Optimisation d’une bathymétrie dérivée satellite pour le lagon de Reao, Tuamotu

Bathymetric surveys are rare for isolated lagoons, but recent approaches offer promising prospects for reducing the costs associated with acquisitions, by coupling bathymetric in situ data with a satellite image (the satellite-derived-bathymetry SDB method). For coral ecosystems in particular, the use of an “Iterative Multi Band Ratio” algorithm has provided satisfactory results (Amrari et al., 2021). The reliability of the method, which has so far been developed on a shallow coastal barrier reef (< 4 m), nevertheless raises questions for deeper lagoons. In this study, we propose to test an SDB approach inspired by Amrari et al (2021) on an atoll lagoon in the Tuamotu archipelago, Reao. The most satisfactory results were obtained by segmenting the lagoon into several parts and optimising an SDB on each of the parts rather than on the whole lagoon. The bathymetric product obtained is considered satisfactory for feeding hydrodynamic models and ecological studies on the scale of the lagoon, with 77.6% of estimates within the error interval < 10%, and a mean square error of 1.35 m.