福建平海湾外湾表层沉积物粒度特征及冲淤变化

摘要

Surface sediments samples were collected from 106 stations in the outer Pinghai Bay and analyzed by la ser particle size instrument for the composition and distribution of grain size parameters.The grain size trend model is used to discuss the transport trend of marine sediment,and the contrastive analysis of new and old maps based on ArcGis is used to analyze the erosion and deposition variation in Pinghai Bay.According to the Pinghai Bay Development Planning,representative stations are arranged to calculate the erosion of seabed sediments caused by tidal current and wave.The results show that surface sediments 5 types of which the clayey silt is the most important.The distribution of sediment types trend to finer with the increasing water depth.The average particle size of sediment (Mz),sorting coefficient (σi),skewness (Ski) and kurtosis (Kg) are corresponding to marine sedimentary environment and hydrodynamic conditions.Sediment transport is mainly focused on the northwest and southeast direction.Chart comparison and the observations show that the area investigated is in a state of weaker siltation.The analysis and calculation proves that sea bottom sedimentation is not affected by tidal current but the waves.%通过对平海湾外湾106个表层沉积物样品的粒度分析,阐述了平海湾外湾表层沉积物的物质组成和粒度参数分布特征.利用沉积物粒径趋势模型初步探讨了平海湾外湾的沉积物输运趋势,结合新老海图对比,分析了该海域的冲淤变化特征,并结合平海湾发展规划选取代表站位来分析计算潮流和波浪对海底沉积物的冲刷.结果表明,研究海域表层沉积物可分为5种类型,主要为粘土质粉砂,随着水深的增加,沉积物呈逐渐变细的趋势.沉积物的平均粒径(Mz)、分选系数(oσi)、偏态(Ski)及峰态(Kg)的分布与研究区海域沉积环境和水动力条件等相对应.粒径趋势分析显示研究区袁层沉积物的输运趋势主要为NW向和SE向.对比不同年代海图及观测资料表明,研究海域呈弱淤积状态;经过分析计算,研究区海底沉积物不是受到潮流而是波浪的冲刷.