基于遥感的广西防城湾海岸线变迁分析

随着人口增长、城市化和工业化的迅速发展、政策刺激以及对外贸易的日渐加强,防城湾沿岸海岸线变迁加剧。本文利用1973,1979,1990,2000年的Landsat卫星遥感影像和2010年的HJ-1B(环境与灾害监测预报小卫星星座B星)卫星遥感影像,分析了近40 a来防城湾海岸线的变化特征。结果表明:1973—2010年间,防城湾沿岸不断向海推进,陆域面积共增加了4 216.61 hm²;海岸线总长度则减少了36.96 km,其中淤泥质岸线减少最为剧烈,其次为基岩岸线;海岸线变化主要受人为因素影响。根据防城湾的区域特征,将整个研究区划分为防城江口、暗埠口江和渔澫岛3个岸段分别进行详细分析表明:防城江口沿岸以基岩岸线为主,海岸线在1973—2010年间变迁程度很小,仅在防城江河口沿岸向海扩张了约74.58 hm²;暗埠口江沿岸以淤泥岸线为主,近40 a间该岸段岸线不断向海推进,许多原本曲折多变的鹿角湾被逐渐填充;渔澫岛海岸线变迁最为剧烈,近40 a来陆域面积共增加了2 027.41 hm²,岸线长度缩短了2.46 km,遥感影像监测显示1990年时渔澫岛已经陆连,同时从渔澫岛的分形维数计算结果可以看出其海岸线日趋平直。

Analysis of shoreline changes in the Fangcheng Bay of Guangxi based on remote sensing technique

With the population increasing, the boom of industry and city, the policy stimulation, as well as the rise of external trade, shoreline changes accelerated in the Fangcheng Bay. Using Landsat data of 1973, 1979, 1990, 2000 and HJ-1B data of 2010, shoreline changes of the Fangcheng Bay during past 40 years were analyzed. The results show that the shoreline of the Fangcheng Bay kept expanding seaward constantly from 1973 to 2010, resulted in the land area increased by 4 216.61 hm², while the shoreline length decrease by 36.96 km, which was mainly induced by anthropogenic factors. As for the decreased shoreline, the muddy shoreline occupied mostly and the rocky shoreline occupied secondly. Based on the regional character of the Fangcheng Bay, the study area was divided into three parts: the Fangchengjiangkou coast, the Anbukoujiang coast and the Yuwan Island. The rocky shoreline along the Fangchengjiangkou changed slightly from 1973 to 2010, with an increase near the Fangcheng River Estuary of only 74.58 hm². Since the shoreline along Anbukoujiang is muddy, it has kept expanding seaward during past 40 years, therefore, many flexuous bays were filled. The shoreline of Yuwan Island changed the most dramatically. There's a 2 027.41 hm² increase of land area and a 2.46 km decrease of shoreline length. The remote sensing image of Yuwan Island indicates that it had united with the continent in 1990. The fractal dimension shows that the shoreline becomes straighter.