Quantification of bio-physico-chemical properties of intertidal sediment at different spatial scales using remote sensing

Abstract

Coastal-erosion models require accurate and detailed information on bio-physico-chemical properties of intertidal sediments. In this article, the potential of remotely sensed data at different spatial scales for the quantification of sediment properties was assessed. The focus on specific absorption features of water at 1450 nm, clay at 2206 nm and chlorophyll-a at 673 nm provided a physically based approach and interpretable results. The moisture content in unsaturated sediment could be accurately related to absorption (coefficient of determination r ² = 0.89 and root-mean-square error of prediction (RMSEP) = 3% relative gravimetric moisture content) in laboratory and field measurements. The empirical model relating chlorophyll-a content with its field absorption (r ² = 0.6) was successful on airborne sensor measurements. Though suitable in laboratory conditions, the absorption of shortwave infrared light by clay was not observed in field or airborne spectra. The empirical models showed clear dependency on the study area and sensor, suggesting more research on intercalibration of spectrometers and on factors influencing the interaction of light with sediment properties.

Acknowledgements

The CISS-project is funded by the Research Foundation-Flanders (FWO Vlaanderen) under contract no. G0480.05. The TideSed, SedOptics and ALGASED projects are supported by the Belgian Federal Science Policy in the framework of the STEREO programme, project 043, 072 and 109. The authors are grateful to Annelies De Backer and Dr Steven Degraer from the Marine Biology Section of the University of Gent, to Profs Koen Sabbe and Renaat Dasseville from the Laboratory for Protistology and Aquatic Ecology of the University of Gent, to Dr Daphne van der Wal from The Netherlands Institute of Ecology (NIOO-CEME) and to Dr Rodney Forster from the Centre for Environment, Fisheries and Aquaculture Science (Cefas) for their help during the field campaigns, the loan of equipment and the sediment analysis. We would like to thank Estuarine, Coastal and Shelf Science and Bart Deronde of the Flemish Institute for Technological Research (VITO), Belgium, for the reproduction of the figure of the Molenplaat. The comments of Dr Aaike De Wever of the Laboratory for Protistology and Aquatic Ecology of the University of Gent were highly appreciated. Finally, the authors are grateful to two anonymous referees for their useful remarks.

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