Aquatic Earth Observation: State-of-the-art, case studies, and looking forward
by Dr. Magnus Wettle (1), Dr. Thomas Heege (2), Kevin Mackay (3)
(1) EOMAP Australia, Sunshine Coast, QLD, Australia, (2) EOMAP Germany, Seefeld Castle, Bavaria, Germany,
(3) NIWA, Greta Point, Wellington, New Zealand
Aquatic earth observation, with significant applications in sectors such as navigation, defence, oil and gas, and environmental management, can be broadly divided into two areas: monitoring water quality (e.g. turbidity, sediment loads or chlorophyll-a concentrations in the water column) and mapping the seafloor (e.g. bathymetry, seafloor reflectance, and benthic habitats).
Monitoring water quality using remote sensing has traditionally been done using sensors - such as on the MODIS satellites – with relatively coarse spatial resolution but frequent re-visit times. Applications for this have typically been in open ocean waters, limited by the complexities of inland and coastal aquatic environments and the lack of suitable higher resolution sensors. Dr Magnus Wettle will present a selection of case studies with government agencies, environmental consultancies and industry, which illustrate the state-of-the-art operational monitoring of inland and near coastal water quality using the latest generation of higher resolution satellite sensors.
Detecting the seafloor using remote sensing, particularly estimating water depth, has been in development since the 1970s, but it is in the last decade that the required physics-based algorithms and processing work flows have become sufficiently robust to offer an operational service - applicable worldwide with known accuracies - without the requirement for a priori, in situ field data. Dr Wettle will present a selection of case studies with government agencies, research institutes, environmental consultancies and industry which illustrate the state-of-the-art in mapping water depth, seafloor colour, and benthic habitats, using earth-orbiting satellite sensor data. In particular, he will present two New Zealand-based aquattic earth observation projects: mapping the bathymetry and shallow seafloor habitats of Marlborough Sounds together with NIWA, and mapping the shallow water bathymetry of Tonga and surrounding areas together with LINZ. Both projects were done with very high spatial resolution (2m pixel) satellite imagery, and the Tonga project will be one of the largest satellite-derived bathymetry projects completed worldwide, to date, at this level of resolution.
Looking forward, the next generation of platforms and sensors together with advancements in big data and AI, will further drive potential applications and continue lowering costs to the end user. Unmanned aerial vehicles (UAVs), capable of carrying multi- and hyper-spectral sensors, offer an additional platform for sourcing remotely sensed aquatic data. The potential opportunities and pitfalls for these will be briefly addressed.