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The paper presents a process-based distributed modelling approach for estimating sediment budget at a river basin scale with partitions of suspended and bed loads by simulating sediment loads and their interactions. In this approach, a river basin is represented by hillslopes and a network of channels. Hillslopes are divided into an array of homogeneous grid cells for modelling surface runoff and suspended sediments. Channels are defined by incorporating flow hydraulic properties into the respective hillslope grids as sub-grid attributes for modelling both suspended and bed loads. Suspended sediment transport is modelled using one dimensional kinematic wave approximation of Saint-Venant’s principles of conservation of mass and momentum. Transport capacity of runoff or streamflow is used to set the limit of suspended sediment transport rate. Bed load in channels is estimated based on the instantaneous water and hydraulic parameters. Fractional interchange between suspended load and bed load is then back calculated. The performance of the model was evaluated through a case study application in a large river basin in Japan. The model satisfactorily calculated the sediment transport and total sediment budget in the basin. The simulated bed load was found to be reasonable and consistent with the water flow and suspended sediment flux. The results showed the bed load can be expressed as a linear function of the suspended load. The fractions of different sediment loads also exhibit linear relationships with water discharge for the rising and recession limbs of the flood hydrographs. The case study has demonstrated that the process-based distributed modelling approach can efficiently describe the basin-scale sediment budgets with due consideration of the suspended and bed loads and their interactions in the hillslopes and channels. 相似文献
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平面二维河床变形的数值模拟 总被引:31,自引:3,他引:28
为了研究河道平面二维的河床变形问题,及由此而引起的对防洪、航运等造成的影响,本文给出出非均匀沙的平面二维全沙动床数学模型方程组,并考虑了移质不和饱和输移、非均匀沙推移质输移及床沙级配的调整。在求解水流泥沙运动方程时,采用控制体和只法及动边界技术,对水流速度场、悬移质浓度场及河床变形进行了数值模拟。该模型采用正交曲线网格来克服天然河道边界形状复杂、长度尺度相差悬殊以及由于水位波动引起计算边变化等等困 相似文献
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《水动力学研究与进展(B辑)》2016,(1)
The purpose of this study is to establish a depth-averaged 2-D hydrodynamic and sediment transport model for the dambreak flows with vegetation effect. The generalized shallow water equations are solved using an explicit finite volume method with unstructured quadtree rectangular grid, and in the hydrodynamic model, a Harten-Lax-Van Leer(HLL) approximate Riemann solver is used to calculate the intercell flux for capturing the dry-to-wet moving boundary. The sediment transport and bed variation equations in a coupled fashion are calculated by including the bed variation and the variable flow density in the flow continuity and momentum equations. The drag force of vegetation is modeled as the sink terms in the momentum equations. The developed model is tested against lab experiments of the dam-break flows over a fix bed and a movable bed in vegetated and non-vegetated channels. The results are compared with experimental data, and good agreement is obtained. It is shown that the reduced velocity under vegetated conditions leads to a decrease of the peak discharge and a rise of the water level of rivers and also an enhancement of the sediment deposition. 相似文献
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复式断面河槽流速横向分布及其对滩唇形成的影响 总被引:1,自引:0,他引:1
通过对水流微小控制体进行受力分析,建立了复式断面流速横向分布模型,该模型考虑了侧向副流惯性力的影响。采用实验资料对该模型进行检验,模型计算值与实测值符合较好。运用该模型计算了不同条件下复式断面流速和挟沙力的横向分布,并定量分析了横向分布特性对滩唇形成的影响。分析表明,水流漫滩时,复式断面的横向挟沙力变幅较大,尤其是在主槽和河漫滩交界处,挟沙力减小迅速,而含沙量减小相对较小,泥沙发生淤积,容易形成滩唇。单从水流挟沙力角度考虑,水流漫滩后水深越小、滩槽的糙率差越大,越容易形成滩唇。 相似文献
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泥沙数学模型近底边界条件Ⅱ:非平衡输沙 总被引:3,自引:0,他引:3
由基于湍流猝发的可自由冲刷床面泥沙上扬通量函数,直接构造床面可自由冲刷时近底含沙量Neuman边界条件,考虑刚性床面上泥沙不一定能得到充分补给之事实,给出相应的近底边界条件提法。 相似文献
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Sampson Asante Akrasi 《Lakes & Reservoirs: Research and Management》2005,10(3):179-186
Information on a river basin's sediment yield is an important requirement for water resources development and management. In the Volta River basin of Ghana, data on suspended sediment yield are limited due to the lack of logistic support for systematic sediment sampling activities. This paper presents the results of a study using the available measurements of suspended sediment transport for eight monitoring stations in order to develop a simple predictive tool for estimating the suspended sediment yields for catchments for which no sediment measurements had been undertaken. Regression analysis was used to establish a relationship between specific suspended sediment yield and both the mean annual run‐off and the drainage basin area. The prediction model was used to estimate the sediment loads of the Volta River and its main tributaries (Black Volta, White Volta and Oti Rivers) in order to estimate the total suspended sediment input to the reservoir and the equivalent specific suspended sediment yield from the catchment surface. Although these sediment yield values are relatively low by world standards, the results obtained provide a basis for assessing future sedimentation problems in Lake Volta and for underpinning the development of sediment control and management strategies for the reservoir. 相似文献
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长江口二维非均匀悬沙数值模拟 总被引:3,自引:0,他引:3
针对长江口水流泥沙运动的特点建立了非均匀悬沙的平面二维数值模型。在模型中考虑了波浪对流场的影响和对水流挟沙力的影响 ,在确定悬沙絮凝沉速时考虑了泥沙粒径、盐度、含沙量及水流紊动的影响。悬沙模型建立在曲线坐标下 ,悬沙输运方程采用破开算子的方法求解 ,平流项采用UltimateQuickest格式求解 ,提高了计算的精度。通过实测资料对数学模型计算的悬沙含量进行检验 ,表明它较好地反应了长江口地区泥沙的运动规律 相似文献
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明渠挟沙水流中悬移质的床面平衡浓度 总被引:1,自引:1,他引:0
本文通过泥沙颗粒运动的概率密度输运方程,推导出床面附近运动的泥沙颗粒的概率密度函数及相应的泥沙颗粒向上运动和向下运动的通量,建立了计算明渠挟沙水流悬移质床面平衡浓度的关系式。通过与试验资料及经验公式的比较对本文建立的关系式进行了检验,结果表明本文所得计算公式与实际符合较好,可用于悬沙床面平衡浓度的计算。 相似文献
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泥沙公式在伶仃洋的适应性研究 总被引:1,自引:0,他引:1
本文用ECOMSED模型中的三维水动力模块和泥沙模块,模拟了1978年7月21日到23日的水动力和泥沙沉积过程,并与实测资料进行了比较,模拟的结果合理,得到了伶仃洋水域的水动力和泥沙的基本规律。此外,对部分的泥沙沉降概率公式、沉降速度公式和再悬浮通量公式进行了验证和对比,通过误差分析,结果表明,大部分公式在伶仃洋是适用的。 相似文献
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Simulation of Runoff and Suspended Sediment Transport Rate in a Basin with Multiple Watersheds 总被引:1,自引:1,他引:0
Accurate runoff and suspended sediment transport rate models are critical for watershed management. In this study, a physiographic
soil erosion–deposition (PSED) model is used in conjunction with GIS, to simulate the runoff and sediment transport process
during storm events in a multi-watershed basin. This PSED model is verified using three typhoon events and 33 storm events
in Cho-Shui River Basin, located in central Taiwan. Cho-Shui River Basin has 11 sub-watersheds displaying a variety of hydrologic
and physiographic conditions as well as high concentrations of suspended sediment in river flow and a steep average channel
bed slope of 2%. The results show the capability, applicability, and accuracy of the PSED model for multi-watershed basins. 相似文献
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本文从水沙两相紊流的双流体数学模型出发,采用直接数值计算的方法,研究了海床面附近边界层内往复流对悬移质泥沙运动的影响。研究方法的有效性通过典型问题的流速分布、紊动能量分布以及泥沙浓度分布的计算结果和实验观测结果的比较得到了良好的验证。本研究还探讨了往复流条件下各类相间作用力的时空变化规律及其对悬移质泥沙运动的影响。 相似文献
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A new model for predicting bed evolution in estuarine area and its application in yellow river delta
This article discusses the process of sediment transport and proposes a morphological model to predict the bed evolution in estuaries.The hydrodynamic module is based on an existent model-Depth Integrated Velocity And Solute Transport (DIVAST) and the wetting and drying method is adopted to deal with the moving boundary.Both cohesive sediment and non-cohesive sediment are taken into consideration in the sediment transport module with the capability of simulating the transport of graded sediments under non-e... 相似文献
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P. A. Carling 《河流研究与利用》1988,2(3):369-387
The history of investigations of channel change consequent upon river regulation is traced from the late 1960s until the present. The associated sediment transport and depositional processes are also reviewed. Conveniently the approaches adopted historically have fallen into three basic groups, these are: (1) analyses of the changes in channel networks as evident in adjustments to hydraulic geometry related to catchment area; (2) analyses concerned with sediment transport processes and channel adjustments at the reach scale (typically utilizing regime-type concepts), and finally; (3) more recent attempts at an integrated approach utilizing holistic concepts of channel change over extended time periods. A major conclusion drawn from this review is that each reservoir-catchment system is unique, producing singular responses that cannot easily be integrated into a basic general model except at a facile level. The continuing lack of complete theoretical models of channel adjustment is a hindrance in predicting regulation effects and may be related to limited understanding of such factors as sediment supply dynamics and bank collapse mechanisms. Emphasis is placed on: the importance of the aggregational as well as the well-known degradational response of channels below dams; the recognition of suitable temporal frameworks; the potentially destabilizing effect of rare large floods; and the local effects of unregulated tributary inflows. In addition more sophisticated theory and analysis needs applying to the transport and subsequent deposition of suspended sediments in gravel-beds whilst the three-dimensional facies relationships of regulated river alluvial suites need clarification in the light of recent initiatives concerning the sedimentary architecture of other alluvial systems. 相似文献
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Effects of projected climate on the hydrodynamic and sediment transport regime of the lower Athabasca River in Alberta,Canada 下载免费PDF全文
The potential effects of climate change on the hydrodynamic and sediment transport regime of the lower Athabasca River (LAR) in Alberta, Canada, is investigated. Future climate projections for the region suggest a potential increase in mean air temperature and precipitation by about 2.8–7.1 °C and 8–25%, respectively, by the end of this century. Implications of these climatic changes on the hydrologic regime of the LAR are found to be significant with spring flows expected to increase by about 11–62% and 26–71% by the end of the century for a moderate and high emissions scenarios respectively with corresponding decreases in summer flows. The effects of such changes are examined using the MIKE‐11 hydrodynamic and sediment transport modelling system with inflow boundary conditions corresponding to the changing hydro‐climatic regime. The results suggest that there will be an overall increase in flow velocity, water level, and suspended sediment concentration and transport for most seasons except in the summer months when there may be some decreases. The projected changes in suspended sediment concentration will result in an overall increase in mean annual sediment load in the LAR and to the Peace Athabasca Delta by over 50% towards the latter part of this century (2080s) compared with the 1980s base‐line period. Implications of such potential changes in the transport characteristics of the river system to the mobilization and transport of various chemical constituents and their effects on the region's aquatic ecosystems are subjects of other ongoing investigations. 相似文献
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Retention of suspended particles by settling is among the main physical treatment processes in constructed wetland ponds. Laboratory experiments were conducted to study the transport and deposition of suspended particles in the slow, near-stagnant flows typical of constructed wetland ponds with emergent vegetation. The presence of stems was found to create a velocity field which is much more uniform than its counterpart without vegetation. This property was used to obtain an approximate mathematical model, for which an analytical solution could be given to describe sediment transport and deposition. The deposition rates predicted by this formula were compared to the data from the above-mentioned laboratory experiments and found to agree closely. 相似文献