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Design of sediment detention basins: Scaled model experiments and application 认领
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作者 Anita Moldenhauer-Roth Guillaume Piton +2 位作者 Sebastian Schwindt Mona Jafarnejad Anton JSchleiss 《国际泥沙研究:英文版》 SCIE 2021年第1期136-150,共15页
Sediment detention basins are implemented on mountain rivers to trap solid material that may aggravate the flooding of downstream settlements.However,retention structures built in the past may unnecessarily retain sed... Sediment detention basins are implemented on mountain rivers to trap solid material that may aggravate the flooding of downstream settlements.However,retention structures built in the past may unnecessarily retain sediment during non-hazardous flood events,resulting in high maintenance costs and sediment deficit downstream.In addition,the so-called spontaneous self-flushing of previously retained sediment during floods has occasionally been observed.Recent research suggests to design sediment detention basins for controlling sediment passage with a guiding channel across the deposition area upstream of a hybrid barrier.Such barriers consist of a check dam with a slot orifice and an upstream bar screen with a bottom clearance in order to benefit from a combined mechanical-hydraulic retention control.The present paper enhances this pioneering research with the help of new experimental data,including a wide range of sediment mixtures and large wood,as well as variable barrier heights.Improved design criteria are provided regarding the bar screen and the basin storage capacity.The functionality of the enhanced concept for sediment detention is illustrated by a case study on a physical model:the protection of the Villard-Bonnot village(France)against torrential hazards. 展开更多
关键词 Sediment continuity Sediment trap BEDLOAD Open check dam Sediment flushing
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文章速递Experimental study on the effect of bottomless structure in front of a bottom outlet on a sediment flushing cone 认领
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作者 Hadi Haghjouei Majid Rahimpour +1 位作者 Kourosh Qaderi Sameh AKantoush 《国际泥沙研究:英文版》 SCIE CSCD 2021年第3期335-347,共13页
One of the main problems in reservoirs is sedimentation which reduces the operating life of dams if a proper plan and analysis method are not in place.The techniques to manage sediment in reservoirs include several su... One of the main problems in reservoirs is sedimentation which reduces the operating life of dams if a proper plan and analysis method are not in place.The techniques to manage sediment in reservoirs include several sustainable management techniques that route sediment through or around the reservoir.One of the main economical methods in arid and semi-arid regions is pressurized flushing using moderate drawdown of the water level of the reservoir to evacuate sediment deposited behind dams.In the current study,the effect of a new structure called a dendritic bottomless extended(DBE)outlet structure at three angles of 30°,45°,and 60°on pressurized flushing efficiency was investigated.Consequently,45 experiments were designed for three discharge rates (Qo),three sediment levels(Hs),four types of structure,and a no-structure condition(reference test).The results indicated that the DBE structure with a 30°angle between the branches,a sedimentary dimensionless index of Hs/Do=4.59,and a flow dimensionless index of Qo=/√gD05=1:43(where g is the acceleration of gravity and Do is the diameter of the bottom outlet)lead to 10-fold increase in the sediment flushing cone dimensions and sediment removal efficiency compared to the results of the reference test.Finally,according to a statistical analysis of the results,a dimensionless equation for calculating the sediment flushing cone dimensions was developed for the tested sediment characteristics. 展开更多
关键词 Reservoir Sediment removal efficiency Sediment flushing cone Bottom outlet Dendritic bottomless extended structure
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文章速递Fenton体系处理黑臭河道沉积物的效果初探 认领
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作者 罗春燕 巩小丽 +2 位作者 张巧颖 陈煜 杜瑛珣 《湖泊科学》 EI CAS CSCD 北大核心 2021年第1期148-157,共10页
沉积物中有机质的削减是黑臭水体治理的关键.Fenton(Fe^2++H2O2)试剂在有机污染废水和土壤原位修复中的应用广泛且效果良好;Fenton试剂也能很好地去除黑臭水体中的色度和浊度,但其氧化沉积物有机质的研究未见报道.为探究Fenton试剂对黑... 沉积物中有机质的削减是黑臭水体治理的关键.Fenton(Fe^2++H2O2)试剂在有机污染废水和土壤原位修复中的应用广泛且效果良好;Fenton试剂也能很好地去除黑臭水体中的色度和浊度,但其氧化沉积物有机质的研究未见报道.为探究Fenton试剂对黑臭水体沉积物的氧化效果,本研究通过室内模拟实验用Fenton氧化法对黑臭河道沉积物进行处理,考察氧化过程沉积物特征和性质的变化;分析覆水后沉积物中污染物的释放特征,并和H2O2体系(无Fe^2+)进行比较.结果表明:Fenton体系显著提高了沉积物与上覆水的氧化还原电位,对黑臭河道沉积物中的有机质具有很强的氧化效率.在温度为28℃、H2O2为20%Q(Q为体系中沉积物有机质完全矿化的理论H2O2用量)和Fe^2+∶H2O2(摩尔比)为0.5∶1时,反应1 d,酸挥发性硫化物去除率为70.13%,沉积物总有机碳减少了22.14%,总有机氮减少了87.60%,生成了较多的铵态氮和硝态氮;由于铁对磷的钝化,沉积物中溶解性反应磷含量大幅减少.H2O2体系的氧化速度较Fenton体系慢,覆水后对体系中的Eh提高不明显.值得注意的是,Fenton体系会降低上覆水的pH,释放较多的铵态氮.需要联合其他技术(如微生物法),强化水体中有机质和氨氮的降解,以取得理想的修复作用. 展开更多
关键词 Fenton 黑臭水体 沉积物 有机质
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文章速递鄱阳湖网箱养殖区沉积物有机质来源分析 认领
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作者 王毛兰 熊鑫 +2 位作者 何昶 赵茜宇 刘景景 《湖泊科学》 EI CAS CSCD 北大核心 2021年第1期158-167,共10页
通过对鱼苗时期鄱阳湖网箱养殖区沉积物、饵料及鱼粪等样品总有机碳(TOC)含量、总氮(TN)含量、碳氮比(C/N)、δ^13 C及δ^15 N的测定,分析探讨了鄱阳湖网箱养殖区沉积物有机质来源,量化了网箱养殖废物对养殖区沉积物有机质的贡献.结果表... 通过对鱼苗时期鄱阳湖网箱养殖区沉积物、饵料及鱼粪等样品总有机碳(TOC)含量、总氮(TN)含量、碳氮比(C/N)、δ^13 C及δ^15 N的测定,分析探讨了鄱阳湖网箱养殖区沉积物有机质来源,量化了网箱养殖废物对养殖区沉积物有机质的贡献.结果表明,网箱养殖区沉积物的δ^13 C和δ^15 N值分别为-27.67‰~-25.65‰和5.19‰~7.27‰,饵料的δ^13 C和δ^15 N值分别为-24.73‰和10.28‰,鱼粪的δ^13 C和δ^15 N值分别为-26.30‰和15.54‰.网箱养殖区沉积物有机质来源主要有残饵、浮游生物及其他来源,其贡献率分别为48.3%±11.4%、25.6%±11.3%及26.0%±5.8%,而鱼粪的贡献几乎可以忽略不计.在水动力平流引起的扩散及沉积物的再悬浮的影响下,网箱养殖源有机质的扩散距离达1500 m.在鱼苗时期,鱼类网箱养殖的残饵是鄱阳湖网箱养殖区沉积物有机质的主要来源. 展开更多
关键词 网箱养殖 碳同位素 氮同位素 沉积物 鄱阳湖
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文章速递三峡水库中段库底水体CH4浓度变化及其主要影响因素 认领
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作者 秦宇 苏友恒 +2 位作者 李哲 刘正勉 张渝阳 《湖泊科学》 EI CAS CSCD 北大核心 2021年第1期299-308,共10页
甲烷(CH4)是一种重要的温室气体,对全球气候变化有不可忽视的影响.三峡水库是中国最大的水库,其潜在的CH4释放近年来备受关注.然而,此地区现存研究主要集中于水气界面通量观测,对库底沉积物同底层水体CH4浓度变化之间关系的认知仍然欠缺... 甲烷(CH4)是一种重要的温室气体,对全球气候变化有不可忽视的影响.三峡水库是中国最大的水库,其潜在的CH4释放近年来备受关注.然而,此地区现存研究主要集中于水气界面通量观测,对库底沉积物同底层水体CH4浓度变化之间关系的认知仍然欠缺.为探究三峡水库泥沙主要沉降淤积的中段区域库底水体CH4浓度变化及其主要影响因素,本研究于2017年8月2018年11月在涪陵南沱镇、忠县石宝寨、万州小周镇采集库底上覆水体和底泥样本,并结合三峡水库调度运行特征进行分析.结果表明,三峡水库中段库底上覆水CH4浓度范围为0.02~0.91μmol/L,二氧化碳(CO 2)浓度范围为0.006~0.105 mmol/L,沉积物有机碳含量范围为7~90 g/kg,总氮含量范围为0.27~45.6 g/kg.另外,三峡水库低水位运行时期(59月),上游及陆源输入大量异源性有机碳是该时期三峡库中段底部CH4积累的充分条件.在水库高水位运行时期(10月次年4月),水位与径流变化对三峡水库中段底部CH4的影响并不明显,库底自源性有机质相对比重有所增加,温度是该时期影响水库底层水体CH4浓度分布的主要水环境因素. 展开更多
关键词 三峡水库 甲烷 流量 水位 沉积物
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文章速递雨强和地下孔(裂)隙度对喀斯特坡耕地养分流失的影响 认领
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作者 姚一文 戴全厚 +3 位作者 甘艺贤 高儒学 严友进 王玉红 《中国农业科学》 CAS CSCD 北大核心 2021年第1期140-151,共12页
【目的】研究不同降雨强度和地下孔(裂)隙下,喀斯特区坡耕地表和地下土壤养分流失途径及流失规律,为喀斯特坡耕地土壤养分流失控制和农业面源污染防治提供理论依据。【方法】以喀斯特区坡度为15°的坡耕地为研究对象,通过模拟其地... 【目的】研究不同降雨强度和地下孔(裂)隙下,喀斯特区坡耕地表和地下土壤养分流失途径及流失规律,为喀斯特坡耕地土壤养分流失控制和农业面源污染防治提供理论依据。【方法】以喀斯特区坡度为15°的坡耕地为研究对象,通过模拟其地表形态和地下孔(裂)隙特征,设置不同雨强(30、50、70、90 mm·h^-1)和地下孔(裂)隙度(1%、3%、5%)交叉试验共36场降雨,探索喀斯特坡耕地地表和地下养分流失特征。【结果】(1)雨强对喀斯特区坡耕地产流产沙影响显著(P<0.05),地表、地下产流产沙量随雨强增大而增加,其产流产沙从地下过渡到地上的临界雨强可能在30—50 mm·h^-1;随地下孔(裂)隙度增大,地下产流产沙量增加,地表呈相反的规律。(2)喀斯特坡耕地径流养分主要通过地表流失,小雨强下通过地下孔(裂)隙流失;径流中全氮(TN)、全磷(TP)、全钾(TK)流失量和流失模数均随雨强增大而上升,雨强对各径流养分流失浓度影响不明显。地表养分流失量和流失模数随地下孔(裂)隙度增加而下降,地下反之。地下孔(裂)隙度的增加使地下径流养分流失占比逐渐增加。(3)养分会通过附着于泥沙流失,其中以地表泥沙流失为主。地表、地下各泥沙养分平均流失浓度、流失量和流失模数均随降雨强度增大而增加,其中TK流失平均浓度和流失量在不同雨强下显著高于TN和TP。同雨强下,地表泥沙各养分平均流失浓度、流失量和流失模数随孔(裂)隙度增加呈减小趋势,地下反之,但流失量从地表为主到地表与地下二者并重。(4)相关性分析表明,降雨强度与径流和泥沙流失量均呈现显著正相关关系,雨强对各养分径流的影响高于泥沙,地表径流受雨强影响最大。地下孔(裂)隙度对泥沙养分流失量的影响高于径流,而泥沙养分中地下泥沙养分流失量受其影响较大。【结论】喀斯特坡耕地养分主要通过地表流失,但地下孔(裂)隙对养分流失的影响不容忽视。在坡耕地养分流失防治上,地表通过增加植被覆盖度和添加枯落物等方式减缓坡耕地产流产沙量,地下通过植被根系固定土壤,防止养分通过孔(裂)隙向地下渗漏进而达到减少坡耕地土壤养分流失。 展开更多
关键词 养分流失 雨强 地下孔隙度 径流 泥沙 喀斯特坡耕地
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文章速递Experimental investigation on scour topography around high-rise structure foundations 认领
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作者 Yang Xiao Hao Jia +3 位作者 Dawei Guan Dongfang Liang Saiyu Yuan Hongwu Tang 《国际泥沙研究:英文版》 SCIE CSCD 2021年第3期348-361,共14页
The current study aims to investigate the characteristics of scour topography around High-Rise Structure Foundations(HRSFs)via physical modeling tests.Clear-water scour tests with a uniform non-cohesive bed are modele... The current study aims to investigate the characteristics of scour topography around High-Rise Structure Foundations(HRSFs)via physical modeling tests.Clear-water scour tests with a uniform non-cohesive bed are modeled under the action of unidirectional steady flows.Time variations of the erosion and deposition topography are measured.The results show that deposition downstream of the first dune behind the HRSF is not located on the centerline of the wake.The deposition pattern indicates that a long steady wake region exists behind the permeable foundation.The scour depth around an HRSF is much less than that around a monopile because of the structural permeability,which gives rise to the bleed flow and a weakened downflow and horseshoe vortex.Additionally,the asymmetry of the HRSF affects the scour rate but not the final equilibrium scour depth.The average scour slope decreases along the direction of the flow.On the contrary,the scour radial distance increases along the direction of the flow,with the average value changing from 1.36De to 2.35De(where De is the equivalent diameter of the foundation).Furthermore,the scour hole around the HRSF is serrated rather than smooth owing to the presence of multiple piles.Empirical formulae are suggested for estimating the evolution of scour depth and volume.These laboratory experiments provide reference information for relevant numerical modeling studies and can be applied to guide engineering designs in an ocean area. 展开更多
关键词 High-rise structure foundation Scour Sediment transport Pile groups
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文章速递Mineral composition and particle size distribution of river sediment and loess in the middle and lower Yellow River 认领
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作者 Shimin Tian Zhiwei Li +3 位作者 Zhaoyin Wang Enhui Jiang Wenlong Wang Meng Sun 《国际泥沙研究:英文版》 SCIE CSCD 2021年第3期392-400,共9页
Hyperconcentrated flows often occur in the middle and lower Yellow River(MLYR)and its tributaries,within which the main sediment source originates from the Loess Plateau of China due to serious water erosion.Little is... Hyperconcentrated flows often occur in the middle and lower Yellow River(MLYR)and its tributaries,within which the main sediment source originates from the Loess Plateau of China due to serious water erosion.Little is known about the properties of river sediment that is transported by hyperconcentrated flows,particularly with respect to the mineral composition and size distribution.Samples of sediment and loess were collected in the northern,middle,and southern Loess Plateau and the mainstream and tributaries of the MLYR.A total of 18 loess samples and 24 river sediment samples were analyzed to determine their sediment size distribution and mineral composition.The bottom loess samples reflected the original sedimentary features of the Loess Plateau,and the median particle size reduced,and the clay content increased from the north to the south of the study region.The surface loess has been weathered under the action of wind and rainfall,and the clay particle content in the surface loess samples was higher than that in the undisturbed bottom loess.Erosion of the surface soil due to rainfall and surface runoff means that fine particles(mostly clay)have been washed away.The median diameter of surface loess particles was a little larger than that of the bottom loess particles where water erosion dominates.The particle size became coarser with increasing distance from the estuary in the MLYR,which reflects depositional sorting in the river channel.Significant logarithmic relations were found between the median diameter of the sediment particles and the i)non-clay mineral content and ii)clay mineral content.Thus,clay and non-clay mineral compositions can be conveniently estimated from the particle size distribution. 展开更多
关键词 River sediment Loess Mineral composition Particle size distribution Clay minerals
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文章速递Comparison of Pb(Ⅱ) and Cd(Ⅱ) micro-interfacial adsorption on fine sediment in the Pearl River Basin, China 认领
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作者 Qunsheng Fang Zhihe Chen +1 位作者 Jianpeng Zheng Zhihua Zhu 《国际泥沙研究:英文版》 SCIE CSCD 2021年第3期401-418,共18页
The complex micro-interfacial interaction theories of heavy metal ions such as Pb(Ⅱ)and Cd(Ⅱ)adsorption on fine sediment in aqueous solution were not systematically investigated.The aim of this work was to reflect t... The complex micro-interfacial interaction theories of heavy metal ions such as Pb(Ⅱ)and Cd(Ⅱ)adsorption on fine sediment in aqueous solution were not systematically investigated.The aim of this work was to reflect the micro-interfacial adsorption characteristics.Sediment samples were collected from an estuary.The Isothermal and kinetics adsorption experiment were done to acquire the data.Isothermal,kinetics,film diffusion and intraparticle diffusion models were adopted to fit the adsorption experimental data.The results indicated that the Langmuir,Freundlich and Temkin models were suitable for analyzing the isothermal experimental data.The maximum adsorption capacities of Pb(Ⅱ)and Cd(Ⅱ)on the sediment were 1.1377 and 0.9821 mg·g-1,respectively.The qm and KL of the Langmuir model,Kf and nF of the Freundlich model,and b and A of the Temkin model all exhibited a power function relationship with the initial adsorbate concentration.The pseudo-second-order model provided a better fit for the experimental kinetics data compared with the fit of the pseudo-first-order and Elovich models.The pseudo-second-order parameters k2 and qe of Pb(Ⅱ)and qe of Cd(Ⅱ)both had a power function relationship with adsorption time,additionally,the k2 of Cd(Ⅱ)had an exponential function relationship with adsorption time.The liquid-film diffusion parameters kfd of Pb(Ⅱ)and Cd(Ⅱ)were 0.0569 and 0.1806 min1,respectively.The intraparticle diffusion parameter kid values of Pb(Ⅱ)and Cd(Ⅱ)were 0.0055 mg$g1$min1/2 and 0.0049 mg$g1$min1/2,respectively.The physical significance of the model parameters showed that Pb(Ⅱ)adsorption on sediment was stronger than Cd(Ⅱ).The results of this study provided a theoretical reference for the micro-interfacial mechanism of heavy metal ion adsorption on sediment. 展开更多
关键词 Sediment Heavy metal ions Micro-interfacial interaction Isotherms Kinetics Model parameters
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Characteristics of sedimentation and channel adjustment linked to the Three Gorges Reservoir 认领
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作者 Xiaoya Tang Sichen Tong +4 位作者 Guoxian Huang Guangxiang Xu Xinghua Li Kun Lei Shiming Yao 《国际泥沙研究:英文版》 SCIE 2021年第2期177-189,共13页
Construction of large dams is attractive because of their great benefits in flood control,hydropower generation,water resources utilization,navigation improvement,etc.However,dam construction may bring some negative i... Construction of large dams is attractive because of their great benefits in flood control,hydropower generation,water resources utilization,navigation improvement,etc.However,dam construction may bring some negative impacts on sediment transport and channel dynamics adjustments.Due to the effects of recent water and soil conservation projects,sediment retention in the newly constructed large upstream reservoirs,and other factors,the sedimentation in the Three Gorges Reservoir(TGR)is quite different from the amount previously predicted in the demonstration stage.Consequently,based on the measured data,characteristics of sedimentation and the related channel deformation in the TGR were analyzed.The results imply that sediment transport tended to be reduced after the Three Gorges Project(TGP).Sedimentation slowed dramatically after 2013 and indicated obvious seasonal characteristics.Due to the rising water level in the TGR in the flood season,the yearly sediment export ratio(Eratio)was prone to decrease.The water level near the dam site should be reasonably regulated according to the flow discharge to improve the sediment delivery capacity and reduce sedimentation in the TGR,and to try to avoid situations where the flood retention time is close to 444 h.The depositional belt was discontinuous in the TGR and was mainly distributed in the broad reaches,and only slight erosion or deposition occurred in the gorge reaches.Sedimentation in the broad and gorge reaches accounted for 93.8% and 6.2% of the total sedimentation,respectively.The estuarine reach located in the fluctuating backwater area experienced alternate erosion-deposition,with a slight accumulative deposition in the curved reach.Sedimentation mainly occurred in the perennial backwater area.The insight gained in this study can be conducive to directly understanding of large reservoir sedimentation and mechanism of channel adjustment in the reservoir region in the main channel of large river. 展开更多
关键词 Three Gorges Reservoir Sedimentation characteristics Channel adjustment Reduced sediment load
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Characteristic analysis of phospholipid fatty acids (PLFAs) in typical nutrient polluted lake sediment in Wuhan 认领
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作者 Xia Zhang Qianru Chen +6 位作者 Chuan Wang Hongpei Zhang Yuqing Zhao Liping Zhang Biyun Liu Zhenbin Wu Qiaohong Zhou 《国际泥沙研究:英文版》 SCIE 2021年第2期221-228,共8页
The process of urbanization aggravates the endogenous pollution of urban lake sediment,and polluted sediment may seriously affect the quality of the water in lakes.At present,it is difficult to distinguish the differe... The process of urbanization aggravates the endogenous pollution of urban lake sediment,and polluted sediment may seriously affect the quality of the water in lakes.At present,it is difficult to distinguish the difference between sediment that is heavily polluted by nitrogen(N)and phosphorus(P)when using an analysis based on a physicochemical index classification.The current study applied phospholipid fatty acid(PLFA)technology to further analyze the sediment characteristics from the perspective of microbiology.Surface sediment from five urban lakes that are heavily polluted with N and P in Wuhan were sampled.Statistical approaches were used to analyze the microbial community structure in the sampled sediment,and to determine the correlations between the microorganisms and physicochemical indices.The most severely polluted lake sediment had similar PLFA structures,the highest saturated fatty-acid content,and bacteria as the dominant microorganism.However,there were differences between the microbial biomass of the various sediment samples,which may have been related to the degree of N and P pollution.Analysis of the microbial diversity in the sediment samples indicated that the bacteria were experiencing starvation and nutrient pressure,which may have been due to the dissolved oxygen concentration of the heavily polluted lake sediment.A correlation analysis showed that the endogenous N and P had different effects on the microbes of the polluted sediment.A redundancy analysis(RDA)demonstrated that the N/P ratio had the greatest influence on the PLFA species,accounting for 83%of the cumulative interpretation.To effectively promote the role of sediment microorganisms on circulating elements,it is necessary to regulate the N/P ratio of the sediment to some extent.When the N/P ratio in sediment exceeds 6,N pollution should be prioritized. 展开更多
关键词 Lake sediment Endogenous pollution Phospholipid fatty acid(PLFA)analysis Microbial population N/P ratio
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A new portable in situ flume for measuring critical shear stress on river beds 认领
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作者 Cheng He James Nodwell Taylor +1 位作者 Quintin Rochfort David Nguyen 《国际泥沙研究:英文版》 SCIE 2021年第2期235-242,共8页
A new portable in situ flume(PISF)for measuring critical bed shear stress(CBSS)was developed in this study.The PISF consists of an open bottom sediment erosion chamber and an electrically-driven pump.Unlike most exist... A new portable in situ flume(PISF)for measuring critical bed shear stress(CBSS)was developed in this study.The PISF consists of an open bottom sediment erosion chamber and an electrically-driven pump.Unlike most existing in situ flumes with similar designs,the new PISF does not rely on monitoring the flow conditions or particle density in the sediment erosion chamber;instead,it is a pre-calibrated flume.The calibration was performed by first determining CBSS of various selected sediment samples of known particle size and density(using the law of the wall),based on flow velocity-depth profiles measured in a 6 m straight open-channel flume using a Particle Image Velocimetry(PIV)system.These same particles of known CBSS were then used in the new in-situ flume under controlled lab conditions to obtain a series of calibration curves of CBSS vs.pump electrical power.A wide variety of particle types and sizes(simulated sediments)were used in this two-step calibration procedure to widen CBSS measurement range and simulate cohesive force effects.The size of the PISF is much smaller and more practical than other similar devices as lamellar flow conditions are not required and it can be applied to a wide range of sediment types including cohesive sediments. 展开更多
关键词 Sediment erosion In situ flume Critical bed shear stress Particle image velocimetry Law of the wall
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Evaluation of sediment contamination in the Red Sea coastal area combining multiple pollution indices and multivariate statistical techniques 认领
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作者 Yousef Saeed Saleh 《国际泥沙研究:英文版》 SCIE 2021年第2期243-254,共12页
In the recent years,the Red Sea coast of Yemen has been severely affected by intensive anthropogenic activities.The current study constitutes a thorough inquiry to evaluate the extent of heavy metals pollution in Yeme... In the recent years,the Red Sea coast of Yemen has been severely affected by intensive anthropogenic activities.The current study constitutes a thorough inquiry to evaluate the extent of heavy metals pollution in Yemen's Red Sea coast sediment and identifies the possible sources of pollution.The concentrations of five metals(copper(Cu),zinc(Zn),cadmium(Cd),lead(Pb),and nickel(Ni))collected from nine sites along the Red Sea coast of Yemen were assessed using an atomic absorption spectrophotometer(ASS).Sediment quality indices,such as the sediment quality guidelines(SQGs),potential ecological risk(RI),contamination factor(CF),pollution load index(PLI),geoaccumulation index(Igeo),and modified degree of contamination(mCd)were computed.In addition,multivariate statistical techniques(principal component analysis(PCA),hierarchical cluster analysis,and Pearson's correlation analysis)were applied to identify the potential sources of metals.The mean concentrations of Cu,Zn,Cd,Pb,and Ni were 51.3,61.9,4.02,9.9,and 33.4 mg/kg dry wt,respectively.The spatial distribution revealed that the metals concentrations were high at the middle zone and low southward of Hodeida city.According to the SQGs,the adverse biological effects of metals were occasionally associated with Cu and Cd,frequently associated with Ni,and not expected to occur with Zn and Pb.The RI indicated that the sediment of the studied sites pose low(RI<50)to considerable(100≤RI<200)ecological risk.The mean effect range-median quotient(M-ERM-Q)indicated that the combination of the studied metals had the toxicity probability of 21%at all studied sites.Igeo and CF indicated that the metals concentrations were in the descending order of:Zn>Ni>Pb>Cd>Cu,whereas the PLI and mCd indicated that Ras Isa(Site 5)and Urj village(Site 6)were the most polluted sites.PCA,cluster analysis,and correlation analysis found that Cd,Pb,and Ni mostly originated from anthropogenic sources while Cu and Zn were mainly derived from natural sources.Thus,it is evident that the intensive anthr 展开更多
关键词 Red Sea Heavy metals POLLUTION Spatial distribution Sediment quality
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General velocity formula of boundary layer above mobile sediment bed induced by asymmetric waves 认领
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作者 Xin Chen Minghong Chen 《国际泥沙研究:英文版》 SCIE 2021年第2期255-267,共13页
Sediment movement in the wave boundary layer above a mobile sediment bed is complex.A velocity formula for the boundary layer is proposed for sheet flow induced by asymmetric waves above a mobile sediment bed.The form... Sediment movement in the wave boundary layer above a mobile sediment bed is complex.A velocity formula for the boundary layer is proposed for sheet flow induced by asymmetric waves above a mobile sediment bed.The formula consists of a free stream velocity and a defect function which contains a phase-lead,boundary layer thickness and mobile sediment bed.Phase-lag of sediment movement is considered in the formula for the mobile sediment bed.The formula needs six dependent variables about asymmetric wave and sediment characteristics.Asymmetry effects on parameters(orbital amplitude,roughness height,bed shear stress,and boundary layer thickness)are properly considered such that the formula can yield velocity differences among onshore,offshore,acceleration,and deceleration stages.The formula estimates the net boundary layer velocity resulting from the mobile sediment bed and asymmetric boundary layer thickness.In addition,a non-constant phase-lead also contributes to the net boundary layer velocity in asymmetric oscillatory sheet flow.Results of the formula are as good as that of a two-phase numerical model.Sheet flow transport induced by asymmetric waves,and the offshore net sediment transport rate with a large phase-lag under velocity-skewed waves,can be adequately estimated by the formula with a power sediment concentration function. 展开更多
关键词 Asymmetric wave Boundary layer Mobile sediment bed Sheet flow Velocity formula
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Climatic and anthropogenic impacts on the decrease of sediment discharge to the Mediterranean coast from the largest river of Maghreb 认领
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作者 Ali Hadour Gil Mahé Mohamed Meddi 《国际泥沙研究:英文版》 SCIE 2021年第2期268-278,共11页
The current study focuses on the issue of the decrease in sediment discharge to the Mediterranean Sea by the largest river in Algeria,the Wadi Cheliff(i.e.Cheliff River).This study clarifies the effect of climatic and... The current study focuses on the issue of the decrease in sediment discharge to the Mediterranean Sea by the largest river in Algeria,the Wadi Cheliff(i.e.Cheliff River).This study clarifies the effect of climatic and anthropogenic factors on the changes in the sedimentary dynamics of the Cheliff River discharging to the sea.The data used(rainfall,water discharge,and sediment discharge)concern the Sidi Bel Attar gaging station on the Cheliff River,only 18 km from discharge to the Mediterranean Sea.A power-type statistical regression model was used to fill the 74.2% gap in Suspended Solids(SS)measurements in the establishment of a SS database for the period 1951e2012.The study results show that the transport of suspended sediment discharged to the sea is about 487 t/km^2/yr.Statistical tests of breaks highlight that rainfall decreased by 26% and that water and sediment input to the sea declined from 74%to 63% for the period of 1981e2012.The correlation analysis shows a decrease in the contribution of rainfall on sediment and water input at the outlet equal to 77.9% and 77.8%,respectively,during the period of 1980 e2012,compared to the period of 1968e1980.However,the double mass method reflects the contribution of factors other than rainfall to the decrease of sediment input to the sea.These other factors mainly include large dams,which intercepted about 71%of the total volume of sediment discharged to the sea during the period of 1968e2010.In addition the contribution of large dams to the reduction of sedimentary input to the sea is more important than that of the decrease in rainfall.The management of large dams also contributes to the increase in the sediment deficit to the sea through the prioritization of interception of sediment at the expense of releases,for socio-economic purposes,68.4%of the Cheliff River discharge is diverted for human use.This has led to an increase in the mean water bed level at bankfull downstream,where the Cheliff River gave up 51%of its width to the floodplain between 1996 and 2009.I 展开更多
关键词 Sediment discharge Cheliff River Algeria North Africa DAMS Mediterranean Sea
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One-dimensional morphodynamic model for retrogressive erosion based on a sediment entrainment theory at high flow velocity 认领
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作者 Zenghui Wang Junqiang Xia +2 位作者 Meirong Zhou Shanshan Deng Tao Li 《国际泥沙研究:英文版》 SCIE 2021年第2期306-316,共11页
Retrogressive erosion is a high-speed erosion process that usually occurs during the rapid release of stored water in reservoirs built on sandy rivers.Retrogressive erosion has been utilized in the practice of reservo... Retrogressive erosion is a high-speed erosion process that usually occurs during the rapid release of stored water in reservoirs built on sandy rivers.Retrogressive erosion has been utilized in the practice of reservoir sedimentation control,but accurate prediction of the bed deformation process by numerical models has rarely been reported.The current study presents a one-dimensional morphodynamic model for simulating the evolution process of retrogressive erosion induced by high-velocity flows on steep slopes.The governing equations apply a Cartesian coordinate system with a vertically oriented z axis.The bed surface gradient and friction terms in the flow equations include correction factors to take account of the effects of high slope on flow movement.The net vertical sediment flux term in the sediment transport and bed deformation equations is calculated using an equation of erosion velocity.Particularly,this equation is based on an empirical relation between the sediment entrainment rate and the Shields parameter in contrast to the traditional sediment transport capacity,and the critical Shields parameter is modified by taking into account the permeability of the sediment layer and the stability of particles on a slope.The feedback of scoured sediment on the flow movement is considered by additional terms in the governing equations.Flume experiments of retrogressive erosion in literature were simulated to validate the model.The temporal variations of the longitudinal profiles of the free surface and channel bed and the sediment transport rate were well predicted.The algorithm calculating sediment entrainment in the proposed model also was validated for an experiment measuring entrainment rate from the literature.More importantly,it was found that the morphodynamic model using the sediment transport capacity equation predicts the trend of cumulative erosion contrary to the measurements,while results of the proposed model can follow a similar trend with the observed data in the retrogressive erosion process. 展开更多
关键词 Retrogressive erosion Sediment entrainment High slope Morphodynamic model RESERVOIR
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Equilibrium relations for water and sediment transport in the Yellow River 认领
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作者 Xujian Chen Yuqi An +1 位作者 Zhihao Zhang Chunhong Hu 《国际泥沙研究:英文版》 SCIE 2021年第2期328-334,共7页
The equilibrium relations for water and sediment transport refer to the relative balance of sediment transport and the relative stability of river courses formed by the automatic adjustment of riverbeds.This is the th... The equilibrium relations for water and sediment transport refer to the relative balance of sediment transport and the relative stability of river courses formed by the automatic adjustment of riverbeds.This is the theoretical basis for the comprehensive management of sediment in the Yellow River.Based on the theories of sediment carrying capacity and the delayed response of riverbed evolution,in this study,the equilibrium relations for water and sediment transport in the Yellow River are established.These relations include the equilibrium relationships between water and sediment transport and bankfull discharge in the upper and lower Yellow River and between water and sediment transport and the Tongguan elevation in the middle Yellow River.The results reveal that for the Ningmeng reach,the Tongguan reach,and the lower Yellow River,erosion and deposition in the riverbeds are adjusted automatically,and water and sediment transport can form highly constrained equilibrium relationships.These newly established equilibrium relationships can be applied to calculate the optimal spatial allocation scheme for sediment in the Yellow River. 展开更多
关键词 Yellow River Water and sediment transport Riverbed evolution Bankfull discharge Equilibrium relationship
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Experimental assessment and prediction of temporal scour depth around a spur dike 认领
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作者 Manish Pandey Manousos Valyrakis +2 位作者 Meilan Qi Anurag Sharma Ajay Singh Lodhi 《国际泥沙研究:英文版》 SCIE 2021年第1期17-28,共12页
Spur dikes are river training structures that have been extensively used worldwide for towards enhancing flood control and the stability of embankments and riverbanks.However,scour around spur dikes can be a major pro... Spur dikes are river training structures that have been extensively used worldwide for towards enhancing flood control and the stability of embankments and riverbanks.However,scour around spur dikes can be a major problem affecting their stability and hydraulic performance.The precise computation of temporal scour depth at spur dikes is very important for the design of economical and safe spur dikes.This study focuses on experimentally assessing the temporal variation of scour depth around a vertical wall spur dike and identifying the parameters,which mostly influence spur dike performance for a channel bed surface comprised of sand-gravel mixtures.In the current study,the authors did physical experiments in a flume based study to obtain new data,aimed at deriving a new predictive model for spur dike scour and comparing its performance to others found in the literature.It was found that the dimensionless temporal scour depth variation increases with an increase in(i)the threshold velocity ratio,(ii)the densimetric Froude number of the bed surface sediment mixture,(iii)the flow shallowness(defined as the ratio of the approach flow depth,y,to the spur dike’s transverse length,l),and(iv)the flow depth-particle size ratio.It is also concluded that the temporal scour depth variation in the sediment mixture is influenced by the non-uniformity of sediment and decreases with an increase in the non-uniformity of the sediment mixture.A new mathematical model is derived for the estimation of temporal scour depths in sand-gravel sediment mixtures.The proposed equation has been calibrated and validated with the experimental data,demonstrating a good predictive capacity for the estimation of temporal scour depth evolution. 展开更多
关键词 Spur dike Sand-gravel sediment mixture Clear-water scour Time-dependent scour depth
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Effect of shrub-grass vegetation coverage and slope gradient on runoff and sediment yield under simulated rainfall 认领
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作者 Dandan Han Jingcheng Deng +3 位作者 Chaojun Gu Xingmin Mu Peng Gao Jianjian Gao 《国际泥沙研究:英文版》 SCIE 2021年第1期29-37,共9页
Evaluating the benefits of sediment and runoff reduction in different vegetation types is essential for studying the mechanisms of soil and water conservation on the Loess Plateau.The experiment was conducted in shrub... Evaluating the benefits of sediment and runoff reduction in different vegetation types is essential for studying the mechanisms of soil and water conservation on the Loess Plateau.The experiment was conducted in shrub-grass plots with nine levels of mixed vegetation coverage from 0%to 70%,three slopes(10,15,and 20)and two rainfall intensities(1.0 and 2.5 mm/min).The results showed that the vegetation coverage and slope gradient significantly affect runoff and sediment yield.Shrub-grass vegetation coverage had a significant effect on the runoff start-time,runoff flow velocity,runoff rate,and soil erosion rate on hillslopes.Mixed vegetation coverage could effectively delay the runoff starttime and decrease the runoff flow velocity.However,the effects of the slope gradient on runoff and sediment yield are opposite to those of vegetation coverage.Shrub-grass vegetation coverage could effectively increase runoff and sediment yield reduction benefits,while their benefits were affected by the rainfall intensity.At the 1.0 mm/min rainfall intensity,the reduction in the sediment production rate was greater than that under the 2.5 mm/min intensity.However,when the shrub-grass vegetation coverage exceeded 42%,the runoff reduction benefit was more obvious at higher rainfall intensities.The cumulative sediment yield increased with increasing cumulative runoff,and the rate of increase in the cumulative runoff was greater than that of the cumulative sediment yield with increasing of shrub-grass vegetation coverage.Moreover,there was a power function relationship between cumulative sediment yield and cumulative runoff yield(P<0.05).Our paper is expected to provide a good reference on the ecological environment and vegetation construction on the Loess Plateau. 展开更多
关键词 Simulated rainfall Shrub-grass coverage SLOPE Runoff and sediment yield
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Coupled and splitting bedload sediment transport models based on a modified flux-wave approach 认领
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作者 Hossein Mahdizadeh Soroosh Sharifi 《国际泥沙研究:英文版》 SCIE 2021年第1期38-49,共12页
Numerical modeling of free-surface flow over a mobile bed with predominantly bedload sediment transport can be done by solving the shallow water and Exner equations using coupled and splitting approaches.The coupled m... Numerical modeling of free-surface flow over a mobile bed with predominantly bedload sediment transport can be done by solving the shallow water and Exner equations using coupled and splitting approaches.The coupled method uses a coupling of the governing equations at the same time step leading to a non-conservative solution.The splitting method solves the Exner and the shallow water equations in a separate manner,and is only capable of modeling weak free-surface and bedload interactions.In the current study,an extended version of a Godunov-type wave propagation algorithm is presented for modeling of morphodynamic systems using both coupled and splitting approaches.In the introduced coupled method the entire morphodynamic system is solved in the form of a conservation law.For the splitting technique,a new wave Riemann decomposition is defined which enables the scheme to be utilized for mild and strong interactions.To consider the bedload sediment discharge within the Exner equation,the Smart and Meyer-Peter&Müller formulae are used.It was found that the coupled solution gives accurate predictions for all investigated flow regimes including propagation over a dry-state using a Courant-Friedrichs-Lewy(CFL)number equal to 0.6.Furthermore,the splitting method was able to model all flow regimes with a lower CFL number of 0.3. 展开更多
关键词 Bedload sediment transport Coupled solution Flux-wave method Shallow water equations Splitting technique Wave propagation algorithm
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