三亚湾海岸动力演变的数值模拟研究

近年来,海岸侵蚀呈现不断加剧的趋势,给沿海地区经济社会的发展造成了极大危害。关于三亚湾海岸侵蚀过程及其动力学研究多停留在定性或半定量阶段。从海岸动力地貌学角度出发,基于沉积物迁移理论,利用数值模拟方法,定量研究了三亚湾海岸在波浪和潮流作用下的动力演变过程。计算结果重现了海水波浪的传播形态及动态特征:涨潮时,波高极值相对较大,水位随之升高,波动现象明显,波动形态复杂;落潮时,波高极值相对减小,水位也随之降低,海面相对较平静,波形态在离岸区域较单一,仅在近岸区域相对多样化。同时,数值模拟结果也很好地显示了三亚湾岸线附近的沉积或侵蚀过程特征:三亚湾西段海洋动力条件较强,沉积或侵蚀现象明显,沉积/侵蚀能力由三亚湾西段逐渐向东段减小。此外,以海洋动力学机制为基础,定量模拟了三亚湾海岸侵蚀与演变物理过程,为该地区海岸开发利用、海岸环境保护提供科学依据。

Numerical Simulation of Coastal Dynamic Evolution of the Sanya Bay

In recent years, coastal erosion tends to be intensified continuously and has caused serious damage on the economic and social development in the coastal regions. Previous studies on the coastal erosion process and dynamic evolution of the Sanya Bay stayed mostly in a qualitative or semi-quantitative stage. In the present paper, the coastal dynamic evolution process of the Sanya Bay under the actions of waves and tide currents is studied quantitatively based on the theories of coastal dynamic geomorphology and sediment transportation and by means of numerical simulation. The propagation forms and dynamic characters of the waves in the bay are reproduced by numerical calculations. During the high tide the extreme of wave height is relatively larger, with which the water level rises and the fluctuation of the sea surface is obvious and complex in forms, whereas during the ebb tide the extreme of wave height decreases relatively, with which the water level goes down, the sea becomes relatively calm and the wave form is simplified in the offshore area and relatively diversified only in the coastal waters. The simulated results also display well the deposition/erosion process in the area near the coastline of the Sanya Bay. At the western coastal segment of the bay the deposition/erosion phenomenon is obvious due to strong ocean dynamic condition and toward the eastern segment of the coast the deposition/erosion ability decreases gradually. Moreover, the physical process of coastal erosion and evolution of the Sanya Bay is quantitatively simulated based on ocean dynamic mechanism, which would provide a scientific base for the coastal development and utilization and the coastal environment protection in the area studied.