POSTER Session 1

Retrieval of benthic habitat abundance and bathymetry from hyperspectral satellite data (DESIS and PRISMA) in shallow waters

Benthic habitats are threatened by anthropogenic activities in coastal ecosystems. As an example, the deployment of ship anchors significantly contributes to the degradation of seagrass herbarium. The current on-orbit hyperspectral satellite sensors, namely DESIS (DLR, Germany) and PRISMA (ASI, Italy) show a high spatial resolution (30 m), a wide spectral range (between 400 and 1000 nm) and a relevant spectral resolution from 2.5 nm (DESIS) to 10 nm (PRISMA). The goal of this study is to evaluate the benefit of these sensors for the retrieval of the bathymetry, and the composition of benthic habitats in shallow waters. The inversion of the satellite-derived water reflectance is performed using a semi-analytical model. The retrieved bathymetry is validated using the Litto3D model dataset. The seabed composition and the abundances of benthic species are compared with in-situ data acquired by a ROV. The bathymetry is retrieved with a root mean square error (RMSE) value of 1.69 m (DESIS) and 2.1 m (PRISMA) within the depth range 0-10 m. The RMSE values of the proportion of benthic habitat such as Posidonia and brown algae are 37% and 4% respectively when using DESIS sensor and 24% and 6% when using PRISMA data. This study confirms the added-value and relevance of hyperspectral satellite sensors for improving knowledge of aquatic ecosystems particularly the abundance of benthic habitat and the seabed depth. However, the spatial resolution of 30 m could be a limitation of the retrieval performance especially for the case of steep bottom slopes at low bathymetry.

Malik Chami, Lagrange-OCA, Sorbonne Université, France, https://orcid.org/0000-0001-7815-0533

Audrey Minghelli, Laboratoire d’Informatique et des Systèmes (LIS), Université de Toulon, France

Mireille Guillaume, Institut Fresnel, Marseille, France

Manchun Lei, Institut Géographique National (IGN), France

Claire Dune, COSMER, Université de Toulon, France

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