Mapping benthic substrate coverage and bathymetry using bio-optical modelling — An enmap case study in the coastal waters of helgoland

摘要

Kelp forests, which are dense stands of brown seaweeds of the taxonomic order Laminariales, often are used as indicator species for assessing the environmental state of coastal waters. To this end, large scale monitoring approaches are required apart from traditional labor-intensive point sampling techniques. Bio-optical modelling with hyperspectral remote sensing data provides the possibility to take on the task. Yet, hyperspectral imagery mainly originates from airborne data. Within in the scope of the EnMAP Preparatory Program the bio-optical model WASI-2D was tested to the coastal area of Helgoland. A simulated EnMAP scene was spectrally unmixed for the two substrate types Laminariales and sediment. Inverse modelling yielded plausible patterns and gradients of substrate coverages and bathymetry. Comparisons with in situ data revealed results tended to overestimate sediment and to underestimate Laminariales coverage and bathymetry. WASI-2D, however, was able to resolve the complex bottom and bathymetric structure at the rocky coast of Helgoland.