海南岛港湾演变与工程建设

海南岛沿岸多港湾，主要有3种类型的潮汐汊道型港湾：（1）沙坝-泻湖型潮汐汊道港湾主要分布在东南部海岸，以三亚港最为典型。三亚港原始岸线为基岩港湾海岸，由中生代花岗岩构成。花岗岩风化泥沙充填谷地港湾连成陆地，以沙坝-泻湖体系形式逐渐堆积成海积平原。（2）港湾型潮汐汊道主要分布在海南岛西部，起源于构造断裂带的港湾。其演化的主要因素是河流及海岸侵蚀向湾内供应的沉积物以及巨大的纳潮量形成的潮流动力。消费品流及海岸供沙使纳潮水域淤积，纳潮量相应减少，同时在口门内外形成潮流三角洲（拦门沙浅滩）。（3）溺谷型潮汐汊道主要分布在海南岛北岸、东北岸。其演化过程是：古河口溺谷，沿岸输沙发育海岸沙坝，古河口溺谷逐渐淤积衰退，潮流作用形成 口门外落潮流堆积体及涨潮带入海相细粒物质，使纳潮水域进一步淤浅缩小，目前这类汊道处于发育演化的晚期，接近汊道整体的消亡。

Estuarine Evolution and Engineering Construction of the Hainan Island

Hainan Island coast has many tidal branch estuaries,mainly grouped under 3 types,namely sand bar lagoon type,estuarine type and drowned valley type.The first type is mostly distributed in the southeastern coast,and Sanya Port is its representative.The primary coastline of the port was bedrock embayment and composed of Mesozoic granite.Estuarine valleys were filled with the weathered granite sand and mud to become land and gradually turned into sea built plain with sand bars and lagoons scattering in.The second one is mainly distributed in the west of the island,rising from estuaries within tectonic fault zones.Its significant formation is due to deposits from river and coast erosion into the estuaries and tidal dynamics coming from great tide holding capacity as well.And the third one is mainly found along the north and northeast coast sections of the island,but such type is now in its late evolution and going near to the end of their lives.