Mapping Posidonia meadow from high spatial resolution images in the Gulf of Oristano (Italy)

This work deals with the retrieval of distribution of seabed vegetation cover (essentially Posidonia Oceanica) in the coastal waters (1-10m) of the Gulf of Oristano. A physical approach was used to derive bottom cover map from airborne and satellite imagery (MIVIS, KOMPSAT-2 and RapidEye) acquired in summer 2001, 2011 and 2013. A bathymetric map was also derived from the RapidEye image of 2003. A field campaign was held on 1-8 August 2013 to parameterize the physical model and to validate the 2013 results. Accuracy of bottom cover map and regression between measured and modelled water depths was good providing an overall accuracy of 0.88% and a correlation coefficient of 0.84, respectively. The retrospective analysis revealed that P. oceanica meadow seems to be stable over the 12 years showing only very small variations (-0.2km²). Sea bottom morphology and vegetation cover were also related.