人工岛对沙质海岸动力泥沙环境及岸滩冲淤演变的影响研究

Study on the influence of artificial island on dynamic sediment environment and beach erosion and deposition evolution of sandy coast

基于历史海图、历史时期卫星遥感影像、2019年实测水下地形和潮流、波浪数值模拟成果,研究该海域岸滩的发育演变背景、海床和岸线自然冲淤动态、动力泥沙环境及岸滩冲淤动力机制。采用LITLINE岸线演变数学模型,模拟计算了不同离岸距离和不同平面形态人工岛布置型式对近岸岸线变形的影响,岸滩泥沙动力机制和岸滩演变趋势表明,人工岛实施后近岸最大潮流流速小于近岸泥沙起动流速,不具备起动近岸岸滩泥沙的基本条件;SSE向波浪作用时,人工岛西北侧波高明显减弱,波向西偏;S向波浪作用时,人工岛北侧波高明显减弱;SSW向波浪作用时,人工岛东北侧波高明显减弱,波浪传播方向东偏;波浪场改变后人工岛掩护区东西两侧岸滩附近泥沙分别具有向东和向西运移至人工岛掩护区的趋势,形成掩护区的淤积和东西两侧岸线冲刷。

Based on the historical charts,satellite remote sensing images,the latest underwater topographic map and the numerical simulation results of tidal current,sediment and wave,studies are carried out the development and evolution background,natural erosion and deposition conditions of seabed and shoreline,hydrodynamic and sedimention environment and mechanism of beach erosion and deposition.By using the numerical simulation method of shoreline evolution,the influence of the deformation of nearshore shoreline is simulated and calculated on the two types of artificial island layout patterns,i.e.different offshore distances and different plane shapes.The results show that the maximum tidal current velocity is less than the incipient velocity of the nearshore sediment after implementation of the artificial island,which does not have the basic conditions for incipient nearshore sediment.The main wave changes in the sea area behind the artificial island are obvious.Wave form SSW will be obviously weekend on the northwest side of the artificial island,wave form S and SSW will be obviously weekend in the sea areas on the north and northeast sides of the artificial island respectively.After the change of wave field,the sediment on the shore of west and east sides of the sheltered section has the conditions of eastward and westward transportation respectively toward the sheltered section of the artificial island.A condition of shoreline accretion in the sheltered section and erosion on the ease and west sides of the sheltered area is formed.