Satellite-Derived Bathymetry (SDB) for the eastern platform of Rio Grande do Norte: a proposal applied to tropical shallow environments.
Shallow Continental Shelves, Satellite Images; Band Ratio.
Shallow continental shelves are coastal areas influenced by currents, waves and tides, closely related to erosion and sedimentation processes, but suffer from a lack of data. Although the platform relief is mostly obtained by hydroacoustic geophysical methods, they present logistical limitations, high costs and time consumption. Satellite-Derived Bathymetry (BDS) is an economical solution for obtaining these mappings, enabling high temporal and spatial resolution. This study used BDS techniques to characterize the submerged morphology of the eastern RN platform area. The technique uses underwater reflectance and optical data to estimate depths, validated with Navy bathymetry. The satellite images were loaded and worked on in a GIS environment, where the Band Ratio Transformation was applied, logarithmizing the blue (B2) and green (B3) bands to estimate the bathymetry, according to the proposal by Stumpf (2003). The best results for depth prediction occurred for the SENTINEL-2 image, du e to its better spatial resolution, with a coefficient of determination (R2) of 0.9008, while 0.8319 was obtained for the LANDSAT-8 image. Images with greater cloud cover had inferior results. The mouth of the Potengi River did not significantly influence the results. Depths greater than 30 m did not show good correlation, limiting the method to shallower regions, as the bibliography points out. The BDS technique to estimate depths for the studied region proved to be viable, especially in clear waters and with low cloud cover.