粤东靖海湾海岸地貌动力演变及其工程影响

受人为工程的影响,相对稳定的岬湾海岸地貌常经历显著的动态调整。本文以粤东靖海湾典型岬湾海岸为例,运用Mc Laren模型、波浪动力场数值模拟、等深线对比、冲淤计算等多种方法,从海岸地貌动力学角度,对人为岬角工程前后岬湾海岸地貌动力过程和冲淤演变进行综合分析。结果表明:1)海岸地貌动力系统内常存在负反馈机制以维持系统的稳定。岬角工程后上岬角防波堤沿SSW延伸,ESE和E向浪经过防波堤时发生绕射,波能削减,湾顶动力减弱,海滩沉积物从下岬角向湾顶反向运移;2)海滩的蚀积状态在工程前后发生了转换,工程前遮蔽段侵蚀、开敞段堆积;工程后遮蔽段堆积、开敞段侵蚀;3)海湾水下地形对岬角工程的响应敏感,工程后海湾水下地形冲淤剧烈。

Effects of engineering on coastal morphodynamic evolution of Jinghai Bay in Southern China

Significant dynamic adjustments occur constantly on headland-bay coasts after artificial engineering. In this study, McLaren model, morphodynamic simulations (CMS-Wave), bathymetric comparison and erosion-accretion calculation were used to study beach morphodynamic behavior and morphological evolution of Jinghai Bay (Southern China), a typical headland-bay coast influenced by an artificial headland. Results indicate that: 1) Morphodynamic system has negative feedback mechanism to maintain a stable bay. The upper headland extends in the direction of SSW after the breakwater construction, leading to wave diffraction and reflection, with lower wave energy in the shadow zone than in the open sector. The headland-bay beach follows a general sediment transport trend from the open sector on the down coast to the shadow sector on the upper coast in accordance with wave conditions and energy regimes. 2) The headland bay beach presents a slight erosion state before the engineering, with erosion in the shadow sector and accretion in the open sector. After the engineering, the beach comes to a deposition state, with accretion in the open sector and erosion in the shadow sector. 3) The nearshore emerged a sensitive response to the headland engineering, and there is increased erosion-accretion after the engineering.