冲积河床的河床阻力

本文利用520组水槽实验资料对修正的Engelund-Fredsoe(1982)床面阻力公式进行了检验，该公式虽然反映了阻力变化的趋势，但公式的总体精度有待进一步提高。作者通过分析影响床面阻力的水沙因子，利用泥沙实验数据建立了新的床面阻力公式，并利用第一作者收集整理的国内外2261组水槽实验资料和592组河渠观测资料进行了检验，检验结果表明该公式的精度令人满意     

伏格特理论的研究

本文作者在白山重力拱坝的设计中对伏格特理论从波辛涅斯克解开始，从数学上进行了推导，发现推出的公式和国内书籍中列出的公式不同，和日本编写的《在电子计算机上计算拱坝的解析分析》一书所列的公式也不一样，并用自已推出的公式制成表格，发现原理论对Ｋ５和Ｋ３的处理是错误的，作者对此做了修正。另外经研究提出美国垦务局的Ｋ１、Ｋ２、Ｋ３、Ｋ４也有错误。     

迭代法推求暴雨强度公式参数

作者通过对常熟市暴雨强度公式修编的实践，总结出一种线性近似非线性、迭代法逐次逼近最优公式参数的推求方法，由此推得的暴雨强度公式的绝对均方差均优于文中提到的其它方法，且具有无需人为干预，迭代收敛稳定、迅捷等优点。并提出了在推求包含频率变数的暴雨强度总公式时，依据公式的应用要求采用不同的目标函数推求可提高公式精度的观点。     

再论泥沙起动流速

本文是作者４０年来研究泥沙起动公式的小结。文中对颗粒间的粘结力，水的下压力和阻力等有关参数进行了修改。通过瞬时作用流速，明确了三种起动状态间的关系，消除了起动切应力和起动流速间的不协调。对导得的起动切应力公式和起动流速公式进行了较为全面的验证，说明公式较好地反映了粗，细颗粒泥沙和轻质沙的起动规律，为研究工程泥沙问题提供了实用公式。     

粘性泥石流运动流速与流量计算

粘性泥石流作为最常见的一种泥石流，普遍存在于固体物质组成松散、降雨持续集中的陡峻山区。作者首先对现有的粘性泥石流运动速度的有关成果进行扼要评述。根据曼宁公式的结构形式，通过对大量泥石流沟的实测资料进行统计分析，得出涉及参数较为全面、具有一定普遍意义的粘性泥石流运动速度公式，经验表明该公式的可靠度令人满意，据此提出粘性泥石流的流量公式及其计算方法，从而为泥石流灾害治理工程规划设计提供了科学依据。     

再论泥沙起动流速

本文是作者40年来研究泥沙起动公式的小结。文中对颗粒间的粘结力、水的下压力和阻力等有关参数进行了修改。通过瞬时作用流速，明确了三种起动状态间的关系，消除了起动切应力和起动流速间的不协调。对导得的起动切应力公式和起动流速公式进行了较为全面的验证，说明公式较好地反映了粗、细颗粒泥沙和轻质沙的起动规律，为研究工程泥沙问题提供了实用公式。     

弯曲型河道容积计算方法探讨

本文根据水下地形的一般物理模式，通过适当的数学处理，推导出河流弯道河段的容积计算公式。作者认为，该公式具有一定的实用价值。     

砂卵石起动临界条件

阐述了砾卵石均匀沙的运动机理，通过对附加质量力和床面颗粒相对暴露度参数的引入，推得了均匀沙起动无因次拖曳力公式，并对公式中的系数进行了计算，结果表明，在起动状态一定时，该系数并非为一个常量，而是介于某个区间，且随颗粒在床面上的相对暴露度的变化而变，通过转化推得了散粒体均匀沙起动流速公式，同时考虑了砾卵石扁度的影响，其系数同样不是一个常量，同学者们的公式相对照较为合理，该系数包含了其它公式的系数，结论部分可以解释为何不同的作者通过实验所拟合的系数各异，且差别较大，说明文中公式基本能反映均匀沙的起动特性。     

水流挟沙能力公式的转化与统一

水流挟沙能力作为河道水力与泥沙因子和河床补给条件相互作用的重要综合性参数，一直是河流动力学中的核心问题之一，倍受学术界关注。本文首先基于悬移质运动效率系数等泥沙悬浮能量的角度建立水流挟沙能力统一结构公式；然后对前人众多的水流挟沙能力公式进行分类、归纳为含沙量型与输沙率型两种主要形式，并通过进一步的推导转化，将现行的主要挟沙能力公式统一于通用的结构公式，表明统一结构公式具有良好的通用性与实用性；文中最后应用黄河、长江等大量的天然实测资料对张红武等四家同时能适合于高、低含沙水流挟沙力公式的可靠性进行验证与分析，结果表明张红武和作者公式的计算精度令人满意，该项研究成果对于河流动力学学科发展及指导河道整治工程规划设计具有重要意义。     

反演法洪水演算问题探讨

在水利水电工程设计中，无论是推求入库洪水或设计洪水的地区组成，均涉及到反演法洪水演算问题。作者在目前较常用的马斯京根公式反演法的基础上，探讨了马斯京根图解反演法和马斯京根迭代反演法．本文详细地介绍了马斯京根公式反演法、图解反演法、迭代反演法，并进行了比较。     

Intangible Flood Damage Quantification

Flooding is a natural disaster that may cause tremendous tangibleand intangible damage to the national economy. The tangible damage assessment, i.e. the monetary value of all direct and indirect physical damages, has already been studied, whileintangible damages have not yet been taken into account. Thisarticle, therefore, is the first systematic attempt to assess bothtangible and intangible damages. The new proposed Anxiety-Productivity and Income Interrelationgship Approach (API) has been developed to quantify the intangible damage in monetary terms. The Bangkok area has been selected as the research area because several severe flood events have occurredthere over the last two decades. The 1983 Bangkok flood caused 6600 million baht in damage, according to estimates by the National Statistical Office (NSO). This article examines the totalflood damage (including the intangible damage) at different flood magnitudes. Case studies with and without flood mitigation projects are studied and compared. Furthermore, thisarticle also discusses the improvements over the conventional approach offered by the new API methodology.     

SPATIAL AND TEMPORAL WATER QUALITY VARIABILITY IN AQUATIC HABITATS OF A CULTIVATED FLOODPLAIN

The floodplains of lowland rivers contain diverse aquatic habitats that provide valuable ecosystem services but are perturbed when intensively cultivated. Hydrologic, water chemistry and biological (fish) conditions in five aquatic habitats along the Coldwater River, Mississippi, were measured for more than 4 years: the river, two severed meanders that functioned as backwaters, a managed wetland and an ephemeral channel draining cultivated fields. Off‐channel habitats were connected to downstream regions 0.10% to 32% of the dry season and 24% to 67% of the wet season. The median temperatures for the five monitored sites ranged from 18°C to 23°C, the median total solids concentration for all sites was 135 mg L^?1, the median total phosphorus was 0.29 mg L^?1 and the median total nitrogen was 1.56 mg L^?1. Chemical and physical water quality displayed strong seasonal differences between the wet winter/spring and the dry summer/fall periods so that temporal variation consisted of gradual seasonal trends superimposed on strong diurnal variations. All off‐channel habitats exhibited periods of hypoxia and temperatures >30°C during the dry season. Between‐site gradients of water and habitat quality were strongly coupled to water depth and runoff loading. The rehabilitation of one backwater by increasing water depth and diverting agricultural runoff was associated with improved water quality and fish species richness relative to an adjacent untreated backwater. The diversion of polluted runoff and the use of water control structures to maintain greater water depth were observed to be effective management tools, but the former reduces the water supply to habitats that tend to dry up and the latter reduces connectivity. Published in 2011 by John Wiley & Sons, Ltd.     

小浪底水库运用方式研究的回顾与进展

回顾了小浪底水利枢纽工程初步设计以来水库减淤运用的研究情况，总结以往的经验，结合当前的实际，对水库减淤作用、水库运用方式与分阶段运用、主汛期调水及运用方式的动态研究等问题提出了一些新的认识。分析论证了调水调沙与拦粗排细、近期调度与长远分析、小浪底工程与其他治黄工程建设等问题的辩证关系。提出水库初期运用应以调水为主，其后逐步抬高运用应与适时降低水位冲刷相结合。要及时总结经验，不断跟踪研究，及时合理调整运用方案。     

Water Demand Theory and Projections in South Africa

Abstract

This study estimates Rand Water's water demand in South Africa for 2000 to 2020. It indicates lower growth in water consumption in the foreseeable future than in the past century. The reduced growth is due to: Economic slowdown (international and South African); Lower standard of living/residences for the “white” population; Corresponding decrease in formal business growth; Limitations of services in built up areas; Increased water costs; Improved loss control; HIV/Aids; Unwillingness of informal residents to contribute for services. This is offset by: Migration of poor to cities and creation of peri-urban growth; Increased standards for previously disadvantaged people; Improved health facilities; Growth in informal economy; New political freedom. A net growth of 2 percent annually is forecast. A statistical approach is adopted to obtain confidence limits for individual sectors. A decomposed demographic model is developed and used to predict water demand until 2020. A wider uncertainty in future consumption is foreseen. Conservative planning is recommended for future water resource projects, e.g. low capital, and operating intensive schemes are preferable. A methodology for planning in the face of uncertainty and low growth is developed.     

Effects of reservoir management on abundance,condition, parasitism and reproductive traits of downstream mussels

The large‐scale impoundment of rivers has led to global declines in freshwater mussel populations. It is important to understand the mechanisms underlying these declines to initiate an effective recovery strategy. We examined population traits of three Quadrula species (Quadrula pustulosa, Q. cylindrica and Q. quadrula) at three locations that were exposed to two different reservoir management regimes: releases that mimicked natural flow patterns and releases that were higher and colder in summer months than the natural system. We found lower mussel density, higher hermaphroditism and parasitism rates, and reduced body condition downstream of the dam with unnatural flow regimes. Sex ratios varied on a species and site basis. We found more Quadrula cylindrica females than males averaged across all three sampling sites while Q. pustulosa was male biased across all sites and at site 1. We observed approximately equal sex ratios in Quadrula quadrula. Population disturbances downstream of the more naturally‐regulated dam were not as severe. Our data indicate that dam operation can have effects on a variety of mussel life history characteristics that may ultimately reduce population viability. Copyright © 2010 John Wiley & Sons, Ltd.     

广西钦江流域水沙年际变化规律分析

为了探究河流水沙的变化规律及影响因素,利用钦江陆屋流域1957—2016年的长时序年降水量、年径流量和年输沙率数据,采用5年滑动平均法、R/S检验法、Mann-Kendall突变检验法、累积距平法及复Morlet小波分析法分析以上序列的趋势性、突变性和周期性;运用双累积曲线法分析降水和径流输沙关系的变化;最后结合流域森林转型特征来进行分析。结果表明:(1)降水量弱上升、径流量减少、输沙率显著减少,在α=0.05和β=0.01的显著水平下,降水量和径流量无变异,输沙率弱变异。降水量在1962年、1971年、1989年和2013年发生突变,径流量在1963年、1971年、1989年和2007年发生突变,输沙率在1967年、1971年、1981年和2001年发生突变。降水量存在4类时间尺度,23 a、13 a分别为第一、二主周期;径流量序列存在3类时间尺度,14 a、9 a分别为第一、二主周期;输沙率序列存在4类时间尺度,22 a、5 a分别为第一、二主周期。(2)降水量-径流量累积关系分为两个阶段,即1957—1988年和1989—2016年,斜率分别为0.006 8、0.005 8;降水量-输沙量累积关系分为四个阶段:1957—1962年、1963—1988年、1989—1998年和1999—2016年,斜率分别为0.014、0.019 4、0.016 4、0.009,造成水沙关系变化的原因是人类活动的影响。(3)广西林业建设和森林转型的发展过程是径流量和输沙量不断发生变化的原因。     

A Study of the Process of Fabrication of Polymer Replicas

A method of fabricating polymer replicas with the use of polymer solutions is described. It is shown that the adequacy of a replica is determined by the physicochemical processes on the microsection – polymer solution interface, in particular, by surface tension and wetting. The limiting wetting angle is determined for a number of polymer materials and solvents. The limiting wetting angle is shown to depend on the kind of material and on the kind of solvent as well as on their proportion in the solution. Polymer materials and solvents, the appropriate combination of which provides better wetting and hence better reflection of the studied microstructure by the replicas, are determined. The optical properties of polymer replicas, i.e., their reflectivity, resolving power, and contrast, are determined. The study makes it possible to pass from empirical to scientifically substantiated choice of materials, solvents, and their proportion for obtaining adequate replicas.     

浅谈优化Vray渲染在制作三维场景的应用研究

用Vray三维渲染引擎来渲染三维场景,其质量和速度是由一些影响因素和参数设置决定的,不同的参数和因素,可以得出不同的三维渲染效果.因此,分析、优化三维渲染质量和速度的影响因素,正确、合理的选择参数对提高Vray最后渲染阶段的质量和速度非常重要.     

Seasonal variation in nutrient retention during inundation of a short‐hydroperiod floodplain

Floodplains are generally considered to be important locations for nutrient retention or inorganic‐to‐organic nutrient conversions in riverine ecosystems. However, little is known about nutrient processing in short‐hydroperiod floodplains or seasonal variation in floodplain nutrient retention. Therefore, we quantified the net uptake, release or transformation of nitrogen (N), phosphorus (P) and suspended sediment species during brief periods (1–2 days) of overbank flooding through a 250‐m floodplain flowpath on the fourth‐order Mattawoman Creek, Maryland U.S.A. Sampling occurred during a winter, two spring and a summer flood in this largely forested watershed with low nutrient and sediment loading. Concentrations of NO increased significantly in surface water flowing over the floodplain in three of the four floods, suggesting the floodplain was a source of NO. The upper portion of the floodplain flowpath consistently exported NH, most likely due to the hyporheic flushing of floodplain soil NH, which was then likely nitrified to NO in floodwaters. The floodplain was a sink for particulate organic P (POP) during two floods and particulate organic N and inorganic suspended sediment (ISS) during one flood. Large releases of all dissolved inorganic N and P species occurred following a snowmelt and subsequent cold winter flood. Although there was little consistency in most patterns of nutrient processing among the different floods, this floodplain, characterized by brief inundation, low residence time and low nutrient loading, behaved oppositely from the conceptual model for most floodplains in that it generally exported inorganic nutrients and imported organic nutrients. Published in 2007 by John Wiley & Sons, Ltd.     

The role of riparian vegetation and woody debris in the development of macroinvertebrate assemblages in streams

Riparian vegetation development and macroinvertebrate assemblages were studied in 16 streams formed between 35 and 230 years ago, following glacial recession in Glacier Bay National Park, southeast Alaska. Riparian vegetation established most rapidly in streams where flow variation in downstream reaches was buffered by a lake. Riparian vegetation development was positively correlated with lower bank stability, but was independent of stream age. Roots and branches of riparian vegetation trailing into streams (trailing riparian habitat—TRH) were shown to be an important habitat for a number of macroinvertebrate taxa. In young and unstable streams, TRH was colonized mainly by Plecoptera whereas in more stable lake‐influenced streams Simuliidae dominated. Significant coarse woody debris (CWD) accumulations were not observed until after approximately 130 years of stream development had occurred when certain channel features, such as gravel bars, were stabilized by dead wood. Where dead wood was present, opportunistic wood taxa were abundant, even in the younger streams. However, a xylophagous species, Polypedilum fallax, was not recorded until streams were over 100 years old. Two‐way indicator species analysis (TWINSPAN) using presence/absence of macroinvertebrate taxa on TRH, initially divided streams into lake and non‐lake systems, but subsequent divisions were consistent with differences in stream age. TWINSPAN of macroinvertebrate assemblages on dead wood again highlighted differences in stream age. Canonical correspondence analysis indicated that bed stability and stream age were the most important environmental variables influencing macroinvertebrate distribution on TRH. Trailing riparian habitat was most abundant in moderately unstable streams where it facilitates invertebrate colonization. CWD contributes markedly to channel stabilization, provides habitat for invertebrate xylophages, and confers additional habitat complexity. Maximum levels of CWD are predicted to occur in non‐lake streams after approximately 300 years, but at least a further 100 years will be required in stable streams below lakes where dead wood entrainment is not enhanced by flooding, channel migration and bank undercutting. A conceptual model summarizing the role of TRH and CWD on stream development in Glacier Bay is presented. Copyright © 2005 John Wiley & Sons, Ltd.