中文摘要：

渔港硬式构筑物如防波堤等对海岸的影响显著。以福建泉州崇武半月湾渔港防波堤修建前后的海滩变化为例，通过对2003～2011年不同阶段海滩地貌形态、岸线变化分析以及2个海滩剖面多期监测比较发现，防波堤修建后海湾下游西侧海滩发生显著蚀退，西端侵蚀强度最大，向东（靠近防波堤遮蔽段）逐渐减小，中东部遮蔽段转为淤涨。海滩变化的主要原因：1）E～sE向主人射波浪受到防波堤的阻挡作用，在堤头发生绕射，港内波影区动力变弱；2）防波堤阻碍了从东向西的沿岸流运动，形成东向为主的沿岸输沙，使得东端发生堆积，造成下游的西侧海岸的沉积物亏损，发生侵蚀。针对海岸变化机理提出了海滩养护防御措施，并通过数值模拟预测说明养护海滩以由西向东输沙为主，年均输沙量约3万m3，堆积于遮蔽段，最后，提出采用周期性抽取遮蔽段养护沙补充到西端的方法来实现海滩循环养护。

英文摘要：

Harbor structure such as breakwater has significant impacts on coastal morphology. The study focuses on the beach erosion downstream of the harbor breakwater by taking Banyue Bay beach as an example. Based on the beach morphological change, shoreline position measurement in different periods and beach profiles comparison in different times from 2003 to 2011, beach performance re- sponse to harbor breakwater is studied. Banyue Bay beach was eroded and damaged severely after the construction of Chongwu harbor breakwater in 2003. The process and mechanism of the beach morphological evolution are analyzed. The main incident wave is blocked by the breakwater extending out to the sea and disturbing the continuity of the littoral drift, which sharply decreases the sediment trans- port from the east to the west, thus resulting in continuous coastal retreat. The enormous change of hydrodynamic conditions triggered by harbor breakwater is considered to be the main cause. And an engineering approach to mitigate the adverse effects of harbor break- water is finally proposed, and beach nourishment with coarse sand is recommended according to the strong hydrodynamic conditions and longshore sediment transport. Shoreline evolution of nourished beach is simulated. The sediment deposited in the east section by long- shore transport will be used for renourishment in every 5 years to make a sediment recirculation within the coastal system.