**5. Acknowledgment**

This work is supported by the Centre National d'Etudes Spatiales (CNES) for the preparation of the 'Pleiades' mission and joins the *Infolittoral-1* project funded by the French "Unique Inter-ministerial Fund" and certified by the "Aerospace Valley competitiveness cluster" (http://infolittoral.spotimage.com/). Nicolas Barbier has a Marie Curie (UE/IEF/FP7) grant. Research in central Africa is supported by the *Programme Pilote Régional* (PPR FTH-AC) of IRD. We thank J-L. Smock and Michel Tarcy for their strong motivation in mangrove field measurements. We also thank Bruno Roux and Michel Assenbaum for their kind support in providing us for free several Avion Jaune© images (http://www.lavionjaune.fr).
