潮滩上波高的时空变化及其影响因素——以长江三角洲海岸为例

于2009—2010年的不同季节在崇明东滩北部、中部、南部以及杭州湾北岸东段的芦潮港岸段,利用目前先进的SBE 26plus浪潮仪进行了多个潮周期的波浪观测。研究表明,观测期间潮周期平均风速为1.9～11.0m/s、最大风速为2.8～12.1m/s,各测点潮周期平均水深为0.28～2.12m,高潮位最大水深为0.37～3.19m,潮周期有效波高为0.03～0.45m,最大波高为0.08～1.59m。波高的时空变化受风速、风向、水深和岸滩坡度的综合影响。通常情况下,向岸风期间的波浪较大;风速、水深、岸滩坡度越大,潮滩上的波高也越大。空间上,岸滩坡度最小的崇明东滩中部(坡度0.6‰)测点波高和水深之间的相关性最好,岸滩坡度最大的芦潮港潮滩(坡度8.7‰)测点两者间的相关性最差。时间上,波高和水深之间的相关性与风速、风向的变化有关。因此,只有在潮滩坡度较小(例如<1‰),风速、风向较为稳定时,波高和水深之间的显著正相关关系才存在。要了解某个潮滩的波浪特征,有必要利用先进的仪器进行系统的原位观测,而非简单地借助其它潮滩的波浪研究结果。研究推断,在向岸强台风和大潮高潮位阶段,崇明东滩中潮线附近的最大波高可达1.5～2.0m,芦潮港堤外潮滩的最大波高可达2m以上。

Temporal and Spatial Variations in Wave Height Over Intertidal Mudflats and the Influencing Factors:A Case Study From the Yangtze River Delta

Observations of waves in several tidal periods were carried out by means of advanced SBE 26plus Wave & Tide Recorder in the northern,middle and southern parts of the eastern flat of Chongming and the Luchaogang Port section of the northern coast of the Hangzhou Bay in different seasons from 2009to 2010.The results show that during the observations,the tidal-period averaged wind speed is 1.9～11.0 m/s,with the maximum being 2.8～12.1m/s;the tidal-period averaged water depth ranges from 0.29m to 1.66mat all observation sites,with a maximal value being 0.37～3.19mat high water level;and the average significant wave height in the tidal period is 0.03～0.45m,with the maximum being 0.08～1.59 m.The temporal and spatial variations of the wave height are influenced mainly by wind speed,wind direction,water depth and tidal flat slope.Commonly,the waves are high during shoreward winds and the greater the wind speed,the water depth and the tidal flat slope,the higher the waves.Spatially,the correlation between the wave height and the water depth is the best in the middle part of the eastern flat of Chongming in which the slope(0.6‰)of the flat is the smallest.In the tidal flat of the Luchaogang Port,where the slope(8.7‰)of the flat is the largest,the correlation between the wave height and the water depth is the poorest.Temporally,the correlation between the wave height and the water depth is related to the variations of wind speed and direction.A prominently positive correlation occurs between the wave height and the water depth only at a small flat slope(e.g.<1‰)and a stable state of wind speed and direction.From all these observations,it can be predicted that the maximal wave height may possibly reach to 1.5～2.0mover the eastern flat of Chongming and exceed 2mover the flat outside the bank of the Luchaogang port.