Sediment trapping mechanism by salinity stratification in a river-dominted estuary: A case study of the Modaomen Estuary in flood season

Xie Rongyao; Liu Feng; Luo Xiangxin; Niu Lixia; Cai Huayang; Yang Qingshu

doi:10.12284/hyxb2021065

Volume 43 Issue 5

May 2021

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Xie Rongyao，Liu Feng，Luo Xiangxin, et al. Sediment trapping mechanism by salinity stratification in a river-dominted estuary: A case study of the Modaomen Estuary in flood season[J]. Haiyang Xuebao，2021, 43(5)：38–49 doi: 10.12284/hyxb2021065

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Sediment trapping mechanism by salinity stratification in a river-dominted estuary: A case study of the Modaomen Estuary in flood season

doi: 10.12284/hyxb2021065

Xie Rongyao^1
,,
Liu Feng^{2, 3, 4
,
,},
Luo Xiangxin^{2, 3, 4},
Niu Lixia^{2, 3, 4},
Cai Huayang^{2, 3, 4},
Yang Qingshu^{2, 3, 4}

1.
School of Marine Science, Sun Yat-Sen University, Zhuhai 519082, China
2.
Institute of Estuarine and Coastal Research, School of Marine Engineering and Technology, Sun Yat-Sen University, Zhuhai 519082, China
3.
Guangdong Provincial Engineering Research Center of Coasts, Islands and Reefs, Guangzhou 510275, China
4.
State and Local Joint Engineering Laboratory of Estuarine Hydraulic Technology, Guangzhou 510275, China

Received Date: 2020-03-03
Rev Recd Date: 2020-05-04

Available Online: 2021-06-24

Publish Date: 2021-07-06

Abstract

Abstract

Salinity mixing and stratification in the river-dominated estuaries are important dynamic mechanisms for controlling transport and diffusion of suspended sediment. Based on the synchronous field investigation with three surveying vessels in the flood season in 2017, covering the spring and neap tidal cycles, the influence mechanism of salinity stratification on suspended sediment distribution in the Modaomen Estuary was analyzed in this study. Vertical distribution of salinity in the estuary also displayed spatial differences under the influence of interaction between riverine and tidal dynamics. The salinity at M1 Station (Guading Jiao), dominated by runoff, was mixed well vertically over the tidal cycles; salinity stratification occurred at the M2 Station (outlet location) and at M3 Station (outside the mouth), which were influenced by interaction between runoff and tide over the tidal cycles. Spatial distribution of suspended sediment was closely related to spatial distribution of salinity. In general, salinity mixing promoted the vertical mixing of suspended sediment, while salinity stratification constrained the suspended sediment to be concentrated in the bottom water layer, and high suspended sediment concentration (SSC) tended to appear at the layer where salinity stratified occur. The vertical distribution curve of SSC was L-shape or paracurve shape, while high SSC always concentrated in the front of the salinity wedge in the longitudinal direction, indicating a significant sediment trapping effect caused by salinity stratification. Comparing the stratification ratio and vertical diffusion coefficient at three gauging stations, there was a negative relationship between them, the larger stratification ratio is, the smaller vertical diffusion coefficient is, indicating the suppression effect of stratification on vertical diffusion. Furthermore, the higher stratification is, the larger suppression effect is. Such mechanism contributes to the sediment trapping caused by stratification. This study is helpful to reveal the mechanism of fine sediment movement and the mechanism of evolution of mouth bar in a complicated estuary, and provide scientific basis for regulation of mouth bar in the Modaomen Estuary.
- suspended sediment distribution,
- salinity stratification,
- sediment trapping,
- Modaomen Estuary,
- the river-dominated estuary

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References

[1]	Milliman J D, Syvitski J P M. Geomorphic/tectonic control of sediment discharge to the ocean: the importance of small mountainous rivers[J]. The Journal of Geology, 1992, 100: 525−544. doi: 10.1086/629606
[2]	Simpson J H, Brown J, Matthews J, et al. Tidal straining, density currents, and stirring in the control of estuarine stratification[J]. Estuaries, 1990, 13(2): 125−132. doi: 10.2307/1351581
[3]	Chou Yiju, Nelson K S, Holleman R C, et al. Three-dimensional modeling of fine sediment transport by waves and currents in a shallow estuary[J]. Journal of Geophysical Research: Oceans, 2018, 123(6): 4177−4199. doi: 10.1029/2017JC013064
[4]	Zhang Guang, Cheng Weicong, Chen Lianghong, et al. Transport of riverine sediment from different outlets in the Pearl River Estuary during the wet season[J]. Marine Geology, 2019, 415: 105957. doi: 10.1016/j.margeo.2019.06.002
[5]	田枫, 欧素英, 杨昊, 等. 伶仃洋河口泥沙絮凝特征及影响因素研究[J]. 海洋学报, 2017, 39(3): 55−67. Tian Feng, Ou Suying, Yang Hao, et al. Study on the flocs characteristic and dynamics effects in the Lingdingyang Estuary[J]. Haiyang Xuebao, 2017, 39(3): 55−67.
[6]	矫恒晨, 王盼盼, 简慧敏, 等. 长江口及邻近海域沉积物再悬浮对水体磷酸盐的影响的模拟研究[J]. 海洋学报, 2017, 39(4): 28−38. Jiao Hengchen, Wang Panpan, Jian Huimin, et al. Simulation study of the effects of sediment resuspension on phosphate loading in the Changjiang Estuary and its adjacent area[J]. Haiyang Xuebao, 2017, 39(4): 28−38.
[7]	孙继涛, 张庆河, 严冰, 等. 盐度层化对长江口水动力的影响[J]. 水道港口, 2015, 36(2): 93−104. doi: 10.3969/j.issn.1005-8443.2015.02.001 Sun Jitao, Zhang Qinghe, Yan Bing, et al. Effects of salinity stratification on hydrodynamics in the Yangtze River Estuary[J]. Journal of Waterway and Harbor, 2015, 36(2): 93−104. doi: 10.3969/j.issn.1005-8443.2015.02.001
[8]	黄睿, 张庆河, 邢恩博, 等. 盐度层化对水体紊动特性影响的实验研究[J]. 水力发电学报, 2020, 39(3): 45−55. Huang Rui, Zhang Qinghe, Xing Enbo, et al. Experimental investigation on effects of salinity stratification on turbulence characteristics of water body[J]. Journal of Hydroelectric Engineering, 2020, 39(3): 45−55.
[9]	Geyer W R. The importance of suppression of turbulence by stratification on the estuarine turbidity maximum[J]. Estuaries, 1993, 16(1): 113−125. doi: 10.2307/1352769
[10]	Pritchard D W. Estuarine circulation patterns[M]//Washington D C: Proceedings of the American Society of Civil Engineers, 1955, 81: 1−11.
[11]	Li Li, He Zhiguo, Xia Yuezhang, et al. Dynamics of sediment transport and stratification in Changjiang River Estuary, China[J]. Estuarine, Coastal and Shelf Science, 2018, 213: 1−17. doi: 10.1016/j.ecss.2018.08.002
[12]	Li Xiangyu, Zhu Jianrong, Yuan Rui, et al. Sediment trapping in the Changjiang Estuary: observations in the north passage over a spring-neap tidal cycle[J]. Estuarine, Coastal and Shelf Science, 2016, 177: 8−19. doi: 10.1016/j.ecss.2016.05.004
[13]	Wu Jiaxue, Liu J T, Wang Xia. Sediment trapping of turbidity maxima in the Changjiang Estuary[J]. Marine Geology, 2012, 303: 14−25. doi: 10.1016/j.margeo.2012.02.011
[14]	Xiao Yang, Wu Zheng, Cai Huayang, et al. Suspended sediment dynamics in a well-mixed estuary: the role of high suspended sediment concentration (SSC) from the adjacent sea area[J]. Estuarine, Coastal and Shelf Science, 2018, 209: 191−204. doi: 10.1016/j.ecss.2018.05.018
[15]	王世俊, 易小兵, 李春初. 磨刀门河口水沙变化与地貌响应[J]. 海洋工程, 2008, 26(3): 51−57. doi: 10.3969/j.issn.1005-9865.2008.03.009 Wang Shijun, Yi Xiaobing, Li Chunchu. Variation of flow and sediment and response of morphology in Modaomen Estuary of Xijiang River[J]. The Ocean Engineering, 2008, 26(3): 51−57. doi: 10.3969/j.issn.1005-9865.2008.03.009
[16]	Tan Chao, Huang Bensheng, Liu Feng, et al. Recent morphological changes of the mouth bar in the Modaomen Estuary of the Pearl River Delta: Causes and environmental implications[J]. Ocean & Coastal Management, 2019, 181: 104896.
[17]	胡达, 李春初, 王世俊. 磨刀门河口拦门沙演变规律的研究[J]. 泥沙研究, 2005, 4: 71−75. doi: 10.3321/j.issn:0468-155X.2005.04.012 Hu Da, Li Chunchu, Wang Shijun. Study on evolutional processes of the sand bar in Modaomen Estuary[J]. Journal of Sediment Research, 2005, 4: 71−75. doi: 10.3321/j.issn:0468-155X.2005.04.012
[18]	欧素英, 田枫, 郭晓娟, 等. 珠江三角洲径潮相互作用下潮能的传播和衰减[J]. 海洋学报, 2016, 38(12): 1−10. Ou Suying, Tian Feng, Guo Xiaojuan, et al. Propagation and damping of tidal energy in the Pearl River Delta[J]. Haiyang Xuebao, 2016, 38(12): 1−10.
[19]	任杰, 刘宏坤, 贾良文, 等. 磨刀门水道盐度混合层化机制[J]. 水科学进展, 2012, 23(5): 715−720. Ren Jie, Liu Hongkun, Jia Liangwen, et al. Research on salinity mixing and stratification mechanisms at the Modaomen channel[J]. Advances in Water Science, 2012, 23(5): 715−720.
[20]	吕紫君, 冯佳佳, 郜新宇, 等. 磨刀门河口环流与咸淡水混合层化机制[J]. 水科学进展, 2017, 28(6): 908−917. Lü Zijun, Feng Jiajia, Gao Xinyu, et al. Estuarine circulation and mechanism of mixing and stratification in the Modaomen Estuary[J]. Advances in Water Science, 2017, 28(6): 908−917.
[21]	梁娟, 李春初. 人类活动影响下磨刀门河口的泥沙输运沉积[J]. 泥沙研究, 2010, 3: 67−72. Liang Juan, Li Chunchu. Tendency of sediment transport and sedimentation in the Modaomen Estuary under influence of human activities[J]. Journal of Sediment Research, 2010, 3: 67−72.
[22]	林凤标, 郑国栋, 刘壮添. 磨刀门水道近50年河床演变及其冲淤成因分析[J]. 泥沙研究, 2017, 42(3): 48−53. Lin Fengbiao, Zheng Guodong, Liu Zhuangtian. Evolution and causes of the Modaomen River during the last 50 years[J]. Journal of Sediment Research, 2017, 42(3): 48−53.
[23]	中华人民共和国水利部. 中国河流泥沙公报（2017）[M]. 北京: 中国水利水电出版社, 2018: 45. Ministry of Water Resources of the People's Republic of China. Zhongguo Heliu Nisha Gongbao (2017)[M]. Beijing: China Water & Power Press, 2018: 45.
[24]	广东省水利电力勘测设计研究院. 珠江河口整治近期防洪实施工程可行性研究报告[R]. 广州: 广东省水利电力勘测设计研究院, 2002. Guangdong Water Conservancy and Electric Power Survey and Design Institute. Feasibility study report on the recent flood control project of the Pearl River Estuary[R]. Guangzhou: Guangdong Water Conservancy and Electric Power Survey and Design Institute, 2002.
[25]	贾良文, 吕晓莹, 程聪, 等. 珠江口磨刀门月际尺度地貌演变研究[J]. 海洋学报, 2018, 40(9): 65−77. Jia Liangwen, Lü Xiaoying, Cheng Cong, et al. Study on the morphological evolution of the Modaomen Estuary in monthly scale[J]. Haiyang Xuebao, 2018, 40(9): 65−77.
[26]	Stacey M T, Rippeth T P, Nash J D. Turbulence and stratification in estuaries and coastal seas[J]. Treatise on Estuarine and Coastal Science, 2011, 2: 9−35.
[27]	Geyer W R, MacCready P. The estuarine circulation[J]. Annual Review of Fluid Mechanics, 2014, 46: 175−197. doi: 10.1146/annurev-fluid-010313-141302
[28]	Pu Xiang, Shi J Z, Hu Guodong, et al. Circulation and mixing along the north passage in the Changjiang River Estuary, China[J]. Journal of Marine Systems, 2015, 148: 213−235. doi: 10.1016/j.jmarsys.2015.03.009
[29]	Bowden K F. Turbulent mixing in estuaries[J]. Ocean Management, 1981, 6(2/3): 117−135.
[30]	Simpson J H, Williams E, Brasseur L H, et al. The impact of tidal straining on the cycle of turbulence in a partially stratified estuary[J]. Continental Shelf Research, 2005, 25(1): 51−64. doi: 10.1016/j.csr.2004.08.003
[31]	Cameron W M, Pritchard D W. Estuaries[M]//Hill M N. The Sea, vol 2. New York: John Wiley and Sons, 1963: 306−324.
[32]	Simpson J H, Allen C M, Morris N C G. Fronts on the continental shelf[J]. Journal of Geophysical Research: Oceans, 1978, 83(C9): 4607−4614. doi: 10.1029/JC083iC09p04607
[33]	Simpson J H, Bowers D. Models of stratification and frontal movement in shelf seas[J]. Deep−Sea Research Part A: Oceanographic Research Papers, 1981, 28(7): 727−738. doi: 10.1016/0198-0149(81)90132-1
[34]	Mehta A J. On estuarine cohesive sediment suspension behavior[J]. Journal of Geophysical Research: Oceans, 1989, 94(C10): 14303−14314. doi: 10.1029/JC094iC10p14303
[35]	Officer C B. Physical Oceanography of Estuaries (and Associated Coastal Waters)[M]. New York: Wiley, 1976: 209−218.