EVOLUTIONAL CHARACTERISTICS OF HYPER－CONCENTRATED FLOW IN BRAIDED CHANNEL OF THE YELLOW RIVER

ＥＶＯＬＵＴＩＯＮＡＬＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＯＦＨＹＰＥＲ－ＣＯＮＣＥＮＴＲＡＴＥＤＦＬＯＷＩＮＢＲＡＩＤＥＤＣＨＡＮＮＥＬＯＦＴＨＥＹＥＬＬＯＷＲＩＶＥＲ￥ＱＩＰｕ；ＬＩＷｅｎｘｕｅ（Ｓｅｎｉｏｒｅｎｇｉｎｅｅｒ，ＩｎｓｔｉｔｕｔｅｏｆＨｙ...     

IMPACT OF DEBRIS FLOW ON RIVER CHANNEL IN THE UPPER REACHES OF THE YANGTZE RIVER

IINTRODUCTIONDebrisflowisaphenomenonhappeninginextremeseveresit'Uationofsoilerosion(Guan,1996).ItoccursfrequentlyanddistributesdenselyinupperreachesoftheYangtzeRiverandtransportsahugeamountofsedimentilltotheriver.Debrisflowdepositinfluencesthecompositionofsedimentandthemorphologyoftheriverbedfromupstreamt6downstreamandthenaffectsthedynamiccharactersandsedimentbudgetoftheYangtzeRiver.Furthermore,itimpactsonthefloodandwaterconservancyengineering.2DEBRISFLOWGULLY--HIGHWAYOFSEDI…     

ON THE SHRINKAGE OF RIVER CHANNEL

ＯＮＴＨＥＳＨＲＩＮＫＡＧＥＯＦＲＩＶＥＲＣＨＡＮＮＥＬＣＨＥＮＤｏｎｇ１,ＣＡＯＷｅｎｈｏｎｇ２ａｎｄＺＨＡＮＧＱｉｓｈｕｎ３ＡＢＳＴＲＡＣＴＡｌｏｎｇｗｉｔｈｔｈｅｒａｐｉｄｄｅｖｅｌｏｐｍｅｎｔｏｆｓｏｃｉａｌｅｃｏｎｏｍｙ,ｄｅｖｅｌｏｐｍｅ...     

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.     

CHANNEL SHRINKAGE AND ITS INSTABILITY IN THE LOWER YELLOW RIVER

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…     

CHANNEL SHRINKAGE AND ITS INSTABILITY IN THE LOWER YELLOW RIVER1

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.     

ECONOMIC EVALUATION OF REDUCTION OF DEPOSITION IN THE LOWER YELLOW RIVER BY THE SANMENXIA PROJECT

ＥＣＯＮＯＭＩＣＥＶＡＬＵＡＴＩＯＮＯＦＲＥＤＵＣＴＩＯＮＯＦＤＥＰＯＳＩＴＩＯＮＩＮＴＨＥＬＯＷＥＲＹＥＬＬＯＷＲＩＶＥＲＢＹＴＨＥＳＡＮＭＥＮＸＩＡＰＲＯＪＥＣＴＬＩＧｕｏｙｉｎｇａｎｄＴＵＱｉｈｕａＡｓｓｉｓｔａｎｔＣｈｉｅｆＥｎｇｉｎｅｅｒ，...     

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…     

FLOOD AND FLOOD CONTROL OF THE YELLOW RIVER

1 INTRODUCTION Flood of the Yellow River occurred frequently in history. The natures of large impact and heavy losses have made the flood of the Yellow River being in the front rank among major rivers in China. Statistics shows that during the period 602 AC to 1938 BC, embankment of the Lower Yellow River had been breached 1590 times and the channel had changed its course for 26 times among which 6 times were major ones. Thus, flood of the Yellow River has endangered economic cons…     

SPATIAL AND TEMPORAL CHANGES IN THE BRAHMAPUTRA RIVER BED

1 INTRODUCTION Originating in the Kanglung Kang Glacier near Konggya Tso Lake (Lat. 30°30' N - long. 82°10'E) at an altitude of 4,877 m and 63 km southeast of the Manasarowar Lake in the Kailash Range of the Great Himalayas, the Brahmaputra River flows …     

THE FORMING CONDITIONS OF ALLUVIAL RIVER CHANNEL PATTERNS

1 INTRODUCTION It is well known that the river channel patterns are determined by long-term water-sediment conditions. However, quantitative expressions for river channel patterns and their fluvial processes still remain not clear. Existing theories in this aspects, such as geomophological theory, theory of maximum energy consuming rate, stability theory, theory of probability, and statistic analysis, are developed based on certain simplified assumptions and can not be successfully used t…     

CHANNEL WIDENING DURING DEGRADATION OF ALLUVIAL RIVER

1 INTRODUCTIONThe fluvial processes such as transihon of river pattrms, bank chat and advance, sedimentation anderosion of flood plains and channel beds can be Observed in alluvial rivers. These fluvial PrOcesses are allattributed to variations of the sediment caping caPacity of the flow and the erodibillty of bank matrialor soil. A river sechon may be widened by bank erosion and failure.For examPle, a river channel downstream of a reservoir is scoured because the flow released frOm the…     

GEOMORPHIC THRESHOLDS FOR CHANNEL EVOLUTION IN THE LOWER YELLOW RIVER

Channel evolution refers to boundary changes of rivers affected by fluvial actions. This paper provides an analysis of the development and formation of stream patterns in the lower Yellow River and presents intensive studies of several critical problems relating to channel evolution, including thresholds of channel gradient and longitudinal profile adjustment, channel surface morphology, response of channel pattern to boundary conditions, critical discrimination of cross sections and the discrimination of channel pattern changes using hydrologic parameters.     

CHARACTERISTICS OF SEDIMENT TRANSPORT AND CHANNEL FORMATION BY FLOODS AT HYPERCONCENTRATIONS OF SEDIMENT IN THE YELLOW RIVER

1. INTRODUCTIONThe Yellow River is a heavily sediment--laden river. Floods at Hyperconcentrationso f sediment (hereinafter simply referred to as hyperconcentrated flood) frequently occurring in the main river and its tributaries possess different characteristics of sedimenttransport. Sometimes they cause severe deposition whereas at other times they are capable of carrying substantial amount of sediment over long distances. The study on the lawof sediment transport is of significance to …     

PRINCIPLES OF RIVER TRAINING AND MANAGEMENT

River regulation and river training have been performed for various purposes and negative effects have been shown in numerous cases. In some cases the negative effects are so serious that humans have to consider to "renaturalize" the regulated rivers. Only by using the strategy of integrated river management the diverse river uses and natural fluvial processes and ecological systems may be harmonized. Based on analysis of case studies and data collected from literatures this paper presents the concept of integrated river management and four principles of river training. The integrated river management comprises: 1) taking the watershed, upper stream basin including the tributaries, middle and lower reaches and the estuary as an integrated entity in the planning, design and management; and 2) mitigating or controlling the negative impacts on hydrology, erosion and sedimentation, fluvial processes, land use and river use, environment and ecology while in achieving economic benefit from water resources development, flood safety management and hydropower exploitation. River training and management should be in accordance with the four principles: 1) extending the duration of river water flowing on the continent, which may be achieved by extending the river course or reducing the flow velocity; 2) controlling various patterns of erosions and reducing the sediment transportation in the rivers; 3) increasing the diversity of habitat and enhancing the connectivity between the river and riparian waters; and 4) restoring natural landscapes.     

SEDIMENT LOAD AND ITS INFLUENCE ON CHANNEL PROCESSES OF SOME LARGE RIVERS IN RUSSIA AND CHINA~1

I INTRODUCTIONThe volume and regime of sediment load are the most important factors, which are responsible for theformation, direction and deformation rate of the river channels. Despite the long history of study anddevelopment of sediment load calculation methodology, there are still numerous problems that remain tobe solved such as river pattern and sediment movement and so on (Wang et al, 1997).In this respect, the comparative analysis of sediment load and river channel processes of la…     

NUMERICAL SIMULATION OF FLOOD DETENTION OPERATION IN MULTIPLY CONNECTED RIVER CHANNEL NETWORK

IINTRODUCTIONAccuratepredictionoftheconsequencesofaflooddetelltion-diversionoperationincomplexriverchannelnetworkisofgreatimportancetothedecisionmakingprocess.InthisregardtWotypesofmodelavailableforsimulatingsuchoperationsarefarfromsatisfactory,duetotheintricatenatUreofprocessesinvolvedintheseoperations.Thefirstmodeltype,i.e.,thewidelyusedhydrologicalmodels,dependsonsystematicwaterstageanddischargemeasurementsatgaugestations,andtheirpredictionsarelimitedtovariationsimwaterstageanddischar…     

REGULATION OF FLOW AND SEDIMENT LOAD IN THE YELLOW RIVER

Small runoff, large sediment load, and incompatible relationship of flow and sediment load are very important characteristics of the Yellow River. They are also the crux of the most prominent problems of the Yellow River. To solve these problems, the regimes of flow and sediment load have to be improved by increasing water, reducing sediment load, and by using reservoirs to regulate flow and sediment load. The results of experiments for regulating the flow and sediment load in the last three years by the Xiaolangdi Reservoir have indicated that this measure is a realistic and effective way to mitigate the prominent problems in flood control of the Lower Yellow River at present and in the near future. However, the regulation system is still imperfect. It is advisable to speed up the pace of research and construction of the system for regulating flow and sediment load.     

FLUVIAL PROCESSES IN THE LOWER YELLOW RIVER AFTER LEVEE BREACHING AT TONGWAXIANG IN 1855

I. CHAncEL CHANGal m THE FLOODED AREA ArVER BREACHING AT TONGWAXIANG AND THEIR IMPACTSIn mid--June of 1855 a great flood occurred in the lower reaches of the Yellow River. The findmainly came down from the main stem of the river and itS tributary Qinhe River. In the meantimethe riparian area of the Yellow River had just been subjected to a heavy rain, and large amountS of water from mountains and hills were flowing into the river and lakes were also full. The Weis…     

THE 1998 FLOOD OF THE YANGTZE RIVER

1INTRODUCTIONDuringthefloodseasonof1998,anothercatastrophicfloodoccurredinthemiddleandlowerYangtzeRiverfollowingthecatastrophicfloodin1954.Ascomparedwiththe54flood,the1998floodwascharacterizedbythefactsthatthedurationofthehighwaterstagewasmuchlonger,thefloodcontrolwasmuchmoredifficult,andthetotalmanpowerandmaterialresourcesexpelldedintilefloodfightingweremuchmoreenormous.TOsummarizetheexperienceandlessonsfromthefloodissignificanttotilehydraulicengineeringandfloodcontroloftheYangtzeRiver.…