Storm influence on the burial of objects in a shallow sandy shelf environment

• Two short intense storms on shallow water were studied using Burial Recording Mines.
• Repetitive storms cause a “cascade effect” where objects are vertically relocated.
• The wave energy decay rate is a main factor causing post-storm sedimentation.
• Oscillating water velocities amplify the current velocity at the seafloor.
• Storms provoke fast phases of erosion and deposition on a small time resolution.

For rapid assessments of occurrences of sea mines or objects, and probability modelling of object burial mechanisms, knowledge is needed on sediment processes under a variety of hydro-meteorological conditions. One approach is to use test mines that record burial mechanisms over longer time periods.A Burial Recording Mine (BRM) was deployed in the Belgian part of the North Sea, in water depths of 7 to 12 m. The area is predominantly sandy, with a continuous spectrum of small to medium and large dunes. Three months of data were recorded and allowed monitoring of small-scale seabed variation; this was correlated to ruling current and wave conditions.During the recording period, two short intense storms affected the area. The burial behaviour of the cylindrical object revealed that the depth-related wave energy decay rate, immediately after the storm, was the main factor causing sedimentation. Moreover, sequential storms caused a “cascade effect” with the object being vertically relocated in a deeper position.The results gave insight into the processes and the timing of erosion and sedimentation during and post-storm, providing more efficient strategies for the detection of missing objects. Results are relevant to assess storm impact on any man-made object at sea.