摘要
对长江口崇明东滩盐沼边缘及邻近光滩处的水深、流速和悬沙含量的潮周期变化过程进行了现场实测,并对横向悬沙通量进行了计算和分析。研究结果表明,在平静天气条件下光滩和盐沼上的流速过程有明显差异,植被缓流作用在落潮期更为显著,流速在涨潮由光滩向盐沼不断增大。与涨潮流速优势相对应,涨潮期平均悬沙含量是落潮期的1.8倍。横向悬沙通量以向岸输移为主,悬沙总通量与潮次内最大水深的四次方呈显著正相关。在平静天气条件下潮汐作用控制着盐沼前缘地带泥沙输移水平,盐沼滩面保持稳定淤积,前缘光滩淤积速率高于盐沼处的,盐沼逐渐向海延伸。在大风天气条件下潮次内的流速和悬沙含量水平提高了数倍,悬沙输移量大增,净输移仍以向岸方向为主,在盐沼上部和前缘光滩均可能在短期内发生大量淤积。
Between April 2002 and April 2003,time series measurements of water depth,current velocity and suspended sediment content（SSC） were carried out on the marsh fringe and adjacent mudflat of Chongming eastern beach in the Changjiang Estuary.A cross-shore suspended sediment flux was calculated and analyzed.Under the calm weather condition,different types of the time series of current velocity between a salt marsh and a mudflat were observed during semidiurnal tidal cycles.Marsh vegetation reduced ebb currents,current velocity enhanced in flood on the salt marsh.Owing to current velocity asymmetry,mean SSC during flood phase was 1.8 times higher than ebb phase.As a result,net onshore sediment flux controlled cross-shore suspended sediment transport process and salt marsh pioneer zone was generally accreting.There was significant positive correlation between the total sediment flux and the quartic power of maximum water depth.It indicated that tidal forces dominate suspended sediment transport and sedimentation process in the salt marsh pioneer zone under the calm weather condition.Sedimentation rate on the adjacent mudflat was higher than the salt marsh,which induced stably accreting of salt marsh towards the sea.Wind events enhanced the SSC and the current velocity during the semidiurnal tides.And remarkable onshore net sediment flux could occur on the high marsh and mudflat close to the marsh fringe during the short period under the rough weather condition.
出处
《海洋学报》
CAS
CSCD
北大核心
2009年第1期143-151,共9页
基金
国家自然科学基金资助项目(4057101240571006)
国家自然科学基金重点资助项目(40730526)
华东师范大学河口海岸学国家重点实验室开放基金资助项目(SKLEC0510)
关键词
流速
悬沙含量
通量
盐沼
东滩
current velocity
suspended sediment content
flux
salt marsh
eastern beach
