DISTRIBUTION PATTERN AND CONTROL FACTORS OF SAND WAVES IN SOUTHEAST BEIBU GULF

To access the main factors influencing development and distribution of sand waves, analyses have been undertaken on the characteristics of sediment, hydrodynamics and sea level changes using the latest high-resolution multibeam, surface sediment and hydrodynamic data collected in the southeast of Beibu Gulf, where sand waves are abundantly developed. Results suggest that sand waves in this area are widespread, mostly developed on the sand ridges and in the troughs between sand ridges. Sand waves are smaller in scale in the offshore area but larger in the area nearshore. The development and distribution features of sand waves depend upon modern hydrodynamics and sediment supply. Geometric features and dimension of sand waves depend upon tidal inlet and flow velocity. Surface sediments are usually "finer offshore and coarser nearshore", corresponding to the distribution of sand waves referred above. Besides, some of the symmetrical sand waves are found in certain areas with residual properties, perhaps as the result of different hydrodynamics while sea level changes in different periods.