Research status and analysis of seafloor topography survey and model development

The sea depth is the vertical distance from the sea surface to the seafloor, reflecting the ups and downs of the seafloor topography. Seafloor topography affects the marine natural disasters, resource development, military defense, etc. The detection methods of seafloor topography have evolved from traditional shipborne sonar technology to relying on gravity data to invert water depth. Foreign countries have used shipborne and satellite altimetry data to develop global water depth models since the 1980s, and released water depth models have reached a spatial resolution of 15". In recent years, domestic researchers have released several global and local water depth models which are more accurate than certain foreign products. This paper summarizes the research status of sonar, laser bathymetric radar, satellite altimetry gravity data, and remote sensing image inversion of water depth. And the advantages and disadvantages of each bathymetric method are analyzed. Then we introduce the development of five representative series of water depth models ETOPO, DTU, GEBCO, SRTM and SIO topo. Moreover, the accuracy of the latest products of each series of models: ETOPO1, DTU18BAT, GEBCO_2021 Grid, SRTM15+V2.3 and topo_23.1 was evaluated using single-beam and multi-beam ship water depth data from NGDC (National Geophysical Data Center) in offshore waters of China. The results show that the accuracy of the recently released product is significantly better than the ETOPO1 released in 2009. The error standard deviation of ETOPO1 is 88.544 meters, while the other four models are less than 35 meters. SRTM15+V2.3 has the highest accuracy, with a error standard deviation of 30.297 meters, and 87.2% of the data with an error less than 50 meters. Finally, the seafloor topography model's current problems and development direction have prospected. This paper can provide a reference for understanding and selecting sounding methods and water depth models.