长江下游崩岸段动力分区特征与地貌适应机制  

Characteristics of hydrodynamic zone and microgeomorphic adaptation mechanism of the bank failure section in the lower reaches of the Yangtze River

作　　者：陈锦锋 滕立志 刘瑞清 程和琴[1,2] 任仲达 金阳 张鸿[3] 贾正阳 周权平 邢海斌[4] CHEN Jinfeng;TENG Lizhi;LIU Ruiqing;CHENG Heqin;REN Zhongda;JIN Yang;ZHANG Hong;JIA Zhengyang;ZHOU Quanping;XING Haibin(State Key Laboratory of Estuarine and Coastal Research,East China Normal University,Shanghai 200062,China;Institute of Eco-Chongming,Shanghai 202150,China;Nanjing Center of the China Geological Survey,Nanjing 210016,China;Shanghai Huiyao Instrument Equipment Co.,Ltd.,Shanghai 201803,China)

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200062 [2]崇明生态研究院,上海202150 [3]中国地质调查局南京地质调查中心,南京210016 [4]上海绘耀仪器设备有限公司,上海201803

出　　处：《地理学报》2024年第9期2246-2260,共15页Acta Geographica Sinica

基　　金：国家自然科学基金项目(42271009);中国地质调查局项目(DD20221728)。

摘　　要：近年来长江下游潮区界上移、涉水工程建设增多,河道崩岸灾害强度增大。前人通过现场观测、物理模型、数值模拟发现崩岸段存在强烈竖轴回流,但未探讨滩槽交互带水动力分区特征及地貌的微观适应机制。本文基于频繁窝崩岸段多普勒声学流速剖面仪(ADCP)、多波束测深系统获得的高分辨率动力、地貌同步观测数据,结合以往高分辨水下地形资料,研究发现:滩槽交互带流速、流向具有显著分区特性,根据纵向流速u及其与横向流速v的比值|u/v|,即回流强度α,自槽向岸分为主流区(α<1,u>0)、掺混区(α≥1)和贴岸回流区(α<1,u≤0);主流区发育大中型沙波、冲刷槽、冲刷坑,掺混区发育堆积体、小型沙波,回流区发育有窝脊、小型沙波;主流区主流顶冲、回流区回流侧蚀是冲刷地貌发育、崩岸拓展的主要动力,掺混区近主流区一侧的高流速梯度产生冲刷地貌、其余部分低流速使泥沙落淤形成堆积体。本文可为崩岸灾害整治和近岸工程设计监测提供重要参考。In recent years,the tidal limit of the lower reaches of the Yangtze River has shifted upward,the construction of water-related projects has increased,and the intensity of river bank failure disasters has been on the rise.Previous researchers have found the existence of strong vertical-axial backflow in the bank failure section through field surveys,physical modeling,and numerical simulation,and that there is a strong vertical-axial backflow in the bank failure section;however,the hydrodynamic zone characteristics of the bank-channel interactive zone and the microgeomorphic adaptation mechanism have not been explored.Based on the Doppler acoustic current profiler(ADCP)in the frequent bank failure sections,multibeam system,combined with previous high-resolution underwater topographic data,it is found that the flow velocity and flow direction in the interactive zone of the bank-channel have significant zone characteristics,and according to the backflow strengthα,i.e.,the longitudinal flow velocity u and its ratio to the transverse flow velocity v,|u/v|,the zone from the channel to the bank is identified into the main stream zone(α<1,u>0),the mixing zone(α≥1),and the near-bank backflow zone(α<1,u<0).The mainstream zone develops large and medium-sized dunes,scour grooves,and scour pits,the mixing zone develops accumulators and small dunes,and the backflow zone develops spines and small dunes;the main stream direct flushing in the mainstream zone and the backflow lateral erosion in the backflow zone are the main driving forces for the development of scouring microgeomorphic type and the development of bank failures,and the high flow velocity gradient in the mixing zone near the main stream zone generates scouring geomorphology,and the remaining part of mixing zone remains a low flow-velocity to make the sediment fall and silt to form the accumulation body.The findings can provide important references for the disaster remediation and near-shore engineering design and monitoring.

关 键 词：滩槽交互带 切变灾害 水动力分区 微地貌 地貌演变 

分 类 号：P931.1[天文地球—自然地理学] TV85[水利工程—水利水电工程]