Andréfouët Serge, Bruyère O., Trophime T. (2025). Multisource mapping of lagoon bathymetry for hydrodynamic models and decision-support spatial tools : the case of the Gambier Islands in French Polynesia. Geomatics, 5 (4), p. 81 [18 p.].
Titre du document
Multisource mapping of lagoon bathymetry for hydrodynamic models and decision-support spatial tools : the case of the Gambier Islands in French Polynesia
Precise lagoon bathymetry remains scarcely available for most tropical islands despite its importance for navigation, resource assessment, spatial planning, and numerical hydrodynamic modeling. Hydrodynamic models are increasingly used for instance to understand the ecological connectivity between marine populations of interest. Island remoteness and shallow waters complicate in situ bathymetric surveys, which are substantially costly. A multisource strategy using historical point sounding, multibeam surveys and well calibrated satellite-derived bathymetry (SDB) can offer the possibility to map entirely extensive and geomorphologically complex lagoons. The process is illustrated here for the rugose complex lagoon of Gambier Islands in French Polynesia. The targeted bathymetry product was designed to be used in priority for numerical larval dispersal modeling at 100 m spatial resolution. Spatial gaps in in situ data were filed with Sentinel-2 satellite images processed with the Iterative Multi-Band Ratio method that provided an accurate bathymetric model (1.42 m Mean Absolute Error in the 0-15 m depth range). Processing was optimized here, considering the specifications and the constraints related to the targeted hydrodynamic modeling application. In the near future, a similar product, possibly at higher spatial resolution, could improve spatial planning zoning scenarios and resource-restocking programs. For tropical island countries and for French Polynesia, in particular, the needs for lagoon hydrodynamic models remain high and solutions could benefit from such multisource coverage to fill the bathymetry gaps.
Plan de classement
Sciences du milieu [021]
;
Limnologie physique / Océanographie physique [032]
;
Ressources halieutiques [040]
;
Télédétection [126]
