福建软质海崖蚀退机理及过程分析——以平潭岛东北海岸为例

Recession mechanic and process analysis of soft cliff in Fujian Coast——In case of northeast coast of Pingtan Island

通过对福建平潭岛东部岸段软质海崖为期两年的监测,结合历史岸线变化,分析了不同时期的海崖后退变化差异和原因,初步探讨了后退量与影响因素之间关系,得出以下结论:(1)近50 a来研究区海岸蚀退速率呈增大趋势,海平面上升与海崖蚀退率增大之间存在对应关系。(2)软质海崖侵蚀的主要外部影响因素为降水和海洋动力作用,内部因素为海崖抗蚀能力较弱。(3)软质海崖蚀退并非匀速过程,强降水和风暴潮等极端气候作用时期是海崖蚀退最强烈的阶段,侵蚀影响因素的变化也造成蚀退量的差异。(4)软质海崖的蚀退是冲刷、滑坡以及搬运共同作用的结果,海崖蚀退过程可以归结为稳定期,作用期,滑坡期和搬运期4个阶段。

Based on the measurements of monitoring profiles in east coast of Pingtan Island,combining with the coastline variation between 1961,1983 and 2009,the process and causes of soft coastal cliff retreated were focused,and the relationship between the influencing factors and retreat distance in different period discussed.The study showed that：（1） the coastal erosion rate was kept the increase in last 50 years with the sea level rise.（2） The major outer influencing factors are the precipitation and hydrodynamic,the inner one is weak.（3） The cliff recession is not a steady process,the rainstorm and storm surge may accelerate it,the change of the factors will induce the variation of the recession.（4） The recession process is composed of 4 stages as stable,action,landslide and transporting stage.