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1.
Two-Dimensional Mathematical Model of Tidal Current and Sediment for Oujiang Estnary and Wenzhou Bay 总被引：1，自引：0，他引：1
A 2-D mathematical model of tidal current and sediment has been developed for the Oujiang Estuary and the WenzhouBay. This model accomodates complicated features including multiple islands, existence of turbidity, and significant differ-ence in size distribution of bed material. The governing equations for non-uniform suspended load and bed load transport arepresented in a boundary-fitted orthogonal curvilinear coordinate system. The numerical solution procedures along with theirinitial conditions, boundary conditions, and movable boundary technique are presented. Strategies for computation of thecritical condition of deposition or erosion, sediment transport capacity, non-uniform bed load discharge, etc. are suggested.The model verification computation shows that, the tidal levels computed from the model are in good agreement with the fielddata at the 18 tidal gauge stations. The computed velocities and flow directions also agree well with the values measuredalong the totally 52 synchronously observed verticals distributed over 8 cross sections. The computed tidal water throughputsthrough the Huangda‘ao cross section are close to the measured data. And the computed values of bed deformation fromYangfushan to the estuary outfall and in the outer-sea area are in good agreement with the data observed from 1986 to 1992.The changes of tidal volumes through the estuary, velocities in different channels and the bed form due to the influence of thereclamation project on the Wenzhou shoal are predicted by means of this model. 相似文献
2.
Two-Dimensional Mathematical Model of Tidal Current and Sediment for Oujiang Estuary and Wenzhou Bay 总被引：3，自引：0，他引：3
A 2-D mathematical model of tidal current and sediment has been developed for the Oujiang Estuary and the Wenzhou Bay. This model accomodates complicated features including multiple islands, existence of turbidity, and significant differ-ence in size distribution of bed material. The governing equations for non-uniform suspended load and bed load transport are presented in a boundary-fitted orthogonal curvilinear coordinate system. The numerical solution procedures along with their initial conditions, boundary conditions, and movable boundary technique are presented. Strategies for computation of the critical condition of deposition or erosion, sediment transport capacity, non-uniform bed load discharge, etc. are suggested. The model verification computation shows that, the tidal levels computed from the model are in good agreement with the field data at the 18 tidal gauge stations. The computed velocities and flow directions also agree well with the values measured along the totally 52 synchronously ob 相似文献
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珠江口的黏性泥沙输运对区域海洋工程和河口海洋环境有着重要的影响。本文利用SELFE模型,针对珠江河口海域建立了一个采用非结构三角形网格的三维斜压水动力模型,可耦合模拟海流、潮流及风海流水动力环境,并在此基础上开发了包括底床模块的黏性泥沙输运模型。模拟结果与实测值验证较好,再现了丰水期珠江河口的泥沙输运特征以及最大浑浊带的变化和分布特点。研究表明,丰水期珠江口悬沙质量浓度西侧大于东侧,泥沙主要来自河口上游。河口浅滩上会形成最大浑浊带,最大质量浓度可达0.5 g/L。珠江口最大浑浊带的形成主要受潮动力、重力环流及泥沙再悬浮和沉积过程影响,其中泥沙再悬浮和沉积过程对中滩的最大浑浊带影响显著,而重力环流作用对西滩的最大浑浊带影响显著。 相似文献
5.
河口作为陆海相互作用的关键带,是河流入海泥沙及污染物的主要归宿地。钦江作为广西第二大河流,在茅尾海资源开发利用和生态环境保护与修复中发挥着重要作用。为进一步认识钦江河口地区的沉积动力过程,2021年10月27日至12月8日在此展开水动力和水体环境要素的连续观测。现场观测与分析结果表明,观测期间钦江河口潮汐类型为正规全日潮,浅水分潮显著,平均潮差为3.07 m,具有落潮优势;潮流以全日分潮流为主导,平均流速为0.12 m/s,运动形式主要为往复流;余流流向主要为西南方向。钦江河口潮汐和潮流性质较外湾和茅尾海中部海域全日潮特征更显著。枯季期间河口表层沉积物随潮汐运动表现为侵蚀-沉降交替的变化规律,垂向上侵蚀通量大于沉降通量,水平方向上悬沙净向海输运。冷空气过境带来的降雨使得钦江河口水体盐度降低、浊度增大,悬沙浓度及输沙量增加,同时冷空气南下时北风增强引起钦江河口减水效应并使潮差略有增加,水动力强度增大,增加表层沉积物的活动性,从而引起底部沉积物再悬浮强度和频率增加。 相似文献
6.
In this study, the combined actions of waves and tidal currents in estuarine and coastal areas are considered and a 2D mathematical model for sediment transport by waves and tidal currents has been established in orthogonal curvilinear coordinates. Non-equilibrium transport equations of suspended load and bed load are used in the model. The concept of background concentration is introduced, and the formula of sediment transport capacity of tidal currents for the Oujiang River estuary is obtained. The Dou Guoren formula is employed for the sediment transport capacity of waves. Sediment transport capacity in the form of mud and the intensity of back silting are calculated by use of Luo Zaosen＇ s formula. The calculated tidal stages are in good agreement with the field data, and the calculated velocities and flow directions of 46 vertical lines for 8 cross sections are also in good agreement with the measured data. On such a basis, simulations of back silting after excavation of the waterway with a sand bar under complicated boundary conditions in the navigation channel induced by suspended load, bed load and mud by waves and tidal currents are discussed. 相似文献
7.
开展枯季河口悬沙输运机理研究对于揭示弱径流条件下的陆海相互作用、河口季节性冲淤和水沙关系等具有重要的科学意义.本文根据2018年12月18-25日长江口南槽3个站位连续13个潮周期的同步流速、流向和悬沙浓度等观测资料,运用通量机制分解法研究了各输沙项的特征、贡献和输运机理.结果 表明,从小潮至大潮流速和悬沙浓度不断增加,由南槽上部至下部流速和悬沙浓度逐渐降低.观测期间平均流速与平均悬沙浓度存在明显的正线性关系,但受底质空间差异影响,悬沙浓度对流速的响应强度存在显著的空间变化.枯季期间南槽存在着中上部向陆净输沙、下部向海净输沙的空间输运格局.平流输沙和潮泵输沙是影响和控制净输沙的关键因素,二者的强度和贡献存在明显的潮周期变化和空间变化,垂向环流输沙的强度很弱,对净输沙贡献很小.南槽涨落潮输沙不对称现象明显,流速、悬沙浓度和历时都具有一定的涨落潮不对称性,这些不对称现象共同调节和控制着潮周期净输沙强度和方向的时空变化. 相似文献
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In this paper the characteristics of tidal flow and seasonal variation of seidment content in theHangzhou Bay and their affecting factors are studied.Field investigations and data analysis indicate thatthe sediment movement is mainly influenced by the Yangtze estuary and the sediment of the Yangtze estua-ry is induced by wind wave and tidal flow.Owing to the variation of dynamic conditions,the instanta-neous sediment content is controlled by tidal flow,wind wave,depth of water and tidal range synthetically.A sediment content relationship formula is established with related factors.A non-equilibrium2-dimensional numerical model of suspended sediment transportation is set up,and the finite element meth-od is applied.The computation results of the model is in accordance with field data. 相似文献
9.
A two-dimensional depth-integrated numerical model is refined in this paper to simulate the hydrodynamics, graded sediment transport process and the fate of faecal bacteria in estuarine and coastal waters. The sediment mixture is divided into several fractions according to the grain size. A bed evolution model is adopted to simulate the processes of the bed elevation change and sediment grain size sorting. The faecal bacteria transport equation includes enhanced source and sink terms to represent bacterial kinetic transformation and disappearance or reappearance due to sediment deposition or re-suspension. A novel partition ratio and dynamic decay rates of faecal bacteria are adopted in the numerical model. The model has been applied to the turbid water environment in the Bristol Channel and Severn estuary, UK. The predictions by the present model are compared with field data and those by non-fractionated model. 相似文献
10.
Wim van Leussen 《Geo-Marine Letters》1991,11(3-4):119-126
The behavior of fine-grained sediment transport under tidal action is reviewed. Erosion/sediment cycles are the characteristic
features, indicating the suspended sediment concentration is primarily governed by local phenomena. The long-term transports
cannot be understood without insight into the strongly variable short-term transports. The distribution of fine-grained sediment
deposits within an estuary and the properties of the top layer of the bed are essential. The amount of fine-grained sediment
in the bottom, potentially available for resuspension under specific conditions, can vary enormously within an estuary. Accurate
fine-grained sediment transport predictions often fail because of insufficient knowledge of this factor. 相似文献
11.
Observations of the residual fluxes of water, salt and suspended sediment are presented for seven stations along the Tamar Estuary. The data include measurements over single spring and neap tidal cycles, and are generally applicable to medium or high run-off conditions.Surface to bed differences in salinity are typically of the order of several parts per thousand. Gravitational circulation is an important component of residual flow in the deep, lower reaches of the estuary. Here, Stokes drift is insignificant. In the shallow upper reaches, the major residual currents are generated by Stokes drift and freshwater inputs. Data are compared with predictions from Hansen and Rattray's (1966) model of estuarine circulation.Salt fluxes due to tidal pumping and vertical shear are directed up-estuary at spring tides, tidal pumping being dominant. Tidal pumping of salt is also directed up-estuary at neap tides, although it is insignificant in the lower reaches, where vertical shear dominates.Tidal pumping of suspended sediment is directed up-estuary near the head at spring tides, and probably contributes to the formation of the turbidity maximum. The existence of the turbidity maximum is predicted using a simplified model of the transport of water and sediment. The model shows that an additional mechanism for the existence of the turbidity maximum is an up-estuary maximum in the tidal current speeds (and thus resuspension). In the lower reaches, transport of suspended sediment is directed down-estuary at both spring and neap tides, and sediment is essentially flushed to sea with the fresh water. 相似文献
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青草沙水库是长江河口的一个重大工程,显著改变了北港上段的河势。河势的变化会引起流场和泥沙质量浓度的变化,进而影响河床的冲淤。本文应用三维水动力和泥沙数值模式,计算和分析了青草沙水库工程对附近水域流场、泥沙质量浓度和冲淤的影响。青草沙水库工程建设后,北港河道束窄,导致水库北侧河道主槽流速和泥沙质量浓度增加。水库工程使得进入北港的径流量和纳潮量减少,导致青草沙水库以东、北港下段和拦门沙区域流速和泥沙质量浓度下降。应用半理论半经验河床冲淤公式和模式计算的工程前后流速、泥沙质量浓度和水位数据,给出了由水库工程造成的河床冲淤变化分布。在水库以北北港水域发生普遍冲刷,冲刷强度最大可达2~3 m,冲淤分布和量值与工程前后实测水深变化吻合良好。数值模式较好地模拟了青草沙水库工程对附近水域冲淤分布的影响和变化量值。 相似文献
14.
Morphology, hydrography and sediment dynamics in a mangrove estuary: The Konkoure Estuary, Guinea 总被引：1，自引：0，他引：1
The Konkouré Estuary in the Republic of Guinea is a poorly understood atypical mangrove system. Sediment dynamics in tropical estuaries are controlled by a combination of processes including river discharge, morphology, salinity, erosion and deposition processes, the settling of mud, physico-chemical processes and mangrove swamps. Here we present a consistent set of data aimed at characterising the estuary and thus, increasing our understanding of tropical systems, as well as studying the impact of human intervention in the region. Water elevations, current measurements, salinity, suspended sediment concentrations, bathymetry and sediment cover are presented following a 3 year survey of the Konkouré Estuary. Here we provide conclusive evidence that the Lower Konkouré is a shallow, funnel shaped, mesotidal, mangrove-fringed, tide dominated estuary, well mixed during low river discharge. The estuary becomes stratified during high river flows and spring tides whereas a salt wedge appears during neap tides. The Konkouré Estuary has been described as hypersynchronous, and has three terminal outlets, two of which are landward-directed, attesting to a tidal pumping effect, while the third one is seaward-directed, and is controlled by the mangrove. The suspended matter is transported by the tidal effect within the middle estuary and is therefore trapped in the Turbidity Maximum zone (TMZ). The location of the TMZ is river-controlled and is correlated with residual currents but not with salinity front. A dam, constructed 130 km upstream, impacts on the hydrodynamics, and reduces the salinity intrusion by about 25%. It causes an increased low river discharge whereas its efficiency over high river flows is unclear. 相似文献
15.
Effect of Development of Caofeidian Harbor Area in Bohai Bay on Hydrodynamic Sediment Environment 总被引：4，自引：1，他引：3
Based on the characteristics of waves, tidal currents, sediment and seabed evolution in the Caofeidian sea area in the Bohai Bay, a 2D sediment mathematical model of waves and tidal currents is employed to study the development schemes of the harbor. Verification of spring and neap tidal currents and sediment in the winter and summer of 2006 shows that the calculated values of tidal stages as well as flow velocities, flow directions and sediment concentration of 15 synchronous vertical lines are in good agreement with the measured data. Also, deposition and erosion of the sea area in front of Caofeidian ore terminal induced by suspended load under tidal currents and waves are verified; it shows that the calculated values of depth of deposition and erosion as well as their distribution are close to the measured data. Furthermore, effects of reclamation scheme of island in front of the land behind Caofeidian harbor on the hydrodynamic environment are studied, including changes of flow velocities in the deep channels at the south side of Caofeidian foreland and Laolonggou and in various harbor basins, as well as changes of deposition and erosion of seabed induced by the project. 相似文献
16.
南汇潮滩是长江河口重要的后备国土资源,其地貌的动态变化过程可敏锐反映河海相互作用的强弱。本文利用地面LiDAR获取了南汇南滩2016年4月—2017年5月逐月大潮低潮期间滩面地貌高分辨率点云数据,根据平均小潮高、低潮位将潮滩划分为上、中和下部,由此结合水文泥沙资料分析区域潮滩动力地貌演变过程。结果表明:(1)潮滩在观测期间整体向海淤涨,其一年间垂向淤积值为10 cm,其中潮滩中部面积增大,而潮滩上部和下部的面积均减小;(2)滩面变化具有明显的夏秋季弱侵蚀调整、冬春季强淤积推进的季节性特征,潮滩地貌侵蚀-淤积则呈现明显的空间分异。在潮滩上部中侧-中部西侧形成贯通的冲刷带(10—80cm),上部沿堤西侧植被区出现强淤积带(20—85cm),整个滩面中东部潮滩出现大面积的弱淤积(5—30cm);(3)南汇南滩并未因长江入海泥沙的剧烈减少而遭受侵蚀,这可能受控于局地基本未变的动力环境和悬浮泥沙浓度,冲刷-淤积的纵向分带性则与区域海堤导致的潮流流向发生改变有关。 相似文献
17.
长江口南汇边滩冲淤变化规律与机制 总被引：2，自引：2，他引：0
根据1842—2004年海图资料分析发现,南汇边滩存在近百年尺度的强烈冲刷—淤积旋回。长江主泓走南港或北港是造成冲刷期"北滩、东滩淤积,南滩、过渡带冲刷"或淤积期冲淤态势反相的主要原因;冲刷期内风暴强度和频数明显多于淤积期,造成冲刷期滩面叠置记忆的是暴风浪成因的"高滩冲刷、低滩淤积"的冲淤态势,而淤积期保存的是弱风浪成因的"高滩淤积、低滩冲刷"叠置增强的剖面特征。尽管三角洲整体冲淤态势的转变主要受流域来沙量的控制,但不同岸段受河口河势分水分沙作用、潮流和波浪等共同作用,明显存在此冲彼淤、冲淤动态调整等特征。已有的入海泥沙含量阈值研究以点代面或以局部代整体,这是造成阈值估算偏高的主要原因。2003年三峡水库开始蓄水后平均年输沙量154 Mt/a已低于低阈值184 Mt/a,但三角洲尚未如预测那样发生由净淤积向净侵蚀的转变。已有的河口水文观察资料显示,水体含沙量也未发生明显下降,这可能是潮控型三角洲潮流对泥沙在河口的再分配起主导作用,并可能由此延长三角洲冲淤转变对入海泥沙量减少的滞后。今后需进一步加强潮控型河口复杂过程的综合研究,提高对泥沙含量阈值估算和应对可能面临的海岸侵蚀及其相关的环境地质灾害的能力。 相似文献
18.
长江口悬沙动力特征与输运模式 总被引：5，自引：0，他引：5
本项研究用ADCP在长江河口进行高频、高分辨率三维流速和声学浊度的定点观测,通过对定点站位潮周期内的悬沙浓度、流速和盐度的分析,计算悬沙输运率;悬沙输运机制分析表明平流作用、斯托克斯漂移效应在悬沙输运中占据主导地位.此外,从河口内向河口外,潮周期内的水动力特征与悬沙净输运具有明显的地域性差异,主要表现在悬沙输送的贡献因子、盐度的垂向混合和分布特征、垂向流速等方面.在拦门沙下游和口外地区,悬沙均向西、北方向输送,而拦门沙上游则向东、南方向输送.这种悬沙输运格局,对于长江口拦门沙及附近最大浑浊带的形成有着重要的作用. 相似文献
19.
An experimental survey of the estuary of Milford Haven has been carried out in which velocity, temperature and salinity have been measured over the full extent of the estuary during a complete spring and a complete neap- tidal cycle. The measurements were taken from three survey vessels, each of which was used to service six or seven survey points so that the measurements comprised a total of about 40 vertical profiles distributed over a grid of 20 survey points for each tide. Tide level measurements at two points were made simultaneously. The experimental measurements of tidal level have been used to calibrate a two-dimensional mathematical model based upon a new numerical representation of the shallow water equations. The predictions of velocity for the model have been compared with vertically integrated velocities calculated from experiments, and good agreement has been found over the full extent of the estuary.The effect of a strong south-westerly wind in the estuary has been examined in numerical simulation. 相似文献
20.
DOU Xiping LI Tilai DOU Guoren
Senior Engineer River Harbour Engineering Department Nanjing Hydraulic Research Institute Nanjing P. R. China Senior Engineer Nanjing Institute of Hydrology Water Resourses Nanjing P. R. China
Academician Nanjing Hydraulic Research Institute Nanjing P. R. China 《中国海洋工程》1999,(3)
Based on the non-equilibrium suspended load transport equation,bed load transport equationand sediment transport capacity formulas derived by Dou et al.,a 2-D numerical model of total sedimenttransport in the Yangtze Estuary is presented.In the model,the actions of tidal currents and wind waves andthe effect of salinity on sediment transport are considered.An automatically generated boundary-fitted grid isused to fit the boundaries of the estuary and the boundaries of engineering projects.The verification of calcu-lations shows that the sediment concentration,the deformation of riverbed and siltation in the channels causedby typhoons can be successfully simulated. 相似文献