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Hydropower reservoirs on the upper Mekong River modify nutrient bioavailability downstream

National Science Review 2020年第9期7卷 1449-1457页

作者： Qiuwen Chen Wenqing Shi Jef Huisman Stephen C.Maberly Jianyun Zhang Juhua Yu Yuchen Chen Daniele Tonina Qitao Yi State Key Laboratory of Hydrology-Water Resources & hydraulic Engineering Nanjing Hydraulic Research Institute Center for Eco-Environment research Nanjing Hydraulic Research Institute Department of Freshwater and Marine Ecology Institute for Biodiversity and Ecosystem DynamicsUniversity of Amsterdam Lake Ecosystems Group UK Centre for Ecology & Hydrology 5. Department of Eco-Environment Conservation Yangtze Institute for Conservation and Development 6. Center for Ecohydraulics Research University of Idaho

Hydropower development is the key strategy in many developing countries for energy supply,climate-change mitigation and economic development. However, it is commonly assumed that river dams retain nutrients and therefore reduce downstream primary productivity and fishery catches, compromising food security and causing trans-boundary disputes. Contrary to expectation, here we found that a cascade of reservoirs along the upper Mekong River increased downstream bioavailability of nitrogen and *** dams caused phytoplankton density to increase with hydraulic residence time and stratification of the stagnant reservoirs caused hypoxia at depth. This allowed the release of bioavailable phosphorus from the sediment and an increase in dissolved inorganic nitrogen as well as a shift in nitrogen species from nitrate to ammonium, which were transported downstream by the discharge of water from the base of the dam. Our findings provide a new perspective on the environmental impacts of river dams on nutrient cycling and ecosystem functioning, with potential implications for sustainable development of hydropower worldwide.

关键词： Mekong River cascade reservoirs downstream nutrient bioavailability nitrogen phosphorus

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Centrifugal model tests and numerical simulations for barrier dam break due to overtopping

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Journal of Mountain Science 2019年第3期16卷 630-640页

作者： ZHAO Tian-long CHEN Sheng-shui FU Chang-jing ZHONG Qi-ming Key Laboratory for hydraulic and Waterway Engineering of Ministry of Education Chongqing Jiaotong University Nanjing hydraulic research institute Key Laboratory of Failure Mechanism and Safety Control Techniques of Earthrock Dam of the Ministry of Water Resources Department of Geotechnical Engineering Nanjing Hydraulic Research Institute

The present study focuses on the breaching process and failure of barrier dams due to overtopping. In this work, a series of centrifugal model tests is presented to examine the failure mechanisms of landslide dams. Based on the experimental results, failure process and mechanism of barrier dam due to overtopping are analyzed and further verified by simulating the experimental overtopping failure process. The results indicate that the barrier dam will develop during the entire process of overtopping in the width direction, whereas the breach will cease to develop at an early stage in the depth direction because of the large particles that accumulate on the downstream slope. Moreover, headcut erosion can be clearly observed in the first two stages of overtopping, and coarsening on the downstream slope occurs in the last stage of overtopping. Thus, the bottom part of the barrier dam can survive after dam breaching and full dam failure becomes relatively rare for a barrier dam. Furthermore, the remaining breach would be smaller than that of a homogeneous cohesive dam under the same conditions.

关键词： Barrier dam Overtopping Failure mechanism Centrifugal model test Numerical simulation

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Numerical Simulation of Random Wave Overtopping of Rubble Mound Breakwater with Armor Units

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China Ocean Engineering 2021年第2期35卷 176-185页

作者： LI Jing-yuan ZHANG Qing-he LU Yong-jun State Key Laboratory of hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China State Key Laboratory of Hydrology-Water Resources and hydraulic Engineering Nanjing Hydraulic Research InstituteNanjing 210029China

Based on the open source code OpenFOAM,a three-dimensional model is presented for simulation of the interaction between waves and rubble mound breakwater with armor *** armor units with their real geometries are depicted through computational *** volume-averaged RANS equation and the seepage equation containing nonlinear term are used to describe the percolation in the core and underlayer of the *** independence analysis are carried out,the horizontal and vertical grid size are recommended to take as one-fifteenth of the mean nominal diameter D_(50) of the armor units and one-fifteenth of the wave height *** wave overtopping of rubble mound breakwater with armor units is simulated through the proposed *** results show good agreement between the simulated and measured overtopping discharge rates for different types of armor *** developed numerical model can be used to evaluate the random wave overtopping in design of rubble mound breakwater with artificial armor blocs.

关键词： random wave armor units seepage equation overtopping discharges grid independence

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Analysis of seismic disaster failure mechanism and dam-break simulation of high arch dam

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Earthquake Engineering and Engineering Vibration 2014年第2期13卷 327-335页

作者： Zhang Jingkui Zhang Liaojun Anhui and Huaihe River institute of hydraulic research College of Water Conservancy and Hydropower Engineering Hohai University

Based on a Chinese national high arch dam located in a meizoseismal region, a nonlinear numerical analysis model of the damage and failure process of a dam-foundation system is established by employing a 3-D deformable distinct element code(3DEC) and its re-development functions. The proposed analysis model considers the dam-foundation-reservoir coupling effect, infl uence of nonlinear contact in the opening and closing of the dam seam surface and abutment rock joints during strong earthquakes, and radiation damping of far fi eld energy dissipation according to the actual workability state of an arch dam. A safety assessment method and safety evaluation criteria is developed to better understand the arch dam system disaster process from local damage to ultimate failure. The dynamic characteristics, disaster mechanism, limit bearing capacity and the entire failure process of a high arch dam under a strong earthquake are then analyzed. Further, the seismic safety of the arch dam is evaluated according to the proposed evaluation criteria and safety assessment method. As a result, some useful conclusions are obtained for some aspects of the disaster mechanism and failure process of an arch dam. The analysis method and conclusions may be useful in engineering practice.

关键词： high arch dam complex foundation 3DEC disaster mechanism dam-break process simulation seismic safety evaluation

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Incipient motion of sediment by waves

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Science China(Technological Sciences) 2001年第3期44卷 309-318页

作者：窦国仁窦希萍李褆来 Nanjing hydraulic research institute Nanjing China Nanjing institute of Hydrology and Water Resources Nanjing China

In this paper, the forces acting on sediment particles are analyzed in all the aspects. Considering the cohesive force between particles, the additional static water pressure induced by the solid-body characteristics of film water and the inertia force of waves, a unified formula of the incipient motion for both coarse and fine particles is defined. The formula can reflect the variation in the initial velocity of fine particles with the volume weight of sediment. The verification of the formula is carried out by use of both experimental data and field observation data accumulated by experts at home and abroad. The verification shows that the formula expresses the law governing the incipient motion of sediment of all particle sizes inclusive of natural sediment and light-weight materials, and thus a basic formula for the study and solution of sediment problems in estuarine and coastal regions is provided.

关键词： wave sediment incipient motion

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Targeting Epac2 and GluA3-containing AMPARs:a novel therapeutic strategy for Alzheimer's disease

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Neural Regeneration research 2025年第11期20卷 3223-3224页

作者： Tong Zhang Martina Schmidt Department of Molecular Pharmacology Groningen Research Institute of PharmacyUniversity of GroningenGroningenThe Netherlands School of Pharmacy Tianjin Medical UniversityTianjinChina

Alzheimer's disease(AD)is a neurodegenerative disease that manifests progressive decline in memory and *** the early stage of AD,memory retrieval is impaired preceding memory acquisition and consolidation(Roy et al.,2016).Prior to the onset of symptoms,pathological amyloid-β(Aβ)plagues and tau protein tangles accumulate in extracellular and intracellular spaces,respectively,leading to *** these hallmark pathologies,Aβ is proposed to be the primary etiology by triggering a cascade of pathogenic events,including neuroinflammation,oxidative stress,tau hyperphosphorylation,synaptic/neuronal dysfunction,and neuronal death(Zhang et al.,2023b).

关键词： Alzheimer impaired Aβ

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Overtopping breaching of cohesive homogeneous earth dam with different cohesive strength

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Science China(Technological Sciences) 2009年第10期52卷 3024-3029页

作者： ZHANG JianYun LI Yun XUAN GuoXiang WANG XiaoGang LI Jun Nanjing hydraulic research institute Nanjing 210029China State Key Laboratory of Hydrology-Water Resources and hydraulic Engineering Nanjing 210029China

In consideration of the range of clay content of Chinese earth dams, the world's highest prototype tests have been made to research on the effects of cohesive strength of filling of cohesive homogeneous earth dam on breach formation. Three breach mechanisms were presented, they were the source-tracing erosion of dam body with the form of "multilevel headcut", "two-helix flow" erosion of dam crest and collapse of breach sidewalls due to instability. It can be concluded that the cohesive strength of filling of earth dam has great effect on breach formation. When the cohesive strength is bigger, the breach process becomes slower, and the peak outflow and the final width and depth of breach become smaller. The main character of the breach formation is head cutting and dumping collapse. When the cohesive strength is smaller, the breach process becomes faster, and the peak outflow, the final width and depth of breach become bigger. The main character of the breach formation is single level head cutting and shearing collapse.

关键词： earth dam breach mechanism headcut two-helix flow

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Analysis and application of the scale effect of flood discharge atomization model

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Science China(Technological Sciences) 2011年第S1期54卷 64-71页

作者： WU ShiQiang 1,WU XiuFeng 1,2,ZHOU Hui 1,CHEN HuiLing 1,SHA HaiFei 1 & ZHOU Jie 1 1 State Key Laboratory of Hydrology-Water resources and hydraulic Engineering,Nanjing hydraulic research institute,Nanjing 210029,China 2 Hohai University,Nanjing 210098,China State Key Laboratory of Hydrology-Water resources and hydraulic Engineering Nanjing Hydraulic Research Institute Nanjing China Hohai University Nanjing China

The phenomenon of discharge atomization occurs as hydraulic structures discharging,which influences the safety of power station,electrical equipment and produces environmental pollution.A series of physical model tests and feedback analysis are adapted to preliminarily study the scale effect of discharge atomization model by use of the field observation data of discharge *** effect of Re and We numbers of flow on the atomization intensity is analyzed.A conversion relationship of atomization intensity between prototype and model results and the similarity criteria of the atomization range are developed. The conclusion is that the surface tension of discharge atomization model could be ignored when the Weber number is larger than *** case studies are given by use of the similitude criteria of the atomization model.

关键词： discharge atomization scale effect energy dissipation model test feedback analysis

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Heterogeneous tide-surge interaction during co-occurrence of tropical and extratropical cyclones in the radial sand ridges of the southern Yellow Sea

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Journal of Oceanology and Limnology 2019年第6期37卷 1879-1898页

作者： XIONG Mengjie ZHANG Jinshan ZHANG Weisheng YIN Chengtuan Nanjing hydraulic research institute Nanjing 210029China State Key Laboratory of Hydrology Water Resources and Hydraulic EngineeringNanjing 210029China

The Radial Sand Ridges(RSRs)area in the southern Yellow Sea are subject to tropical and extratropical cyclone activities frequently,in which the special geometry feature and moving stationary tidal system result in complex storm-induced hydrodynamic processes,especially the tide-surge *** studied a rare weather event influenced simultaneously by an extratropical cyclone EX1410 and Typhoon Vongfong as an example to investigate the characteristics of storm surges,wave-surge,and tide-surge interaction in the RSRs area,and applied a high-resolution integrally-coupled ADCIRC+SWAN model,in which the meteorological forcing inputs are simulated by the WRF-ARW *** model is validated by records from 4 tide gauges and 2 wave buoys along the Yellow Sea *** show that the tide-surge interactions are of considerable regional *** surge curves at Lüsi(in south RSRs)and Jianggang(in middle RSRs)have abrupt falls near the time of low tide,where the peak occurrence time of interaction residuals tend to shift towards the mid-ebb *** increase of bed shear stress in shallow waters was proved the dominant factor to affect the tide-surge interaction in broad tidal flats of the RSRs ***,the interaction pattern in the Xiyang Trough(in north RSRs),showed a unique rising in mid-flood period due to the phase advances of real surge waves in relatively deep ***,we suggested to the local flood risk management that the tide-surge interaction tends to alleviate the flooding risk in the RSRs area around the time of high tide,but aggravate the risk on the rising tide in the Xiyang Trough and on the falling tide in large-scale tidal flats of the southem RSRs area.

关键词： ADCIRC+SWAN model Radial Sand Ridges Jiangsu coast extratropical cyclone tide-surge interaction

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Study on the assessment of the comprehensive benefits of the utilization of sediment resources in reservoir areas

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International Journal of Sediment research 2017年第3期32卷 313-323页

作者： Jingmin Hou Yuanjian Wang Business School of Hohai University Yellow River institute of hydraulic research

The utilization of sediment in reservoirs as resources is an efficient way to reduce reservoir sedimentation and turn disadvantage into benefit. Based on economic, social and ecological functions of sediment resources, this paper puts forward a two-layer, three-dimensional evaluation index system. It also establishes six direct and indirect indicators with their formulas to calculate the comprehensive benefits of sediment utilization in the Xixiayuan reservoir of the Yellow River with a volume of 2000 m;.The results show that social benefits would be more prominent, with the ecological benefits coming second. This demonstrates that the indirect public value of utilizing the sediment resources in the Yellow River Basin can be far greater than its direct economic value.

关键词： Reservoir sedimentation Comprehensive benefits Evaluation method Yellow River The Xixiayuan Reservoir

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