Quantifying and characterizing contemporary riparian sedimentation

Fluvial processes of erosion, sediment transport and deposition determine the changing form and sedimentary structure of naturally adjusting riparian zones. Riparian sediment storage has both scientific and management importance in relation to: (i) the quantities of sediment that are involved; (ii) the quality of the sediment; and (iii) the dispersal of biological materials, notably the vegetation propagules that are transported and deposited in association with the sediment. After discussing the significance of riparian sedimentation processes, this paper reviews methods for quantifying contemporary sediment deposition within water bodies and their margins. Methods for investigating contemporary riparian sedimentation are given particular emphasis, and the extent to which different methods provide comparable estimates and have been used to support the analysis of different physical and chemical properties of the sediment are outlined. The importance of the following are stressed: (i) selecting a sampling method that is suited to the sedimentation environment; (ii) incorporating careful cross‐calibration if measurements from different methods are to be combined; and (iii) replicating measurements to give more robust estimates if small traps are employed. It is concluded that artificial turf mats provide a useful design of sediment trap across a range of environmental conditions because: (i) their surface roughness reduces problems of sediment removal by flood waters or rainfall; (ii) their pliability permits installation on irregular surfaces; (iii) they can be securely attached to the ground with metal pins to resist high shear stresses from river flows; (iv) they are robust and light and so easily manipulated in the field and laboratory; (v) it is possible to fully recover the deposited sediment to accurately determine the amount of sediment deposited and to support a range of other analyses. Results are presented to illustrate how artificial turf mats can be used to estimate the quantity and quality of deposited sediment and to explore the associated deposition of viable seeds. This provides one example of the important hydroecological role of riparian sedimentation processes and of the potential for the development of innovative, interdisciplinary research on riparian sediment dynamics. Copyright © 2003 John Wiley & Sons, Ltd.     

伶仃洋三维潮流输沙的数值模拟

作者使用垂向坐标变换技术，结合有限差分方法建立了三维潮流输沙的数学模型。为了增加模型的稳定性和减少数值耗散，对悬沙对流扩散方程中的水平对流项采用三阶迎风格式离散。应用本模型对伶仃洋的枯季和洪季的潮流输沙的悬沙场进行了数值模拟，将模拟结果与实测资料进行比较，二者吻合较好。模拟结果分析表明：伶仃洋悬沙运动主要集中在西滩，对伶仃航道影响不大；洪季水体含沙浓度高于枯季；水体含沙浓度沿水深存在浓度梯度，且洪季的浓度梯度明显大于枯季。     

永定新河河口潮流动力及泥沙特征初步分析

依据永定新河河口１９９７年潮汐观测资料及河道１９９０～１９９７年潮汐观测资料，通过实测资料的整理分析，初步揭示了永定新河河口潮流动力及泥沙特征，为河道的治理规划提供了科学的依据。     

Ionic transport in amorphous anodic titania stabilised by incorporation of silicon species

Incorporation of silicon species from an alloy substrate into anodic titania is shown to stabilise the structure of the film, facilitating investigation of the ionic transport processes in amorphous titania grown at high efficiency. Thus, an amorphous anodic film developed on a sputtering-deposited Ti-6 at.%Si alloy formed to 100 V in phosphoric acid electrolyte in contrast to a partially crystalline film developed on relatively pure titanium at <20 V. Silicon species, which are immobile and act as marker species in the growing film, are present in the inner 58% of the film thickness. Evidently, the film material forms simultaneously at the film/electrolyte and alloy/film interfaces by co-operative transport of cations and anions, as is usual in amorphous anodic oxides. The phosphate anions incorporated from the electrolyte migrate inward at 0.34 times the rate of O²⁻ ions and hence are present in the outer 62% of the film thickness.     

铁路冷藏运输运价分析

本文对各种运输方式易腐货物的运价进行了比较分析,对铁路冷藏运输的现行运价和保本运价进行了讨论,提出了铁路冷藏运输运价改革的若干建议,可供铁路进行冷藏运输改革参考。     

20世纪的泥沙运动力学

在20世纪，泥沙运动力学的研究取得了不少突出的成绩，但与其他学科同时期的进展相比，发展还是比较缓慢的。按取得的进展来看，20世纪可分为两个阶段；在上半叶，有6项突破性进展，逐步积累，到1950年，Einstein集大成，提出了第1 个泥沙运动力学理论体系。在下半叶，进入了百家争鸣的时代，一些研究者提出了自己的泥沙运动理论体系，作者列举了8个有代表性的理论体系。受计算机时代的影响，从20世纪70年 代开始出现了根据大量实测资料，利用计算机进行回归分析而得出的阻力和输沙率公式，而不拘泥于发展新的理论。与此同时，一些与实际偏离较远的理论逐渐被淘汰。在21世纪，要搜集系统完整的资料，特别是近底层的资料，并拓宽研究领域到环境，生态等学科。     

黄河黑山峡河段大柳树水库比小观音水库原始库容多40亿m3的作用

一级开发大柳树高坝原始库容比二级开发小观音高坝多 4 0亿m3 ,库容大带来的好处体现在 5～ 7月可多向下游增供水量 ,缓解下游河道断流 ;延长泄放清水时间 ;增加发电效益 ;满足宁蒙河段防凌要求 ;增加汛期集中泄水 ,减缓下游河道淤积萎缩 ;满足南水北调西线工程水量调节要求等。为了更好优化配置黄河水资源 ,从全局和长远利益考虑 ,应采用一级开发方案 ,修建大柳树高坝大库     

明渠水流泥沙运动水深平均及力矩方程的理论和验证

首次提出了水流泥沙运动水深平均及其力矩方程的概念 ,并从理论上推导出这套方程组。提出水流泥沙运动力矩方程的目的有两个 ,一是在不增加空间维数的情况下可以有效地恢复水流泥沙因子沿水深分布信息 ,克服目前普遍使用的水深平均方程过多地忽略沿水深分布信息的缺点 ;二是增强模型的模拟能力。针对这两个目的是否能真正得到体现 ,分别从理论和实验室资料两个方面对新推导的力矩方程进行了全面的检验。理论验证结果表明 ,一维的力矩方程除了能模拟水深平均的流速和含沙量 ,还能够较好地模拟水流泥沙因子沿水深分布信息 ,这充分说明了一维力矩方程的二维特性。为了检验力矩方程的模拟能力 ,特别选取了一些极端的水流泥沙运动实验 ,如清水冲刷、点源加沙和深槽回淤等。模拟结果表明 ,力矩方程对于这些极端的水沙运动具有较好的模拟能力     

小浪底水利枢纽的初期运行

总结了小浪底水利枢纽投运初期的水沙情况、孔板洞原型观测试验、调水调沙试验和枢纽的安全监测情况,介绍了大坝防渗、转轮裂纹问题的处理方案,总结了枢纽在防洪、防凌、减淤、供水和发电等方面发挥的作用。试验和对监测资料的分析表明,枢纽运行稳定,孔板洞设计合理、消能效果显著,各部位建筑物性态稳定,发挥了巨大的综合效益。     

Analysis of protein transport through the golgi in a reconstituted cell-free system

The processes which transport membrane proteins between compartments of the Golgi apparatus have been reconstituted in vitro using isolated Golgi fractions. This cell-free system allows a detailed analysis of protein transport not possible in intact cells. Transport of the membrane glycoprotein (G protein) of vesicular stomatitis virus (VSV) is measured from a “donor” to an “acceptor” Golgi fraction. The donor Golgi fraction is prepared from VSV-infected Chinese hamster ovary (CHO) mutant cells deficient in the glycosylation enzyme N-acetylglucosamine transferase I. “Acceptor” is prepared from uninfected wild-type CHO cells. Transport is measured by the addition of N-acetylglucosamine to G protein, which can occur only upon movement of G protein from donor to acceptor. Transport requires physiological pH and osmolarity, is dependent on nucleotide triphosphates, and is mediated by proteins both from cytosol and on the Golgi membranes. Protein movement is inhibited by the non-hydrolyzable GTP analogue, GTPγS. The process of transport proceeds through the budding, pinching off, targeting, and fusion of transport vesicles. In this system these vesicles are initially coated with a non-clathrin coat and are targeted with this coat intact. Several of the proteins which mediate transport have been characterized, and isolated to homogeneity. The successful development of this assay has led to the formulation of cell free assays for protein transport between other compartments. Comparison of these systems indicates that some common mechanisms of vesicular movement are used in transport between a variety of membrane compartments.