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A preliminary study on vegetation-erosion dynamics and its applications

Science china Earth Sciences 2005年第5期48卷 689-700页

作者： WANG Zhaoyin 1.2 , WANG Guangqian 1., LI Changzhi 1.& WANG Feixin 1.1. Department of Hydraulic Engineering, Tsinghua University, beijing 1.0084,{1. 2. international research and training center on erosion and sedimentation, beijing 1.0084,{1. 1. Department of Hydraulic Engineering Tsinghua University 100084 Beijing China 2. international {1. and training center on erosion and sedimentation 100084 Beijing China

Vegetation-erosion dynamics is a new interdisciplinary science, studying the laws of evolution of watershed vegetation under the action of various ecological stresses. Introducing a qualitative expression of ecological stresses in this paper, the present authors establish the cou- pled differential equations for the vegetation-erosion process and derive a theoretical solution. The model is applied to the Anjiagou watershed on the Loess Pateau and the Xiaojiang water- shed and its sub-watersheds on the Yunnan Plateau. The calculated results agree well with the vegetation development processes. Abstracted from the differential equations the so-called vegetation-erosion chart is worked out, with which we can predict the development trend of vegetation under no human stresses. It is demonstrated that the erosion control is important for vegetation development and reforestation must be a long-term strategy. On the Yunnan Plateau with relatively high precipitation and temperature, vegetation can be greatly improved if erosion is controlled. On the dry and cold Loess Pateau suffering from high rate of soil erosion, however, vegetation can effectively control erosion but erosion reduction exhibits low effectiveness on vegetation development. Vegetation in the area is not stable and management is always needed to maintain the vegetation.

关键词： vegetation-erosion dynamics, human activities, coupled differential equations, erosion control, vigor ofvegetation.

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Optimizing the design of in situ sediment oxygen demand measurement chambers

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international Journal of Sediment {1. 2011年第2期26卷 222-229页

作者： HE Yun and LIU Cheng 1.Senior Engineer,Dr.,china Institute of Water Resources and Hydropower {1.,beijing 1.0038,china, 2 Prof.,Dr.,international {1. and training center on erosion and sedimentation,beijing 1.0048,china [a]Senior Engineer Dr. China Institute of Water Resources and Hydropower Research Beijing 100038 China [b]Prof. Dr. International Research and Training Center on Erosion and Sedimentation Beijing 100048 China

Sediment Oxygen Demand(SOD) is a key parameter for water quality analysis and for water quality modeling in rivers,lakes,estuaries and *** SOD can be measured both in the laboratory and in ***,the in situ technique appears to be the better approach for measuring SOD,as it likely to provide more representative and accurate *** order to optimize the design of in situ SOD measurement chambers,the three-dimensional flow fields in cylindrical SOD measurement chambers, commonly used for in situ measurements,have been numerically simulated by using the RNG-based k-s double equation turbulence *** chambers with three different inflow pipe configurations were *** results show that chamberⅢpresents distinct advantages over the other designs for in situ SOD measurement,because good flow mixing can be achieved and bottom sediment suspension can be avoided in the *** numerical simulation results were validated by comparison with existing results derived from laboratory *** SOD measurement chamber designed to reflect the results of the numerical simulations was successfully tested for in situ SOD measurements in both fresh and saline waters.

关键词： Sediment Oxygen Demand(SOD) Renormalization group(RNG) Velocity field In situ measurement Field tests

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ANALYSIS ON PECULIARITIES OF "92.8"FLOOD EVENTIN THE LOWER YELLOW RIVER

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international Journal of Sediment {1. 1999年第2期14卷 205-213页

作者： WANG Gang XU Mingquan (1.2 international {1. and training center on erosion and sedimentation (IRTCES), P.O. Box 366, beijing 1.0044, P.R. china)

From 7~th through 1.~th, August, 1.92, a series of heavy rainstorms took place in Shaanxi province. The rainfall moved from the north to the south in sequence, resulting in flood events in tributaries of the Middle Yelow River, such as Huangfuchuan, Kuye, Wuding, Yanhe, Beiluo, Jinhe and Weihe rivers. These floods, converged from various tributaries, propagated downstream and formed four continuing flood crests at Huayuankou Hydrometric Station in the Lower Yellow River with a max. peak discharge of 6260m3/s, which is referred as "92.8" flood. Although the peak discharge of 6260m3/s is a frequent one for the Lower Yelow Rived, the water stage reached 94.33m, the second record of the station, even 0.34m higher than that in 1.82 when the peak discharge was 1.300 m3/s. The "92.8" flood brought about a lot of damages, including inundation of 40000 ha of farmland on the floodplain of the Lower Yellow Rived The extremely high water stage, occurred in Huayuankou Hydrometric Station was caused directly by the previous deposition in main channel and unfavorable combination of incoming flow and sediment regime. But the primary cause is the change in incoming runoff and sediment load in the Lower Yellow River. Since the middle of 1.80's remarkable reduction has taken place both in runoff and sediment load, and to some extent becomes definitely a tendency in furture. As some unforeseen troubles in flood control in Lower Yellow River might occur, more attention should be paid for it.

关键词： Yellow River Hyperconcentrated flood Discharge Level Changes in runoff and sediment load.

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Modified vegetation-erosion dynamics model and its application in typical watersheds in the Loess Plateau

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international Journal of Sediment {1. 2011年第01期26卷 78-86页

作者： CHEN Yuehong~1,WANG Feixin~2,LIU Guangquan~3,YU Xinxiao~4, JIA Guodong~5,and GAN Ping~6 china Institute of Water Resources and Hydropower research,beijing 100048 international research and training center on erosion and Sediment research,beijing 100048,china beijing Forestry University,beijing 100083,china. Key Lab of Dredging Technology of CCGRP,Shanghai Waterway Engineering Design and Consulting Co., Ltd,Shanghai 200120,china. international research and training center on erosion and sedimentation china Institute of Water Resources and Hydropower research,beijing 100048 Northwest A&F University,Yangling 712100,china, beijing Forestry University,beijing 100083,china, beijing Forestry University,beijing 100083,china. china Institute of Water Resources and Hydropower research,beijing 100048,and international research and training center on erosion and Sediment research,beijing 100048,china [a] Assoc. Prof. Dr. china Institute of Water Resources and Hydropower {1. beijing 1.0048 international {1. and training center on erosion and Sediment {1. beijing 1.0048 china beijing Forestry University beijing 1.0083 china [b] Dr. Key Lab of Dredging Technology of CCGRP Shanghai Waterway Engineering Design and Consulting Co. Ltd Shanghai 2001.0 china [c] Prof. Dr. international {1. and training center on erosion and sedimentation china Institute of Water Resources and Hydropower {1. beijing 1.0048 Northwest A&F University Yangling 71.1.0 china [d] Prof. Dr. beijing Forestry University beijing 1.0083 china [e] Dr. beijing Forestry University beijing 1.0083 china [f] Engineer china Institute of Water Resources and Hydropower {1. beijing 1.0048 and international {1. and training center on erosion and Sediment {1. beijing 1.0048 china

The vegetation-erosion model was applied in three typical watersheds of hilly and gully area in the Loess Plateau in northwestern{1. to study the dynamic relations between vegetation coverage and soil erosion rate and various *** model was improved by introducing rainfall and runoff *** the modified model was applied in the Luergou and Luoyugou *** calculation results with the modified model were compared with the results of the original *** precisions of simulated vegetation coverage and soil erosion rate with the modified model were greatly improved compared with the original *** erosion rate reduced with increasing vegetation coverage and the human disturbance caused high soil erosion.

关键词： Soil erosion Vegetation coverage Vegetation-erosion dynamics model Loess Plateau Modified model

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EVALUATION OF WATER AND SEDIMENT QUALITIES AT RIVER MOUTHS IN THE HAIHE RIVER SYSTEM

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international Journal of Sediment {1. 2007年第4期22卷 318-326页

作者： Cheng LIU1, Zhao-Yin WANG1,2, Yun HE3, and Dongsheng CHENG3 1 Prof., Dr., international research and training center on erosion and sedimentation, beijing, 100044, china 2 Prof., Dr., Dept. of Hydraulic Engineering, Tsinghua University & international research and training center on erosion and sedimentation, beijing, 1.0084, china 3 Dr., Senior Engineer, china Institute of Water Resources and Hydropower research, beijing, 100044, china Int Res & training Ctr Eros & Sedimentat Beijing 100044 Peoples R China Tsinghua Univ Dept Hydraul Engn Beijing 100084 Peoples R China Int Res & training Ctr Eros & Sedimentat Beijing 100084 Peoples R China china Inst Water Resources & Hydropower Res Beijing 100044 Peoples R China

Water and sediment qualities are studied by analyzing samples taking from the mouths of the Haihe, Duliujian, New Ziya and Beipai rivers in the Haihe river basin in north china in 2005 and 2001. in order to find the changes of water and sediment pollutions. The concentrations of heavy metals, arsenic, total nitrogen (TN) and total phosphorus (TP) are analyzed and results have been compared for the two times. The in-situ measurement for Dissolved Oxygen (DO) and Sediment Oxygen Demand (SOD) rates were carried at the Haihe and Duliujian river mouths in 2006. The results show that the waters of the 4 river mouths are still seriously polluted, though much improved in the case of the Haihe and Duliujian rivers. The main pollutants are TP and TN in the New Ziya and Beipai rivers and mercury (Hg) at all 4 river mouths. Compared with those in 2001. the concentrations of almost all metals and arsenic in the 4 river mouths have decreased. Water quality at Haihe and Duliujian shows an improving trend, while the water quality at Beipai is similar to that of 2001. In contrast, water at the New Ziya river mouth is more severely polluted. The sediments in the 4 river mouths are not seriously polluted by heavy metals but are polluted by nitrogen and phosphorus. Most of the pollutant contents in the sediments show little change between 2001.and 2005. The in-situ DO and SOD measurement shows that the waters at the Haihe river mouth is in the state of oxygen depletion, and SOD is important consumer of DO at the river mouths. The overall analysis shows that increasing water pollution and eutrophication in waters far from cities are ongoing causes of concern.

关键词： River mouth Water quality Sediment quality Eutrophication Sediment oxygen demand

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Strategies for managing reservoir sedimentation

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international Journal of Sediment {1. 2009年第4期24卷 369-384页

作者： Zhao-yin WANG 1.and Chunhong HU 21.Prof., State Key Lab of Hydroscience and Engineering, Tsinghua University, beijing 1.0084,{1.. 2 Prof., Secretary General of international research and training center on erosion and sedimentation, beijing 1.0048,{1. and Vice President of{1. Institute of Water Resources and Hydropower research, No. A-1. Fuxing Rd, beijing 1.0038,{1.. [a] Prof. State Key Lab of Hydroscience and Engineering Tsinghua University beijing {1. china [b] Prof. Secretary General of international {1. and training center on erosion and sedimentation beijing 1.0048 china and Vice President of{1. Institute of Water Resources and Hydropower research No. A-1 Fuxing Rd beijing 1.0038 china

Sediment deposition in reservoirs has caused the loss of 66% of the reservoir capacity in china. The main {1. control strategies are: 1. storing the clear water and releasing the turbid water; 2) releasing turbidity currents; 3) Draw-down flushing and empty flushing; and 4) dredging. The paper summarizes these strategies with examples. Sediment transport in many Chinese rivers occurs mostly during the 2-4 month flood season, that is, 80-90% of the annual sediment load is transported with 50-60% of the annual runoff. By storing the clear water after the flood season and releasing the turbid water during the flood season, less sediment deposits in the reservoir while the reservoir is still able to store enough water for power generation in the low flow season. The Three Gorges and Sanmenxia reservoirs apply this strategy and control {1. effectively. Turbidity currents have become the main {1. control strategy for the Xiaolangdi Reservoir. Empty flushing involves reservoir draw-down to temporarily establish riverine flow along the impound reach, flushing the eroded sediment through the outlets. Case studies with the Hengshan Reservoir and Zhuwo Reservoir are presented. Jet dredgers have been used to agitate the reservoir deposit so that the deposit is released from the reservoir with currents. The sediment releasing efficiency is 30-1.0% for storing the clear and releasing the turbid; 6-40 % for turbidity current; and 2,400-5,500% for empty flushing. Empty flushing causes high ecological stress on the ecosystem to the downstream reaches. Storing the clear and releasing the turbid is the best strategy to control reservoir {1. while achieving hydro-power benefit and maintain ecological stability.

关键词： Reservoir sedimentation Storing clear and releasing turbid Flushing Turbidity current Three Gorges Reservoir

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DEVELOPMENT OF STEP-POOL SEQUENCE AND ITS EFFECTS IN RESISTANCE AND STREAM BED STABILITY

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international Journal of Sediment {1. 2004年第3期19卷 161-171页

作者： Zhao-Yin WANG, Jiang XU and Changzhi LI Professor, Dept. of Hydraulic Engineering, Tsinghua University, beijing & Chairman of Advisory Council, {1. research and training center on erosion and sedimentation, 1.0084, china, Email: zywang@***.M. Phil., Dr. & Post Doctorate research fellow, Dept. of Hydraulic Engineering, Tsinghua University, beijing, 1.0084, china Dept. of Hydraulic Engineering Tsinghua University Beijing & Chairman of Advisory Council International Research and Training Center on Erosion and Sedimentation 100084 China Dr. & Post Doctorate research fellow Dept. of Hydraulic Engineering Tsinghua University Beijing 100084 China

Experiments were conducted and field investigations were performed to study the development of step-pool sequence and its effects on resistance to the flow and stream bed stability. Step-pool sequence develops in incised channels as a result of streambed erosion, which is compared with sand dunes and armor layer of the role in resistance and streambed protection. The tight interlocking of particles in steps gives them an inherent stability which only extreme floods are likely to disturb. That stability suggests that step-pools are a valid equilibrium form, especially when coupled with their apparent regularity form and their role in satisfying the extreme condition of resistance maximization. The development degree of step-pools, SP, is proportional to the streambed slope. If the incoming sediment load is equal to or more than the sediment-carrying capacity of the flow, there is no bed erosion and thence there are no step-pools. If the flow depth increases and is over the step-height the resistance caus

关键词： Step-pool Streambed stability erosion Resistance Rate of energy dissipation Manning’s roughness n

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EFFECT OF SHAPE ON INCIPIENT MOTION OF SEDIMENT PARTICLES

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international Journal of Sediment {1. 1999年第2期14卷 179-186页

作者： Zhao-Yin WANG Andreas DITTRICH ( international {1. and training center on erosion and sedimentation, P.O. Box 366, beijing 1.0044. china Institute of Hydraulic Engineering and Rural Technology, Karlsruhe University 761.8, Karlsruhe, Germany)

The effect of particle shape on the initiation of motion was studied experimentally with 1.at. elliptical and round grains of the same volume-equivalent diameter. An armoring layer with imbricate cluster structure can be formed for flat particles. Experiments demonstrate that the particle shape has no great influence on the initiation of motion of individual particle before the imbricate cluster structure is developed. After the imbricate cluster structure is developed, however. the critical Shields parameter for initiation of flat particles is 65% larger than that for round particles. The influence of the length of the test section is studied in the paper too, which concluded that the influence is negligible as the length longer than 1..4 m. Therefore the results of particles initiation with the 2 m long section is compatible to those from river flows.

关键词： Particle shape Initiation of motion Imbricate cluster structure. Shields parameter

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Sediment load reduction in Chinese rivers

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international Journal of Sediment {1. 2008年第1期23卷 44-55页

作者： Cheng LIU1. Jueyi SUI2, and Zhao-Yin WANG31.Prof., Dr., international {1. and training center on erosion and sedimentation, beijing, 1.0044, china, 2 Associate Professor, Environmental Engineering Program, University of Northern British Columbia, Prince George, BC, Canada 3 Prof., Dr., Dept. of Hydraulic Engineering, Tsinghua University, beijing, 1.0084, china [a]Prof. Dr. international {1. and training center on erosion and sedimentation beijing 1.0044 china [b]Associate Professor Environmental Engineering Program University of Northern British Columbia Prince George BC Canada [c]Prof. Dr. Dept. of Hydraulic Engineering Tsinghua University beijing 1.0084 china

In this paper, the changes in the annual runoff and sediment transport have been assessed by using the long term observation data from 1. gauging stations on 1. large rivers across china from far north to far south. It is found that the annual sediment yield has generally had a decreasing trend in the past half century. According to the changes in annual runoff and the sediment yield per area, rivers in china can be classified into the following three groups: 1. rivers with decreasing annual sediment transport and stable runoff; 2) rivers with both decreasing annual sediment transport and runoff and 3) rivers with greatly reduced annual sediment transport and decreasing annual runoff. The results indicate that, in all southern rivers (to the south of the Huaihe River including the Huaihe River), there has been little change in average annual runoff but a dramatic decrease in annual sediment transport. In the northern rivers, however, both the annual sediment yield and the runoff show significant evidence of reduction. To further investigate the recent changes in annual runoff and sediment transport, the short-term observation data from these 1. gauging stations in the recent 1. years have been assessed. Results show that both the annual sediment transport and the runoff have decreased significantly in the northern rivers in the past 1. years. Using the Yellow River at the Lijin Station as an example, the average annual runoff for the last 1. years is only 1.3 of the long term average value and the average annual sediment yield of the last 1. years is only 1.4 of the long term average value. More unusually, in the Yongding River the annual sediment yield has approached zero and the runoff has decreased significantly. In addition, the impacts of human activities on the changes in both runoff and sediment transport have been discussed.

关键词： china Runoff Sediment load Large rivers Sediment yield Yangtze River Yellow River

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Changes in sediment transport in the Kuye River in the Loess Plateau in china

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international Journal of Sediment {1. 2009年第2期24卷 201-213页

作者： Jueyi SUI1.Yun HE2,and Cheng LIU3 1.Associate Professor,Environmental Engineering Program,University of Northern British Columbia,Prince George,BC,Canada,V2N 4Z9 2 Senior Engineer,china Institute of Water Resources and Hydropower {1.,No. A-1.Fuxing Rd.,beijing 1.0038,china Ph.D 3 international {1. and training center on erosion and sedimentation,20 Chegongzhuang West Rd.,beijing 1.0048,china Ph.D,Prof. [a]Environmental Engineering Program University of Northern British Columbia Prince George BC Canada V2N 4Z9 [b]China Institute of Water Resources and Hydropower Research No. A-1 Fuxing Rd. Beijing 100038 China [c]International Research and Training Center on Erosion and Sedimentation 20 Chegongzhuang West Rd. Beijing 100048 China

In this paper,the changes in sediment transport over 51.years from 1.55 to 2006 in the Kuye River in the Loess Plateau in china are assessed. Key factors affecting sediment yield and sediment transport,such as precipitation depth,discharge,and human activities are studied. To investigate the changes in sediment yield in this watershed,a trend analysis on sediment concentration,precipitation depth,and discharge is conducted. Precipitation depths at 2 Climate Stations(CSs) ,as well as discharge and sediment transport at 3 Gauging Stations(GSs) are used to assess the features of sediment transport in the Kuye River. The runoff modulus(defined as the annual average discharge per unit area,L/(***2) ) and the sediment transport modulus(defined as the annual suspended sediment transport per unit area,t/(yr km2) ) are introduced in this study to assess the changes in runoff and sediment yield for this watershed. The results show that the highest average monthly discharge during the study period in the Kuye River is 66.23 m3/s in August with an average monthly sediment concentration of 88.9 kg/m3. However,the highest average monthly sediment concentration during the study period in the Kuye River is 1.5.34 kg/m3 and occurs in July,which has an average discharge of 42.6 m3/s that is much less than the average monthly discharge in August. It is found that both the runoff modulus and sediment transport modulus at Wenjiachuan GS on the Kuye River has a clear downward trend. During the summer season from July to August,the sediment transport modulus at Wenjiachuan GS is much higher than those at Toudaoguai and Longmen GSs on the Yellow River. The easily erodible loess in the Kuye River watershed and the sparse vegetation are responsible for the extremely high sediment yield from the Kuye River watershed. The analyses of the grain size distribution of suspended load in the Kuye River are presented. The average monthly median grain size of suspended load in the Kuye River is large

关键词： Grain size distribution Kuye River Loess Plateau Precipitation Runoff modulus Sediment transport modulus Soil erosion Yellow River

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