SEDIMENT CHARACTERISTICS AND HYDRODYNAMICS OF NEARSHORE GUDONG IN THE YELLOW RIVER DELTA
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摘要: 根据黄河三角洲孤东近岸海域表层沉积物取样、水文泥沙观测和风浪资料推算,分析沉积物特征和运移趋势,并通过水动力条件(潮流和波浪)探讨沉积物起动和输移特征。结果表明,孤东海域沉积物多为粉砂类物质,由内向外逐渐变细,分选变差,丁坝的修建对周围粒径分布影响明显;沉积物运移趋势受风成余流、岸线轮廓和丁坝工程修建的影响,不同区域表现为不同的输移方向;研究区水动力表现为波浪掀沙、潮流输沙的特征,由于潮流较小,不足以引起泥沙的起动,泥沙起动主要由波浪引起。Abstract: The sediment stirring-up and transporting have been studied based on the data of wind, tidal currents and bottom sediments observed during the period from 2004 to 2006. The results show that sedi-ments at the Gudong coasts are mostly silt and poorly-sorted. Sediment particles become finer and poorersorted with water depth. Influenced by wind-residual currents, coastal line and groynes, sediments show different transporting trends in different regions. Analysis of sediment grain-size tendency shows that the study area can be divided into three areas:in the north embankment nearshore area of Gudong, sediments are mainly transported towards northeast;in the east embankment nearshore area, sediments go from north to south except the area between NO 2 Groyne and NO 18 Groyne where sediments show an opposite direction of transportation; in the Xintan area of the Yellow River delta on the south side of Gudong, sediments migrate from west to east. Tidal current velocity is not great enough to stir up bottom silt in the nearshore Gudong, but silt is often suspended by waves around groynes that have made tidal currents change. Waves are often seen to be 1.0 m high,and silt suspension is concentrated in area shallower than 5 m of water depth. Silt stirred up by waves is carried to open sea by tidal currents. Erosion becomes serious due to short of silt recharge.
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