Casey Church, Steve Elgar, Robert Guza
Naval Research Laboratory
The overall objective is to understand the behavior of small, potentially mobile objects (eg, mines)within the surf zone and inner shelf. Specific research goals of this pilot project include observing the migration and the scour and burial of the objects as a function of wave and current hydrodynamic forcing, location within the swash and inner surf zone, and geometry of the object. Information from this pilot study will be used to evaluate the potential utility of a deterministic mine burial model for operational Navy requirements and to design future experiments.
Small inert mines will be monitored as they respond to waves and currents in the inner surf and swash zones. Single mines (with small marker buoys attached for visual tracking) will be deployed for periods of several hours under a range of wave and current conditions. Burial depths, scour, and horizontal migration will be monitored with video imaging and with detailed bathymetric surveys in the immediate mine vicinity. Visiblility permitting, mine scour and burial will be monitored continuously with underwater video. It is important to distinguish between mine burial owing to the complex interactions between mine, fluid, and sediment motion, and mine burial owing to general accretion of the beach, bar movement, or ripple formation. Supporting observations from the nearby cross shore transect of sonic altimeters, pressure gages, and current meters will determine the presence or absence of general accretion/erosion, bar movement, and ripples, as well as provide background environmental information.
The experiment will be conducted during September when interference with DUCK94 experiments and sensors will be minimal. Mine loss (and possible subsequent interference with October experiments) will be minimized by the wading depth/swash zone deployment of the mines coupled with close monitoring.
For a list of addresses of the investigators involved in Duck 94 click here.