长江口崇明东滩响应风暴作用的沉积动力过程

Storms, being characterized by high frequency, strong destructiveness and poor predictability, are the primary marine disasters causing erosion of the delta and estuarine tidal flat. Understanding sediment dynamic response of estuarine tidal flat to storms is of vital significance to both stability maintenance of the coast and vulnerability assessment of the delta. In the case study of the Eastern Chongming Shoal (ECS), the largest sandbar edge tidal flat of the Changjiang Estuary, systematic survey involving hydrological, sedimentological and geomorphological data are planned to conduct during storms (including typhoons and winter storms). Then the statistical methods, the GIS technique and numerical modelling are carried out to quantitatively diagnose storm-induced changes of the hydrodynamic characteristics, adjustment of the sediment budget pattern and the erosion/deposition and recovery processes of the shore-face in different regions of the ECS’s intertidal flat and to clarify the linkage mechanism in the response of the shore-face dynamic-sediment-morphology to storms. Thereafter, an analytical model based on the dynamic equilibrium theory is proposed to predict the storm-period erosion/deposition and post-storm evolution of the tidal flat under storms of different intensities. The expected results can enrich the understanding of the land-ocean interactions under extreme high-energy environment, replenish the sediment dynamic theory, and provide scientific supports for the tidal flat utilization security and coastal defense stability.

高频率、强破坏及难预报的风暴是诱发河口三角洲及潮滩强侵蚀的主要海洋灾害。弄清河口潮滩响应风暴作用的沉积动力过程，对于维持岸滩稳定和评估三角洲脆弱性均具有重要的指示意义。申请者拟以长江口最大的沙州岸缘潮滩——崇明东滩为研究对象，开展并强化风暴期（包含台风和冬季风暴）水文、沉积和地形的多站点系统与集成观测，综合数理统计、GIS和数值模拟技术，定量诊断风暴作用下的崇明东滩不同潮间带区域的水动力变化特性、泥沙收支格局调整与滩面地形冲淤及恢复过程，阐明滩面动力-泥沙-地形冲淤响应风暴作用的联动机制；以此为基础提出基于动态平衡理论的潮滩风暴响应解析模型，预测不同风暴作用强度下的滩面冲淤及后续演化。预期成果可丰富对极端高能事件下河口陆海交互作用的认识，充实沉积动力学理论体系，为潮滩利用安全及海岸防护稳定提供科学支撑。

河口潮滩响应风暴作用的沉积动力过程研究，对于维持岸滩稳定具有重要的指导意义。本项目以长江口最大的沙洲前沿潮滩——崇明东滩为研究对象，开展并强化风暴期（包含台风和冬季风暴）水文、沉积和地形多站点集成观测，定量诊断风暴作用下的潮滩横向水动力变化特性、泥沙收支格局调整与地形冲淤模式转换，揭示潮滩动力-泥沙-地貌响应风暴作用的联动机制。.团队按照既定研究计划，在长江口典型潮滩有序开展一系列探索，包括：1）开展2次风暴针对性观测和1次半年期连续观测，成功捕捉到2次台风事件，构建潮滩响应风暴作用的沉积动力过程研究数据库；2）聚焦波浪动力，阐明不同波浪成分经过光滩和盐沼的衰减差异及机制，揭示风暴作用下盐沼植被运动状态转变和消浪效率减低模式，提出风暴期盐沼消浪效率算式；3）围绕沉积格局，阐明径流洪枯节律调控的潮滩沉积物搬运、堆积的季节性转换模式，揭示台风引发的沉积物横向输移异变和局部粗化过程，指出冬季风暴主导的潮滩大-中-小潮沉积分带迁移格局；4）针对地形冲淤，阐明人类活动引发的潮滩地貌模式转换，基于多时相遥感量化崇明东滩常态全局冲淤速率，揭示风暴作用下潮滩不同地貌单元的侵蚀-恢复规律及沉积动力机制。预期成果可丰富对极端高能事件下河口陆海交互作用的认识，充实沉积动力学理论体系，为潮滩利用安全及海岸防护稳定提供科学支撑。