【摘要】 根据2002年5月至2005年10月在杭州湾北岸和长江口口门交汇处一固定观测点表层每日取样的悬沙浓度资料和同期的潮差、潮位、风向风速以及长江大通水文站的水沙资料,利用Spss、MatLab分析软件,采用小波分析和相关性分析方法,探讨了悬沙浓度变化的周期性及其影响机制。研究结果表明:1)悬沙浓度具有显著的大、小潮和季节性变化,变化周期分别为14.7 d和368 d,平均而言,大潮为小潮的2.96倍,冬季为夏季的2倍;2)平均大、小潮半月周期中日悬沙浓度与同日潮差之间的相关系数为0.86,与前1日潮差之间的相关系数为0.99,与前2日潮差之间的相关系数为0.93,反映潮差变化对悬沙浓度的影响有1~2 d的滞后效应;3)月均悬沙浓度与长江大通站的月均流量呈显著负相关,尤其与流量滞后19 d的相关性最好。研究区日悬沙浓度变化主要为大、小潮和季节性周期变化,前者受潮动力引起的泥沙沉降—再悬浮控制,后者受径流冲淡作用、海平面高度、潮差、风况的季节性变化控制。更多还原

【Abstract】 The daily observed data of surface suspended sediment concentration(SSC) at the Nanhui headland from May 2002 to October 2005,the observed data of tidal range,tidal level,wind speed and direction at the Nanhui hydrometeorological station and the water and sediment discharge data observed at Datong hydrographic station in the same period were used to study the periodicity and affecting mechanism of SSC variation.It is shown from the study results that(1) SSC has obvious neap-spring and seasonal variations with periods being 14.7 days and 368 days,respectively,on an average,SSC during the spring tide was 2.96 times as much as that during the neap tide,and SSC in winter was twice as much as that in summer;(2) correlation coefficient between daily SSC and tidal range on the same day in a mean neap-spring period of 15 days was 0.86,and correlation coefficients between tidal range and daily SSC with one day and two day lag were 0.99 and 0.93,respectively,which indicates that the effect of tidal range variation on SSC has a one day or two day hysteresis;(3) the monthly mean SSC was negatively correlated with the monthly mean water discharge at the Changjiang River Datong station,especially well with the water discharge with a lag of 19 days.The variations in daily SSC in the study area were mainly the neap-spring and seasonal variations,the neap-spring variations are controlled by the sediment settling and resuspension mechanism caused by the tidal dynamics,and the seasonal variations are controlled by the seasonal variations in riverine runoff,sea level,tidal range and wind condition in a year.更多还原