WAVE-CURRENT BOTTOM SHEAR STRESSES AND SEDIMENT RESUSPENSION IN CLEVELAND BAY, AUSTRALIA

The bottom sediment resuspension is an important process in Cleveland Bay, North Australia. Hydrodynamics and suspended sediment concentrati ons (SSC) were measured from January to April 1993. During this field work, two high sediment resuspension events were observed. An iterativ e method of calculating the bottom shear stress under wave-current mot ion has been applied. Using the calculated bottom shear stresses the r esuspension mechanisms of bottom sediment in Cleveland Bay has been in vestigated by analysing data collected during two periods in January a nd March 1993. Swell has been found to be the most important factor in sediment suspensions for both high SSC events. Wind waves have little effect on SSC levels. Tidal currents are too weak to stir up bottom s ediment particles into the flow, but affect the detailed SSC structure by tidal convection. The critical shear stress for sediment resuspens ion in Cleveland Bay is about 2.0 N/m(2).