The development of underwater shoals at upper reach and the process of hydrodynamics and sediment transport in the North Branch of Changjiang Estuary
-
摘要: 最近10余年长江口北支入口处发育了新江心沙沙体，该沙体日渐淤涨，有堵塞北支入口的趋势。认识新江心沙发育后北支的水沙动力特征，有助于进一步辨识河道演化趋势。基于2023年1月和8月洪枯季大潮期间，沿北支河道多站位的同步水沙观测数据，分析表明：(1)洪季水动力强于枯季，北支水动力强于南北支分汊口，枯季下段水动力强于中上段，洪季反之。(2)新江心沙附近处悬沙浓度低，北支河道内中断悬沙浓度高，洪季悬沙浓度显著大于枯季。(3)北支输沙率大于新江心沙附近，新江心沙与周边水域的泥沙交换强度较小。(4)在人类活动影响下，束窄和淤浅的北支河道加剧了新江心沙的淤涨发育，高浊度的北支及涨潮优势为新江心沙的发育提供丰富的物源，北支涌潮上溯及南北支分汊口涨潮流相位差为新江心沙淤积提供了动力条件。这些认识可以解释新江心沙淤涨的泥沙来源和动力机制，可为北支河道治理提供科学依据。Abstract: In recent decades, a newly formed sand bar has developed at the entrance to the North Branch of the Changjiang Estuary, gradually accumulating sediment and showing signs of blocking the entrance to the North Branch. Understanding the hydrodynamics and sediment transport in the North Branch after the formation of the Xinjiangxin Shoal can help to further identify the trend of channel evolution. Based on the synchronised water-sediment observation data from several stations along the North Branch during flood season and dry season in January and August 2023, the analysis shows that: (1) The water dynamics in the flood season is stronger than that in the dry season, the water dynamics in the North Branch is stronger than that in the branch point. In the dry season, the water dynamics in the lower part is strong, and that in the middle and upper part is weak. The situation is reversed in the flood saeson. (2) The suspended sediment concentration near the Xinjiangxin Shoal is low, that in the North Branch is high. The suspended sediment concentration along the river gradually increases and then decreases spatially. The suspended sediment concentration in the flood season is significantly greater than that in the dry season. (3) The sediment transport in the North Branch is greater than that near the Xinjiangxin Shoal, and the exchange intensity between the Xinjiangxin Shoal and the surrounding waters is small. (4) With the influence of human activities, the narrow and shallow North Branch intensified the sedimentation and development of the Xinjiangxin Shoal, and the North Branch with high turbidity provided rich material sources for the development of the Xinjiangxin Shoal, and the phase difference of the upflowing tide to the branch point of the North Branch and South Branch provided dynamic conditions for the sedimentation of the Xinjiangxin Shoal, explaining the sediment source and dynamic mechanism of the Xinjiangxin Shoal. The understanding of the hydrodynamics and sediment transport can provide the basis for the treatment of the North Branch.
-
Key words:
- Changjiang Estuary /
- North Branch /
- hydrodynamics /
- Xinjiangxin Shoal /
- tidal bore
-
图 4 2023年1月和8月洪枯季新江心沙周边悬浮物漂流示踪观测(a. 枯季；b. 洪季)
Fig. 4 Floating tracer observation of suspended sediment around the newly generated sandbank in January and August 2023 during flood and dry season (a. dry season; b. flood season)
图 1 长江口北支综合调查区域示意图
Fig. 1 Schematic diagram of the comprehensive survey area of the North Branch of the Changjiang River Estuary
图 2 长江口北支进口段新江心沙演变
Fig. 2 Evolution of the newly generated sandbank in the North Branch entrance of the Changjiang River Estuary
图 3 2023年1月枯季观测期间长江口北支潮周期流矢图
Fig. 3 Periodic streamer map of the North Branch of the Changjiang River Estuary during dry season observation in January 2023
图 5 2023年洪枯季观测期间长江口北支测点悬沙浓度
Fig. 5 Suspended sediment concentration in the North Branch of the Changjiang River Estuary during flood and dry season observation in 2023
图 6 长江口北支进口处的涌潮及清浑水交界面
Fig. 6 The tidal bore and the interface of turbidity and clarity at the inlet of the North Branch of the Changjiang River Estuary
图 7 长江口北支两次涌潮的观测数据
Fig. 7 Observational data of two tidal bores in the North Branch of the Changjiang River Estuary
图 8 长江口北支涌潮和南支涨潮流示意图
Fig. 8 Schematic diagram of tidal bore in the North Branch and flood tide in the South Branch of the Changjiang River Estuary
表 1 洪枯季长江口北支测点垂线平均流速、盐度、含沙量对比
Tab. 1 Comparison of the vertical average velocity, salinity and sediment concentration in the North Branch of the Changjiang River Estuary during flood and dry season
测点 流速/(m·s−1) 盐度 含沙量/(kg·m−3) 枯季 洪季 枯季 洪季 平均 枯季 洪季 平均 涨潮 落潮 平均 涨潮 落潮 平均 1 0.53 0.70 0.62 0.90 0.81 0.84 0.21 0.21 0.21 0.12 0.33 0.22 2 0.51 0.45 0.48 − − − 0.23 0.20 0.22 0.13 0.23 0.18 3 0.49 0.44 0.46 1.59 0.95 1.18 0.26 0.23 0.25 0.25 0.77 0.51 4 0.44 0.61 0.52 0.98 1.42 1.33 2.59 0.73 1.66 0.97 2.89 1.93 5 0.81 0.67 0.74 0.99 1.18 1.10 12.49 2.67 7.58 1.19 3.76 2.47 6 0.91 0.63 0.77 1.11 1.13 1.12 26.34 18.16 22.25 0.58 1.18 0.88 
下载: 导出CSV
表 2 长江口北支各站观测期间单宽潮平均和表底层输沙量
Tab. 2 The average of single broad tide and the sediment transport of surface and bottom layer at each station in the North Branch of the Changjiang River Estuary during the observation period
测点 单宽潮平均输沙量/(t·m−1) 表层输沙 底层输沙 大通流量/(m−3·s) 涨潮 落潮 净输移 表层输沙量(t·m−1) 角度/(°) 底层输沙量(t·m−1) 角度/(°) BK1 33.34 62.57 37.06 3.15 140.69 4.74 150.42 8000 ～10000 BK2 12.54 13.88 1.49 0.23 155.9 0.17 169.68 BK3 31.31 34.23 32.95 1.76 106.5 4.28 118.73 BK4 122.14 156.64 37.61 3.49 313.98 3.91 136.95 BK5 235.63 192.50 −49.87 6.45 5.16 7.27 339.13 BK6 191.08 116.95 −82.85 7.49 309.33 7.30 338.98 BH1 95.94 147.66 54.60 2.60 67.09 8.38 95.7 26000 ～27000 BH2 − − − − − − − BH3 360.88 204.94 419.84 20.24 140.84 79.46 137.25 BH4 561.47 1235.65 730.52 15.86 83.12 135.54 86.36 BH5 1576.39 1278.98 2374.97 121.83 59.18 479.39 82.8 BH6 339.82 402.02 262.30 4.58 45.21 56.96 26.97 注：净输移正值表示向海输移，负值表示向陆输移。
下载: 导出CSV
表 3 长江口北支洪枯季各处悬沙及沉积物粒度特征
Tab. 3 Suspended sediment and sediment grain size characteristics in the North Branch of the Changjiang River Estuary during flood and dry season
泥样类别 区域 枯季 洪季 D50/μm 组分体积含量/% D50/μm 组分体积含量/% 黏土 粉砂 砂 粘土 粉砂 砂 江心沙 新江心沙 43.8 8.4 58.4 33.1 悬沙 BZ1 10.9 26.2 64.0 9.8 9.6 26.7 68.7 4.6 BZ2 10.5 28.0 62.7 9.3 12.7 23.3 69.5 7.1 BZ3 14.4 25.9 64.3 9.8 6.5 34.7 63.1 2.1 BZ4 6.9 40.5 54.2 5.4 4.5 54.0 45.1 0.9 BZ5 5.3 43.1 52.9 4.0 3.6 56.1 43.3 0.6 BZ6 7.2 33.0 62.9 4.0 7.0 29.7 69.3 1.0 表层沉积物 新江心沙周边 42.0 14.8 47.1 38.1 74.5 10.9 43.5 45.6 崇头−青龙港 47.8 12.7 46.6 40.8 63.2 9.4 44.0 46.5 青龙港−头兴港 80.1 12.6 32.5 54.9 64.6 9.3 50.1 40.6 头兴港−连兴港 9.8 28.1 64.6 7.3 9.5 27.5 66.5 5.9
下载: 导出CSV
-
[1] Coleman J M, Gagliano S M, Smith W G. Sedimentation in Malaysian high-tide tropical delta: ABSTRACT[J]. AAPG Bulletin, 1967, 51(3): 459. [2] Wolanski E, King B, Galloway D. Salinity intrusion in the Fly River estuary, Papua New Guinea[J]. Journal of Coastal Research, 1997, 13(4): 983−994. [3] Fagherazzi S, Overeem I. Models of deltaic and inner continental shelf landform evolution[J]. Annual Review of Earth and Planetary Sciences, 2007, 35: 685−715. doi: 10.1146/annurev.earth.35.031306.140128 [4] Song Dehai, Wang Xiaohua, Zhu Xueming, et al. Modeling studies of the far-field effects of tidal flat reclamation on tidal dynamics in the East China Seas[J]. Estuarine, Coastal and Shelf Science, 2013, 133: 147−160. doi: 10.1016/j.ecss.2013.08.023 [5] Aldridge J N. Hydrodynamic model predictions of tidal asymmetry and observed sediment transport paths in Morecambe Bay[J]. Estuarine, Coastal and Shelf Science, 1997, 44(1): 39−56. doi: 10.1006/ecss.1996.0113 [6] Wang Z B, Jeuken M C J L, Gerritsen H, et al. Morphology and asymmetry of the vertical tide in the Westerschelde estuary[J]. Continental Shelf Research, 2002, 22(17): 2599−2609. doi: 10.1016/S0278-4343(02)00134-6 [7] Prandle D. Relationships between tidal dynamics and bathymetry in strongly convergent estuaries[J]. Journal of Physical Oceanography, 2003, 33(12): 2738−2750. doi: 10.1175/1520-0485(2003)033<2738:RBTDAB>2.0.CO;2 [8] Bolle A, Wang Zhengbing, Amos C, et al. The influence of changes in tidal asymmetry on residual sediment transport in the Western Scheldt[J]. Continental Shelf Research, 2010, 30(8): 871−882. doi: 10.1016/j.csr.2010.03.001 [9] Barnard P L, Erikson L H, Elias E P L, et al. Sediment transport patterns in the San Francisco Bay Coastal System from cross-validation of bedform asymmetry and modeled residual flux[J]. Marine Geology, 2013, 345: 72−95. doi: 10.1016/j.margeo.2012.10.011 [10] 陈吉余, 沈焕庭, 恽才兴, 等. 长江河口动力过程和地貌演变[M]. 上海: 上海科学技术出版社, 1988.Chen Jiyu, Shen Huanting, Yun Caixing, et al. Processes of Dynamics and Geomorphology of the Changjiang Estuary[M]. Shanghai: Shanghai Scientific and Technical Publishers, 1988. (查阅网上资料, 未找到本条文献英文翻译, 请确认) [11] Guo Leicheng, Xie Weiming, Xu Fan, et al. A historical review of sediment export–import shift in the North Branch of Changjiang Estuary[J]. Earth Surface Processes and Landforms, 2021, 47(3): 1−13. [12] 陈宝冲. 长江口北支河势的变化与水、沙、盐的输移[J]. 地理科学, 1993, 13(4): 346−352.Chen Baochong. The change of the general form and the transport of the water, load and salt in the North-Branch of the Changjiang River mouth[J]. Scientia Geographica Sinica, 1993, 13(4): 346−352. [13] 罗小峰, 陈志昌. 径流和潮汐对长江口盐水入侵影响数值模拟研究[J]. 海岸工程, 2005, 24(3): 1−6. doi: 10.3969/j.issn.1002-3682.2005.03.001Luo Xiaofeng, Chen Zhichang. Numerical simulation study of effect of runoff and tide on the Changjiang River mouth saltwater intrusion[J]. Coastal Engineering, 2005, 24(3): 1−6. doi: 10.3969/j.issn.1002-3682.2005.03.001 [14] 陈沈良, 严肃庄, 李玉中. 长江口及其邻近海域表层沉积物分布特征[J]. 长江流域资源与环境, 2009, 18(2): 152−156. doi: 10.3969/j.issn.1004-8227.2009.02.010Chen Shenliang, Yan Suzhuang, Li Yuzhong. Characteristics of surface sediment distribution in the Yangtze Estuary and its adjacent waters[J]. Resources and Environment in the Yangtze Basin, 2009, 18(2): 152−156. doi: 10.3969/j.issn.1004-8227.2009.02.010 [15] 李伯昌, 余文畴, 陈鹏, 等. 长江口北支近期水流泥沙输移及含盐度的变化特性[J]. 水资源保护, 2011, 27(4): 31−34. doi: 10.3969/j.issn.1004-6933.2011.04.008Li Bochang, Yu Wenchou, Chen Peng, et al. Variation characteristics of sediment transport and salinity in north branch channel of Yangtze River estuary in recent years[J]. Water Resources Protection, 2011, 27(4): 31−34. doi: 10.3969/j.issn.1004-6933.2011.04.008 [16] 陈炜, 李九发, 李占海, 等. 长江口北支强潮河道悬沙运动及输移机制[J]. 海洋学报, 2012, 34(2): 84−91.Chen Wei, Li Jiufa, Li Zhanhai, et al. The suspended sediment transportation and its mechanism in strong tidal reaches of the North Branch of the Changjiang Estuary[J]. Haiyang Xuebao, 2012, 34(2): 84−91. [17] 赵方方, 李占海, 李九发, 等. 长江口北支小潮至大潮水沙输运机制研究[J]. 泥沙研究, 2013(4): 55−62. doi: 10.3969/j.issn.0468-155X.2013.04.009Zhao Fangfang, Li Zhanhai, Li Jiufa, et al. Mechanism of water and suspended sediment transport from neap tide to spring tide in North Branch of Changjiang Estuary[J]. Journal of Sediment Research, 2013(4): 55−62. doi: 10.3969/j.issn.0468-155X.2013.04.009 [18] Dai Zhijun, Fagherazzi S, Mei Xuefei, et al. Linking the infilling of the North Branch in the Changjiang (Yangtze) estuary to anthropogenic activities from 1958 to 2013[J]. Marine Geology, 2016, 379: 1−12. doi: 10.1016/j.margeo.2016.05.006 [19] 周春煦. 长江口盐水入侵特征及规律[J]. 长江科学院院报, 2018, 35(12): 28−33. doi: 10.11988/ckyyb.20170434Zhou Chunxu. Characteristic and law of saltwater intrusion in Yangtze River Estuary[J]. Journal of Yangtze River Scientific Research Institute, 2018, 35(12): 28−33. doi: 10.11988/ckyyb.20170434 [20] 朱巧云, 张志林, 乔红杰. 长江口北支河段整治工程实施后沉积物特征分析[J]. 人民长江, 2019, 50(10): 26−31.Zhu Qiaoyun, Zhang Zhilin, Qiao Hongjie. Analysis on sediment characteristics after harnessing project implement in North Branch of Yangtze Estuary[J]. Yangtze River, 2019, 50(10): 26−31. [21] 乔红杰, 刘大伟, 闻卫东, 等. 2022年长江口北支咸水倒灌传播特征分析[J]. 人民长江, 2023, 54(2): 63−69.Qiao Hongjie, Liu Dawei, Wen Weidong, et al. Diffusion characteristics of saltwater intrusion in north branch of Yangtze River Estuary in 2022[J]. Yangtze River, 2023, 54(2): 63−69. [22] 王凌霄, 戴志军, 梅雪菲, 等. 长江口南北支分流口江心洲动力地貌变化过程研究[J]. 海洋通报, 2024, 43(5): 595−607.Wang Lingxiao, Dai Zhijun, Mei Xuefei, et al. Study on morphodynamic change process of mid-channel bar at distributary mouth of North and South branches of the Changjiang Estuary[J]. Marine Science Bulletin, 2024, 43(5): 595−607. [23] 季永兴, 李路, 袁琳, 等. 长江口北支上段岸滩侵蚀及保护实施效果分析[J]. 海洋地质前沿, 2024, 40(2): 11−19.Ji Yongxing, Li Lu, Yuan Lin, et al. Beach erosion and protection effect analysis on the upstream of the North Branch of the Changjiang (Yangtze) Estuary[J]. Marine Geology Frontiers, 2024, 40(2): 11−19. [24] 闵凤阳, 汪亚平, 高建华, 等. 长江口北支潮周期尺度水沙通量及分流分沙比[C]//第十四届中国海洋(岸)工程学术讨论会论文集. 北京: 海洋出版社, 2009: 7.Min Fengyang, Wang Yaping, Gao Jianhua, et al. Water sediment flux, water and sediment spilt ratio of North Branch of Yangtze Estuary in a tidal cycle scale[C]//The 14th China Ocean(Coast)Engineering Workshop Proceedings. Beijing: China Ocean Press, 2009: 7. (查阅网上资料, 未找到本条文献英文翻译, 请确认) [25] 周良平, 周东泉, 杜德军, 等. 长江北支进口段演变特征及治理[J]. 水运工程, 2022(12): 128−133,169. doi: 10.3969/j.issn.1002-4972.2022.12.020Zhou Liangping, Zhou Dongquan, Du Dejun, et al. Evolution characteristics and treatment of inlet section of northern branch of the Yangtze River[J]. Port & Waterway Engineering, 2022(12): 128−133,169. doi: 10.3969/j.issn.1002-4972.2022.12.020 [26] 陈沈良, 谷国传, 刘勇胜. 长江口北支涌潮的形成条件及其初生地探讨[J]. 水利学报, 2003, 34(11): 30−36. doi: 10.3321/j.issn:0559-9350.2003.11.005Chen Shenliang, Gu Guochuan, Liu Yongsheng. Formation conditions and initial site of tidal bore in the north branch of Yangtze River estuary[J]. Journal of Hydraulic Engineering, 2003, 34(11): 30−36. doi: 10.3321/j.issn:0559-9350.2003.11.005 [27] 刘曦, 杨丽君, 徐俊杰, 等. 长江口北支水道萎缩淤浅分析[J]. 上海地质, 2010, 31(3): 35−40.Liu Xi, Yang Lijun, Xu Junjie, et al. The evolution of the North Branch of Yangtze River Estuary characterized by being narrower and shallower[J]. Shanghai Geology, 2010, 31(3): 35−40. [28] 冯凌旋, 李九发, 戴志军, 等. 近年来长江河口北支水沙特性与河槽稳定性分析[J]. 海洋学研究, 2009, 27(3): 40−47. doi: 10.3969/j.issn.1001-909X.2009.03.006Feng Lingxuan, Li Jiufa, Dai Zhijun, et al. Analysis of the river channel stability and the characteristics of suspended sediment and water in the North Branch of the Changjiang River Estuary in recent years[J]. Journal of Marine Sciences, 2009, 27(3): 40−47. doi: 10.3969/j.issn.1001-909X.2009.03.006 [29] Yang Haifei, Li Bochang, Zhang Chaoyang, et al. Recent spatio-temporal variations of suspended sediment concentrations in the Yangtze Estuary[J]. Water, 2020, 12(3): 818. doi: 10.3390/w12030818 [30] 张二凤, 陈沈良, 谷国传, 等. 长江口北支悬沙浓度及输移的时空变化[J]. 海洋学报, 2015, 37(9): 138−151. doi: 10.3969/j.issn.0253-4193.2015.09.014Zhang Erfeng, Chen Shenliang, Gu Guochuan, et al. Temporal and spatial variations in suspended sediment concentration and transport in the North Branch of the Yangtze Estuary[J]. Haiyang Xuebao, 2015, 37(9): 138−151. doi: 10.3969/j.issn.0253-4193.2015.09.014 [31] 游博文, 张国安, 李一鸣, 等. 近30年来长江口北支及口外沉积特征及输移趋势[J]. 长江流域资源与环境, 2018, 27(10): 2328−2338.You Bowen, Zhang Guoan, Li Yiming, et al. Sediment characteristics and transport trend in North Branch and offshore area of Yangtze Estuary in the last 30 years[J]. Resources and Environment in The Yangtze Basin, 2018, 27(10): 2328−2338. [32] 张二凤, 陈沈良, 刘小喜. 长江口北支异常强盐水入侵观测与分析[J]. 海洋通报, 2014, 33(5): 491−496. doi: 10.11840/j.issn.1001-6392.2014.05.002Zhang Erfeng, Chen Shenliang, Liu Xiaoxi. Observation and analysis of abnormal strong saltwater intrusion in the North Branch of the Yangtze Estuary[J]. Marine Science Bulletin, 2014, 33(5): 491−496. doi: 10.11840/j.issn.1001-6392.2014.05.002 [33] Zhu Jianrong, Cheng Xinyue, Li Linjiang, et al. Dynamic mechanism of an extremely severe saltwater intrusion in the Changjiang estuary in February 2014[J]. Hydrology and Earth System Sciences, 2020, 24(10): 5043−5056. doi: 10.5194/hess-24-5043-2020 [34] 吴增斌. 潮控河道水沙净输运机制研究—以长江口北支为例[D]. 上海: 华东师范大学, 2022.Wu Zengbin. Sediment transport in tide-dominated channels: A case study of the North Branch in the Yangtze Estuary[D]. Shanghai: East China Normal University, 2022. [35] 潘存鸿, 郑君, 胡成飞, 等. 钱塘江涌潮影响因素研究[J]. 泥沙研究, 2023, 48(1): 13−20.Pan Cunhong, Zheng Jun, Hu Chengfei, et al. Study on the impact factors of tidal bore on the Qiantang River[J]. Journal of Sediment Research, 2023, 48(1): 13−20. [36] 陈沈良, 陈吉余, 谷国传. 长江口北支的涌潮及其对河口的影响[J]. 华东师范大学学报(自然科学版), 2003, 2003(2): 74−80.Chen Shenliang, Chen Jiyu, Gu Guochuan. The tidal bore on the North Branch of Changjiang Estuary and its effects on the estuary[J]. Journal of East China Normal University(Natural Sciences), 2003, 2003(2): 74−80. [37] Chen Jiyu, Eisma D, Hotta K, et al. Engineered Coasts[M]. Springer, 2002: 185−197. (查阅网上资料, 未找到本条文献出版地, 请确认) -
图(10) / 表(3)
计量
- 文章访问数: 111
- HTML全文浏览量: 33
- PDF下载量: 40
- 被引次数: 0
