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

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...

Full description

Saved in:
Bibliographic Details
Published inGeosciences (Basel) Vol. 10; no. 12; p. 495
Main Authors Koop, Leo, van der Reijden, Karin J., Mestdagh, Sebastiaan, Ysebaert, Tom, Govers, Laura L., Olff, Han, Herman, Peter M. J., Snellen, Mirjam, Simons, Dick G.
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.12.2020
Subjects
Acoustic data
Acoustics
angular response curve
Azimuth
Backscatter
Backscattering
Bathymeters
Bathymetry
Classification (sedimentation)
Continental shelves
Earth science
Echo sounding
Echosounders
Morphology
North Sea
Ocean floor
Orientation
Ripples
Sand
Sand ripples
seafloor characterization
Sediment composition
survey azimuth
Surveying
Tides
underwater video
North Sea
Online AccessGet full text

Cover

More Information
Summary: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.
ISSN:2076-3263
2076-3263
DOI:10.3390/geosciences10120495