevel in Holocene will be investigated through the model, and the formation of the tidal sandbanks at the west and east mouths of the Qiongzhou strait will be explored.. Headland-associated linear sandbank is a common landform in the coastal ocean,whose mechanism has been studied extensively. This study will examine the sedimentary structures,sediment sources, dynamic mechanism and formation processes of the Baisha and Yubao sandbanks on the south coast of the Qiongzhou Strait.It is aimed to enrich the theorotic study on linear sandbanks and also benefit the sustainable use of marine resources.

琼州海峡位于海南岛与雷州半岛之间，最窄处仅18km左右，中部深槽最大水深超过100米。目前对于琼州海峡的研究主要集中在地质地貌、水动力环境和形成年代等方面，对琼州海峡全新世以来的动态发育过程则鲜有研究。本项目将以EFDC三维数值模型为基础，恢复琼州海峡全新世时期的古水深及古潮汐动力环境，构建百到千年尺度的长周期动力-沉积-形态模型，研究全新世海平面上升过程中，在潮汐动力作用下琼州海峡的形成演变过程，并且对琼州海峡东、西口潮成沙脊的形成过程进行深入分析。. 岬角型线形沙脊是一种常见的地貌，对于其形成机理已有众多研究，本项目将对琼州海峡南岸的线形沙脊-白沙浅滩和玉苞浅滩的沉积结构、泥沙来源、水动力机制以及形成过程进行研究。本研究将丰富线形沙脊理论研究的内容，同时对于合理开发和保护海洋资源也具有实践意义。

海南岛周边的古潮流和潮汐分析结果显示：靠近越南附近的全日分潮O1、K1无潮点随着海平面的上升，逐渐往南移动；全日分潮的相位在琼州海峡里面发生较为显著的变化，其它区域并无明显的改变。M2、S2半日分潮随着琼州海峡不断冲刷和海平面不断的上升，6.2kaBP时在西口出现了半日分潮的无潮点。.在广东沿岸海域，西南流占据主导地位，西南流大于东北流，粤西沿岸流大于粤东沿岸流；粤西沿岸流只有在夏季西南季风较大的时候才会有东北向流，其他月份都是西南向流；琼州海峡的广东沿岸海流受季风影响不大，余流基本上都是西向流。.动力-泥沙-地貌模型计算的结果表明，在琼州海峡中部，深槽雏形已经初步形成，海峡西口也形成了显著的线性潮成沙脊，海峡东口出现了不规则的浅滩—深槽地貌分布。局部岬角水动力的不对称性确实能够导致岬角东侧浅滩的出现。