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1.
1 wrsoorCnoxThe Yenow mver delta is ereated by the river transponing sediment bom the Loess Plateau to the shallOWBOhai Gulf during the paSt l45 years. lh recent years, the water discharge and sediment load enedg thesea have bein ched dramacaily The river end chann shital northeastWed hom QingshulgOuN to qngshulgou-Chah chaDnel in 1996, resulting in a new regfor of sedimenboon and erosion ofthe subaqucous delta.,A nUInerial model for river sediInen dispersion and seabed mOrPhofogy of t…  相似文献   

2.
Tidal shear front off the Yellow River mouth has been observed and modeled in the previous studies. However, a detailed investigation of the front generation has not been conducted. The aim of this paper is to use a three-dimensional tidal model coupled to a sediment transport module to examine the front formation. The model predicted a tidal shear front that propagated offshore and lasted 1–2 h at both flood and ebb phase off the Yellow River mouth. The sensitivity numerical experiments showed that the topography with a strong slope off the Yellow River mouth was a determining factor for the front generation, and a parallel orientation between the major axes of ellipses and co-tidal lines of maximum tidal current was a necessary condition. While the bottom friction and the river runoff had no effect on the front location but affected the front intensity, the front generation was not sensitive to the coastline variation. The study concluded that the bottom slope off the river mouth induces a strong variation in the bottom stress in a cross-shore direction, which produces both maximum phase gradient and sediment concentration variability across the tidal shear front. With the extending Yellow River delta, the tidal shear front under the new bathymetry of year 2003 has been strengthened and pushed further offshore due to an increased bottom slope.  相似文献   

3.
1. INTROOUCnONFor a long time, the Lower Yellow River has been aggtading. As a result, the river bed becomesmuch higher than the adjacent land beyond the levees and poses a threat to the safety of the GreatNorthern Plain of China. Since the founding of the New China, great success has been achieved insafeguarding the levee for forty years. The trend of aggravation in lower reaches however is still Soingon and is at a rate even higher than before. That makes the flood control on the LO…  相似文献   

4.
1INTRODUCTIONTheHaiheRiverBasinislocatedinNorthChinawithareaof262.6km2.Itisaquicklydevelopedareawithmanyimportantcitiesandindustrialhubs,includingBeding,Tianjin,Tangshan,Cangzhou,DezhouandHuanghua.Theareawatchedfastprogressesinurbanizationinthepastdecades,andhumanactivitieshaveresultedingreatinfluencesontheenvironment,riverhydrologyandsedimentbudget.Theareaisprojectedtobemoreprosperouswithmoreoilandgasfields,chemicalindustrybases,anddenserrailwaysandexpresshighwaysinthenextcent'Ury.T…  相似文献   

5.
１ＩＮＴＲＯＤＵＣＴＩＯＮＦｒｏｍ１４ｔｏｅａｒｌｙ２０ｃｅｎｔｕｒｙ,ｔｈａｔｉｓｉｎｔｈｅＭｉｎｇａｎｄＱｉｎｇＤｙｎａｓｔｉｅｓｉｎＣｈｉｎａ,ｔｈｅｒｅｅｘｉｓｔｅｄａｐｏｉｎｔｏｆｖｉｅｗｔｈａｔｔｈｅｃｏｎｔｉｎｕｏｕｓｓｉｌｔａｔｉｏｎ...  相似文献   

6.
洪泽湖和淮河入洪泽湖河口的形成与演化   总被引：9，自引：1，他引：8  
王庆  陈吉余 《湖泊科学》1999,11(3):237-244
根据历史文献资料和前人研究成果,对洪泽湖和淮河入洪泽湖河口及三角洲的形成与演化进行了探讨。结果表明,洪泽湖是明,清两代治黄,保运工程的产物和组成部分,现代洪泽湖主要形成于１７世纪的靳治水时期,其形成后百余年中湖水位变化总趋势是不断上升,同时具有大幅度的年内年龄变化。  相似文献   

7.
１ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＢｒａｈｍａｐｕｔｒａＲｉｖｅｒｏｒｉｇｉｎａｔｅｓｆｒｏｍｔｈｅＪｉｍａｙａｎｚｈｏｎｇｇｌａｃｉｅｒａｔｔｈｅｎｏｒｔｈｆｏｏｔｏｆｔｈｅＨｉｍａｌａｙａＭｏｕｎｔａｉｎｓｉｎＳｏｕｔｈＴｉｂｅｔ,Ｃｈｉｎａ．Ｉ...  相似文献   

8.
ONE D AND TWO D COMBINED MODEL FOR ESTUARY SEDIMENTATION   总被引：3，自引：0，他引：3  
１ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｆｌｕｖｉａｌｐｒｏｃｅｓｉｎａｎｅｓｔｕａｒｙｉｓｃｏｍｐｌｉｃａｔｅｄｕｎｄｅｒｔｈｅａｃｔｉｏｎｏｆｒｕｎｏｆ,ｔｉｄａｌｆｌｏｗ,ｗｉｎｄｉｎｄｕｃｅｄｃｕｒｅｎｔａｎｄｗａｖｅｅｔｃ．Ｅｓｐｅｃｉａｌｙ,...  相似文献   

9.
The main hydrological and morphological features of the Columbia River mouth area, including its tidal estuary, are discussed. Close attention is given to the characteristics of large-scale hydraulic projects in the river basin as well as to dredging and channel training operations in the river mouth area and to the assessment of the impact of these operations on hydrological and morphological processes. Variations in the regime of river flow after its regulation, processes of dynamic interaction and mixing of river and sea water in the estuary are characterized. Changes of the mouth bar and sea coasts near the Columbia River mouth as a result of construction of stream-training jetties are discussed.  相似文献   

10.
ON THE SHRINKAGE OF RIVER CHANNEL   总被引：1，自引：0，他引：1  
ＯＮＴＨＥＳＨＲＩＮＫＡＧＥＯＦＲＩＶＥＲＣＨＡＮＮＥＬＣＨＥＮＤｏｎｇ１,ＣＡＯＷｅｎｈｏｎｇ２ａｎｄＺＨＡＮＧＱｉｓｈｕｎ３ＡＢＳＴＲＡＣＴＡｌｏｎｇｗｉｔｈｔｈｅｒａｐｉｄｄｅｖｅｌｏｐｍｅｎｔｏｆｓｏｃｉａｌｅｃｏｎｏｍｙ,ｄｅｖｅｌｏｐｍｅ...  相似文献   

11.
This study describes the formation of two successive baymouth spits systems on the south‐eastern Brazilian coast and the degradation of the first system. The study area includes the Jureia Beach spit, the deflected Ribeira de Iguape River mouth, the central Iguape sandy headland, the Icapara Inlet of the Mar Pequeno Lagoon and the northern end of the Comprida Island barrier spit. The wave and river flow patterns were combined with the coastline evolution and the alongshore migration rates deduced from satellite images. Initially, both spits showed convergent alongshore migration rates equal to or less than 83 m/yr. However, the extreme river flow due to high rainfall during a very strong El Niño event in 1983 eroded the inland side of the Jureia Beach spit, which finally retreated due to wave erosion. In 1989, a sand bank emerged in the river mouth, which attached to the central headland forming a recurved northeastward spit. In 1994, the high fluvial discharge associated with another very strong El Niño event caused the landward migration of the new spit and emersion of a second sand bank. This second sand bank merged with the Jureia Beach spit in 1997 at an alongshore migration rate of 1795.6 m/yr. Wave erosion of the central headland continued and the attached spit disappeared in 2000. In 2009, the headland erosion merged the river mouth and the Icapara Inlet, which resulted in flanking baymouth spits in a configuration that remains today. Therefore, two models for the formation of baymouth spits have been documented for wave‐dominated microtidal coasts in humid tropical regions with intense fluvial discharge. The convergent longshore migration of the spits is controlled by both the bidirectional longshore drift and the fluvial discharge, the latter eroding the fronting spit, supplying sediments and acting as a hydraulic blockage for longshore drift. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

12.
ＤＹＮＡＭＩＣＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＯＦＳＥＡＣＵＲＲＥＮＴＳＡＮＤＳＥＤＩＭＥＮＴＤＩＳＰＥＲＳＩＯＮＩＮＴＨＥＹＥＬＬＯＷＲＩＶＥＲＥＳＴＵＡＲＹＨＵＣｈｕｎｈｏｎｇ１,ＪＩＺｕｗｅｎ２ａｎｄＷＡＮＧＴａｏ３ＡＢＳＴＲＡＣＴＤｙｎａｍｉｃ...  相似文献   

13.
This paper examines the morphological development of the Yangtze River mouth, which has been diverting southeasterly (dextrally), according to historical (150 years) chart‐based digital evolution model and on‐site measured tidal flow data. We reveal a significantly narrowing of the northern river mouth branch from formerly >30 km wide to presently 10 km wide due to rapid siltation. Net siltation there, however, decreases gradually, which largely contrasts with the fact that the siltation has shifted to the southern river mouth area, as shown by many newly‐emerged estuarine islands, sandy shoals and bifurcated branches. Our data have further demonstrated that the ebb flow that dominates in the study area changes its direction gradually from east to southeast from the inner to outer river mouth area, and its duration is much longer than the flood flow in the inner river mouth area, but nearly equal at the river mouth area. Accordingly, the sediment transport pathway has been diverted from east to southeast. We examine whether the Coriolis Force could explain the dextral diversion of the ebb flow and the altered morphodynamical processes. Although too weak to strengthen the tidal flows, the Coriolis Force can drag the ebb flow southeasterly, and so influence sediment transport paths at the estuarine scale. The Coriolis Force is limited in the inner river mouth, but substantial at and in the outer river mouth area when gradually free of estuarine topographic constraints. The Coriolis Force causes an offset in propagation of in‐out flow directions at the river mouth area to form a slack water setting prone to estuarine siltation. Using the present approach also enables explanation of the morphological development of the Holocene Yangtze delta‐coast that extends to the southeast. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

14.
Few hyperpycnal flows have ever been observed in marine environments although they are believed to play a critical role in sediment dispersal within estuarine and deltaic depositional systems. The paper describes hyperpycnal flows observed in situ off the Huanghe (Yellow River) mouth, their relationship to tidal cycles, and the mechanisms that drive them. Simultaneous observations at six mooring stations during a cruise off the Huanghe mouth in the flood season of 1995 suggest that hyperpycnal flows observed at the river mouth are initiated by high concentrations of sediment input from river and modulated by tides. Hyperpycnal flows started near the end of ebb tides, when near‐bottom suspended sediment concentration (SSC) increased rapidly and salinity decreased drastically (an inverse salt wedge). The median grain size of suspended particles within the hyperpycnal layer increased, causing strong stratification of the suspended sediments in the water column. Towards the end of flood tides, the hyperpycnal flow attenuated due to frictions at the upper and lower boundaries of the flow and tidal mixing, which collapsed the stratification of the water column. Both sediment concentration and median grain size of suspended particles within the bottom layer significantly decreased. The coarser sediment particles were deposited and the hyperpycnal flows stopped. The intra‐tidal behaviors of hyperpycnal flows are closely associated with the variations of SSC, salinity, and stratification of the water column. As nearly 90% of riverine sediment is delivered to the sea during the flood seasons when hyperpycnal flows are active, hyperpycnal flows at the Huanghe mouth and the river's high sediment loads have caused rapid accretion of the Huanghe delta. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

15.
1 INTRODUCTION Shortage of water resources is one of the important issues in the Yellow River basin in China. The runoff and sediment in the Yellow River come from different sources. The runoff comes from the dry areas of its upper reaches, while the sedi…  相似文献   

16.
From the mid 1980s through the late 1990s, the channel of the lower Yellow River experienced serious shrinkage, which has decreased the flood conveyance of the channel and the sediment carrying capacity of the flow, raised the water levels of floods, and, thus, severely threatened the safety of flood control along the river. The completion of Xiaolangdi Dam in 1999 could help mitigate the channel shrinkage problem, but the situation has not changed yet. This paper analyses the characteristics, mechanisms, and conditions resulting in channel shrinkage, points out channel instabilities, and puts forward approaches of channel rehabilitation.  相似文献   

17.
The subaerial tidal sand area in the northern Jiangsu Province (Subei), stretching from Dongtai towards east with a fan shape, is an early developing stage of radial sand ridges distributed in the South Yellow Sea. Since 5000–6000 a BP, after the Holocene transgression maximum in the northern Jiangsu Province, subaqueous tidal sand bodies were exposed and changed into land gradually. The environmental magnetism analysis shows that subaerial tidal sand strata are formed by the convergent-divergent paleo-tidal current field. The sediment source of tidal sand strata came early from the Changjiang River and late from the Yellow River. Sea floor erosion by tidal currents also served as an important sand source. Drilling cores and ground-penetrating profile show that there exists no probability of sand supplying directly by a large river through the apical area of tidal sand ridges either on land or in the sea. Fluvial deposits supplied the tidal sand bodies by alongshore transportation, which corresponds to the conclusions obtained by the analyses of provenance and paleocurrent field. Project supported by the National Natural Science Foundation of China (Grant Nos. 43236120 and 49676288).  相似文献   

18.
The factors that govern the distribution and transformation of tidal waves in the macrotidal estuary of the Mezen River have been considered, including tide range in the mouth section, water discharge in the river’s lower reaches, estuary shape, and bed resistance coefficient. Data on variations of water discharge over period 1920–2008 are given. The parameters of estuary channel narrowing in horizontal and vertical sections have been considered. The effect of narrowing and bed hydraulic friction on tide wave amplitude has been evaluated. Froude number values for the tidal estuary suggest that tidal bore can form at the Mezen mouth. The conditions of the propagation of tidal waves to the mouths of different rivers and tidal bore formation in them are considered.  相似文献   

19.
Tidal straining effect on sediment transport dynamics in the Huanghe (Yellow River) estuary was studied by field observations and numerical simulations. The measurement of salinity, suspended sediment concentration, and current velocity was conducted during a flood season in 1995 at the Huanghe river mouth with six fishing boats moored at six stations for 25-h hourly time series observations. Based on the measurements, the intra-tidal variations of sediment transport in the highly turbid river mouth was observed and the tidal straining effect occurred. Our study showed that tidal straining of longitudinal sediment concentration gradients can contribute to intra-tidal variability in sediment stratification and to asymmetries in sediment distribution within a tidal cycle. In particular, the tidal straining effect in the Huanghe River estuary strengthened the sediment-induced stratification at the flood tide, thus producing a higher bottom sediment concentration than that during the ebb. A sediment transport model that is capable of simulating sediment-induced stratification effect on the hydrodynamics in the bottom boundary layers and associated density currents was applied to an idealized estuary to demonstrate the processes and to discuss the mechanism. The model-predicted sediment processes resembled the observed characteristics in the Huanghe River estuary. We concluded that tidal straining effect is an important but poorly understood mechanism in the transport dynamics of cohesive sediments in turbid estuaries and coastal seas.  相似文献   

20.
WATER POLLUTION IN THE RIVER MOUTHS AROUND BOHAI BAY   总被引：10，自引：0，他引：10  
Twelve water samples were collected and analyzed. The samples were taken from the river mouths around Bohai Bay including the Jiyun. New Yongding, Haihe, Dagu, Duliujian, Qingjinghuang, Qikou, Dakou, and Yellow Rivers, and tested for concentrations of heavy metals, arsenic, total nitrogen (TN) and total phosphorus (TP). The results show that the river mouths are polluted and the water quality exceeds Class V of the Environmental Quality Standard for Surface Water (EQSSW). The main pollutants are Hg, nitrogen (N) and phosphorus (P). The concentrations of the other pollutants are within Class II of the Standard. The Hg content in the Haihe River mouth is now 10 times higher than it was 20 years ago, indicating that the accelerating water pollution has reached an alarming level. The high concentrations of N and P cause eutrophication of the waters. Analysis indicates that the terrestrial pollutants and nutrients are the main cause of frequently occurring red tides in the Bohai Sea.  相似文献   

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