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Article

Measuring Centimeter-Scale Sand Ripples Using Multibeam Echosounder Backscatter Data from the Brown Bank Area of the Dutch Continental Shelf

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Acoustics Group, Faculty of Aerospace Engineering, Delft University of Technology, 2629 HS Delft, The Netherlands
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Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, P.O. Box 11103, 9700 CC Groningen, The Netherlands
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Department of Estuarine and Delta Systems, NIOZ Royal Netherlands Institute for Sea Research and Utrecht University, P.O. Box 140, 4400 AC Yerseke, The Netherlands
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Wageningen Marine Research, Wageningen University and Research, P.O. Box 77, 4400 AB Yerseke, The Netherlands
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Department of Coastal Systems, NIOZ Royal Netherlands Institute for Sea Research and Utrecht University, P.O. Box 59, 1790 AB Den Burg, The Netherlands
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Department of Marine and Coastal Systems, Deltares, P.O. Box 177, 2600 MH Delft, The Netherlands
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Department of Hydraulic Engineering, Faculty of Civil Engineering and Geosciences, Delft University of Technology, 2629 HS Delft, The Netherlands
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Department of Applied Geology and Geophysics, Deltares, 3508 AL Utrecht, The Netherlands
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Author to whom correspondence should be addressed.
Geosciences 2020, 10(12), 495; https://doi.org/10.3390/geosciences10120495
Received: 28 October 2020 / Revised: 27 November 2020 / Accepted: 4 December 2020 / Published: 9 December 2020
Backscatter data from multibeam echosounders are commonly used to classify seafloor sediment composition. Previously, it was found that the survey azimuth affects backscatter when small organized seafloor structures, such as sand ripples, are present. These sand ripples are too small to be detected in the multibeam bathymetry. Here, we show that such azimuth effects are time dependent and are useful to examine the orientation of sand ripples in relation to the flow direction of the tide. To this end, multibeam echosounder data at four different frequencies were gathered from the area of the Brown Bank in the North Sea. The acoustic results were compared to video and tide-flow data for validation. The sand ripples affected the backscatter at all frequencies, but for the lowest frequencies the effect was spread over more beam angles. Using the acoustic data made it possible to deduce the orientations of the sand ripples over areas of multiple square kilometers. We found that the top centimeter(s) of the seafloor undergoes a complete transformation every six hours, as the orientation of the sand ripples changes with the changing tide. Our methodology allows for morphology change detection at larger scales and higher resolutions than previously achieved. View Full-Text
Keywords: angular response curve; survey azimuth; seafloor characterization; underwater video; North Sea angular response curve; survey azimuth; seafloor characterization; underwater video; North Sea
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MDPI and ACS Style

Koop, L.; van der Reijden, K.J.; Mestdagh, S.; Ysebaert, T.; Govers, L.L.; Olff, H.; Herman, P.M.J.; Snellen, M.; Simons, D.G. Measuring Centimeter-Scale Sand Ripples Using Multibeam Echosounder Backscatter Data from the Brown Bank Area of the Dutch Continental Shelf. Geosciences 2020, 10, 495. https://doi.org/10.3390/geosciences10120495

AMA Style

Koop L, van der Reijden KJ, Mestdagh S, Ysebaert T, Govers LL, Olff H, Herman PMJ, Snellen M, Simons DG. Measuring Centimeter-Scale Sand Ripples Using Multibeam Echosounder Backscatter Data from the Brown Bank Area of the Dutch Continental Shelf. Geosciences. 2020; 10(12):495. https://doi.org/10.3390/geosciences10120495

Chicago/Turabian Style

Koop, Leo, Karin J. van der Reijden, Sebastiaan Mestdagh, Tom Ysebaert, Laura L. Govers, Han Olff, Peter M.J. Herman, Mirjam Snellen, and Dick G. Simons. 2020. "Measuring Centimeter-Scale Sand Ripples Using Multibeam Echosounder Backscatter Data from the Brown Bank Area of the Dutch Continental Shelf" Geosciences 10, no. 12: 495. https://doi.org/10.3390/geosciences10120495

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