Analysis on morphodynamics of sandy beaches in South China

Eight profiles of sandy beaches distributed in different geographical coast sections and different coast geomorphologies were repeatedly surveyed on the spot in winter and summer and analysed in laboratory to discuss the morphodynamics of the sandy beaches along the coast of South China.On the basis of the research,combined with the analysis on the coastal geological structure,geomorphology and the changes of modern coastal dynamical environments with geog raphical location,the sandy coast of South China is differentiated into three basic types of coastal geomorphology:cape-bay coast,barrier lagoon coast and straightened coast.The morphodynamics of the beaches were studied through the analysis on the beach in cline,coastal dynamic changes,the seasonal scouring silting changes tendency,the sediment grain size of the beach face and the dynamic response of beach slope.The results show that the morphodynamics was enslaved to many environmental factors,in which geological structure background and sea level changes played an important base for the development of the geomorphology of sandy beaches in a large scale distribution.After the Holocene transgression,the sea level was relatively stable,the moulding action of modern coastal dynamic condition became decisive,and the index of tide wave was an important factor.