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嘉陵江流域骤发干旱时空演变特征分析

水利水电科技进展 2024年第4期44卷 23-30,58页

作者：孟长青董子娇刘柯莹王远坤张验科钟德钰华北电力大学水利与水电工程学院北京102206 清华大学水圈科学与水利工程全国重点实验室北京100084

为探究嘉陵江流域骤发干旱可识别特性与时空演变特征,基于标准化蒸发胁迫比研究了1980—2020年嘉陵江流域骤发干旱的时空分布特征,通过密度聚类算法提取骤发干旱斑块分析了斑块质心的轨迹变化,并探讨了骤发干旱暴发初期气象要素的异常... 详细信息

为探究嘉陵江流域骤发干旱可识别特性与时空演变特征,基于标准化蒸发胁迫比研究了1980—2020年嘉陵江流域骤发干旱的时空分布特征,通过密度聚类算法提取骤发干旱斑块分析了斑块质心的轨迹变化,并探讨了骤发干旱暴发初期气象要素的异常情况。结果表明:流域西北部骤发干旱强度更高且发展速度更快,流域南部骤发干旱持续时间更长;流域骤发干旱事件主要发生在4—11月,且骤发干旱事件的质心主要沿东北和西北方向迁移;嘉陵江流域的骤发干旱主要由高温和降水共同主导。

关键词：骤发干旱标准化蒸发胁迫比密度聚类算法质心迁移时空演变嘉陵江流域

A new mixing equation for bed material composition in bed form dominant conditions

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International Journal of Sediment Research 2022年第4期37卷 435-446页

作者： Baozhen Jia deyu zhong State Key Laboratory of Hydroscience and Engineering Tsinghua University Joint-Sponsored State Key Laboratory of Plateau Ecology and Agriculture Qinghai University

Vertical mixing beneath the bed surface and its effect on sediment composition has long been underestimated. This paper proposes a mixing equation to illustrate the temporal and spatial variations of bed material composition for bed form dominant rivers. A continuous mass conservation equation for elevation-specific nonuniform bed material composition is initially presented. A vertical mixing equation is finally derived as a diffusion-type partial differential equation with a source term characterized by a vertical diffusion coefficient and the geometric dimensions of bed forms. Coupled with boundary conditions, this equation is further developed in a vertical mixing model at the scale of bed forms, in which the variations of bed material composition are clearly illustrated. The equation accounts for vertical exchange fluxes driven by bed form migration and their effect on bed material composition, which helps elucidate the mixing mechanism. In application to riverbed degradation, the proposed equation is capable to describe armoring development in consideration of the interior mixing, which provides more satisfying predictions for bed surface materials. The new mixing equation helps gain insight into predicting the variations of bed material composition during morphological changes.

关键词： Mixing equation Active layer Bed forms Grain size distribution

Effect of sediment particles on the velocity profile of sediment-water mixtures in open-channel flow

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International Journal of Sediment Research 2023年第3期38卷 361-373页

作者： Lei Zhang Jianzhao Guan deyu zhong Yousheng Wang State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower Research Joint Sponsored State Key Laboratory of Plateau Ecology and Agriculture Qinghai University State Key Laboratory of Hydroscience and Engineering Tsinghua University

The presence of sediment particles in open-channel flow has an important effect on turbulence; thus, an empirical, turbulent eddy viscosity formula was established for application in the limit for low concentrations. The current study establishes a theoretical relation for the mixture viscosity based on the two-phase mixture model. The percentage contribution of the three mechanisms of mixture viscosity,namely, fluid turbulence(FT), particle turbulence(PT), and inter-particle collisions(IPCs), was calculated under different conditions. The study results indicate that the contribution of FT is dominant, whereas those of PT and IPCs are not significant when the particle inertia(PI) is small, suggesting that the movement of sediment-laden flows is mainly controlled by the fluid properties. The effects of PT and IPCs increase with increases in sediment concentration and PI. Specifically, the effect of collisions among particles generally becomes dominant near the bed surface. A good agreement between the calculated velocity profile of the mixture and available experimental data for large particle sizes and high concentrations proves that the proposed relation for mixture viscosity is more reasonable than the previous empirical relation owing to the consideration of the effects of PT and IPCs, and, thus, can be applied to both dilute and dense suspensions.

关键词： Velocity profile Sediment particles Viscosity Collisions Turbulence

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浅埋煤层双回撤通道保护煤柱合理宽度确定

陕西煤炭 2024年第8期43卷 8-13页

作者：刘晓勤任钦华周虎安升种德雨陕西能源凉水井矿业有限责任公司陕西榆林719300

保护煤柱的宽度对于回撤通道的围岩稳定和提升工作面搬家倒面的效率具有重要意义。为合理确定浅埋煤层双回撤通道的煤柱宽度,以凉水井煤矿42206工作面预掘双回撤通道为工程背景,通过理论分析和数值模拟,研究分析了回撤通道变形机理、工... 详细信息

保护煤柱的宽度对于回撤通道的围岩稳定和提升工作面搬家倒面的效率具有重要意义。为合理确定浅埋煤层双回撤通道的煤柱宽度,以凉水井煤矿42206工作面预掘双回撤通道为工程背景,通过理论分析和数值模拟,研究分析了回撤通道变形机理、工作面煤柱的超前影响范围,最终确定通道间合理煤柱尺寸。结果表明,理论计算得出回撤通道保护煤柱宽度为15.8 m,数值模拟得出回撤通道保护煤柱宽度在14 m与在20 m处的应力差值仅为0.11 MPa,且大于14 m时稳定,而与20 m相比顶板下沉量差值仅为1 cm。综合考虑,最终确定将煤柱尺寸优化为15 m。

关键词：浅埋煤层双回撤通道煤柱宽度塑性区顶板下沉量

Application of the Conditional Nonlinear Local Lyapunov Exponent to Second-Kind Predictability

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Advances in Atmospheric Sciences 2024年第9期41卷 1769-1786页

作者： Ming ZHANG Ruiqiang DING Quanjia zhong Jianping LI deyu LU State Key Laboratory of Earth Surface Processes and Resource Ecology(ESPRE)/Key Laboratory of Environmental Change and Natural Disasters of Chinese Ministry of EducationBeijing Normal UniversityBeijing 100875China Department of Ocean Science Hong Kong University of Science and TechnologyHong KongChina College of Oceanic and Atmospheric Sciences/Frontiers Science Center for Deep Ocean Multispheres and Earth System(DOMES)/Key Laboratory of Physical Oceanography Ministry of Education/Academy of the Future Ocean/Center for Ocean Carbon NeutralityOcean University of ChinaQingdao 266100China Laoshan Laboratory Qingdao 266237China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth Science University of Chinese Academy of SciencesBeijing 100049China

In order to quantify the influence of external forcings on the predictability limit using observational data,the author introduced an algorithm of the conditional nonlinear local Lyapunov exponent(CNLLE)*** effectiveness of this algorithm is validated and compared with the nonlinear local Lyapunov exponent(NLLE)and signal-to-noise ratio methods using a coupled Lorenz *** results show that the CNLLE method is able to capture the slow error growth constrained by external forcings,therefore,it can quantify the predictability limit induced by the external *** this basis,a preliminary attempt was made to apply this method to measure the influence of ENSO on the predictability limit for both atmospheric and oceanic variable *** spatial distribution of the predictability limit induced by ENSO is similar to that arising from the initial conditions calculated by the NLLE *** similarity supports ENSO as the major predictable signal for weather and climate *** addition,a ratio of predictability limit(RPL)calculated by the CNLLE method to that calculated by the NLLE method was *** RPL larger than 1 indicates that the external forcings can significantly benefit the long-term predictability *** instance,ENSO can effectively extend the predictability limit arising from the initial conditions of sea surface temperature over the tropical Indian Ocean by approximately four months,as well as the predictability limit of sea level pressure over the eastern and western Pacific ***,the impact of ENSO on the geopotential height predictability limit is primarily confined to the troposphere.

关键词： conditional nonlinear local Lyapunov exponent second-kind predictability coupled Lorenz model ENSO

Numerical simulation of pollution process due to resuspension of bed materials adsorbing pollutants in alluvial rivers

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中国科学：技术科学英文版 2015年第7期58卷 1280-1288页

作者： DING Yun XIAO Yang zhong deyu State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University College of Water Conservancy and Hydropower Engineering Hohai University State Key Laboratory of Hydroscience and Engineering Tsinghua University

Resuspension of bed materials absorbing pollutants potentially poses unpredictable challenges to water management in alluvial rivers and its mechanism of transport has not been widely *** this study,a transport equation that defines the movement of pollutants adsorbed on the bed materials in the active bed layer is established,on the basis of mass conservation law and continuum *** transport equation is coupled into the 1-D mathematical model to numerically investigate water pollution process due to the scour of the bed sediment adsorbing *** with the situation in which the dynamics of the active bed layer is not considered indicate that the periodical evolution of the bed layer plays an innegligible role in the pollution process due to sediment ***,comparisons of the results with available experimental observations are presented,and fairly good agreement is obtained.

关键词：河流污染物吸附材料污染过程冲积河流数值模拟悬浮床床层动力学沉积物再悬浮

Analytical solution to one-dimensional mathematical model of flow and morphological evolution in open channels

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Science China(Technological Sciences) 2020年第12期63卷 2606-2616页

作者： DING Yun LI ZuiSen SHI Yongzhong zhong deyu State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing 210098China College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China Zhejiang Institute of Hydraulics and Estuary Hangzhou 310008China Zhejiang Provincial Key Laboratory of Hydraulic Disaster Prevention and Mitigation Hangzhou 310008China Joint-Sponsored State Key Laboratory of Plateau Ecology and Agriculture Qinghai UniversityXining 810016China State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China

The evolution of open-channel flow and morphology can be simulated by one-dimensional(1D) mathematical models. These models are typically solved by numerical or analytical methods. Because the behavior of variables can be explained by explicit mathematical determinations,compared to numerical solutions,analytical solutions provide fundamental and physical insights into flow and sediment transport mechanisms. The singular perturbation technique derives a hierarchical equation of waves and describes the evolutionary nature of disturbances in hyperbolic systems. The wave hierarchy consists of dynamic,diffusion,and kinetic waves. These three types of waves interact with each other in the process of propagation. Moreover,the Laplace transform is implemented to transform partial differential equations into ordinary differential equations. Analytical expressions in the wave front are subtracted by the approximation of kinetic and diffusion models. Moreover,an analytical solution consists of a linear combination of the kinetic wave front and the diffusion wave front expressions,pursuing to describe the physical mechanism of motion in open channels as completely as possible. Analytical solutions are presented as a combination of exponential functions,hyperbolic functions,and infinite series. The obtained analytical solution was further applied to the simulation of flood path and morphological evolution in the Lower Yellow River. The phenomenon of increased peak discharge in the downstream reach was successfully simulated. It was encouraging that the results were in good agreement with the observed data.

关键词： open channel mathematical model analytical solution Laplace transform morphological evolution

Particle inertia effect on sediment dispersion in turbulent open-channel flows

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Science China(Technological Sciences) 2014年第10期57卷 1977-1987页

作者： ZHANG Lei zhong deyu WU BaoSheng State Key Laboratory of Hydroscience and Engineering Tsinghua University

Particle inertia effect plays a significant role in sediment dispersion which has not been fully *** this paper,the profound effect of particle inertia on the sediment dispersion was *** theoretical expression for the drift velocity based on the two-phase mixture theory in turbulent open channels is firstly *** influence of particle inertia on sediment dispersion was investigated through three different aspects including vertical dispersion,motion,and flux properties based on the drift *** show that the dispersion of suspended sediment in turbulent open-channel flows is affected by three major processes including turbulence of water sediment mixtures,particle random motion,and collisions among particles,of which the contributions of particle turbulence and collisions to the sediment dispersion are remarkable for particles of high *** respect to the vertical mean velocity and sediment flux,it shows that the predictive results agree well with the measurements when the term of particle inertia is *** a result,particle inertia considerably affects the behavior of suspended *** particular,the influence of inertia must be accounted for in circumstances of flows laden with high-inertia particles.

关键词：悬浮沉积物惯性效应分散颗粒通道开放式两相混合物沉积物通量漂移速度

Coupling mechanism of mathematical models for sediment transport based on characteristic theory

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Science China(Technological Sciences) 2016年第11期59卷 1696-1706页

作者： DING Yun LI ZuiSen zhong deyu KANG YanPing State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China Zhejiang Institute of Hydraulics and Estuary Hangzhou 310008 China State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China Jiangsu Hydraulic Research Institute Nanjing 210017 China

This paper aims to explore the coupling mechanism between flow movement, sediment transport and riverbed evolution in currently widely used mathematical models for sediment transport. Based on characteristic theory, analytic forms of eigenvalues,eigenvectors and characteristic relationships of total-sediment transport model, bed-load transport model and suspenedload transport model were derived, respectively. The singular perturbation technology was implemented to obtain the asymptotic solutions to different families of eigenvalues. The results indicate that, interactions between motion variables were explicitly coupled in the characteristics of total-sediment transport model and bed-load transport model. Further qualitative and quantitative analysis demonstrates that high sediment transport intensity and significant riverbed change will inevitably affect the property of flow movement. In the process of deposition, sediment-laden flow will move faster when sediment transport intensity becomes stronger. In contrast, the wave of flow will propagate at slower speed as erosion intensity becomes *** most existing suspended-load transport models, however, the characteristics are decoupled as the interactions between motion variables cannot be integrally illustrated in eigenvalues, eigenvectors and characteristic relationship.

关键词：联合机制数学模型沉积运输特征特征值