SEDIMENT CARRYING CAPACITY OF SEA CURRENT AND THE TRAINING OF THE YELLOW RIVER MOUTH

1INTRODUCTIONTheYellowRivercarries1.6billiontonsofsedanmentload,rankedthefirstintheworld.Sedimentationinthelowerreachesresultedinfrequentlyshiftoftherivercourses.ThroughoutthehistoryofChina,theYellowRiverhasbeenassociatedwithfloodsandfamine,earningtherivername"China'ssorrow"(Hu,l996).Instabilityoftheriverchannel,especiallythedeltachannel,restraintstheeconomicdevelopmentofthearea.TheDongyingmunicipalgovernment,theShenliOilCorporationandtheYellowRiverMouthManagementBureauofYRCC(Yel…     

PROGNOSIS OF AGGRADATION IN THE LOWER YELLOW RIVER BY HISTORIC ANALYSIS OF THE MORPHOLOGY OF ITS ABANDONED ANCIENT CHANNEL

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…     

ON THE SHRINKAGE OF RIVER CHANNEL

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PREDICTION OF IMPACT OF THE THREE GORGES PROJECT ON ESTUARY BEACH OF THE YANGTZE RIVER

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Numerical study of generation of the tidal shear front off the Yellow River mouth

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.     

RIVER MORPHOLOGY AND CHANNEL STABILIZATION OF THE BRAHMAPUTRA RIVER IN BANGLADESH

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ANALYSIS ON MOUTH BAR EVOLUTION OF THE YELLOW RIVER ESTUARY

ＡＮＡＬＹＳＩＳＯＮＭＯＵＴＨＢＡＲＥＶＯＬＵＴＩＯＮＯＦＴＨＥＹＥＬＬＯＷＲＩＶＥＲＥＳＴＵＡＲＹＪＩＺｕｗｅｎ；ＨＵＣｈｕｎｈｏｎｇ（Ｅｎｇｉｎｅｅｒ，ＤｅｐａｒｔｍｅｎｔｏｆＳｅｄｉｍｅｎｔａｔｉｏｎＥｎｇｉｎｅｅｒｉｎｇ，ＣｈｉｎａＩｎｓｔｉ...     

Sediment regime and morphological processes in the Hong Ha (Red River) mouth area

Main features of sediment regime in the mouth area of the Hong Ha River (Red River), Vietnam, are discussed. As shown, the hydraulic engineering construction on the Da tributary resulted in a nearly two-fold decrease of river sediment yield. Sediment budget components at the river mouth were analyzed to establish that more than 90% of the sediment yield was detained in the delta branches and in the nearshore zone of the river mouth. Morphological processes in the Hong Ha River mouth area were characterized in detail including delta evolution during Holocene and the dynamics of its channel network, coastline, and mouth bars. Special attention was given to modern processes of delta progradation at the mouths of main branches and to wave erosion of other parts of the delta coastline. The causes for the intensification of this kind of erosion and change of the delta type in the late XX century are discussed.     

IMPACTS OF FLOOD EVENTS IN COARSE SEDIMENT-PRODUCING AREAS ON CHANNEL SILTATION AND FLUVIAL PROCESS OF THE LOWER YELLOW RIVER

The method of multiple regression is used to analyze the influences of flood events from the coarse sediment producing areas on the channel siltation and fluvial process of the lower Yellow River based on the flood events from 1950 to 1985. The results showed that the flood events from the coarse sediment producing areas carry larger amounts of sediment load and coarser particle sizes than from other source areas, which increases deposition in the lower river channel. And there exist good correlations between channel siltation of the lower reaches of the Yellow River and the coming water and sediment of flood events from the coarse sediment producing areas. Through these correlations, the amounts of sediment deposition in the lower river channel could be roughly estimated based on the runoff and sediment load of flood events from the coarse sediment producing areas. The sediment deposition caused the fluvial process. There exists a complex response of channel form change to the coming water and sediment load of flood events from the coarse sediment producing areas. When the sediment concentration is smaller than 200kg/m3, the ratio between wide-depth ratio after flood and wide-depth ratio before flood((B/h)a / (B/h)b) will increase with the increase of the maximum sediment concentration; when the sediment concentration is near 200kg/m3, (B/h)a / (B/h)b reaches the maximum value; and when the sediment concentration reaches the limits of hyperconcentrated flow, (B/h)a / (B/h)b will decrease with the increase of the maximum sediment concentration. Generally, flood events from the coarse sediment producing areas made channel form of the lower Yellow River deeper and narrower, but a large amount of sediment deposition simultaneously occurs. So, the impacts of flood events from the coarse sediment producing areas on the channel of the lower Yellow River are lessened.     

DEVELOPMENT OF LONGITUDINAL PROFILE OF THE LOWER YELLOW RIVER

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ONE D AND TWO D COMBINED MODEL FOR ESTUARY SEDIMENTATION

１ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｆｌｕｖｉａｌｐｒｏｃｅｓｉｎａｎｅｓｔｕａｒｙｉｓｃｏｍｐｌｉｃａｔｅｄｕｎｄｅｒｔｈｅａｃｔｉｏｎｏｆｒｕｎｏｆ,ｔｉｄａｌｆｌｏｗ,ｗｉｎｄｉｎｄｕｃｅｄｃｕｒｅｎｔａｎｄｗａｖｅｅｔｃ．Ｅｓｐｅｃｉａｌｙ,...     

COMPLICATED FILL-SCOUR BEHAVIORS OF THE YELLOW RIVER AND THE CHANNEL-FORMING PROCESSES

IINTRODUCTIONStreamflowformostriversintheworldcanberegardedasasolid-liquidtwo-phaseflow.Theexistenceofsuspendedsedimenthassomeinfluenceonthestreamflow'sphysicalandmechanicalproperties,whichinturnaffectsthestreamflow'ssedimentcarryingbehaviors(ChienandWan,1983;Chien,1989).Forriverswithrelativelylowsuspendedsedimefltconcentrations,theabove-mentionedeffectisnegligible.However,withtheincreasesinsuspendedsedimentconcentration,thiseffectbecomesincreasinglysignificant;thesediment-carryingbehavi…     

SHRINKAGE OF THE ESTUARINE CHANNELS OF THE HAIHE DRAINAGE SYSTEM AND ITS INFLUENCES ON FLOOD HAZARD

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

Quantifying the suspended sediment discharge to the ocean from the Markham River,Papua New Guinea

The Markham River is a small river draining a tropical mountain range with altitudes between 1000 and 3000 m and discharges directly into a submarine canyon, the head of which is at 30 m depth and reaches depths of 500 m only 4 km from the shore. As such, the Markham discharge system serves as a possible analogue for rivers discharging onto margins during low stands of sea-level. Located in a tectonically active area and with high rainfall, sediment supply is high and episodic and is sometimes related to catastrophic mountain landslides. The river has an estimated sediment load of 12 Mt yr⁻¹. Occasionally, high energy flows are generated at the river mouth which is evident from the channel morphology and sediment distribution. Profiles of salinity and suspended sediment concentrations (SSC) show that sediment is dispersed via a plume with components at both the surface, intermediate depth along isopycnal surfaces and near the sea bed. The dispersal pattern of the surface freshwater plume is largely determined by the buoyancy force. The surface plume is very thin with salinity gradients 15 ppt m⁻¹ while a Richardson number greater than unity suggested that the mixing zone is highly stratified. Estimates of the horizontal sediment flux gradient of the surface plume along the estuary axis suggest that about 80% of the sediment discharged is lost from the plume within a distance of 2 km from the river mouth. Particle fall velocities estimated from the vertical flux indicate values less than those of flocculated material. Layers of sediment with SSCs between 500 and 1000 mg l⁻¹ were observed at intermediate depths and near the seabed during periods of both high and intermediate discharge. The mass of sediment in a SSC layer at intermediate depths between 150 and 250 m within the canyon channel was estimated to be equivalent to an average of 2 to 3 days of Markham sediment discharge. SSCs near the seabed of between 250 and 750 mg l⁻¹ suggest that layers of significantly elevated density exist near the seabed, moving under the influence of gravity down steep seabed slopes of the Markham canyon.     

Delta formation processes at the Mississippi River mouth

Specific processes of delta formation at the Mississippi River mouth are discussed. In the last 7000–8000 years, a series of large deltaic lobes was formed in succession at the Mississippi River mouth under the condition of high river sediment runoff and stabilization of the ocean level after its sudden postglacial rise. In the mid-XX century, the formation of a new deltaic lobe began at the Atchafalaya Branch mouth. Over the last centuries, the processes of delta formation at the Mississippi River mouth slowed down as a result of the river sediment runoff decrease after flow regulation of the Missouri and Arkansas tributaries; in some parts of the deltaic plain, these processes gave way to degradation of marshes and seashore erosion under the impact of intense land subsidence. The current processes of delta formation are under the great influence of local economic activities.     

洪泽湖和淮河入洪泽湖河口的形成与演化

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。     

Modeling of ice phenomena in the mouth of the Vistula River

The mouth of the Vistula River, which is a river outlet located in tideless area, is analyzed. The Vistula River mouth is a man-made, artificial channel which was built in the 19th century in order to prevent the formation of ice jams in the natural river delta. Since the artificial river outlet was constructed, no severe ice-related flood risk situations have ever occurred. However, periodic ice-related phenomena still have an impact on the river operation. In the paper, ice processes in the natural river delta are presented first to refer to the historical jams observed in the Vistula delta. Next, the calibrated mathematical model was applied to perform a series of simulations in the Vistula River mouth for winter storm condition to determine the effects of ice on the water level in the Vistula River and ice jam potential of the river outlet.     

INFLUENCE OF THE UPSTREAM RESERVOIRS ON THE ADJUSTMENT OF DOWNSTREAM ALLUVIAL CHANNEL

I. INTRODUCTIONThe Yellow River is a heavily sediment--laden river. The sediment load of the Yellow River ranks the first in the world while its annual runoff is only of medium size. Toharness the river, it is necessary to build reservoirs for regulating runoff to meet the demands of economic development. Since the founding of PRC in 1949, I S4 large and medium--sized reservoirs have been constructed on the main stem and the tributaries with atotal storage capacity of 84.5 billion m3.…     

Wide river or narrow river: Future river training strategy for Lower Yellow River under global change

The choice of a river training strategy is extremely important for the Lower Yellow River (LYR). Currently, the wide-river training strategy applies in the training of the LYR. However, remarkable changes in the hydrological processes in the Yellow River basin, as well as immediate pressure from socio-economic development in the Yellow River basin, make it necessary to consider if there is a possibility to change the river training strategy from wide-river training to narrow-river training. This research investigates the impacts of different river training strategies on the LYR through numerical simulations. A one-dimensional (1-D) model was used to simulate the fluvial processes for the future 50 years and a three-dimensional (3-D) model was applied to study typical floods. The study focused on river morphology, the results show that if the present decreasing trend in both water discharge and sediment load persists, the deposition rate in the LYR will further decrease no matter what strategy is applied. Especially, narrow-river training can achieve the aim to increase the sediment transport capacity in the LYR compared with wide-river training. However, if the incoming water and sediment load recovers to the mean level of the last century, main channel shrinkage due to sedimentation inevitably occurs for both wide-river and narrow-river training. Most importantly, this study shows that narrow-river training reduces the deposition amount over the whole LYR, but it provides little help in alleviating the development of the “suspended river”. Instead, narrow-river training can cause aggradation in the transitional reach where the river pattern changes from highly wandering to meandering, further worsening the “hump deposition” there. Because of uncertainty regarding future changes in hydrological processes in the Yellow River basin, and the lack of feasible engineering measures to mitigate “suspended river” and “hump deposition” problems in the LYR, caution should be exercised with respect to changes in the river training strategy for the LYR.