Estimation of bathymetry along the coast of Mangaluru using Landsat-8 imagery

Determining the bathymetry of ocean is important for many aspects such as generating navigational charts, to study changes in the seafloor profile, sea level rise, and beach erosion. Traditionally, the bathymetry of ocean was determined by a hydrographic ship carrying an echo sounder instrument which was cost effective but time consuming and also often inaccessible in shallow water regions. The alternate solution to infer the bathymetry of ocean is remote sensing technology. The multispectral satellite platform such as Ikonos and WorldView images are commercially available, whereas the Landsat-8 imagery is freely accessible and therefore the Landsat-8 imagery is used. In this study, the first objective was to evolve a procedure to determine the bathymetry of ocean using the ratio transform algorithm. The second objective was to find the effectiveness of improving the spatial resolution of Landsat-8 imagery to estimate the bathymetry of ocean, and the results of both before and after improving the spatial resolution are compared. The statistical indices, root mean square error and mean absolute error, are computed between the algorithm results and the reference hydrographic chart values, and it was found that the improved spatial resolution of Landsat-8 imagery provided better estimation up to 10 m depth.