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.     

A NUMERICAL MODEL FOR SEDIMENTATION IN FENHE RESERVOIR AND THE ADJOINING REACHES

In this paper, a numerical model for sedimentation in Fenhe Reservoir and the adjoining reaches has been presented on the basis of the theory of non-equilibrium sediment transport. The model is calibrated by using a part of the sediment data collected for Fenhe Reservoir and checked by simulating the remaining data. Moreover, the method of optimization in nonlinear programming has been applied to determine the basic parameters of the model applying a concept of fuzzy mathematics to formulate the objective functions. The computed amounts of reservoir deposition and channel deformation arc found to be substantially in agreement with the values observed.     

EFFECTS OF WATERSHED MANAGEMENT ON THE REDUCTION OF SEDIMENT AND RUNOFF IN THE JIALING RIVER,CHINA

The Three Gorges Project is one of the largest hydro-projects in the world and has drawn many debates inside China and abroad. The major concern is that sediment load from the river basin may eventually fail the functions of the project for flood control and power generation. To reduce sedimentation in the reservoir, watershed management has been adopted. However, there is limited information regarding the effectiveness of various control measures such as terracing and afforestation on a watershed scale. The Jialing River, a main tributary of the Yangtze River, contributes approximately 25% of the total sediment load in the main river but only represents 8% of the whole basin area. There have been various land use patterns and extensive human activities for thousands of years in the Jialing River watershed. Based on analysis of the major factors affecting erosion in the Jialing River watershed, the main watershed management strategies (afforestation, farming and engineering practice) are illustrated, and their effects on the reduction of sediment and runoff are studied in detail. The sediment budget of the watershed shows that 1/3 of the sediment yield is trapped by the erosion control measures (afforestation and farming) on the slope, 1/3 is trapped by the reservoirs, ponds and dams within the watershed, and only about 1/3 is transported into the Yangtze River, which will affect the Three Gorges Project.     

CATCHMENT-WIDE ANALYSIS OF THE SEDIMENT REGIME WITH RESPECT TO RESERVOIR SEDIMENTATION

1 INTRODUCTIONIn Anstria reservoirs are frequentiy multi-purpose schemes, being used for power generation, floodprotechon and for wate suPPly downstream. These reservoirs have some adVerse imPaCts on theenvironment around the reservoir and also on the dOwnstream pat:. in rivers with mean annual discharge above 30 m3ls about 36 % of the total length of l884 lQn isimpounded, and only 35% remains as free flowing sections (Muhar, l992),. flooding has been, and continues to be, a serious pr…     

A STUDY ON SEDIMENT PROBLEMS IN THE GONGZUI RESERVOIR

IINTRODUCTIONTheannualaverageruff-offinthewatershedoftheGongzuiReservoiris50billioncubicmeterswithanaveragesedimentloadof34.7milliontonsperyear.Finesedimentwithd,,=0'055mmcompose97%oftheiota]sedimentload.Theannualcoarsegravelpericleswithd,,=58.5mmisaboutonemilliontons.TheendofbackWateris38kmawayfromthedam.Thereservoirwasoriginallydesignedtoatotalstoragecapacityof374millioncubicmeters,inwhich102millioncubicmetersisregulationstoragecapacityand243millioncubicmetersis'dead'storagecapacityfo…     

PRELIMINARY STUDY ON TRANSPORTATION AND DISTRIBUTION OF SEDIMENT LOAD IN THE YANGTZE ESTUARY 1

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THE SOURCE OF COHESIVE SEDIMENT AND ITS TRANSPORT IN THE YANGTZE ESTUARY AND NEAR SEA

In the light of the regional physiography and its effect on clay mineral composition of cohesive sediment (d < 0.005 mm) the source area of cohesive sediment in the Yangtze Estuary can be identified as three supplying regions: the main stem of the Yangtze River, the deltaic region of the abandoned Yellow River including the northwest Huanghai Sea and the Hangzhou Bay. Based on the evaluation of clay mineral composition in the supplying regions and the converging region, a computational model is established. More than 89.6% of cohesive sediment comes from the Yangtze River, a considerable amount is replenished from the deltaic region of the abandoned Yellow River while some part of the cohesive sediment load is transported from the Yangtze Estuary to the Hangzhou Bay. Computation results reveal that the annual deposit of cohesive sediment in the Yangtze Estuary amounts to 45.54 x 106 t. The annual cohesive sediment load replenished from the deltaic region of the abandoned Yellow River is 27.30 x 106t, while the annual cohesive sediment load transported to the Hangzhou Bay is 22.47 x 106 t. The amount of deposit in the Yangtze Estuary has been checked against the value obtained by comparing bathemetry of the Yangtze Estuary in 1915 and 1963.     

SIMULATIONS OF SEDIMENT YIELD AND PHOSPHORUS YIELD FROM A WATERSHED IN TAIWAN, CHINA

1 INTRODUCTION Sediment and nutrients from a watershed may adversely affect a downstream reservoir by reducing its capacity or degrading water quality. Among the output nutrients, phosphorus is often a growth-limiting element for aquatic organisms and pla…     

SEDIMENT DAMAGES AND RECENT TRENDS IN THE UNITED STATES

lINTRODUCTIONWeoftenhavethepercepti0nthatsedimentisthebr0wnishoryell0wishcoloringinrunoffwater,thatlooksunpleasant,buteventually"g0esaway,"downstream,unseen.Butsedimentisn0tonlyaestheticallyunpleasant,itisalsoacarrierofpotentialchemicalc0ntaminants,fillsupwaterb0dies,andcausesphysicaldamaget0farmland,wildlife,andwatertreatmentsystemsandpowergenefat0rs.ThepurposeofthispaPeristoprovidean0verallperspectiveonthemagnitudeandtrendsofsedimelltasap0llutritintheUnitedStates.2CURRENTKNOWLEDG…     

EFFECTS OF SEDIMENT GRADATION ON THE GEOMETRY OF RIVER DELTAS

l INTRODUCTlONIn this study, formation of alluvial deltas was treated as a river-dominated type of topograPhy process,caused simply by sediment deposition from a channel into a wide basin. The influences of waves, tides,and density differences related to coastal effects were excluded. There have been numerous experimentalstUdies on river delta problems. For examPle, Shieh et al. (1988, 1997) used coarse sediment asexperimental material and revealed the development and the geometric simil…     

TRENDS IN ORGANOCHLORINE AND RADIONUCLIDE CONCENTRATIONS IN THE UPPER RIO GRANDE BASED ON SEDIMENT CORE ANALYSES FROM ELEPHANT BUTTE RESERVOIR,NEW MEXICO

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MASINGA RESERVOIR IN KENYA：SEDIMENT DISCHARGE AND IMPLICATIONS FOR ITS CAPACITY

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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…     

SEDIMENT BUDGET OF THE ILLINOIS RIVER

1 BACKGROUND The Illinois River is the most significant river in the state of Illinois. The river drains nearly half of the state and has a drainage area of 28,906 mi2 (74,867 km2). Except for about a 4,000 mi2 (10,360 km2) area in Indiana and Wisconsin, the watershed is located in Illinois (see Fig. 1). The watershed contains the drainage basins of several of the state's significant rivers such as the Sangamon, LaMoine, Spoon, Mackinaw, Vermilion, Fox, Kankakee, and Des Plaines Ri…     

GRAIN SIZE DISTRIBUTION OF SEDIMENT IN THE NORTHERN EAST CHINA SEA AND THE RELATIONSHIP WITH THE SEA CURRENTS

1 INTRODUCTION The East China Sea, one of the largest continental marginal seas in the world, receives large amount of suspended sediment from the land annually (Milliman and Meade, 1983; Shen, 1999). Since late Pleistocene, the deposition of the suspended sediment over the relict sandy sediment induces the complicated distribution of surface sediment (Fig. 1). Many studies have been done on the surface sediment distribution, sedimentation rate, concentration and dispersion of suspen…     

CHARACTERIZATION AND CAUSATION OF RUNOFF AND SEDIMENT VARIATION IN THE JIALINGJIANG RIVER BASIN

The Jialingjiang River basin is one of the main sediment contributing areas in the upper reaches of the Changjiang River. Great changes have taken place in the runoff and sediment discharge in recent years. Comparing the data of 1991-2003 with the data of 1954-1990, the annual runoff of the Jialingjiang River basin decreased by 23 %, and the suspended sediment transport decreased by 74% or 105 million tons. The main factors affecting the reduction include a decrease in rainfall, sediment detention of hydraulic structures, soil and water conservation activities, sedimentation and sand dredging in the river channel. Thorough investigation and analysis of the contribution of each factor to the sediment decrease at Beibei Station was determined for the first time. The following are the contributing percentages for each factor: a decrease in runoff accounted for 32.9%; soil and water conservation measures accounted for 16.4%; sediment detention of hydraulic structures accounted for 30.5%; sedimentation, river channel sand dredging, and other factors accounted for 20.2%. These findings are very important for forecasting the trend of inflow sediment discharge variation.     

EFFECT OF SUSPENDED SEDIMENT ON THE TRANSPORT AND TRANSFORMATION OF 4 - NITROCHLOROBENZENE IN THE YELLOW RIVER

I.INTaonUCTIOXP-NCBisatoxiccompoundwhichmaycausecarcinogenicoramutation.NowthetransPOrtandtransformationofthiskindOfsubstanceinnaturalwaterbodyisthefocusofresearchofscientistsintheworld.ThroughthestudytherelationshipbetweennonionicorganiccomPOunds,suchasP-NCB,andsuspendedsedimentisfoundtobeveryclOSe,suspendedsedimentareload-supPOrtingofmovementandmediateagentofreactionofP-NCBinwater.TheYellowRiverisheavilysediment-laidenriverintheworld.Sometimesthesuspendedsedimentcanbeupto200kgpe…     

THE OPERATION MODE OF "STORING THE CLEAR WATER AND DISCHARGING THE MUDDY FLOW" FOR RESERVOIRS BUILT ON HEAVILY SILT-LADEN RIVERS--A CASE STUDY OF THE SANMENXIA RESERVOIR

Observation of the operation of the Sanmenxia Reservoir on the Yellow River has led to the conclusion that to preserve a certain effective storage volume for reservoirs built on heavily silt-laden rivers is feasible if the reservoir is operated according to the principle known as "storing the clear water and discharging the muddy flow". The relative stability of the bed elevation at the end of the backwater and the reservoir's erosion and deposition equilibrium depend on the compatibility of the pool level maintained in non-flood seasons with the conditions of flow and sediment load during flood seasons. Operating the reservoir to regulate the flood and sediment load during flood seasons can reduce the rate of aggradation in the Lower Yellow River. The basic condition for applying the operation mode of "storing the clear water and discharging the muddy flow" is that a sufficient amount of water should be used for discharging sediment during flood seasons. Under the condition of extremely low flow years, reservoir sedimentation cannot be avoided even if this operation mode is adopted.     

EFFECTS OF RIVER NETWORK WORKS AND SOIL CONSERVATION MEASURES ON RESERVOIR SILTATION

Knowledge of the morphological dynamics of a water course is essential for management of reservoir siltation. With an example of sedimentation in a reservoir in Basilicata, Italy, this paper demonstrates the effect on reservoir siltation of the hydraulic works, which are aimed to reduce sediment transport along the fluvial network and to prevent part of the sediment discharge from reaching the lake. The effect depends on the river type and on the the geological features of river basin slopes. The paper also shows how mass erosion can significantly contribute to development of reservoir siltation. Finally, preliminary results are provided about the time needed for river training works to be effective.     

共和地震的诱发机制与水库诱发地震的研究

本文通过对龙羊峡水库蓄水使共和盆地应力、重力等条件改变的讨论，认为：共和地震的形成和发生与龙羊峡水库蓄水有密切的关联，在将共和地震与水库诱发地震的特征进行了比较后，发现共和地震所表现出来的特征与水库诱发地震特征极其相似，进而提出共和地震应属水库诱发地震的范畴。