Abstract:

The ocean dynamic is strong in the eastern Guangdong waters, with mean wave height of 0.9?1.3m, maximum surf water depth of 5.9?10.0m, and current velocity of 10?60cm·s ?1 . The middle part of the coastal section at the eastern Guang- dong headland-bays is in an obvious eroding state. Using the interface theory based on sea-land interaction, the author ex- pounds the mechanism of bottom shear stress by waves to erode seabed and convey sediments under the circumstances of rough sea or very rough sea. In addition, under the effect of ocean currents, the bottom shear stress that is formed due to bot- tom current velocity may also lead to seabed erosion and sediment transition and deposition, and then change landforms. In conclusion, the author presents two basic modes of this kind of coastal sections, namely, mode of rock headland section, with upper section being steep and lower section being slowly concave, and mode of sedimentary section within the bay, with a concave section and changeable shoreline.