报告题目: 复杂海岸带水文地质系统中宽混合带的形成机理
Title: Mechanisms Responsible for Thick Mixing Zones in Complex Coastal Hydrogeological Systems
报告地点：水电馆 401
报告时间：2014年12月3日14：00
报告人：鲁春辉博士
Department of Civil Engineering at Monash University (Australia)
报告人简介
鲁春辉，2011年毕业于美国佐治亚理工学院（Georgia Institute of Technology），获市政工程博士学位，现任澳大利亚莫纳什大学（Monash University）讲师；主要致力于海岸带海陆交互作用，地下水库工程，及井水力学等方面的学术研究，近年来以第一作者/通讯作者身份在 Nature Climate Change, Water Resources Research, Journal of Hydrology 等国际重要期刊上发表SCI论文20篇。获得2012-2013年度 Advances in Water Resources 杂志年度十大最高引用论文奖、2012澳大利亚弗林德斯大学杰出青年研究员校长奖、2013澳大利亚国家地下水研究和培训中心杰出研究奖及2014犹太人国立基金会的Ma'alot 360 环境奖。
报告主要内容：
Abstract:
The mixing zone developed at freshwater-seawater interface is one of the most important features in complex coastal hydrogeological systems, which controls subsurface flow and reactive transport dynamics. Freshwater-seawater mixing-zone development is influenced by many physical and chemical processes, such as characteristics of geologic formation, hydrodynamic fluctuations of groundwater and sea levels, fluid-rock interactions, and others. Thick mixing zones have been found in many coastal aquifers all over the world, but their mechanisms are not well understood.
In this talk, two hypotheses will be proposed to explain thick mixing zones in coastal aquifers: (1) kinetic mass transfer coupled with transient conditions, which create the movement of the mixing zone, may widen mixing zones; and (2) aquifer stratification may widen the mixing zone. The hypotheses are tested by both multi-scale numerical simulations and laboratory experiments. Major conclusions include (1) the mixing zone can be significantly widened when the mass transfer timescale and the period of transient boundary is comparable due to the nonequilibrium mass transfer effects; and (2) a thick mixing zone occurs in low-permeability layer when it overlays upon a fast flow layer. These results not only improve the understanding of the dynamics of mixing-zone development and its associated geochemical processes in coastal aquifers, but also identify hydrogeological conditions for the model of sharp-interface approximation to be valid.
