长江口特大洪水浑浊带悬沙粒度分布特征  

The distribution of suspended sediment grain size in Changjiang Estuary turbidity maximum zone during the extreme flood

作　　者：董坚 何青[1] 林建良 陈嘉民 周思敏 徐凡 谢卫明 郭磊城 DONG Jian;HE Qing;LIN Jianliang;CHEN Jiamin;ZHOU Simin;XU Fan;XIE Weiming;GUO Leicheng(State Key Laboratory of Estuarine and Coastal Research,East China Normal University,Shanghai 201100,China;Delft University of Technology,Delft 2600 GA,Netherlands)

机构地区：[1]华东师范大学河口海岸学国家重点实验室,上海201100 [2]Delft University of Technology,Delft 2600 GA,Netherlands

出　　处：《海洋通报》2023年第1期48-58,共11页Marine Science Bulletin

基　　金：国家自然科学基金重点项目(U2040216;51739005);国家自然科学基金(51909101);国家自然科学基金青年基金(42006150);科技部政府间(中荷)国际科技创新合作重点项目(2016YFE0133700);上海市科委重点项目(20DZ1204701);上海科委国际合作项目(19230711900)。

摘　　要：2020年长江流域发生了历史第二大洪水,大通站洪峰流量达到84500 m^(3)/s。本文基于2020年7月长江口特大洪水期间最大浑浊带多站位的水沙观测数据,重点分析了悬沙粒度组分的时空分布特征,并与常态水文条件下的粒度数据进行对比。结果表明:(1)最大浑浊带悬沙垂向平均中值粒径为10.4μm,变化范围为6~27μm,以黏性细颗粒泥沙为主;其中核心区南槽、北槽及北港的中值粒径分别为8.4μm、7.6μm和8.5μm,过渡区分别为7.2μm、16.4μm和14.5μm。(2)悬沙中值粒径垂向分布受不同组分影响,核心区底层中值粒径为8.8~9.6μm;底层黏土含量在28%~31%之间,粉砂含量在61%~64%之间,中值粒径主要受黏土及粉砂组分影响;过渡区北港和北槽垂向平均砂组分高达19%,南槽砂组分平均仅占5%,中值粒径主要受砂组分影响。(3)对比2013年洪季浑浊带数据,2020年粒径整体增大5.4μm,核心区黏土含量相较2013年减少12.7%,砂增加6.3%;过渡区北槽与北港平均粒径增大10μm。The Changjiang River suffered the second largest flood in history in 2020,with a peak discharge of 84500 m^(3)/s at the Datong station.Based on the grain size data observed in the estuarine turbidity maximum(ETM)of the Changjiang River during the flood,the spatial-temporal distribution of median grain size and composition of suspended sediment were analyzed and compared with the data in normal hydrological conditions.The results show that depth-averaged median grain size in the ETM is 10.4μm and varied in a range of 6~27μm,dominated by cohesive fine-grained sediment.The median grain size in the core area of the ETM in the South Passage(SP),North Passage(NP),North Channel(NC)is 8.4μm,7.6μm,8.5μm,respectively,while 7.2μm,16.4μm,14.5μm in the seaward transition area.Different compositions of suspended sediment influenced the vertical distribution of median grain size.In the core area of ETM,the median grain size in the bottom layer ranged from 8.8 to 9.6μm,with clay in the range of 28%~31%and silt 61%~64%.In the seaward transition area,however,the suspended sediment was dominated by sand.The depth-averaged percentage of sand was up to 19%in the NP and the NC,while only 5%in the SP.Compared with the observations during the wet season in 2013,the median grain size enlarged by 5.4μm in 2020.In the core area of ETM,the depth-averaged percentage of clay decreased by 12.7%,while sand increased by 6.3%.In the seaward transition of the NP and the NC,the median grain size increased by 10μm.

关 键 词：长江口 浑浊带 悬沙粒径 泥沙组分 特大洪水 

分 类 号：P736.21[天文地球—海洋地质] TV148.1[天文地球—海洋科学]