北部湾环流和沉积物输运的数值模拟

研究环流和沉积物输运对北部湾的环境保护和资源开发十分重要。本文使用区域海洋模型（ROMS），研究了北部湾海域的季节环流、沉积物输运以及长期的地形演变过程。展示了湾内冬季和夏季都存在逆时针环流，冬季的风生环流比夏季强的特征。悬沙浓度较大值主要分布在琼州海峡、海南岛西侧海域，以及越南沿岸、雷州半岛沿岸等近岸地区。沉积物在琼州海峡附近表现为在冬季由东向西输运，夏季则相反；在琼州海峡西口处，沉积物全年以西向输运为主。结果显示，北部湾内沉积物输运主要由潮流引起的再悬浮控制。侵蚀和淤积的分布模式为：（1）湾内大部分区域侵蚀淤积不明显，（2）琼州海峡两侧口门附近淤积比较明显，（3）琼州海峡内深槽侵蚀严重，（4）海南岛西侧海域存在侵蚀和淤积交替发生区域。

Modeling the circulation and sediment transport in the Beibu Gulf

Water circulation and sediment transport in the Beibu Gulf are important for its environmental protection and resource exploitation. By employing the Regional Ocean Modeling System (ROMS), we studied the seasonal variation of circulation, sediment transport and long-term morphological evolution in the Beibu Gulf. The simulation results show that the circulation induced by tide and wind is cyclonic both in winter and summer in the gulf and that the wind-driven circulation is stronger in winter than that in summer. The sediment concentration is higher in the Qiongzhou Strait, west of the Hainan Island and the coast of Vietnam and the Leizhou Peninsula. The sediment is transported westwards in winter and eastwards in summer in the Qiongzhou Strait. The west entrance of the Qiongzhou Strait is dominated by westward transport all the year round. The sediment discharged by rivers is deposited near the river mouths. The simulated result demonstrates that the sediment transport is mainly controlled by tidal induced bottom resuspension in the Beibu Gulf. Four characteristics are summarized for the distribution patterns of erosion and deposition. (1) The erosion and deposition are insignificant in most area of the gulf. (2) Sediment deposition is more significant in the mouths of Qiongzhou Strait. (3) The erosion is observed in the seabed of Qiongzhou Strait. (4) Erosion and deposition occur alternatively in the west of Hainan Island.