丝瓜影院

水文学术报告两则

发布者:指导老师(2019-06-06)

报告题目一:Principle of Parsimony, Fake Science, and Scales(精简原则、伪科学及尺度问题)

Tian-Chyi Jim Yeh, Department of Hydrology and Atmospheric Sciences, The University of Arizona, USA

报告时间:201968日上午9:00-10:00

报告地点:科技园创新大厦515会议室

报告内容:Environmental fluids migrate at velocities of many scales, influenced by many factors at a multiplicity of scales. Due to difficulties in predicting exact motions of water molecules, and consideration of the scale of our interests (bulk behaviors of many molecules), Fick’s law (diffusion concept) has been developed for predicting solute diffusion process in space and time. Further, G.I. Taylor (1921) demonstrated that the random motion of the molecules reach the Fickian regime in less a second and will reach the ergodic condition if our sampling scale is large enough. Fick’s law is widely accepted for describing molecular diffusion as such.This fits the definition of the parsimony principle at the scale of our concern.

Similarly, advection-dispersion or convection-dispersion equation (ADE or CDE) generally has been found suitable for predicting solute concentration breakthroughs in uniformly packed soil columns. This is due to the fact that the solute is released over the entire cross-section of the column, and it thus has encountered many pore-scale heterogeneities and met the ergodicity assumption. Further, the uniformly packed column contains a large number of stationary pore-size heterogeneity. The solute thus can reach the Fickian regime after traveling a short distance along the column. Besides, observed breakthrough curves are the concentrations integrated over the column cross-section (the scale of our interest), andthey meet the ergodicity assumption embedded in the ADE and CDE.

To the contrary, scales of heterogeneity in most groundwater pollution problems evolve as contaminants travel. They are much larger than the scale of our observations and our interests. The ergodic and the Fickian conditions are thus difficult to be met. Upscaling and modifying Fick’s law for solute dispersion, and deriving universal scaling rules of the dispersion for the field- or basin-scale pollutant migrations are merely misuse of the parsimony principle.They create red herrings and fake sciences ( i.e., the development of theories for predicting processes that can not be observed.)The appropriate principle of parsimony for these situations is to map large-scale heterogeneities as detailed as possible (or to the scale of our observations and interests) and to adapt Fick’s law for effects of small-scale heterogeneity resulting from our inability to characterize them at high resolutions.

报告人简介:叶天齐(Tian-Chyi Jim Yeh)教授为著名地下水专家、美国Arizona大学水文水资源系终身教授。主要研究领域是地下水及溶质运移,他首次发现了非饱和水力传导度各向异性与含水量之间的依赖关系,3篇经典论文已被引用600余次。近年来,他开发了一种全新的数据分析、处理软件(Vsaft2D, Vsaft3D),此数据处理分析技术具有巨大发展前景,解决本领域大量数据难于分析的问题。

  

报告题目二: 气候变化和人类活动对中国北方岩溶泉水流量的影响

: 郝永红,教授,天津师范大学水资源与水环境重点实验室

报告时间: 201968日上午10:20-11:30

报告地点:科技园创新大厦515会议室

报告内容: 具体介绍以下研究工作: ①将灰色系统理论引入岩溶水文学,建立了岩溶地下水传播的灰色系统模型,获得了岩溶地下水水力响应时间的灰色计算方法,准确模拟了岩溶地下水压力波传播的过程;②将小波分析方法应用于降水与泉水流量分析中,从能量传播的角度解释了岩溶地下水运动与扩散过程;③运用水力层析技术对含水层裂隙带和岩溶管道进行了识别,为寻找地下水“水脉”提供了有效方法;④运用分阶段模拟分析法研究了气候变化与人类活动对岩溶泉流量的影响,为寻找北方岩溶大泉流量衰减与枯竭的原因进行了初步探索;⑤将极值统计理论应用于岩溶水文学,分析了极端气候变化条件下岩溶泉流量变化过程。

报告人简介:永红教授主要从事地下水数值模拟研究与教授工作。主持完成国家自然科学基金面上项目3项,省部级项目5,正在主持天津市自然科学基金重点项目1项。在国内外重要学术期刊发表论文50余篇,其中40余篇被美国科技索引系统(SCI)收录。

  

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