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闽江口及周边海域沉积物输运及资源效应
王爱军, 叶翔, 赖志坤, 王亮
自然资源部第三海洋研究所 海洋与海岸地质实验室
摘要:
河流入海泥沙的大部分主要分布在河口、三角洲地区及近岸陆架地区,发育了一系列的粗颗粒沉积体系,是海砂资源重要分布区。本文以福建闽江口为研究对象,开展复杂河口地貌影响下的初步探讨了沉积物输运过程及海砂资源的形成机制研究。观测结果表明,闽江河口水体盐度由河口内部向口外海域逐渐增大,水体浊度总体减小;闽江河口附近海域近底部(距离海底25 cm)流速介于0.096 m/s~0.342 m/s之间,流向表现出一定的旋转流特征,潮周期内余流表现为向海输运,而推移质输运主要发生在涨潮期间,并且潮周期内净向西和西北方向陆输运。表层沉积物粒度分析结果表明,闽江河口水下三角洲前缘表层沉积物主要由粗颗粒物质组成,沉积物类型以砂和砂质粉砂为主,中值粒径小于4 Φ;前三角洲地区表层沉积物主要由细颗粒物质组成,沉积物类型以黏土质粉砂为主,中值粒径介于4 Φ~6 Φ之间。沉积物粒径趋势分析结果表明,闽江入海泥沙经梅花水道和长门水道入海后,在盐淡水混合、径流、潮流的作用下,在闽江河口形成了四个粗颗粒沉积物汇聚区,成为闽江口地区海砂资源的重要分布区;而细颗粒物质在河口羽流和潮流的作用下向偏东南、东、东北方向输运,形成了以黏土质粉砂为主的前三角洲。
关键词:  海砂资源  河口羽状流  潮流  沉积物输运  闽江口
DOI:10.11693/hyhz20200100024
分类号:
基金项目:(41776099)、自然资源部第三海洋研究所基本科研业务费项目(海三科2017015、海三科2019018)资助;通讯作者王爱军,Email: wangaijun@tio.org.cn
Sediment transport in Minjiang Estuary and adjacent shelf area and associated resource effect
Wang Ai-jun, Ye Xiang, Lai Zhi-kun, Wang Liang
Laboratory for Coast Ocean Geology,Third Institute of Oceanography,Ministry of Natural Resources,China
Abstract:
Most of sediment delivered by river is mainly distributed in estuaries, deltas and coastal shelf areas, which lead to form a series of coarse-grained deposits, where are important distribution areas of marine sand resources. In this study, we plan to indicateprimarily discuss sediment transport process and the formation mechanism of marine sand resources under the influence of complex geomorphology taking the Minjiang River estuary as an example. The observation results show that the salinity of Minjiang River Estuary gradually increases from the inside to the outside of the estuary, and the water turbidity generally decreases. During the observation, the current velocityflow direction near the bottom (25 cm above the bed) near the Minjiang River estuary ranges from 0.096 m/s to 0.342 m/s, and the current flow direction shows certain of rotation character; the bottom residual current towards to the sea, while the bedload transport is mainly occurred during the flood tide and the net transport landwarddirection towards west and northwest near the observation sites over the entire tidal cycle. The grain-size analysis results of surface sediments show that the surface sediments in the subaqueous delta front of Minjiang River estuary are mainly composed of coarse-grained sediment, and the sediment types are mainly sand and sandy silt, with the median grain size less than 4 Φ; the surface sediments in the prodelta are mainly composed of fine-grained sediment, and the sediment types are mainly clayey silt, with the median grain size between 4 Φ and 6 Φ. The results of grain size trend analysis show that when the sediment discharged by the Minjiang River enters into the sea through Meihua Channel and Changmen Channel, under the influences of salt and fresh water mixing, runoff and tidal current, four coarse-grained sediment convergence areas have been formed in the Minjiang River Estuary, which has become an important distribution area of marine sand resources near the Minjiang River Estuary. However, under the comprehensive effects of river plume and tidal current, fine-grained sediment is transported to southeast, east and northeasteastward to, forming a prodelta dominated by clayey silt sediment.
Key words:  Marine sand resources  river plume  tidal current  sediment transport  Minjiang River estuary
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