Mapping coastal area dynamics in Oristano Gulf (Italy) using PRISMA hypespectral images

Coastal processes are the result of forces acting on coastal areas and leading to the alteration of these environments. Both natural and anthropogenic activities can lead to the degradation of these environments (coastal changes, loss of biodiversity, sea level rise, seawater intrusion, coastal erosion, and flooding). Coastline mapping and change detection are essential for safe navigation, resource management, environmental protection, and sustainable coastal development and planning. Satellite remote sensing has been used for about 50 years to obtain environmental information to support effective management of such landscapes. In this context, the OVERSEE project financed by the Italian Space Agency (ASI) delivers useful integrative Earth Observation information for coastal risk assessment and coastal landscape planning, aiming at a sustainable management of natural and man-made hazards in order to reduce environmental and socio-economic vulnerability. In this work we present the activities related to evaluating the status of benthic substrate in the Oristano Gulf (Italy) target area using PRISMA hyperspectral images in synergies with Sentinel-2 images and in situ data. The Remote Sensing Reflectance images or downloaded directly as Level 2 from the ASI portal or corrected with the code ACOLITE, validated with spectral ground truth, were converted into maps of marine substrates and bathymetry using bio-optical modelling (BOMBER) parametrized with specific Inherent Optical Properties collected in situ. The maps obtained revealed how some coastal areas, influenced by currents, mussel farms, and the turbidity of the lagoons that flow into the sea, present a high seasonal variability in the coverage of Posidonia oceanica in shallow water areas. The PRISMA images, integrated with the Sentinel-2 images, proved to be very useful for characterizing the different substrate areas.