江苏大丰潮间带粉砂滩的潮流边界层特征

Tidally-induced Boundary Layer Properties of the Silt Flat at Dafeng, Jiangsu Province, Eastern China

对江苏大丰潮间带粉砂滩的潮流观测数据，运用 Karman-Prandtl 模型分析了流速对数剖面的出现频率和边界层参数 (摩阻流速与粗糙长度)。结果表明，不同时间尺度 (101～103 s) 的平均流速对计算 u-ln z 线性关系出现频率的影响不大，而不同层位组合的影响较为显著。影响流速对数剖面分布的自然因素为波浪、风、潮流旋转、表底层流向差异、滩面坡度和水流加减速等。相邻层位的流速在时间序列上存在很高的线性关系，回归直线的斜率与水层距底床的高度、粗糙长度和摩阻流速有关。涨潮阶段床面粗糙长度大于落潮阶段，涨潮阶段摩阻流速小于落潮阶段。

Tidally-induced boundary layer properties of the silt flat at Dafeng, Jiangsu Province, are studied by using the Karman-Prandtl Equation. The results show that the number and distribution of measured layers, but not the current velocities on different temporal scales have a remarked influence on the occurrence of logarithmic velocity profiles. Furthermore, wind waves, bed slope, current direction and acceleration and deceleration play an important role in the occurrence of logarithmic profile. A linear correlation exists between the current speed of adjacent layers, and the correlation is dependent on the height of the layer above the seabed, roughness length and shear velocity. Roughness length during the flood phase is larger than that during the ebb phase, whilst shear velocity during the flood phase is smaller than that during the ebb phase.