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连云港疏浚工程的环境效应——以羊窝头抛泥区为例 被引量:19
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作者 张国安 虞志英 《黄渤海海洋》 CSCD 北大核心 2001年第2期46-56,共11页
以连云港羊窝头抛泥区为研究区域 ,对疏浚工程中产生的大量疏浚弃土倾倒入海后 ,所产生弃土的堆积—流失—扩散过程以及海域环境效应 ,进行了现场观测和计算 ,并从物理、化学和生物 3个方面对海区的水质、底质和生态环境的影响作出客观... 以连云港羊窝头抛泥区为研究区域 ,对疏浚工程中产生的大量疏浚弃土倾倒入海后 ,所产生弃土的堆积—流失—扩散过程以及海域环境效应 ,进行了现场观测和计算 ,并从物理、化学和生物 3个方面对海区的水质、底质和生态环境的影响作出客观分析。认为疏浚的环境效应主要取决于疏浚弃土本身的受污染程度 ,而对海域环境的影响 ,则主要是弃土扩散所造成的海水中悬浮沙量增加引起水质浑浊度的增高的物理性影响 ,同时由于弃土中大量的粘粒和胶粒物质具有吸附海水中重金属和有机物等污染物质的能力 ,有利于水质和生态环境的改善 ,因而对各类海洋生物生存环境的影响是十分轻微的。 展开更多
关键词 连云港 疏浚工程 弃土 环境效应 水质 生态环境 悬浮沙量
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Vertical distribution of sediment concentration 被引量:3
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作者 Sai-hua HUANG Zhi-lin SUN +1 位作者 Dan XU Shan-shan XIA 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2008年第11期1560-1566,共7页
A simple formula is proposed to predict the vertical distribution of a suspended load concentration in a 2D steady turbulent flow. The proposed formula significantly improves the well-known Rouse formula where sedimen... A simple formula is proposed to predict the vertical distribution of a suspended load concentration in a 2D steady turbulent flow. The proposed formula significantly improves the well-known Rouse formula where sediment concentration has an infinitely large value at the channel bottom and a zero value at the water surface. Based on this formula and the logarithmic ve- locity profile, a theoretical elementary function for the transport rate of a suspended load is developed. This equation improves the Einstein equation in which the unit-width suspended sediment discharge must be solved by numerical integration and a contra- diction between the lower limit of the integral and that of velocity distribution exists. 展开更多
关键词 Sediment concentration Vertical distribution Suspended load Sediment discharge
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Filling of the Three Gorges Reservoir to the 135-m Level: Instant Effects on the Yangtze Discharge and Suspended Sediment Concentration Entering the Estuary 被引量:2
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作者 CHU Zhongxin ZHAI Shikui ZHANG Jing DING Dong 《Journal of Ocean University of China》 SCIE CAS 2009年第3期291-295,共5页
Via the valuable opportunity of the Three Gorges Reservoir (TGR) 135-m filling in June 2003, the Yangtze discharge and suspended sediment concentration (SSC) entering the estuary during the period from 15 May to 15 Ju... Via the valuable opportunity of the Three Gorges Reservoir (TGR) 135-m filling in June 2003, the Yangtze discharge and suspended sediment concentration (SSC) entering the estuary during the period from 15 May to 15 July 2003 were analyzed to examine the instant effects of the filling on them. The Yangtze discharge and SSC entering the estuary in the periods before, during and after the filling clearly indicated three phases: 1) the pre-storage phase characterized by natural conditions, in which the SSC increased with increasing water discharge; 2) the storage phase, during which the SSC decreased dramatically with decreasing water discharge; and 3) the post-storage phase, during which both the SSC and water discharge remained at relatively low levels first until the end of June, then the SSC increased gradually with increasing water discharge. It seems that the times for the instant effects of the decreasing discharge downstream from the upper Yangtze on the Yangtze discharge and SSC entering the estuary due to the TGR 135-m filling to take place were about 5 d and 1 d respectively, while both were about 18 d for those of the increasing discharge. This probably reflects the buffering and resultantly hysteresis of the 1800-km stretch from the upper Yangtze to the estuary. The results are helpful for scientific and hydrological investigation of the Yangtze mainstream downstream from the TGR Dam and of the estuarine and adjacent coastal waters. 展开更多
关键词 Three Gorges Reservoir (TGR) 135-m filling Yangtze River ESTUARY water discharge suspended sediment concentration
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Daily and Monthly Suspended Sediment Load Predictions Using Wavelet Based Artificial Intelligence Approaches 被引量:6
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作者 Vahid NOURANI Gholamreza ANDALIB 《Journal of Mountain Science》 SCIE CSCD 2015年第1期85-100,共16页
In the current study, the efficiency of Wavelet-based Least Square Support Vector Machine (WLSSVM) model was examined for prediction of daily and monthly Suspended Sediment Load (SSL) of the Mississippi River. For... In the current study, the efficiency of Wavelet-based Least Square Support Vector Machine (WLSSVM) model was examined for prediction of daily and monthly Suspended Sediment Load (SSL) of the Mississippi River. For this purpose, in the first step, SSL was predicted via ad hoc LSSVM and Artificial Neural Network (ANN) models; then, streamflow and SSL data were decomposed into sub- signals via wavelet, and these decomposed sub-time series were imposed to LSSVM and ANN to simulate discharge-SSL relationship. Finally, the ability of WLSSVM was compared with other models in multi- step-ahead SSL predictions. The results showed that in daily SSL prediction, LSSVM has better outcomes with Determination Coefficient (DC)=o.92 than ad hoc ANN with DC=o.88. However unlike daily SSL, in monthly modeling, ANN has a bit accurate upshot. WLSSVM and wavelet-based ANN (WANN) models showed same consequences in daily and different in monthly SSL predictions, and adding wavelet led to more accuracy of LSSVM and ANN. Furthermore, conjunction of wavelet to LSSVM and ANN evaluated via multi-step-ahead SSL predictions and, e.g., DCLssVM=0.4 was increased to the DCwLsSVM=0.71 in 7- day ahead SSL prediction. In addition, WLSSVM outperformed WANN by increment of time horizon prediction. 展开更多
关键词 Suspended Sediment Load Least SquareSupport Vector Machine (LSSVM) WAVELET ArtificialNeural Network (ANN) Mississippi River
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Determining suspended sediment concentration and settling velocity from PC-ADP measurements in the Beibu Gulf, China
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作者 于建清 姜静波 +2 位作者 龚德俊 李思忍 徐永平 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2011年第3期691-701,共11页
Modeling sediment transport depends on several parameters, such as suspended sediment concentration (SSC), shear stress, and settling velocity. To assess the ability of Pulse-Coherent Acoustic Doppler Profiling (PC... Modeling sediment transport depends on several parameters, such as suspended sediment concentration (SSC), shear stress, and settling velocity. To assess the ability of Pulse-Coherent Acoustic Doppler Profiling (PC-ADP) to non-intrusively quantify spatial and temporal SSC and settling velocity at seabed, a field experiment was conducted in the Beibu Gulf (Tonkin Gulf), in the South China Sea. The spatial profiles and temporal variations in SSC at 1 m above bottom were derived from PC-ADP acoustic backscatter intensity determinations after being calibrated with the optical backscatter sensor (OBS) measurements at the same elevation. The PC-ADP and OBS results agreed well. The temporal settling velocity obtained from Rouse profiles agreed well with the Soulsby formula based on size information by LISST (laser in situ scattering and transmissometry). Tides and tidal currents are diurnal in the gulf. SSC increased with increasing ebb and flood flow, and it rapidly decreased with the increase of distance from the seabed. The maximum SSC at 0.16 m and 1.3 m above bottom reached 816 mg/L and 490 mg/L during spring tides, respectively. The sediments consisted of mineral particles 23-162 μm in diameter and 0.05-2.04 crn/s in settling velocity. Generally, both the SSC and settling velocity followed variations in the bottom friction. Results suggest that PC-ADP is able to provide reasonable SSC and settling velocity measurements of both profiles and time series for a long study period. 展开更多
关键词 suspended sediment settling velocity shear velocity acoustic backscatter tidal currents Beibu Gulf
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Principal Denudation Processes and Their Contribution to Fluvial Suspended Sediment Yields in the Upper Yangtze River Basin and Volga River Basin 被引量:1
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作者 VALENTIN Golosov ZHANG Xin-bao +2 位作者 HE Xiu-bin TANG Qiang ZHOU Ping 《Journal of Mountain Science》 SCIE CSCD 2015年第1期101-122,共22页
This paper synthesized the principal land denudation processes and their role in determining riverine suspended sediment yields(SSY) in two typical geographical environments of the Upper Yangtze River Basin in China a... This paper synthesized the principal land denudation processes and their role in determining riverine suspended sediment yields(SSY) in two typical geographical environments of the Upper Yangtze River Basin in China and the Volga River Basin in Eastern Europe. In the Upper Yangtze River Basin, natural factors including topography, climate,lithology and tectonic activity are responsible for the spatial variation in the magnitude of denudation rates.Human disturbances have contributed to the temporal changes of soil erosion and fluvial SSY during the past decades. On one hand, land use change caused by deforestation and land reclamation has played an important role in the acceleration of sediment production from the central hilly area and lower Jinsha catchment; On the other hand, diverse soil conservation practices(e.g., reforestation,terracing) have contributed to a reduction of soil erosion and sediment production since the late 1980 s.It was difficult to explicitly decouple the effect of mitigation measures in the Lower Jinsha River Basindue to the complexity associated with sediment redistribution within river channels(active channel migration and significant sedimentation). The whole basin can be subdivided into seven sub-regions according to the different proportional inputs of principal denudation processes to riverine SSY. In the Volga River Basin, anthropogenic sheet, rill and gully erosion are the predominant denudation processes in the southern region, while channel bank and bed erosion constitutes the main source of riverine suspended sediment flux in the northern part of the basin. Distribution of cultivated lands significantly determined the intensity of denudation processes.Local relief characteristics also considerably influence soil erosion rates and SSY in the southern Volga River Basin. Lithology, soil cover and climate conditions determined the spatial distribution of sheet, rill and gully erosion intensity, but they play a secondary role in SSY spatial variation. 展开更多
关键词 Land denudation Anthropogenicdisturbance Suspended sediment yield UpperYangtze River Volga River
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Numerical Analysis of Adaptation-to-capacity Length for Fluvial Sediment Transport 被引量:1
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作者 LI Zhi-jing CAO Zhi-xian +1 位作者 Gareth PENDER HU Peng 《Journal of Mountain Science》 SCIE CSCD 2014年第6期1491-1498,共8页
Over the last several decades,various sediment transport capacity formulations have been used by geomorphologists and engineers to calculate fluvial morphological changes.However,it remains poorly understood if the ad... Over the last several decades,various sediment transport capacity formulations have been used by geomorphologists and engineers to calculate fluvial morphological changes.However,it remains poorly understood if the adaptation to capacity could be fulfilled instantly in response to differing inflow discharges and sediment supplies,and thus if the calculation of morphological changes in rivers based on the assumed capacity status is fully justified.Here we present a numerical investigation on this issue.The distance required for sediment transport to adapt to capacity(i.e.,adaptation-to-capacity length) of both bed load and suspended sediment transport is computationally studied using a coupled shallow water hydrodynamic model,in line with varied inlet sediment concentrations.It is found that the adaptation-to-capacity length generally decreases as the Rouse number increases,irrespective of whether the inlet sediment concentration increases or reduces.For cases with vanishing inlet sediment concentration a unified relationship is found between the adaptation-to-capacity length and the Rouse number.Quantitatively,the adaptation-to-capacity length of bed load sediment is limited to tens of times of the flow depth,whilst that of suspended sediment increases substantially with decreasing Rouse number and can be up to hundreds of times of the flow depth.The present finding concurs that bed load sediment transport can adapt to capacity much more rapidly than suspended sediment transport,and it facilitates a quantitative criterion on which the applicability of bed load or suspended sediment transport capacity for natural rivers can be readily assessed. 展开更多
关键词 Sediment transport Sediment transport capacity Mathematical river modeling Bed load Suspended load
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