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Stability behavior of the Lanxi ancient flood control levee after reinforcement with upside-down hanging wells and grouting curtain

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Journal of Mountain Science 2024年第1期21卷 84-99页

作者： QIN Zipeng TIAN Yan GAO Siyuan ZHOU Jianfen HE Xiaohui HE Weizhong GAO Jingquan School of water conservancy and environment Engineering Zhejiang University of Water Resources and Electric PowerHangzhou 310018China Department of Civil Engineering Imperial College LondonLondonSW71BFEngland Lanxi water Affairs Bureau Lanxi 321102China Zhejiang water conservancy Engineering Consulting Co. LtdHangzhou 310051China

The stability of the ancient flood control levees is mainly influenced by water level fluctuations, groundwater concentration and rainfalls. This paper takes the Lanxi ancient levee as a research object to study the evolution laws of its seepage, displacement and stability before and after reinforcement with the upside-down hanging wells and grouting curtain through numerical simulation methods combined with experiments and observations. The study results indicate that the filled soil is less affected by water level fluctuations and groundwater concentration after reinforcement. A high groundwater level is detrimental to the levee's long-term stability, and the drainage issues need to be fully considered. The deformation of the reinforced levee is effectively controlled since the fill deformation is mainly borne by the upside-down hanging wells. The safety factors of the levee before reinforcement vary significantly with the water level. The minimum value of the safety factors is 0.886 during the water level decreasing period, indicating a very high risk of the instability. While it reached 1.478 after reinforcement, the stability of the ancient levee is improved by a large margin.

关键词： Stability analysis Multiple factors Antiseepage reinforcement Upside-down hanging well Grouting curtain Ancient levee

Unlocking the potential of thin-film composite reverse osmosis membrane performance:Insights from mass transfer modeling

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Chinese Chemical Letters 2024年第5期35卷 66-76页

作者： Kexin Yuan Yulei Liu Haoran Feng Yi Liu Jun Cheng Beiyang Luo Qinglian Wu Xinyu Zhang Ying Wang Xian Bao Wanqian Guo Jun Ma State Key Laboratory of Urban water Resource and environment School of EnvironmentHarbin Institute of TechnologyHarbin 150090China college of Architecture and environment Sichuan UniversityChengdu 610065China School of Municipal and environmental Engineering Shandong Jianzhu UniversityJi’nan 250101China college of water conservancy and Hydropower Engineering Sichuan Agricultural UniversityYaan 625014China

Thin-film composite(TFC)reverse osmosis(RO)membranes have attracted considerable attention in water treatment and desalination processes due to their specific separation ***,the trade-off effect between water flux and salt rejection poses huge challenges to further improvement in TFC RO membrane *** research works have been dedicated to optimizing membrane fabrication and modification for addressing this *** the meantime,several reviews summarized these ***,the existing reviews seldom analyzed these methods from a theoretical perspective and thus failed to offer effective optimization directions for the RO process from the root *** this review,we first propose a mass transfer model to facilitate a better understanding of the entire process of how water and solute permeate through RO membranes in detail,namely the migration process outside the membrane,the dissolution process on the membrane surface,and the diffusion process within the ***,the water and salt mass transfer behaviors obtained from model deduction are comprehensively analyzed to provide potential guidelines for alleviating the trade-off effect between water flux and salt rejection in the RO ***,inspired by the theoretical analysis and the accurate identification of existing bottlenecks,several promising strategies for both regulating RO membranes and optimizing operational conditions are proposed to further exploit the potential of RO membrane *** review is expected to guide the development of high-performance RO membranes from a mass transfer theory standpoint.

关键词： Reverse osmosis Mass transfer model Trade-off effect Membrane performance Optimization strategies

Characteristics and influencing factors of greenhouse gas emissions from reservoirs in the Yellow River Basin:A Meta-analysis

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Science China Earth Sciences 2024年第7期67卷 2210-2225页

作者： Shurui HUANG Peijia ZHANG Wenxiu ZHENG Jiajia ZHANG Yang LI Yuanjian WANG Enhui JIANG Shaoda LIU Xinghui XIA State Key Laboratory of water environment Simulation School of EnvironmentBeijing Normal UniversityBeijing 00875China Yellow River Institute of Hydraulic Research Yellow River Conservancy CommissionZhengzhou 450003China

Reservoir construction and operation profoundly alter the hydrological,hydrodynamic,and carbon and nitrogen cycling processes of ***,current research still lacks a systematic understanding of the characteristics of greenhouse gas(GHG)emissions from reservoirs in arid/semi-arid *** study integrates existing monitoring data to discuss the characteristics of GHG emissions from reservoirs in the Yellow River Basin and illustrate the controlling factors and underlying mechanism of these *** results indicate that while CO_(2) emission flux from reservoirs is lower than that from river channels,the emission fluxes of CH_(4) and N_(2)O are 1.9 times and 10 times those from rivers,respectively,indicating that the emission of GHG with stronger radiative effect is significantly enhanced in *** to the reservoirs in humid climates(e.g.,the Three Gorges Reservoir),reservoirs in the Yellow River Basin exhibit relatively lower emissions of CO_(2) and CH_4 due to lower organic matter concentrations,but significantly higher N_(2)O emissions due to higher nitrogen *** Carlo simulations for 237 reservoirs in the Yellow River Basin showed that total emission of the three GHGs is 3.05 Tg CO_(2)-eq yr^(-1),accounting for 0.39% of the total emission from global reservoirs and lower than the area percentage of the basin(0.53%).This study has important implications on revealing the GHG emission characteristics and control mechanisms of reservoirs in arid/semi-arid regions.

关键词： Yellow River Basin Reservoir Greenhouse gas Emission flux water quality

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Fractal Study on the Evolution of Micro-Pores in Concrete Under Freeze-Thaw

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Journal of Wuhan University of Technology(Materials Science) 2024年第1期39卷 109-117页

作者：孙浩然邹春霞 XU Deru GUO Xiaosong HUANG Kun college of water conservancy and Civil Engineering Inner Mongolia Agricultural UniversityHohhot 010018China Xi’an HaiTang Vocational college Xi’an 710038China

After exposure to freeze-thaw cycles, scanning electron microscopy(SEM) and nuclear magnetic resonance(NMR) were used to test the four mixtures. The microstructure is qualitatively analyzed from the 2D SEM image and the 3D pore distribution curve before and after freezing and thawing. The fractal dimension is utilized to characterize the two-dimensional topography image and the three-dimensional pore distribution, quantitatively. The results reveal that the surface porosity and volume porosity increase as the freeze-thaw action increases. Self-similarity characteristics exist in micro-damage inside the concrete. In the fractal dimension, it is possible to characterize pore evolution quantitatively. The fractal dimension correlates with pore damage evolution. The fractal dimension effectively quantitatively characterizes micro-damage features at various scales from the local to the global level.

关键词： fractal dimension freeze-thaw cycle concrete SEM NMR

Runoff change in the Yellow River Basin of China from 1960 to 2020 and its driving factors

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Journal of Arid Land 2024年第2期16卷 168-194页

作者： WANG Baoliang WANG Hongxiang JIAO Xuyang HUANG Lintong CHEN Hao GUO Wenxian School of water conservancy North China University of Water Resources and Electric PowerZhengzhou 450046China college of water Resources North China University of Water Resources and Electric PowerZhengzhou 450046China

Analysing runoff changes and how these are affected by climate change and human activities is deemed crucial to elucidate the ecological and hydrological response mechanisms of *** Indicators of Hydrologic Alteration and the Range of Variability Approach(IHA-RVA)method,as well as the ecological indicator method,were employed to quantitatively assess the degree of hydrologic change and ecological response processes in the Yellow River Basin from 1960 to *** Budyko's water heat coupling balance theory,the relative contributions of various driving factors(such as precipitation,potential evapotranspiration,and underlying surface)to runoff changes in the Yellow River Basin were quantitatively *** results show that the annual average runoff and precipitation in the Yellow River Basin had a downwards trend,whereas the potential evapotranspiration exhibited an upwards trend from 1960 to *** approximately 1985,it was reported that the hydrological regime of the main stream underwent an abrupt *** degree of hydrological change was observed to gradually increase from upstream to downstream,with a range of 34.00%-54.00%,all of which are moderate ***,significant differences have been noted among different ecological indicators,with a fluctuation index of 90.00%at the outlet of downstream hydrological stations,reaching a high level of *** the mutation,the biodiversity index of flow in the middle and lower reaches of the Yellow River was generally lower than that in the base *** research results also indicate that the driving factor for runoff changes in the upper reach of the Yellow River Basin is mainly precipitation,with a contribution rate of 39.31%-54.70%.Moreover,the driving factor for runoff changes in the middle and lower reaches is mainly human activities,having a contribution rate of 63.70%-84.37%.These results can serve as a basis to strengthen the protection and restoration efforts in the Yellow River Basin

关键词： Budyko theory hydrological regime attribution analysis ecological responses Yellow River climate change human activity runoff

Large porewater exchange reshapes saltmarsh carbon and greenhouse gas budgets on local and global scales

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Science China Earth Sciences 2024年第7期67卷 2195-2209页

作者： Xiaogang CHEN Isaac RSANTOS Lucheng ZHAN Yu Yan YAU Yan ZHANG Ling LI Key Laboratory of Coastal environment and Resources of Zhejiang Province School of EngineeringWestlake UniversityHangzhou 310024China Department of Marine Sciences University of GothenburgGothenburg 41319Sweden college of water conservancy and Hydropower Engineering Hohai UniversityNanjing 210024China

Saltmarshes are carbon-rich ecosystems that play a role in climate regulation by efficiently sequestrating atmospheric CO_(2).Climate change is a major threat to saltmarshes and will impact saltmarsh carbon ***,porewater-derived carbon outwelling emerges as a crucial pathway for carbon sequestration,but it has been largely overlooked in ***,we assessed the drivers of dissolved carbon exports and greenhouse gas emissions in a saltmarsh and placed those observations into a global *** our study site,porewater exchange(PEX)was the major process controlling dissolved carbon and greenhouse gas *** our results with 33 other studies in saltmarshes worldwide,porewater-derived carbon fluxes were equivalent to~48% of average global saltmarsh primary productivity and 2.2 times greater than global organic carbon ***,our local observations and global upscaling demonstrate the major role played by PEX in saltmarsh carbon *** part of dissolved inorganic carbon returns to the atmosphere as CO_(2),the remaining bicarbonate fraction is stored in the ocean over long time *** findings strengthen global blue carbon assessments and build arguments for the use of saltmarshes as nature-based solutions for global climate change.

关键词： Coastal carbon Global carbon budget Carbon neutrality Nature-based solutions Coastal wetlands Submarine groundwater discharge

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Regulation effects of water and nitrogen on yield,water,and nitrogen use efficiency of wolfberry

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Journal of Arid Land 2024年第1期16卷 29-45页

作者： GAO Yalin QI Guangping MA Yanlin YIN Minhua WANG Jinghai WANG Chen TIAN Rongrong XIAO Feng LU Qiang WANG Jianjun college of water conservancy and Hydropower Engineering Gansu Agricultural UniversityLanzhou 730070China Jingtaichuan Electric Power Irrigation water Resource Utilization Center in Gansu Province Baiyin 730900China

Wolfberry(Lycium barbarum L.)is important for health care and ecological ***,it faces problems of low productivity and resource utilization during *** reasonable models for water and nitrogen management is important for solving these *** on field trials in 2021 and 2022,this study analyzed the effects of controlling soil water and nitrogen application levels on wolfberry height,stem diameter,crown width,yield,and water(WUE)and nitrogen use efficiency(NUE).The upper and lower limits of soil water were controlled by the percentage of soil water content to field water capacity(θ_(f)),and four water levels,i.e.,adequate irrigation(W0,75%-85%θ_(f)),mild water deficit(W1,65%-75%θ_(f)),moderate water deficit(W2,55%-65%θ_(f)),and severe water deficit(W3,45%-55%θ_(f))were used,and three nitrogen application levels,i.e.,no nitrogen(N0,0 kg/hm^(2)),low nitrogen(N1,150 kg/hm^(2)),medium nitrogen(N2,300 kg/hm^(2)),and high nitrogen(N3,450 kg/hm^(2))were *** results showed that irrigation and nitrogen application significantly affected plant height,stem diameter,and crown width of wolfberry at different growth stages(Pwater *** weight per hundred grains and dry weight percentage increased with increasing nitrogen application under W0 ***,under other water treatments,the values first increased and then decreased with increasing nitrogen *** and its component of wolfberry first increased and then decreased as water deficit increased under the same nitrogen *** water use efficiency(IWUE,8.46 kg/(hm^(2)·mm)),WUE(6.83 kg/(hm^(2)·mm)),partial factor productivity of nitrogen(PFPN,2.56 kg/kg),and NUE(14.29 kg/kg)reached their highest values in W2N2,W1N2,W1N2,and W1N1 treatments.R

关键词： water deficit growth characteristics yield water and nitrogen use efficiency principal component analysis

Hydrodynamic characteristics and particle tracking of 90° lateral intakes at an inclined river slope

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water Science and Engineering 2024年第2期17卷 197-208页

作者： Wei He Si-yuan Feng Jian Zhang Hong-wu Tang Yang Xiao Sheng Chen Chun-sheng Liu college of water conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China State Key Laboratory of Hydrology water Resources and Hydraulic Engineering Hohai UniversityNanjing 210098China Collaborative Innovation Center on water Safety and water Science Hohai UniversityNanjing 210098China

Lateral intakes are common in *** pump effciency and sediment deposition are determined by the local hydrodynamic characteristics and mainstream division *** hydraulic characteristics of lateral withdrawal from inclined river slopes at different intake elevations should be ***,the division width exhibits significant vertical non-uniformity at an inclined river slope,which should be ***,a three-dimensional(3-D)hydrodynamic and particle-tracking model was developed with the Open Source Field Operation and Manipulation(Open FOAM),and the model was validated with physical model tests for 90°lateral withdrawal from an inclined side *** flow fields,withdrawal sources,and division widths were investigated with different intake bottom elevations,withdrawal discharges,and main channel *** study showed that under inclined side bank conditions,water entered the intake at an oblique angle,causing significant 3-D spiral flows in the intake rather than two-dimensional closed recirculation.A lower withdrawal discharge,a lower bottom elevation of the intake,or a higher main channel velocity could further strengthen this *** average division width and turbulent kinetic energy were smaller under inclined side bank conditions than under vertical bank *** a low intake bottom elevation,a low withdrawal discharge,or a high main channel velocity,the sources of lateral withdrawal were in similar ranges near the local inclined bank in the vertical *** inclined slope conditions,sediment deposition near the intake entrance could be reduced,compared to that under vertical slope *** results provide hydrodynamic and sediment references for engineering designs for natural rivers with inclined terrains.

关键词： Lateral withdrawal Hydrodynamic characteristics Particle tracking Inclined river slope Bottom elevation of intake OpenFOAM

Numerical simulation of transient characteristics in a bulb turbine during the load rejection process

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Journal of Hydrodynamics 2024年第1期36卷 170-183页

作者： Yue Lu Yu-quan Zhang Zhong-wei He Yuan Zheng college of water conservancy and Hydropower Engineering Hohai UniversityNanjing210098China college of Energy and Electrical Engineering Hohai UniversityNanjing210098China Huadong Engineering Corporation Ltd. Hangzhou311122China

To evaluate the safety of the bulb tubular turbine,the dynamic hydraulic characteristics of a hydropower station system during the load rejection process are studied through numerical simulations and a prototype *** the developed model,a dynamic grid technology(DGT)controls the closure of the guide vane and the blade,whilst the moment balance equation and the user-defined function(UDF)provide the runner’s rotation *** 3-D transient simulation method can well predict the rotation speed and mass flow curves in the state of load *** simulation outcomes of the system performance are basically consistent with the measurement data of the *** observed,the runner is subjected to the reversely increased torque and axial force,the system is in a braking phase,and the maximum speed peaks at 144.6%of the rated ***,the internal flow of the runner is greatly affected by the closure of the guide vane,and the draft tube forms an eccentric spiral vortex *** breaks downstream,aggravating the instability of the draft ***,the transient characteristics span for the first five seconds,demonstrating the importance of establishing an efficient governing *** obtained results are useful for designing the turbine’s flow channel with a double regulating function and comprehending the turbine’s transient characteristics.

关键词： Bulb tubular turbine load rejection numerical simulation dynamic grid prototype test