潮滩地形的冲淤演变规律可以在一定程度上反映动力作用与地貌特征之间的相互耦合机制。根据近几年在长江口南汇嘴潮间带多断面连续观测资料,探讨区域内潮间带滩地的近期冲淤演变特征及其主要影响因子。研究结果表明:(1)南汇嘴潮滩近期主要呈现淤涨态势,而且年内过程季节性差异明显;受区位差异影响,不同观测断面的潮滩冲淤演变呈现特征不尽相同,断面1冲淤变化最为显著,年最大冲淤厚度均在10 cm以上;(2)在波浪、潮流的作用下,区域内沉积物很容易被掀动悬扬,而且输沙环流系统的存在有利于悬沙向浅水区输运且在该区域内沉降淤积,从而为潮滩发育提供泥沙来源;(3)受"碧利斯"台风引起的风暴潮天气影响,研究区域内潮滩出现"大冲大淤"现象,即台风强侵蚀期过后滩面高程短期内恢复明显。由此可见,潮滩短期冲淤演变特征是各种动力因素作用下的综合体现。
To some extent, scouring and silting evolution of tidal flat may reflect the relationship and interaction between dynamic effect and geomorphologic characteristics. On the basis of Shanghai coastal zone investigation project,a continuous observation was made at the intertidal zone of three sections on Nanhui Spit from June 2006 to June 2007, in order to research the properties of short-term scouring and silting changes as well as its influencing factors. The results show that (1) recently,the tidal flat of Nanhui Spit mostly has a scouring posture,and seasonal difference of flat variation in the year is relatively obvious; affected by its location, the respective section shows different developing properties, for example, scouring and silting changes of section one are the most obvious of all,the amount of which is both above 10cm; (2) acted by waves and tidal current,the surface sediment of this zone is easy to be stirred,and the existence of sediment circulation system is favorable for the suspended sediment to settle in shallow water area, which becomes the sediment source of tidal flat; (3)influenced by the storm surge caused by typhoon "Bilis", drastic scouring as well as silting happened in this zone. All of these have proved that the scouring and silting changes of tidal flat were affected by several kinds of dynamic conditions.