Sand wave migration predictor based on shape information

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Description/Abstract

Migration of offshore seabed waves, which endangers the stability of pipelines and communication cables, is hard to measure. The migration rates are small compared to the measurement errors.
Here, sand wave migration rates are determined from the change in the crest position deduced from long time series of bathymetric echo-sounding data. The crests are identified as local extremes in a bathymetric profile, after low-pass filtering. This approach is
applied to both 2-dimensional data and to profiles along
pipelines. A consistent migration rate of several meters per year
is found. A strong correlation between the sand wave shape and the
migration rate is translated in a migration predictor. The
predictor assumes that the sand waves migrate in the direction of
the steepest slope, following a quadratic relation with the
asymmetry. Furthermore it is included that longer waves travel
faster but higher waves travel slower. The predictor is calibrated
against data from nine areas and validated using three additional
areas. An error analysis using markers shows that the error of the
predictor is small compared to the noise in the individual crest
position observations.