近岸人工沙坝养滩的喂养效应研究

Nearshore bar nourishment is an effective strategy for soft beach protection with growing interests for coastal engineers and scientists. Although the lee effect of a nourished bar has been extensively studied, the onshore migration and the feeder effect of a nourished bar are still poorly understood and difficult to predict, due to the incomplete understanding of sediment transport mechanism under wave-undertow interaction. This study aims to improve our knowledge of the feeder effect and eventually the predictability of the nourished bar evolution. Physical experiments are carried out in which the different antecedent bathymetry, bar designs and prevailing wave conditions are considered. From the aspects of hydrodynamics, sediment dynamics and morphological response, the measured data will be used to investigate the effects of a submerged bar on wave and current motion, the sediment transport mechanism for onshore nourished bar migration and bar shape transformation, and the interaction between nourished bar and natural bar/berm. The key scientific points include the non-equilibrium evolution of wave nonlinearities and breaking roller over steep slopes and sharply changed bathymetry, the spatial and temporal evolution of the sediment transport pattern under wave-undertow interaction, and the sand exchange mechanism between nourished bar and natural bar/berm. The improved physical understanding will favor the development of a process-based numerical model for nourished bar evolution. We anticipate this study to provide better theoretical basis and numerical tools for nearshore bar nourishment projects.

近岸人工沙坝养滩已成为逐渐兴起的高效软性海岸防护手段。以往研究集中在人工沙坝的消浪特性及其对海滩的遮蔽效应，但受限于复杂地形条件下波浪向岸输沙和底部离岸流输沙的互制机理尚未得到清楚认识，仍难以解释和预测人工沙坝向岸移动并填补滩肩的喂养效应。本项目将设计不同初始地貌形态、人工沙坝参数和入射波浪条件的物模实验，在水动力演化、泥沙输运和地貌响应三个层面上，对近岸人工沙坝养滩的喂养效应开展系统性研究，具体包括：1）人工沙坝地形突变对波流演化特性的影响机制；2）人工沙坝向岸移动和形态演变的波流互制输沙机理；3）喂养过程中的人工沙坝-天然地貌相互作用机制。重点解决陡变地形和突变水深条件下的波浪非线性和破波水滚非稳态演化机制、波浪和底部离岸流互制输沙格局的时空变化特性、人工沙坝与天然沙坝/滩肩的泥沙交换机制等关键科学问题，旨在阐明近岸人工沙坝养滩的喂养机理，为实际养滩工程提供科学依据。

近岸人工沙坝养滩已成为逐渐兴起的高效软性海岸防护手段。以往研究集中在人工沙坝的消浪特性及其对海滩的遮蔽效应，但受限于复杂地形条件下波浪向岸输沙和底部离岸流输沙的互制机理尚未得到清楚认识，仍难以解释和预测人工沙坝向岸移动并填补滩肩的喂养效应。本项目将设计不同初始地貌形态、人工沙坝参数和入射波浪条件的物模实验，在水动力演化、泥沙输运和地貌响应三个层面上，对近岸人工沙坝养滩的喂养效应开展系统性研究。揭示了人工沙坝引起的地形突变对波浪非线性演化的影响机理，阐明了人工沙坝向岸迁移过程中的波流互制输沙机制，厘清了人工沙坝与天然滩肩的地貌形态耦合规律，为我国海滩养护修复提供科学依据与技术支撑，服务我国海岸带保护修复领域的科技进步。通过项目组全体成员的共同努力，本项目研究达到了预期目标。共发表期刊论文19篇，出版专著1部，授权发明专利7项，计算机软件著作权1项。在项目研究成果的支持下，获2019年度福建省科学技术进步奖一等奖、2021年中国航海学会科技进步奖一等奖、2021年中国水运建设行业协会科学技术奖二等奖。项目执行期间，培养博士后2名，博士研究生3名，硕士研究生5名。项目负责人入选国家级青年人才计划。