SCHELDT - Airborne Hyperspectral Potential for Coastal Biogeochemistry of the Scheldt Estuary and Plume

European estuaries are subject to intense anthropogenic disturbance reflected in elevated loading of detrital organic matter, which induce high respiration rates and the production of large quantities of dissolved CO2. The Scheldt basin covers one of the most populated and industrialised areas of Europe and its tributaries drain an area of about 21,860 km2. The amounts of nutrients discharged by the Scheldt increased considerably during the past 20 years. Due to the dilution and metabolic processes of the downstream river flow in the estuary, an important variability of several parameters can be observed amongst which phytoplankton species and concentration, particulate organic matter, colour dissolved organic matter and suspended matter.
In the present days, researches on the functioning of estuarine and coastal ecosystems are based on highly time consuming, costly sea campaigns and laboratory analyses. Although optical spaceborne remote sensing already proved useful in such coastal ecosystem studies, hyperspectroscopy opened a new dimension by allowing improved distinction of various biogeochemical compounds through characteristic spectral signature identification.
Water quality variables were examined in the Scheldt estuary and plume, using CASI-2 (Compact airborne Spectrographic Imager) hyperspectral sensor and in situ bio-optical observations. The numerous parameters and spectrum measured in each station were used for further remote sensing analysis, as well as to complete the interpretation of the observed environmental processes. Multiple regression approach has been used to derive correlation between classical ground truth measurements and the rich information provided by the numerous CASI spectral bands. From these relations, some synoptic maps of biogeochemical parameters could be derived in the Scheldt estuary and plume.