Validation of Parametric Estimates of Sand Wave Migration on the Outer Continental Shelf of Campos Basin

Existing parametric relations that estimate sand wave migration are validated with data from a 15-year long environmental monitoring program, which includes bottom current measurements and geophysical surveys, at a sand wave field where a subsea system with rigid pipelines are located on the outer continental shelf of Campos Basin, Brazil. Local metocean data and sediment characteristics were used as input in parametric relations for estimation of sand wave migration. The existing simplified parametric model considers homogeneous sediment, including density, porosity and median grain size. The critical current velocity for the threshold of sediment motion at the bed is calculated. Once this threshold is exceeded, sediment transport will prevail, and therefore the sand waves will become active. Migration rates of the sand waves are then estimated based on the frequency of bottom current velocities that are over the threshold. Data from 10 geophysical surveys conducted over a 15-year long monitoring period in the sand wave field was used in the validation. Predictions indicate that the bottom current generates sand waves with wave heights and wave lengths that closely match those observed. The predicted net sand wave migration and migration direction are greatly like the mean value of migration that occurs in the study area.