| 崇明东北潮滩泥沙输运过程的研究 |
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| 引用本文： | 闫天阳,葛建忠,王宪业,周在扬,陆佳玉,丁平兴.崇明东北潮滩泥沙输运过程的研究[J].海洋通报,2021(1). |
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| 作者姓名： | 闫天阳 葛建忠 王宪业 周在扬 陆佳玉 丁平兴 |
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| 作者单位： | 华东师范大学 河口海岸学国家重点实验室， 上海 200241;华东师范大学 河口海岸学国家重点实验室， 上海 200241；崇明生态研究院，上海 200241 |
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| 基金项目： | 国家重点研发计划 （2016YFA0600903；2017YFE0107400）；国家自然科学基金 （41776104） |
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| 摘 要： | 潮滩泥沙的输运过程是河口近岸泥沙输运的重要组成部分,也是诊断潮滩侵蚀-淤积的重要动力指标,特别是在地貌演变过程显著的区域更具指示意义。本研究选择长江口崇明岛东北部潮滩,在2018年3月30日—4月10日进行三脚架多参数观测,获取了高分辨率的流速、含沙量等剖面数据,运用机制分解法分析了连续21个潮周期的泥沙输运过程。结果表明:崇明东北侧潮滩观测站位的含沙量从观测开始至大潮阶段不断增大,在此期间底部含沙量也出现了最大值(7.82 g·L~(-1))。大潮过后直到小潮期间含沙量逐渐减少;观测站位单宽净输沙量有着明显的潮周期差异,从数量上看,大潮期间的单宽净输沙量为1.61×10~4kg·m~(-1),中潮期间为8.28×10~3kg·m~(-1),均远远大于小潮期间的单宽净输沙量,从方向上看,则具有大潮和小潮向口内,中潮向口外的泥沙净输运方向差异;大潮和中潮内的单宽输沙率均大于0.17 kg·m~(-1)·s~(-1),远大于小潮时的单宽输沙率。对各项输沙机制的结果分析来看,"潮泵效应"对输沙量的贡献最大,平流输运次之,而由于水深较浅,垂向环流对输运量影响较小。在观测期间出现了显著的从潮滩向主槽的泥沙输运。总体上看,潮滩泥沙输运过程指示了显著的向口内和主槽的泥沙输运,是北支河口区域泥沙淤积的重要来源。
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| 关 键 词： | 崇明东北滩地 机制分解法 泥沙输运 |
| 收稿时间： | 2020/7/10 0:00:00 |
| 修稿时间： | 2020/9/23 0:00:00 |
Study of sediment transport on tidal flat of northeast Chongming Island |
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| YAN Tianyang,GE Jianzhong,WANG Xianye,ZHOU Zaiyang,LU Jiayu,DING Pingxing.Study of sediment transport on tidal flat of northeast Chongming Island[J].Marine Science Bulletin,2021(1). |
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| Authors: | YAN Tianyang GE Jianzhong WANG Xianye ZHOU Zaiyang LU Jiayu DING Pingxing |
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| Institution: | State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China;;State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China;Institute of Eco-Chongming, Shanghai 200241, China) |
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| Abstract: | The transportation process of sediment on tidal flat is a vital composition of the sediment transportation at estuarine and nearshore area. Moreover, it is a key dynamic index to analyze the erosion-deposition of the tidal flat, especially in the region where the morphology evolution is significant. The research of this paper focused on the tidal flat at northeast of Chongming Island, where the morphological process is apparent. During March 30th - April 10th in 2018, a tripod equipped with instruments was placed at this area to collect high-resolution data of velocity and suspended sediment concentratione along the vertical profile, meanwhile the sediment transportation during the 21 tide cycles was studied by using mechanical decomposition. The result depicted that suspended sediment concentratione of study site increased gradually from the beginning of the measurement to spring, suspended sediment concentratione up to 7.82 g×L-1 which is the maximum value showedup in this period, while from the end of spring till neap , however, decreased gradually. Net unit width sediment transportation performed differently during spring, medium tide and neap, on the term of magnitude a net sediment transportation of 1.61×104kg×m-1 is calculated during spring, meanwhile this figure is 8.28×103kg×m-1 during medium tide, magnitude of net sediment transport in both spring and medium tide are far more significantly larger than it in neap. The direction of net transportation of sediment in spring and neap are similar to the direction of flood, notably transported to the North Branch; and it
reversed in medium tide. The unit width sediment transportation rate is more than 0.17 kg×m-1×s-1 during spring and medium tide, far more exceeded the transportation rate in neap tide. According to the analysis of the result of mechanical decomposition, tidal pumping effect contributes more to the sediment transportation; advection transportation is the next, besides, since the water level is low, transportation due to vertical cycle during tidal cycle is negligible. The sediment transportation process on the tidal flat indicted conspicuous transportation of sediment towards the mouth of North Branch and main channel, and the tidal flat is the important source of the sediment deposition around North Branch area |
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| Keywords: | tidal flat of northeast Chongming Island mechanical decomposition sediment transport |
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