南黄海的辐射沙脊群海域地形地貌复杂多变,应用遥感技术来测量其水下地形不仅有可能,而且势在必行。在对沿海及长江口门内外遥感反演水下地形研究的基础上,选择沙脊群海域中有代表性的一块水域为研究区,同步测量其水下地形和水流、悬沙含量,用实测地形和MODIS影像数据建立水深反演模型,同时分析该区域的悬沙光谱特征,选择悬沙遥感参数,以MODIS数据的水深反演模型和沙脊群水域的悬沙遥感参数为依据,建立削弱悬沙影响的水深遥感模型,从而反演出1.5×104km2的辐射沙脊群水下地形。从反演结果看,所建模型的相关系数二次方的值为0.664,F值为18 662,平均绝对误差为1.52 m,平均相对误差为24%,5~15 m水深段的平均相对误差只有18%,反演效果较好。
The variation of underwater bathymetry in the radial sand ridge group of the southern Huanghai Sea is complex and changeable owing to abundant sediment supply of different sources and varied hydrody- namic processes. Remote sensing has potential and is imperative for the surveying and monitoring variation of underwater topography with quick and large area data acquisition abilities. So based on the experiences of water depth in the Changjiang Estuary and coastal area with the remote sensing reversion, a typical re- gion in radial sand ridge was chosen for bathymetry reversion via remote sensing technology. Tidal current and content of suspended sediments were surveyed synchronously during the measurement of water depth. Spectral characteristics of suspended sediments were analyzed and a spectrum based on sediment reversion parameter was obtained to reduce its influence on water depth information contained in MODIS image. And then real observed bathymetry data were used to establish a remote sensing reversion model. The underwa- ter topography of about 1.5 × 10^4 km2 in the radial sand ridge group region was then acquired with a fairly good precision. The correlation coefficient square between the reversed water depth and the measured reached 0. 664. The mean absolute error was approximately 1.52m and the mean relative error was about 24%. The best reversion results appear at water depth range of 5 to 15m. The mean relative error was only 18%. It is indicated that this remote sensing based on the reversion technology was suitable for the underwater bathymetry reversion in a complex coastal area especially with a relatively shallow water depth.