南黄海辐射沙洲海底地形可视化与定量分析

南黄海辐射沙洲海底地形复杂多变,精细的数字地形模型、不同地形单元的立体可视模型及其定量统计值是进行海洋科学研究、海洋功能区与海域开发利用的基础.利用在辐射沙洲北翼进行的单波束测深获取的水深资料,根据残差分析,选择研究区现有水深数据最佳插值法——克里金法,生成海底地形的数字高程模型.运用水深分层设色法立体可视地表征了辐射沙洲的四种地形单元:浅滩、沙脊、潮流槽和宽谷.根据地形倾角可以定量地分析脊、槽等地形单元的坡形变化,整个沙洲以水平-微倾斜地形(倾角<5°)为主,占总面积的60%,分布在宽谷、沙脊顶部和潮流槽中部等.地形剖面曲率分层设色可以更细致地刻画脊、槽相间地形单元的微地貌,并可定量分析不同地形单元的面积及所占比例.地形平面曲率和切线曲率可以指示不同地形单元的海洋动力特征,即:负值区水深较小、流场较强;正值区水深较大、流场较弱.

Visualization and Statistical Analysis on the Submarine Topography of the Radial Tidal Sandy Ridge System in the south Yellow Sea

The radial tidal sandy ridge system(RTSRS) in the south Yellow Sea has very complex submarine topography.It is fundmental and vital for the scientific research,coastal planning and exploitation to have subtle digital terrain model,3-dimention visual model and statistics of the different topographic units.The bathymetric survey data were recently collected in the north RTSRS with the single-beam echo sounding technique.Kriging interpolation method is considered as the best choice to generate the digital terrain model for the current bathymetric data according to the residual analysis on the measured and interpolated value.The RTSRS can be visually subdivided into four topographic sub-units,including shoal,ridge,channel and broad valley through using the water-depth color bar.The microtopography of ridges and channels can be visually displayed by the profile curvature,like the sub-scale channels on the ridges and the sub-scale ridges in the channels,and quantitatively calculated in area and their percentage of the totall.Quantitatvie analyses on the slope of the ridges and channels shows RTSRS is dominated by the horizontal-to-weakly-inclined topography with slope angle less than 5°,which accounts for 60% of the total in area and is mainly distributed on the broad valleys,the top of the ridges and at the middle of the channels.The topographic plan curvature and tangential curvature bear some information of marine hydrodynamics,in that the inner shallow region with strong currents tends to have negative value,and the outer deep region with weak currents has positive value of the tow parameters.