珠江磨刀门河口底质沉积特征及其泥沙运移趋势

根据珠江磨刀门河口的表层沉积物粒度分析结果,运用Gao-Collins粒径趋势分析方法(GSTA模型),计算河口的沉积物净输运趋势,并分析河口底质沉积特征。结果表明:河口较粗的沉积物分布在交杯沙浅滩和拦门沙顶部,受波浪作用影响分选较好;磨刀门主槽、龙屎窟和口外海滨的沉积物则较细,以粉砂和粘土为主,分选稍差。沉积物在纵向和横向上都表现出细-粗-细的变化趋势。磨刀门主槽泥沙受强径流影响,具有向南的输运趋势;龙屎窟在涨潮流作用下,泥沙净向北输运;在西向沿岸流和东南向浪作用下,拦门沙东侧浅滩泥沙向西侧搬运,口外海滨的泥沙输运趋势则向北。

Analysis on the Sedimentary Characteristics and Sediment Transport Patterns of Modaomen Estuary of the Pearl River

Based upon the grain size analysis of the surficial sediment in the Modaomen estuary, this paper applies the Gao-Collinss grain size trend analysis model (GSTA model) to obtain net sediment transport patterns. Meanwhile, it analyzes the distribution characteristics and source of the sediments. The results indicate that the sediments in Jiaobeisha shoal and estuarine sandbar are mainly composed of sediments of coarser size which are well-sorted by waves, the sediments of finer size, made up of silt and clay, are poorly sorted in the Modaomen deep trough, Longshiku and seashore outside sandbar. Three segments of the sediments along longitudinal distribution and transverse distribution recognized as coarser-finer-coarser were differentiated. The sediments, derived by river, are transported southwards in the Modaomen deep trough, while, driven by westward longshore currents and southeastward waves, the sediments of the estuarine sandbar are transported westwards and the sediments of the nearshore zone outside the sandbar are transported southwards.