Comparison of bathymetry estimated from multibeam echosounder and optical data

Accurate bathymetry estimation is crucial for various marine and coastal applications, including resource management and environmental protection. This study presents a comparison of bathymetry estimated using optical satellite imagery, on sandy bottom, versus multibeam bathymetric data. The study area was the Gulf of Sciacca, on the southern coast of Sicily Island (Italy). High-resolution PlanetScope SuperDove satellite images were processed using a simplified version of the original radiative transfer equation from Jain and Miller (1977) was used to estimate water depth. The model was calibrated and then validated using multibeam data. Multibeam data were acquired using a Reason 8125 multibeam echosounder. Bathymetry was estimated from optical data from the shoreline down to ⁓25m water depth; while approaching this depth, the reflectance assumed an asymptotic value. The results show a strong correlation between the depths estimated from satellite images and those obtained from multibeam data, with a root mean square error lower than 11% with a confidence interval of 95%. However, some discrepancies were observed in areas in mixed pixels or reflectance surface effects.