江苏东台潮滩下部潮流特征及地形演变研究

Tidal flow characteristics and topography evolution at lower part of Dongtai tidal flat,Jiangsu Province,China

为了研究潮滩下部的潮流特征及地形演变过程,本文以江苏东台潮滩下部区域为研究对象,进行了水样采集和连续的定点水文观测,并在白天干滩时沿设定的断面进行了重复的水准测量和表层沉积物采样。研究结果表明,研究区域内涨潮流速明显大于落潮流速,且潮流具有明显的往复流特征,往复流的方向与海岸近似垂直;水体悬沙中砂的含量极低,砂为表层沉积物的主要组分;观测期间滩面处于侵蚀状态,推移质输沙为垂直海岸线向岸净输运。根据研究区域潮流特征和沉积物特征建立了地貌动力学模型,并应用该模型模拟了观测期间潮滩下部的地形演变,并将实测结果和模拟结果进行对比,表明该地貌动力学模型能够模拟潮滩下部的地形演变。

In order to investigate the characteristics of tidal flow and the evolution process of topography at the lower part of Dongtai tidal flat,a comprehensive monitoring program was carried out through continuous hydrological observations and seawater sampling.During the daytime when the tide was low,leveling measurement and surface sediment deposit sampling were performed repeatedly along the pre-designed profiles at the dry beach sections.The results show that the tidal flow at Dongtai has obvious reciprocating feature and its direction is nearly perpendicular to the coastline,and the flow velocity of the flowing tide is much greater than that of the falling tide.It is also indicated that the sand is a major component in the surface sediment deposits,however,its content in the seawater is extremely low.During the monitoring program,it was observed that the lower part of the tidal flat was under the erosion condition and the coastal onshore received a net bed load sediment transport.In this study,a geomorphological dynamics model is also developed based on the characteristics of tidal flow and surface sediment deposit.The model is applied to simulate the evolution process of topography at the lower part of Dongtai tidal flat.The simulated results are compared with the field measurements for model verification.It shows that the developed model can be used to effectively simulate the topography evolution at the lower part of Dongtai tidal flat.