淤泥质海床相邻的岬湾沙滩剖面特征研究

Profile Characteristics of the Beaches Adjacent to Muddy Seabed in the Headland Bays

通过对浙江沿海岬角海湾沙滩多处典型剖面的调查，结果表明沙滩与淤泥质海床存在较明显的沙泥分界线，滩面物质自北至南，粒径差别不大，中值粒径在0．15～0．25mm之间，滩面基本呈现单一坡度，坡度为1：15～1：30，沙滩坡度与波浪动力相关，沙滩前沿波浪动力强，滩面较缓，反之滩面较陡。沙滩退化表现为滩面的截断、粗化和泥化，滩面截断导致沙滩面积减少，中、细沙供给不足；细沙采挖或局部工程导致的沿岸输沙动力条件的改变会使滩面物质变粗；岬湾的水动力条件减弱，易使沙泥分界线抬升，局部泥化；过度挖沙会导致沙滩消失成为泥滩。

The investigations of typical beach profiles in the headland bays along the Zhejiang coast show that a clear boundary of sand and mud is present between beach and muddy seabed.The surface material of the beaches shows little change in grain size from north to south,with a medium diameter ranging between 0.15 and 0.25 mm.The beach face shows a single slope,ranging from 1∶15to 1∶30.The slope of the beaches is related to the wave power.If the wave is strong in the front of the beaches,the beach face is gentle,and otherwise,it is steep.The degradation of the beaches is reflected by truncating,coarsening and argillization.The truncation of the beaches causes the decrease of beach area and the undersupply of middle and fine sands.The digging of fine sand or the local coastal engineering which causes the change in dynamic conditions of sediment transport can lead to the coarsening of the beach surface.The weakening of the hydrodynamic conditions in the headland bays can easily make the sand-mud boundary line uplifting and cause local argillization.The excessively digging of sands can cause the beaches to disappear and become mud flats.