南黄海辐射沙洲主要潮沟的变迁

CHANGE OF TIDAL CHANNELS OF RADIAL SAND RIDGES IN THE SOUTH YELLOW SEA

利用1966年和1977年海图、1995年和2000年合成孔径雷达影像,结合1980年以来的陆地卫星影像和2000年的岸滩实测剖面资料对南黄海辐射沙洲区主要潮沟的位置进行了解译与分析,得出上述4个时期研究区内主要潮沟深泓线位置图。对不同时期潮沟深泓线位置图进行几何校准与叠加,对比潮沟深泓线的迁移。结果表明:潮沟具有往返周期性摆动的特点,短期摆动速度明显快于长期摆动,主沟槽最大变动速度达127m/a,而支沟槽变动速度更大。潮沟摆动与沙洲变化有明显的相关性,但两者间的关系较为复杂。辐射沙洲目前处于破碎、萎缩阶段,除沙洲中心及陆岸岸滩仍有淤积外,大部分沙洲处于侵蚀状况,同时沙洲有整体向陆迁移的趋势。

The nautical charts in 1966 and 1977, Synthetic Aperture Radar (SAR) images in 1995 and 2000,and Landsat images since 1986 and survey data of beach profile in 2000, were interpreted and analyzed to obtain the positions of main tidal channel talwegs.Four charts of the talweg positions for main tidal channel were obtained during different periods. After geometric calibration and overlay, the positions of main tidal channel during 4 different periods were compared and their changes were analyzed. The result showed that the shifts of channels were periodic. Their velocity varied with the length of measured period and the scale dimension of channel itself. The maximum velocity of main channel was up to 127 m/a. There is a complex relationship between the shift of tidal channel and the changes of sand ridges. The total radial sand ridges are in a period of division and shrinking. All sand ridges were in erosion except those in the middle of the sand ridges and near beach. There was a trend that all sand ridges moved toward the mainland.