珠江磨刀门河口洪季悬沙与沉积物颗粒度分布及交换过程

基于洪季磨刀门河口实测水沙观测资料和河床表层沉积物数据,通过对不同区域不同时刻悬沙浓度和粒度、沉积物粒径组成分析,运用因子分析和粒度谱等统计计算方法,重点研究近期洪季磨刀门河口及滨海水域悬沙与河床沙交换过程及其动力机制。结果表明:磨刀门河口拦门沙内河道及汊道口区域的动力以径流为主的涨落潮流流系,悬沙与河床沙交换过程较弱;拦门沙浅滩区域泥沙运动表现为"波浪掀沙,潮流输沙"特性,再悬浮泥沙平均量占实测悬沙浓度的32%;拦门沙外滨海水域悬沙组成受径流与潮汐相对强度影响显著,构成上大潮时以再悬浮泥沙为主,小潮时则以径流下泄悬沙沉积为主,而悬沙输运方向受到东南向波浪和沿岸流控制。

Grain distribution of suspended load and bed sediment with exchange processes in the Modaomen Estuary of Pearl River during flood season

Based on data of hydrologic observation,suspended load and bed material,the processes and physical mechanism are studied based on analysis of suspended sediment concentration and bed material grain size,and on factor analysis and particle size spectrum calculation.Results indicate that the inner channel of Modaomen Estuary and its channel mouth is dominated by tidal current while the ebb tide current is overwhelming.The exchange between suspended load and bed sediment is weak in this area.Bed sediment in the mouth bar and shoal area is winnowed by wave and transported mainly by tidal current.Average proportion of resuspended bed sediment in total observed suspended load is 32％.The composition of suspended load in the area beyond mouth bar is influenced by the relative strength between river discharge and tide dramatically.Suspended load transported by river discharge is the main component during the neap tide while resuspended bed sediment composed the major part of suspended load in this area.The direction of sediment transport is controlled by costal current and SE wave.