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Numerical simulation of channel pattern changes Part Ⅱ:Application in a conceptual channel

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International Journal of Sediment Research 2010年第4期25卷 380-390页

作者： Hong WANG1, Gang ZHOU2, and Xuejun SHAO31 ph.d., Associate Professor, State Key Laboratory of Hydroscience and Engineering, tsinghua university. Beijing 100084, china. 2 Graduate student for a ph.d. degree (at the time of this research work), State Key Laboratory of Hydroscience and Engineering, tsinghua university. Beijing 100084, china. Presently: post-doctoral research fellow, Chinese Research Academy of Environmental Sciences, Beijing 100012, china 3 ph.d., Professor, State Key Laboratory of Hydroscience and Engineering, tsinghua university. Beijing 100084, china. ph.d. Associate Professor State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China Graduate student for a ph.d. degree (at the time of this research work) State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China. Presently: Post-doctoral research fellow Chinese Research Academy of Environmental Sciences Beijing 100012 China ph.d. Professor State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

This paper presents simulated channel patterns for various scenarios in a conceptual alluvial valley by an improved two-dimensional (2-d) mathematical model described in the companion paper. Starting from the same initial channel, different channel patterns have been simulated over a real time period of 250 days for varied boundary and initial conditions, including the inlet water discharge and sediment load, initial valley slope, and erodibility of river banks. Impacts of these control factors are discussed, in terms of the longitudinal bottom profiles of simulated fluvial channels, the geometry of channel cross sections, and the water surface profiles in the conceptual river valley. Results suggest that the upper and lower parts of the same channel may have different planforms because the sediment transport conditions of the two parts differ greatly. Simulated causal relationship between control variables and channel patterns agrees qualitatively with known channel pattern theories.

关键词： Channel pattern changes Numerical simulation Resistance to bank erosion Sediment transport Braided channel

Sediment pollution and its effect on fish through food chain in the Yangtze River

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International Journal of Sediment Research 2008年第4期23卷 338-347页

作者： Yujun YI 1,Zhaoyin WANG 2,Kang ZHANG 3,Guoan YU 4,and Xuehua dUAN 51 dr.,Lecturer,State Key Laboratory of Hydroscience,School of Environment,Beijing Normal university.Beijing 100875,china2 Prof.,State Key Laboratory of Hydroscience and Engineering,tsinghua university.Beijing 100084,china 3 ph.d.,State Key Laboratory of Hydroscience and Engineering,tsinghua university.Beijing 100084,china 4 ph.d.,State Key Laboratory of Hydroscience and Engineering,tsinghua university.Beijing 100084,china 5 ph.d.,State Key Laboratory of Hydroscience and Engineering,tsinghua university.Beijing,100084,china dr. Lecturer State Key Laboratory of Hydroscience School of Environment Beijing Normal University Beijing 100875 China Prof. State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China ph. d. State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China ph. d. State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

Suspended sediment adsorbs pollutants from flowing water in rivers and deposits onto the bed. However, the pollutants accumulated in the river bed sediment may affect the bio-community through food chain for a long period of time. To study the problem the concentration of heavy metals (Cr, Cd, Hg, Cu, Fe, Zn, Pb and As) in water, sediment, and fish/invertebrate were investigated in the middle and lower reaches of the Yangtze River during 2006-2007. The concentrations of heavy metals were 100-10,000 times higher in the sediment than in the water. Benthic invertebrates had relatively high concentrations of heavy metals in their tissues due to their proximity to contaminated sediments. Benthic invertivore fish had moderately high concentrations of heavy metals whereas phytoplanktivore fish, such as the silver carp, accumulated the lowest concentration of heavy metals. The concentrations of Cu, Zn, and Fe were higher than Hg, Pb, Cd, Cr, and As in the tissue samples. The concentration of heavy metals was lower in the river sediments than in the lake sediments. Conversely, the concentration of heavy metals was higher in river water than in lake water. While a pollution event into a water body is often transitory, the effects of the pollutants may be long-lived due to their tendency to be absorbed in the sediments and then released into the food chain. The heavy metals were concentrated in the following order: bottom material > demersal fish and benthic fauna > middle-lower layer fish > upper-middle layer fish > water.

关键词： Sediment pollution Heavy metal Fish Invertebrate Yangtze River

Effects of fluvial processes and human activities on stream macro-invertebrates

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International Journal of Sediment Research 2011年第4期26卷 416-430页

作者： Xue-hua dUAN,Zhao-Yin WANG,and Meng-zhen XU 1 ph.d.,State Key Laboratory of Hydroscience and Engineering,tsinghua university.Beijing 100084,china Jiangyin Water Conservancy and Farm Machinery Bureau,Jiangyin 214431 china, 2 Prof,State Key Laboratory of Hydroscience and Engineering,tsinghua university.Beijing 100084,china, 3 doctoral candidate,State Key Laboratory of Hydroscience and Engineering,tsinghua university.Beijing 100084,china, ph.d. State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China Jiangyin Water Conservancy and Farm Machinery Bureau Jiangyin 214431 China Tel: 86-*** (M) Prof. State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China doctoral candidate State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

Benthic macro-invertebrates are vital components of river *** effects of fluvial processes and human activities on the distribution of macro-invertebrates were studied through field investigations and ***-one sampling sites on 31 rivers in china were selected to investigate the structures of macro-invertebrate *** rivers,according to their fluvial conditions,are classified as streams with a stable channel bed,degrading channel bed,aggrading channel bed,and intensive bed load *** structures of macro-invertebrate fauna for the four types of rivers are very *** rivers have a large number of individuals,abundant fauna, and high biodiversity;while the density and taxa richness for degrading rivers are small,and those for aggrading rivers are much less;whereas the ecology of rivers with intensive bed load motion are the *** paper proposes that streambed stability is the primary influential factor shaping the structure of benthic macro-invertebrate *** pollution can obviously result in the decrease of biodiversity,in the simplification of macro-invertebrate structures,and in the distortion of functional feeding group *** a river with high total nitrogen content,the relative abundance of collector-gatherers is high,and that of collector-filterers,scrapers,shredders,and predators are ***,shredders,and predators disappear in severely polluted *** isolation of aquatic habitat results in a distinct decrease of individual numbers and taxa *** result demonstrates that the connectivity of aquatic habitat significantly affects macro-invertebrate assemblages.A practical method to calculate a Habitat Suitability Index(HSI) is proposed,integrating the effects of the primary physical(including biotic and abiotic) and chemical *** biodiversity and taxa richness increase non-linearly with HSI.

关键词： Macro-invertebrate Streambed stability Substratum Isolation Habitat suitability Water pollution

ON EMBEddEd MATERIAL dERIVATIVE ANd FRAME SPIN

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Acta Mechanica Sinica 1988年第2期4卷 190-194页

作者： Cheng Li*, Beijing Institute of TechnologyHwang Kehchih, tsinghua university.*Now part-time ph.d. student at tsinghua university Beijing Institute of Technology Beijing China tsinghua university Tsinghua China

In the present paper, the concept of embedded material derivative is proposed. thegeneral expression for frame spin is derived, the difference between embedded material derivative andconventional one of triad unit vectors is clarified. Furthermore, the formula for strain-rate framespinis obtained. And by means of this example, the distinction between the two kinds of materialderivatives is discussed. Then, the relations between several frame spins and the rates of corresponoingtensors co-rotating with the frame are elucidated.

关键词： embedded material derivative frame spin method of principal axes

PREdICTIONS FOR THE NEXT FIVE YEARS

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Beijing Review 2010年第37期53卷 28-31页

作者： Hu Angang the center for china studies of tsinghua university

In 2011,china will kick off its 12th Five-Year Plan (2011-15).Now,in this post-crisis era,how can the Chinese economy maintain sustainable growth? And where is the country headed in the next five years? With these questions in mind,Beijing Review reporters Lan Xinzhen and Yu Shujun interviewed Professor Hu Angang,director of the center for china studies of tsinghua university.

关键词： PREdICTIONS FOR THE NEXT FIVE YEARS

THE NAGUMO EQUATION ON SELF-SIMILAR FRACTAL SETS

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Chinese Annals of Mathematics,Series B 2002年第4期23卷 519-530页

作者： HU JIAXINdepartment of Mathematics, tsinghua university. Beijing 100084, china. department of Mathematics Tsinghua University Beijing 100084 China

The Nagumo equation ut = △u+ bu(u-a)(1-u), t＞0is investigated with initial data and zero Neumann boundary conditions on post-critically finite (p.c.f.) self-similar fractals that have regular harmonic structures and satisfy the separation condition. Such a nonlinear diffusion equation has no travelling wave solutions because of the 'pathological' property of the fractal. However, it is shown that a global Holder continuous solution in spatial variables exists on the fractal considered. The Sobolev-type inequality plays a crucial role, which holds on such a class of p.c.f self-similar fractals. The heat kernel has an eigenfunction expansion and is well-defined due to a Weyl's formula. The large time asymptotic behavior of the solution is discussed, and the solution tends exponentially to the equilibrium state of the Nagumo equation as time tends to infinity if b is small.

关键词： Fractal set Spectral dimension Sobolev-type inequality Strong (Weak) solution

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PRINCIPLES OF RIVER TRAINING ANd MANAGEMENT

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International Journal of Sediment Research 2007年第4期22卷 247-262页

作者： Zhaoyin WANG1, Shimin TIAN2, Yujun YI3, and Guoan YU4 1 Prof., State Key Laboratory of Hydroscience and Engineering, tsinghua university. Beijing, 100084, china 2 ph. d., china Institute of Water Resources and Hydro-Power Research, Beijing 100044, china. 3 ph. d., State Key Laboratory of Hydroscience and Engineering, tsinghua university. Beijing, 100084, china 4 ph. d., State Key Laboratory of Hydroscience and Engineering, tsinghua university. Beijing, 100084, china State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China china Institute of Water Resources and Hydro-Power Research Beijing 100044 China

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.

关键词： River training Integrated river management Sediment Erosion control Ecological and landscape restoration

Effect of incoming sediment on the transport rate of bed load in mountain streams

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International Journal of Sediment Research 2009年第3期24卷 260-273页

作者： Guo-An YU1, Zhao-Yin WANG2, Kang ZHANG3, Tung-Chiung CHANG4, and Huaixiang LIU51 dr., Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, china and dept. of Hydraulic Engineering, tsinghua university. 2 Prof., State Key Laboratory of Hydroscience and Engineering, tsinghua university. Beijing 100101, china, 3 ph.d. candidate, State Key Laboratory of Hydroscience and Engineering, tsinghua university. Beijing 100084, china 4 ph.d. candidate, tsinghua university. Beijing 100084, china and Prof., Kaoyuan university. Kaohsiung 82151, Taiwan, china 5 dr., State Key Laboratory of Hydroscience and Engineering, tsinghua university. Beijing 100084, china dr. Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China and Dept. of Hydraulic Engineering Tsinghua University Prof. State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100101 China ph.d. candidate State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China ph.d. candidate Tsinghua University Beijing 100084 China and Prof. Kaoyuan University Kaohsiung 82151 Taiwan China dr. State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

Field experiments were conducted on bed load transport in the diaoga River, a mountain stream in southwest china, to study the variation of bed load transport with varying sediment supply. The rate of bed load transport is greatly affected by incoming sediment (load and size). Under the same flow conditions, bed load transport rates may differ by three orders of magnitude depending on whether measurements were taken before or after the first flood of the year. The relation of the "bed load transport rate versus flow intensity" appears to have similar characteristics as a clockwise looped-rating curve. Experiments also were conducted during the non-flood season to study bed load transport processes with different incoming load from an upstream section. Bed load with different sizes can be grouped into two types: traveling bed load and structural bed load. Traveling bed load is composed of sediment finer than a critical size, dc, and its transport rate depends mainly on the incoming sediment rate. The incoming sediment rate can alter the rate of bed load transport by three orders of magnitude. Structural bed load is composed of coarser sediment and its transport rate closely relies on the flow intensity.

关键词： Mountain streams Bed load transport Sediment supply Sediment size distribution

Effect of streambed sediment on benthic ecology

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International Journal of Sediment Research 2009年第3期24卷 325-338页

作者： Xuehua dUAN1, Zhao-Yin WANG2, Mengzhen XU3, and Kang ZHANG41 ph.d., Jiangyin Environmental Monitoring Station, Jiangyin 214431, china, dept. of Hydraulic Engineering, tsinghua university.2 Prof., State Key Laboratory of Hydroscience and Engineering, tsinghua university. Beijing 100084, china, 3 doctoral candidate, State Key Laboratory of Hydroscience and Engineering, tsinghua university. Beijing 100084, china,4 doctoral candidate, State Key Laboratory of Hydroscience and Engineering, tsinghua university. Beijing 100084, china ph.d. Jiangyin Environmental Monitoring Station Jiangyin 214431 China Dept. of Hydraulic Engineering Tsinghua University Prof. State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China Tel: 86-10-62773448(O) doctoral candidate State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

Benthic macroinvertebrates have been commonly used as indicator species for assessment of aquatic ecology. Streambed sediment, or substrate, plays an important role in habitat conditions for macroinvertebrate communities. Field investigations were done to study the benthic diversity and macroinvertebrate compositions in various stream substrata. Sampling sites with different bed sediment, latitude, and climate were selected along the Yangtze River, the Yellow River, the East River, and the Juma River, in china. The results show that benthic community structures found in different substrata clearly differ, while those found in substrata of similar composition and flow conditions but in different macroclimates are similar. The study, thus, demonstrates that the benthic macroinvertebrate community is mainly affected by substrate composition and flow conditions, but is generally unaffected by latitudinal position and macroclimate. Taxa richness of the macroinvertebrate community was found to be the highest on hydrophyte-covered cobbles, high on moss-covered bedrock, and low on clay beds and cobble beds devoid of plant biomass. Sandy beds are compact and unstable, thus, no benthic macroinvertebrates were found colonizing such substrata. Aquatic insects account for most of the macroinvertebrates collected in these rivers. different insects dominate in different types of substrata: mainly EPT species (Ephemeroptera, Plecoptera, Trichoptera) in cobble, gravel, and moss-covered bedrock; and Chironomidae larvae in clay beds. The relation between the number of species in the samples and the size of the sampling area fits a power function of the species area. One square meter (1m2) is suggested as the minimum sampling area. A substrate suitability index is proposed by integrating the suitability of sediment, periphyton, and benthic organic materials for macroinvertebrates. The biodiversity of macroinvertebrates increases linearly with the substrate suitability index. Benthic ta

关键词： Streambed sediment Macroinvertebrates Benthic ecology Substrate suitability Biodiversity