长江口口内河段冲淤演变特征及控制因子分析
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摘要
基于1958-2015年间多个年份实测地形资料,定量分析了长江口口内河段的冲淤演变过程,结果表明:该河段经历了剧烈的河势调整,深槽冲刷、浅滩淤积为主要特征,其中20世纪80年代尤为显著,之后整体河势趋于相对稳定。冲淤量从净淤积向净冲刷转换,与河流来沙量的变化趋势一致,5～15 m水深范围内对来沙量的变化最敏感。洪水事件和特枯水文年对河槽冲淤量的影响同样显著,包括20世纪90年代的连续洪水年、2010年大洪水及2006年特枯水年。
Processes of decadal morphology in the inner Yangtze Estuary are analyzed based on bathymetric data in 1958-2015. Results indicate that the study area experienced remarkable pattern modification with scour along main channels and accretion at shallow shoals, particularly in 1980 s. Channel-shoal pattern evolved towards relatively stable after 1980 s. Sediment volume changes converted from net accretion to net erosion, which is consistent with sediment load variation, and the river bed between 5 m and 15 m was more sensitive. Impacts of river flood events and extremely dry years on the volume changes were also significant, especially the frequent river floods in the 1990 s, river flood in 2010 and extremely low river inputs in 2006.
Processes of decadal morphology in the inner Yangtze Estuary are analyzed based on bathymetric data in 1958-2015. Results indicate that the study area experienced remarkable pattern modification with scour along main channels and accretion at shallow shoals, particularly in 1980 s. Channel-shoal pattern evolved towards relatively stable after 1980 s. Sediment volume changes converted from net accretion to net erosion, which is consistent with sediment load variation, and the river bed between 5 m and 15 m was more sensitive. Impacts of river flood events and extremely dry years on the volume changes were also significant, especially the frequent river floods in the 1990 s, river flood in 2010 and extremely low river inputs in 2006.
引文
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[2] 赵娟.长江河口(南支)冲淤变化对流域来水来沙的响应研究[D].南京:河海大学,2006.
[3] Wang Y,Dong P,Oguchi T,et al.Long-term (1842-2006) morphological change and equilibrium state of the Changjiang (Yangtze) Estuary,China[J].Continental Shelf Research.2013,56:71-81.
[4] 刘杰,赵德招,程海峰.长江口南支河床近期冲淤演变机制[J].水运工程,2011(7):113-118.
[5] 张晓鹤,李九发,姚弘毅,等.长江河口南支河道近期演变与自动调整过程研究[J].人民长江,2015,46(17):1-6.
[6] 恽才兴.长江河口近期演变规律[M].北京:海洋出版社,2004.
[7] 刘红,何青,王元叶,等.长江口表层沉积物粒度时空分布特征[J].沉积学报,2007(3):445-455.
[8] Luan H L,Ding P X,Wang Z B,et al.Decadal morphological evolution of the Yangtze Estuary in response to river input changes and estuarine engineering projects [J].Geomorphology.2016,265:12-23.
[9] 陈吉余,徐海根.长江河口南支河段的河槽演变[J].华东师范大学学报(自然科学版).1981(2):93-108.
[10] Zhu B,Li Y,Yue Y,et al.Aggravation of north channels‘ shrinkage and south channels’ development in the Yangtze Estuary under dam-induced runoff discharge flattening [J].Estuarine,Coastal and Shelf Science.2017,187:178-192.
[11] Cooper J A G.The role of extreme floods in estuary-coastal behaviour:contrasts between river- and tide-dominated microtidal estuaries [J].Sedimentary Geology.2002,150(1-2):123-137.
[12] 徐俊杰,何青,刘红,等.2006年长江特枯径流特征及其原因初探[J].长江流域资源与环境,2008(5):716-722.
[13] 窦国仁.平原冲积河流及潮汐河口的河床形态[J].水利学报,1964(2):1-13.
[14] Yang S L,Milliman J D,Xu K H,et al.Downstream sedimentary and geomorphic impacts of the Three Gorges Dam on the Yangtze River [J].Earth-Science Reviews.2014,138:469-486.
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