连续风暴对潮滩冲淤过程的影响机制研究

The tidal flats on the estuary and coast is an important landform in the coastal system. It plays an important environmental and ecological function. However, it is also a sensitive and vulnerable system. Its geomorphic stability is highly susceptible to storm events. Studying the response of the tidal flats’ erosion-accretion process to different types of storms is very important to understand the mechanism of tidal flats’ erosion and accretion behavior, as well as the stability of tidal wetlands. Previous studies have focused on the effects of landing typhoons. Less attention has been paid to the effects of distant storms, and their cumulative effects combined with landing storms on the morphological evolution of tidal wetlands. In this study, the applicant is going to carry out the field measurements of hydrodynamic, sediment dynamic, bed-level change parameters on a typical tidal flat in the estuarine and coastal area. Combined with meteorological data and numerical modelling analysis, this study is aimed to reveal the impact of continuous storms, typically the cumulative effects, on the erosion-accretion and related sedimentary processes of the tidal flats in a systematic way, so as to improve the understanding of the bed-level changes of the tidal wetlands during storm seasons. The findings are expected to provide important bases to the establishment and improvement of relevant numerical models, and to the study of coastal protection, disaster warning and prevention in the coastal area.

潮滩是海岸系统中重要的地貌形态，发挥着重要的生态环境服务功能，同时也是较为敏感脆弱的系统，其地貌稳定性极易受到风暴事件的影响。研究潮滩冲淤过程在风暴季节对不同类型和特征的连续风暴的响应，对于全面深入掌握潮滩冲淤机制及系统稳定性具有重要意义。早期的研究多聚焦于登陆风暴的影响，缺乏对远程风暴及其与登陆风暴形成的连续风暴产生的累积效应对潮滩地貌影响的认识。本项目拟选择典型河口海岸的潮滩，基于现场水动力-泥沙-冲淤同步观测，并结合气象资料，运用冲淤模型分析，系统性揭示连续风暴及其累积效应对潮滩的冲淤过程及相关的沉积动力过程的影响，加深对风暴过程中潮滩冲淤规律和机制的认识，为相关数值模型的建立和完善提供重要的依据，并为相关的海岸防灾减灾、灾害预警研究提供重要参考。

潮滩是海岸系统中重要的地貌形态，发挥着极强的生态环境服务功能，同时也是较为敏感脆弱的系统，其地貌稳定性极易受到风暴事件的影响。研究风暴影响下淤泥质潮滩的泥沙输运、沉积动力过程、底床稳定性对于全面深入掌握潮滩冲淤机制及系统稳定性具有重要意义。本项目围绕“连续风暴对潮滩冲淤的影响机制”这一核心科学问题，通过原位观测、室内实验和数值模拟相结合的方式，分析风暴条件下不同粒径的细颗粒泥沙的侵蚀-沉降特性和高浊度层形成机制；解析风暴作用强度与潮滩上的水动力过程与冲淤之间的联系，探讨风暴距离和强度对潮滩冲淤过程的影响机制；探讨连续风暴作用条件下潮滩底床稳定性。主要研究结果包括：（1）通过对台风中心距离和近岸水动力、冲淤相关分析表明，即使台风中心远在1000千米以外，近岸沉积动力环境也会收到台风影响，揭示了远程风暴对近岸潮滩沉积动力过程的影响规律；（2）原位观测和室内实验表明风浪条件下细颗粒环境容易形成近底高浊度层，粒径更细的颗粒更容易被上扬到上层水体增加悬沙浓度，高浊度层形成近底湍流阻滞形成复杂的絮凝沉降，本研究进一步优化了高浊度细颗粒环境的沉降模式；（3）连续波浪–潮流–湍流–悬沙浓度–底床冲淤监测表明，遮蔽型潮滩长期而言相对稳定，但极易受到环境扰动发成短期冲淤变化，冲淤模式因水流和波浪强度变化呈现出一定规律，气候变化和人类活动影响下风暴频次和强度的增加可能降低其稳定性。基于项目研究结果发表了SCI论文5篇，相关成果为系统性掌握极端天气下的潮滩冲淤演变过程、滨海湿地保护修复和海岸防灾减灾研究提供提供了基础科学依据。