青岛市汇泉湾海水浴场表层沉积物粒度特征及输运趋势

Grain-size characteristics and transport trend of surficial sediment in Huiquan Bay beach in Qingdao

粒径趋势分析以其省力、准确地预测沉积物的输运趋势等优点,在多种海洋环境研究中得到应用,但对研究区域冲淤变化的预测却无能为力。为了弥补这一缺陷,采集并分析了青岛市汇泉湾海水浴场149个表层样品的粒度参数特征,结合沉积物水动力观测资料,对海水浴场沉积物的粒径分布特征及输运趋势进行了研究。结果表明,汇泉湾海水浴场沉积物的分布特征与湾内的水动力条件关系密切,湾内由西向东的沿岸流驱动颗粒较细的泥沙顺海岸线向东运动,而较粗颗粒留在了原地,进而产生了由西北向东南,沉积物类型由细砾、粗沙、中沙、细沙依次分布的特征,且表层沉积物类型分布与平均粒径分布呈现出很好的对应关系。汇泉湾海水浴场由高潮线到沙坝的沉积物输运方向为南东向,沙坝向海一翼的沉积物输运方向为北西向;地形测量数据显示侵蚀区域主要分布在3月份沙坝脊线附近,研究期间总侵蚀量为656.17 m3,而3月份槽线附近为主要的堆积区,研究期间总淤积量为12 415.96 m3。潮流观测和地形测量数据很好地验证了粒径分布趋势的分析结果,并弥补了粒径分布趋势分析在预测沉积物输运方面的不足。

For high efficiency and accuracy in sediment transportation trend prediction, grain size trend analysis of seabed surficial sediments are widely used in various sea environments. However, it is useless in seabed erosion and deposition prediction. In order to make up the defects, 149 surficial sediment samples were collected and analyzed over Huiquan beach of Qingdao. Surficial sediment distribution pattern and transportation trend of the beach were analyzed in combination with hydrodynamic measures. The results show that there is a close relationship between the distribution pattern of sediment grain size and hydrodynamic conditions. The fine sands are transported towards east along shoreline driven by the alongshore current, while the coarse sands remain at the original position. The sediment sortation results in an ordinal pattern characterized by fine gravels, coarse sands, medium sands and fine sands from northwest to southeast in the area. In addition, the surficial sediment types are closely consistent with the mean grain size distribution. In Huiquan Bay beach, the sediments are transported towards southeast from the high tide line to the sandbar, while towards northwest from the crest of sand bar to its offshore flank. Topographic measures show that the erosion area is distributed mostly near the crest of sand bar in March with the erosion volume up to 656.17 m^3. But in the same period, the area near the trough is the main depocenter with the deposition volume up to 12415.96 m^3. Tidal current velocity and topography measures validate the results of grain size trend analysis and make up the disadvantages of grain trend size analysis in predicting erosion and deposition.