潮汐水位和盐度变化耦合条件下河口海滩地下水排泄及盐分运移规律研究

项目名称： 潮汐水位和盐度变化耦合条件下河口海滩地下水排泄及盐分运移规律研究

项目编号： No.41302205

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 天文学、地球科学

项目作者： 夏玉强

作者单位： 长江水利委员会长江科学院

项目金额： 26万元

中文摘要： 河口海滩是陆地-海洋交界带的中心区域，是海水（咸水）和地下水（淡水）相互作用和转化的重要场所。近30年来，许多学者对潮汐水位变化作用下的海滩地下水-地表水交互过程进行了广泛研究，但极少关注潮汐引起的河口水域盐度变化（指感潮河地表水盐度随潮汐周期性变化的现象）对海滩地下水动力过程的影响。而盐度在维持海滩生物多样性等方面发挥着重要作用。本项目将以长江河口海滩为研究对象，结合现场原型实验及其监测、数学模型和数值模拟等综合技术手段，系统定量地研究潮汐水位和盐度变化耦合条件下海滩中地下水流和盐分运移的规律。通过敏感性分析，综合考虑该条件下海滩地表渗出面、非均质性等因素对海滩地下水-地表水交换率、海底地下水排泄量（SGD）和海滩中盐度分布（咸淡水混合带/交界面）的影响。该项目将有助于阐明长江河口海滩的海水入侵、咸淡水混合等复杂地下水动力过程，为该类河口海滩生态环境的保护和管理提供理论依据和技术支撑。

中文关键词： 河口潮汐盐度变化；地下水排泄；浅层海滩；盐晕；数值模拟

英文摘要： Numerical simulations of groundwater flow and solute transport in beaches have rapidly evolved over the last three decades accounting for tidal hydraulics and for seaward boundary condition. Most of these studies focused on tide-induced variation of groundwater hydraulic head but with a constant surface water salinity on the seaward boundary. In reality, salinity in tidal creeks varies in response to the combined influences of saline tides from downstream estuary and freshwater flow from upstream river. Existing observations and reports indicated that the variations of salinity in tidal creek are typically corresponding with its water level fluctuations, referring to "tidal salinity fluctuations". The primary goal of this project is to explore the influences of tidal level and salinity fluctuations in estuary on the submarine groundwater discharge (SGD) and solute transport in shallow beaches with sloped intertidal zone. Field study in typical intertidal zone of Changjiang River estuary, laboratory experiments and numerical modelling techniques will be employed for this propose. Sensitivity analyses will be conducted to investigate the effects of seepage face, inland freshwater recharge, and beach permeability on the distribution of salt plumes (freshwater-saltwater interface/mixing zone) in the beach and the SG

英文关键词： Tidal salinity fluctuations；Submarine groundwater discharge (SGD)；Shallow beaches；Saline plumes；Numerical simulation