Some event beds (tempestites) are thought to be emplaced on shallow marine shelves by the combined action of strong coastal currents and high waves during fairly short-lived storms. To test this hypothesis, a storm sedimentation system has been constructed from six numerical models describing a cyclonic wind field, three-dimensional coastal circulation, wind waves generated over the continental shelf, the combined effect of steady and oscillatory currents within the benthic boundary layer, suspended and bed load transport of sediment, and conservation of the seafloor. This model system is used to hindcast winds, currents, waves, and resulting sedimentation during Tropical Storm Delia, which passed over the Texas-Louisiana shelf on September 3--4, 1973. Sensitivity to the initial substrate is investigated in four experiments using uniform silt, uniform sand, a mud line at the 20-m isobath, and a simplified modern sediment distribution. Modeled coastal currents are vertically uniform and do not reveal the structure predicted by the mid-latitude geostrophic storm circulation model, because the predicted depth of the wind-mixed layer is greater than the water depth over the shelf. Shelf currents in excess of 2 m/s flow predominantly along the coast to the southwest during most of the storm, driven by the wind stress and the trapped coastal wave which peaks at 180 cm near Galveston. Significant wave heights reach 8 m on the outer shelf but are less than 4 m over the inner shelf. These waves combined with steady currents to produce bed shear velocities which locally exceed 20 cm/s.

The region of highest stresses always lies to the right of the storm track (viewed down the path) and moves across the shelf with the eye of the storm. Three general sediment transport path are evident: (1) onshore transport of finer sediment over the outer shelf to the right of the storm track, (2) westward-directed along-shelf transport of predominantly fine sediment between approximately 40-m and 20-m water depths, and (3) minor offshore transport of sand from the shoreface to depths less than 30 m. The resulting event bed has a ragged appearance with a maximum thickness of about 20 cm in region 1, and covers an area of approximately 3¿104 km2 to the right of the storm track. Aside from local transport associated with finer sediments, these results are relatively insensitive to initial sediment type. Comparison of model results to observed data from Buccaneer platform shows that the different models performed adequately during the peak of the storm, except for a significant underprediction of the significant wave height by the wind sea model. The estimated uncertainty in the calculated combined shear stresses u*, based on errors produced by the individual model components, is most dependent on the wave bottom orbital amplitude. The total uncertainly in u* is estimated to be approximately 7%. ¿ American Geophysical Union 1993