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Non-barrier mudflats in the Changjiang Estuary is examined to obtain preservation potentials and deposition rates over different time scales. The preservation potential of couplet is ca. 46.6% within daily scale and decreases as the time-interval extending, with 9.2% on a semi-lunar scale and 3.7% on a seasonal scale. In the long term, only 1.6% of daily deposition can potentially be preserved in the tidal flat sequence and other 98.4% have been eroded and leave sedimentary discordances, discernable or un-discernable, in the mudflat deposits. A negative log-linear relationship is examined between sedimentation rates and the time spans. The length of sedimentary hiatuses on the mudflat deposition were estimated with considerable uncertainty, but it can provide from an actualistic base some further insights into the nature and origin of ancient mudflat deposits with emphasis on the sedimentary discordances. 相似文献
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A three-dimensional baroclinic current model with wave effects 总被引:2,自引:0,他引:2
Waves can have a significant impact on nearshore currents. A three-dimensional baro-clinic current model including the influence of waves is presented for shallow water areas from Navier-Stokes equations. It has been found that the effects of waves on currents can be expressed in terms of the momentum flux by waves. The model uses non-orthogonal curvilinear coordinates in the horizontal directions and a Sigma coordinate in the vertical direction so that it can be more reasonably applied in estuarine and coastal regions. 相似文献
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IntroductionAccuratemodellingofsurfacewavedynamicsincoastalregionshasbeenthegoalofmuchrecentresearch ,whichhasbeensummarizedinsurveysbyDingemans( 1 997) [1]andKirby( 1 997) [2 ].Therichnessofcoastalwavedynamicsarisesfromthestrongambientcurrentsandthewidevariations… 相似文献
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非线性海浪的波面高度概率分布及其物理解释 总被引:10,自引:0,他引:10
依据非线性随机海浪模型,通过直接求矩的方法,在三阶近似下导出了一种普遍适用的海浪波面高度统计分布,并解释了它的物理含意。对于深水,且仅考虑两类最简单的波-波相互作用,则此分布在精确至H_6的意义下蜕化为Longuet-Higgins给出的Gram-Charlier级数。 相似文献
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Seasonal changes in sea level, tidal range, wind, riverine discharges, nearshore SSC (suspended sediment concentration) and bed-level of intertidal flat at 4 different sites were shown. In addition, the statistical relationships between the dynamics and the behavior of the sediment surface were examined. The average intertidal elevation seems negatively correlated to sea level while positively correlated to nearshore SSC. The effect of wind on seasonal cycle of average intertidal elevation is not evident although wind is an important factor governing short-term erosion/accretion events. The influence of riverine discharges on seasonal cycle of deltaic intertidal flats is masked by other factors. It is concluded that seasonality on mudflats is more complicated than on beaches. 相似文献
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非均匀水流水域波浪的传播变形 总被引:2,自引:2,他引:0
将两个不同的、考虑波流相互作用和能量耗散项的、依赖时间变化的双曲型缓坡方程分别化
为一组等价的控制方程组,具体分析了底摩阻项对相对频率和波数矢的影响,从而选择了合
适的数学模型. 将所选择的缓坡方程化为依赖时间变化的抛物型方程,并用ADI法进
行数值求解,建立了缓变水深水域非均匀水流中波浪传播的数值模拟模型. 通过和波流共线
的解析解的比较,说明数值解和解析解相一致. 结合Arthur(1950)水流这一经典算例,定
量地讨论了考虑联合折射-绕射作用后的波数和仅考虑折射作用的波数的差别及其对波高分
布的影响. 在基本同样的条件下, 本文的数值解与他人的计算结果一致. 相似文献
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There is a common hypothesis for the presently popular mild-slope equations that wave particle motion is irrotational. In this paper, an attempt is made to abandon the irrotational assumption and to set up new sea wave packet equations on slowly varying topography by use of the WKBJ method. To simplify the deduction, the two-dimensional shallow water equations are used to describe the sea wave particle motion in the very shallow nearshore area. The established equations can give some characteristics of wave propagation near shore. 相似文献