中文摘要：

小海作为海南岛最大的泻湖是一种典型的沙坝-泻湖-潮汐汉道体系，它自上世纪70年代以来发生了巨大变化，变得极不稳定，但其变化过程和机制尚不清楚。本文利用地理信息集成技术，研究小海泻湖面积和潮汐汉道30多年来的变化过程及其相互联系，分析变化的原因，提炼沙坝、泻湖、潮汐汉道体系演变的规律性认识，为小海今后港口航道和生态环境的可持续利用打下基础。

英文摘要：

Xiaohai, the biggest lagoon in Hainan Island, is a typical barrier-lagoon-tidal inlet system. Since 1970 ＇ s, it became more and more unstable,but the procedure and mechanism were not clear. In this paper, using ＂3S＂ technology, change proce-dure and relation of area and tidal inlet in Xiaohai lagoon were analyzed,and the evolution reasons and the change discipline were found,which laid foundations for sustainable utilization of harbor approach and ecological environment of Xiaohai.