Towards continuous long-term measurements of suspended particulate matter (SPM) in turbid coastal waters

Thomas H. Badewien, Elke Zimmer, Alexander Bartholomä and Rainer Reuter

Ocean Dynamics, Special Issue - WATT
Received: 1 September 2008; Accepted: 10 February 2009
Published online: 17. March 2009

DOI:10.1007/s10236-009-0183-8

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Abstract The dynamics of sediment transport in the East Frisian Wadden Sea are important for the coastal zone and for ecosystem functioning. The tidal inlets between the East Frisian islands connect the back-barrier intertidal flats to the North Sea. Here, concentrations of suspended particulate matter (SPM) in the water column are highly variable, depending on weather conditions and tides. In order to estimate the nature and quantity of sediment transport, in situ measurements were carried out at a Time Series Station in the tidal inlet between the islands of Spiekeroog and Langeoog. This study shows the suitability of multispectral transmissometry (MST) for obtaining long-term SPM measurements with high resolution. The comparability of this technique to the standard filter method and the laser diffraction method (LISST) is demonstrated. In addition, the Junge coefficients derived from both MST and LISST measurements are compared.

A time series of SPM data covering nearly four months is presented. As a major result, the data reveal that a single storm surge can have less impact on SPM dynamics than longer lasting gales. This high-resolution long-term data set is very valuable for modelling suspended matter flux. It also provides background information for studying the influence of SPM dynamics on coastal sediments.