Effect of Different Operation of Sanmenxia Reservoir on Water Level at Tongguan

GUO Qingª²chao, HU Chun-hong, LU Qin, CHEN Jian-guo, QI Wei
(China Institute of Water Resources and Hydropower Research)

 Abstract:  Brief summary on the evolution processes of water level at Tongguan in history,  before and after the build of Sanmenxia reservoir is fi rstly described. Reasons resulting in the change of water level at Tongguan in d ifferent periods are then analyzed. Results indicate that the water level at Ton gguan is affected by both reservoir operation and oncoming flow and sediment. Fi nally, awell developed mathematical model is used to simulate the possible tre nd of the water level at Tongguan under different reservoir operations and oncom ing flow series.

Key words:  sediment transport£»reservoir operation£»water level at Tongguan

Tendency of Channel Change of the Lower Yellow River During Its Shrinkage

XU Jiong-xin¹, SUN Ji²
(1.Institute of Geographical Sciences and Natural Resources Research,
Chinese Academy of Sciences;2.Southwest University of Science and Technology)

Abstract: Due to the changes in runoff and sediment load induced  by human activities and the changing natural factors, marked channel shrinkage  has occurred in the lower Yellow River since the 1970s, especially since the mid 1980s. The bankfull width of the channel became smaller, the width to depth ra tio became lower, the lateral shifting of thalweg was greatly reduced, and the t halweg sinuosity became higher. All these indicate that the intensity of wande ring" of the lower Yellow River declined to some degree.

Key words:  channel process; channel pattern; channel shrinkage;  the lower Yellow River

The Application of Tracing Method in the Sediment Study

WANG Xiao-yan, TIAN Jun-liang, YANG Ming-yi
(Institute of Soil and Water Conservation, CAS; Northwest Sciª²Tech Uni versity of Agriculture and Forestry£©

Abstract: Several methods for estimating sediment yield and identifying sediment sources are introduced, compared and evaluated.The predominance of radionuclides trace and geochemical methods in the application of sedime budge,contemporary suspended sediment and historical sediment source are high lighted.Historical information of sediment sources in the catchment in the past  century can be reconstructed by radionuclides tracing and composite fingerprints, which would be the basis of the study of the relationship between the changes  of environment and soil erosion and sediment yield. More explainations should be given to the information contained in the deposited sediments for selecting sc ientific environment control measurements

Key words:  sediment budget; sediment sources; environment change; radionuclides trace; composite fingerprints

Sampling  Efficiency of Vertical Array Sand Traps

LI Zhen-shan^1,2, NI Jin-ren^1,2, LIU Xian-wan³
(1.Department of Environmental Engineering,Peking University;
2.The Key Laboratory of Water and Sediment Sciences,Ministry of Education;
3.Cold and Arid Region Environmental and Engineering Research Institute,Chinese  Academy of Sciences)

Abstract: Numerous data have been obtained form vertical eolian  sand-mass flux profiles by  using a wide variety of vertical array sand traps.These data have not been used  sufficiently because of different efficiencies for different types of traps.The  comparison of the measured data from various traps indicated that the sand-col lecting efficiencies of the traps are usually low and differ significantly for d ifferent traps in the near-bed region,whereas the efficiencies are high and are  close for all kinds of traps in the upper region.The efficiencies of traps incr ease with height above the bed.Accordingly,the difference between trap efficiencies can be described by an index A that is used to express the extent of the  deviation of sand-mass flux in near-bed region from the distribution calibrat edin the upper region.Under the similar conditions of wind speed and sand grain  size,the increase of the index A suggests the increase of the trap efficien cies.The index A computed from existing measured vertical profiles of mass flux of blown sand shows that the efficiency of single-tube trap is the highest,the efficiency of normal array trap the second,and the step-like array trap the  last.The variation of index A may partly depend on the inlet height of cham ber aperture of the traps,which indicates the importance of air outlet in traps. In addition,the effects of wind speed and sand grain size on trap efficiency were discussed,and some means for enhancing trap efficiency were pointed out.

 Key words:  vertical array sand traps; trap types; trap efficiency; wind velocity

The Distribution of Soil Loss on the Surface of Loess Slope

KONG Ya-ping¹£¬2£¬ZHANG Ke-li¹ªª
(1.Department of Resources and Environmental Science, Beijing Normal University;
2.China Academy of Transportation Sciences, Ministry of Communications)

Abstract: The study of the distribution of soil loss on loess slope is a theoretical base  to understand the mechamism of soil loss and control soil loss effectively. In order to study the mechamism of soil loss on different segments and the development of erosion configuration for different slope length, simulated artificial rai nfall experiments of different slope length (2.5,5,7.5, 10m) for different rainf all intensity (0.72,1.16,1.4,2.0,2.4mm/min) were conducted. The results showed t hat under the experimental condition the soil loss increases from the top of t he slope to the down stream, but the increment is different for different rainf all intensity. When the rainfall intensity is less than 2mm/min, the soil loss i ncreases rapidly in the 5¡«7.5m segment. When the rainfall intensity exceeds 2mm /min, the soil loss increases rapidly in the 2.5¡«5m segment. The run on water  is the key factor to affect soil loss on the hillslope.The soil loss increases l inearly with runª²on water under short slope; Rill density is a better parameter to describe the development of rill, and it increases linearly with rainfall in tensity.

Key words:  loess slope; soil loss; rill density; rill erosion

Study on Long-term Average Sediment Transport Modulus of China

 WEI Hong-bo, REN Hong-yu, YANG Qin-ke
(Institute of Soil and Water Conservation, CAS & MWR)

 Abstract: Sediment amount data from two hundred and twenty two hydrolo gical stations in China are first used to make the isoline map of long-term average sediment transport modulus of China based on GIS software, ARC/INFO, database system softw are, and visual foxpro. Then the distribution of sediment transport and depositi on in a great scale in China is analyzed and the areas for different sediment  transport intensity are calculated.

Key words:  China; sediment transport modulus; GIS

 Numerical Simulation on Dredging Channel of Guishui River Mou th Bar of Guanting Reservoir

 ZHANG Yan-jing£¬ZHANG Shi-qi, CHEN Jin-rong
(China Institute of Water Resources and Hydropower Research)

Abstract:  Several dredging plans have been conducted by the mathematical model.The simulated results show that the amount of silt in the dredged channel could  be affected by the oncoming flow and sedi ment, the relative position between the channel and the mouth, and the operation  water level of Guanting reservoir. To restore the water supply to Beijing city,  it is suggested that the dredging plan of 15¡«50m wide dredge channel should be  implemented in the current project. In the future, a 300m wide dredge channel should be applied. In the permission of cost, it would be better to take both mea surements of dredging channel and training dike.

Key words:  Guishui river mouth bar; sedimentation mathematic mo del; dredging plans; the amount of silt

Study on the Benefits of Sediment Reduction and Water Resources Regulation by
¡°Changzhi Project¡±in the Sichuan Basin

LEI Xiao-zhang¹, CAO Shu-you¹, DAI Hua-long¹, DAI Yong-bo²
(1.State Key Hydraulic Laboratory of High Flow,Sichuan University£»
2.Provincial Development and Planning Commission of Sichuan)

Abstract: Large quantity observed data by various water and soil conservation measurements, which is called as¡°Changzhi Project¡±, are used to analyze the effects of sediment reduction and runoff regulation for different measurements conducted on t he slope land or in a watershed. The results show that the¡°Changzhi Project¡± has a significant effect on sediment reduction and surface runoff regulation. Ho wever, more study on the mechanism of runoff movement and sediment transport under different scales is needed in the future.

Key words:¡° Changzhi Project¡± water and soil conservation; effect of sediment reduction

Study on the Restoration and Saturation Coefficient ¦Áin 1-D Over-saturation Sediment Transport

 SHI Chuan wen^£±,LUO Quan sheng^£²
(1.Tsinghua University; 2.Yellow River Conservancy Technical Institute, Water Conservancy Department)

Abstract: Studies indicate that the settling formula in quasi¡ªstatic water is the simplified form of 1-D over saturation sediment tronsport. The affecting factors and physical meanings of ¦Á& k are the same while there is the relation ¦Á=1/k between them. The ¦Ávalue or kvalue can be determined by existing research. The factors to affect coefficient ¦Á and sediment carrying capacity are the same or at least similar.

¡¡¡¡The main factors affecting ¦Ávalue can be obtained through nalyzing the measured data. The average error of the computed settling vetocity by the proposed ¦Ácalculating model is less than 6%, and the probability of the relative error within 20% is 95%. So the accuracy can meet the requirement.

Key words:  restoration & saturation coefficient; relation between ¦Áandk;main affecting factors; calculating model

Experimental Study on the Equilibrium Channel SlopeDuring Yellow River Mouth Sluicing by Seawater

DING Xiang, CHEN Zhi-cong, SHAO Xue-jun
(Tsnghua University)

Abstract: A new method has been proposed to reduce the progressive river channel aggradation in the lower Yellow River by sluicing the distributaries using pumped seawater. This paper presents the results of an experimental study based on this novel idea, which involves a series of flume tests in a 64 meter long mobileª²bed flume, to figure out the discharge, timing and duration of seawater sluicing on the basis of observed processes of progressive erosion downstream of the point of seawater input, and the retro-progressive erosion upstream of it. The equilibrium channel bottom slopes for both cases have been found out based on test data, andan empirical relationship is developed to predict such slopes for various sluicing conditions, which has been validated using independent data from other researchers. Results of this study can be used to finalize the sluicing scheme.

Key words: Yellow River estuary; diverting seawater; scouring; progressive erosion; retrogressive erosion; equilibrium channel bottom slope

Research on Decrease of Water and Sediment Yield Due to Soil &
Water Conservation in Jialing River Xihanshui Basin

 ZHANG Ming-bo, HUANG Yan, GUO Hai-jin, SHEN Yan-zhou
(Bureau of Hydrology, Changjiang Water Resources Commission)

Abstract: Xihanshui River is the fourthª²order tributary of the Jialing River. The river basin locates in the south of Qinling with a loess region of 2 350km². It is one of the main sediment sources of Jialing River basin. After the implementation of soil and water conservation in the Changjiang River from the late 1980's, the soil and water losses have been greatly reduced. The total area that has brought under control reached 40 percent of the total soil and water loss area by 1996. This paper tries to analyze the change in runoff, sediment, and their relationship on the basis of measured hydrologic data at Shunlixia station.

Key words:  Jialing River; Xihanshui River; soil and water conservation; the change in runoff, sediment, and their relationship

Discussion on the Computation of Suspended Sediment Gradation in Model Tests

 ZHANG Ming-yi, SUN Juan, QI Yin-xin, CUI Xiao-hong, LI Jiang-feng
(Xinjiang Research Institute of Water Resources And Hydroelectric Science)

Abstract: The selection of model sand is the key problem in the design of a mobilebed model test. To meet the similarity of flow and sediment movement in the model and prototype, it is necessary to comprehensively consider the character of interested problem, model geometric scale, and other related factors when selecting and designing the density and gradation of model sand. A new method to determine the size distribution of model sand is proposed based on Sha Yuqing's formula, which could partly avoid the shortcoming of previous methods.

Key words:  selection of model sand; model test similarity; grainsize distribution