含沙水体水深遥感方法的研究

Study of remote sensing-based bathymetric method in sand-containing water bodies

遥感测深技术是海岸、河口及其他水体水深测量的一种新方法，应用前景广阔。在海洋的近岸、河口处水体相对浑浊，利用可见光技术测深的精度依赖于建立合适的水深反演模型和考虑水体悬浮物质的影响。选择合适的水深反演因子和比较多种线性、非线性水深反演模型，通过对水体悬浮泥沙光谱特性的研究，建立了适于河口、近岸浅水浑浊水体并考虑悬沙浓度影响的水深反演模型。通过检验，由该模型反演的平均相对误差小于15％，在7～14m的水深段反演效果更好，其平均相对误差小于8．5％。

Remotely sensed bathymetric technology has a wide application for the water-depth measurement in a coastal zone, an estuary and other water bodies of different types. Owing to the turbid characteristic of water, the bathymetry in nearshore and estuary areas by means of visible-light remote sensing technology is comparatively difficult. The improvement for the inversion precision of water depth in these areas mainly relies on two aspects： （1） the reliability of bathymetric inversion model; and （2） considering that how suspended matter in a water body influences the reflection spectrum of water. Taking the Changjiang Estuary as a study area, firstly four appropriate water depth inversion factors were chosen by the correlation analysis between real water depth data and corresponding pixel reflectance value. And then, linear, nonlinear and BP artificial neural network models for the bathymetric inversion were established and compared in detail. On the basis of these models and the study results about the spectral characteristics of suspended sediments, a remote sensing-based bathymetric inversion model was established which was suitable for water depth extraction in shallow, turbid estuary and offshore areas. Inversion results showed that the average relative error is less than 15%. Between the water depths of 7-14 m, the precision is much better and the average relative error only reaches 8.5%.