水电工程总承包建设项目风险处理措施的研究

水电建设项目风险管理是人们对水电建设项目潜在的意外经济损失进行识别、评估、预防和控制的过程，是以最低成本实现最大安全保障的科学管理方法。结合某水电工程实践，从水电勘测设计单位做总承包的角度，就水电建设项目的风险应付和处理进行了初步的探讨。认为风险处理的措施主要有：建立风险管理制度和相应的奖罚规定，选择风险自留，采用履约保函、合适的合同计价方式、安排工程保险，以及运用合同条款与工程保险相结合等方式转移风险。     

工程保险在水电建设中的应用与推广

水电建设项目具有投资大、建设周期长、不确定因素多、风险大的特点,在水电建设项目中推广工程保险尤为重要.分析了制约我国水电建设领域推广工程保险的主要因素及其原因,建议通过对水电建设实行强制保险、开发符合水电建设特点的工程保险险种、培育专业工程保险中介机构、改革水电工程造价管理体制以明确保险费用的来源、建立水电职业责任事故鉴定机构和确定合理的鉴定程序等,以推动水电建设企业广泛开展工程保险.     

水电项目水土流失预测单元与时段划分典型模式

为了解决当前水电建设项目水土流失预测单元与时段划分粗略和水土流失预测精度不高的问题,在对5座已建和在建大中型水电站实际调查的基础上,对水电建设项目水土流失预测单元及时段划分进行了系统研究,首次得出了具有普遍操作性且适用于水电建设项目的水土流失预测单元及时段划分典型模式。研究结果对水电建设的水土流失预测精度、水土流失防治责任范围的界定、水土流失防治措施的合理布设、水土保持监测点位合理布置、效益分析等有重要的意义,能有效提高水电建设项目水土保持方案报告的编制质量,同时可供水电建设项目及类似的其他项目参考、借鉴。     

浅析实物期权方法与净现值财务评价方法在水电站投资决策中的应用

水电是清洁能源，是国民经济体系中的基础和战略产业。在水电建设项目投资方案决策之前，财务评价是水电项目投资决策的核心内容。本文针对水电建设项目投资规模大、建设周期长、受到不确定性因素影响大等特点，比较了传统净现值财务评价方法和实物期权评价方法的优缺点，并在传统经济评价的基础上探讨实物期权方法在水电建设项目投资决策中应用的可行性。     

水电建设项目预算风险及防范措施初探

水电建设项目工程规模大、工作繁多、涉及面广、建设周期长,诸多因素制约了预算的准确性。分析总结了水电建设项目的主要预算风险,阐述了预算管理对风险防范的作用,提出了预算风险的防控措施。     

西藏自治区水电建设项目工程造价问题的思考

西藏自治区水电建设项目工程造价高于全国平均水平的现状制约了其水电建设的发展。科学、合理地分析水电建设项目工程造价成为西藏自治区水电建设未来发展中一个重要问题。在分析西藏自治区水电建设项目较高工程造价产生原因的基础上,提出合理确定、有效控制其工程造价的思路。     

水电建设项目财务评价实践与分析

本文从水电建设项目投资方角度,研究分析了简便实用的水电建设项目财务评价方法,并结合实际工作经验对财务评价涉及的销售收入、税金及附加费用、总成本费用、流动资金等各类数据如何取值进行了分析。通过对目前水电建设项目开发现状的分析研究,总结提炼出水电建设项目财务评价指标的分析方法,并对政府、行业组织和投资方如何做好水电建设项目财务评价工作提出了具体建议。     

关于水电建设项目开展后评价问题的探讨

根据水电项目建设程序的现状及存在的问题,介绍水电建设项目开展后评价的意义、阐述其主要内容和实施程序。指出,开展水电建设项目后评价工作可以不断提高决策、设计、施工、管理水平,为合理利用资金、提高投资效益、改进管理、制定相关政策等提供科学的依据。通过水电建设项目后评价这个基础性工作,可以促进未来水电建设事业稳步、健康发展。     

小水电建设项目国民经济评价方法探析

小水电建设项目的国民经济评价不宜采用大中型水电建设项目通用的替代法，而宜采用影子电价法。在应用该法进行经济评价时，对影子电价要进行科学合理地分析及修正，其嵵邪悸俏锛鬯秸庖灰蛩亍⒖悸切∷缃ㄉ璧氐愕木咛迩榭霾⒖悸切∷缯镜牡鹘谛阅軑及调峰能力等因素。影子电价采用客观合理后，用影子电价法将小水电建设项目对国民经济的嵕恍б婺苷媸档胤从Τ隼础     

浅谈水电建设项目后评价工作的实施及发展趋势

水电建设项目后评价工作是一项具有重要意义的工作,与可行性研究等项目前评价相比,水电建设项目后评价更具有现实性、全面性、探索性、反馈性及效益性等特点。后评价工作可以使水电建设项目管理步入程序化、规范化、工作方法、科学化的轨道,强化全行业宏观管理机制,提高水电建设项目的管理水平,促进水电建设项目投资效益的提高。     

Call for Papers

正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.     

库水波动下库岸边坡地下水浸润线解析解及误差分析

解析法是库岸边坡地下水浸润线计算中便于实际应用的方法,但该方法须基于若干假定并对潜水运动基本方程线性化后才能求解。针对各假定和线性化过程建立不同的地下水渗流数学模型,用解析法和有限元法解答上述数学模型,分析各误差大小及其规律。结果表明：库岸垂直处理带来的误差要小于方程线性化处理和不考虑非饱和渗流带来的误差,而且它们都随渗透系数变大而减小;在三峡库区库水调度情况下,假定库水位等速变化带来的误差对大多岸坡而言可以忽略;计算库岸边坡地下水浸润线时,解析法只适用于水位变化幅度相比含水层厚度较小,且几何边界规则、岩土结构简单、岩土体渗透性较好时的情况。     

Changes in Summer Irrigated Crop Area and Water Use in Southeastern Turkey from 1993 to 2002: Implications for Current and Future Water Resources

Changes in summer irrigated cropland acreage and related water use are estimated from satellite remote sensing and ancillary data in semi-arid Southeastern Turkey where traditionally dry agricultural lands are being rapidly transformed into irrigated fields with the help of water from the Euphrates-Tigris Rivers. An image classification methodology based on thresholding of Landsat NDVI images from the peak summer period reveals that the total area of summer irrigated crops has increased three-fold (from 35,000 ha to over 100,000) in the Harran Plain between 1993 and 2002. Coupled analysis of annual irrigated crop area from remote sensing and potential evapotranspiration based estimates of irrigation water requirements for cotton indicate a corresponding increase in agricultural water use from about 370 million cubic meters to over one billion cubic meters, a volume in accordance with the state estimates. These estimates have important implications for understanding the rapid changes in current agricultural withdrawals in Southeastern Turkey and form a quantitative basis for exploring the changes in future water demands in the region. For example, expansion of irrigated lands have led to a steady decrease in potential evaporation due to increased roughness and decreased humidity deficit in the Harran Plain. Assuming that the changes in future evaporation conditions will be of similar nature, water use for irrigation is expected to decrease over 40 percent in future irrigation sites. Incorporating this decrease in overall planning of the irrigation projects currently under construction should lead to improved management, and by extension, sustainability of water resources in the region.     

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.     

Site modelling methods for detecting hydrologic alteration of flood frequency and flood duration in the floodplain below the carlyle dam,lower Kaskaskia River,Illinois, USA

Reports concerning the influence of dams on river hydrology vary among researchers, interest groups and government agencies. These often contradicting statements may occur because changes in hydrology caused by dams are distinct for each dam and river watershed. The objective of this research was to use site specific techniques to determine if the 1967 installation of the Carlyle Dam, lower Kaskaskia River, Illinois, altered flood frequency and duration within the forested floodplain located below the dam. Results indicated a decrease in flood duration and frequency, and a decrease in annual flood frequency variation at a site 6.4 km below the dam. Pre‐dam versus post‐dam differences in flood frequency and duration at the site 32.2 km below the dam were related to climate rather than dam effects. Although dam impacts are a concern, this research shows that distance downstream from the dam and downstream tributary and watershed characteristics should be considered before assuming that the dam has changed hydrologic parameters for portions of rivers. This research also indicates that areas of the lower Kaskaskia River may still maintain hydrologic ecological integrity, and could be targeted for restoration and adaptive management purposes. Hydrologic modelling combined with river gage and on‐site well measurement techniques presented in this study could provide detailed flood frequency and duration information for land use, sociological and geomorphological questions in focus areas within river floodplains. Copyright © 2008 John Wiley & Sons, Ltd.     

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.     

固结、渗流和沉积控制方程研究

本文从两相流体动力学的守恒方程出发，考虑固相、液相的相对运动，推导了可以考虑场的不均匀性和流体压缩性的统一形式的控制方程，并对方程所基于的物理概念和相互联系进行了必要的分析。通过对方程适当形式的表达，可导出用于大、小变形固结、渗流和沉积的简化方程，显示了在不同领域的三个理论存在一定的统一性。方程推导过程并未对本构关系加以限制，适用范围较广。依据实际问题的要求，作了不同形式的简化。     

四川省及重庆市中型水电站效益分析

该文分析了四川省及重庆市几座中型水电站的调查材料表明：四川省及重庆市中型水电站不仅在川渝主网和地方电网中起着很大的作用，并具有巨大的社会效益，同时还有综合利用效益，说明修建中型水电站的优越性．     

Spatio‐temporal variation of gross CO2 and CH4 diffusive emissions from Australian reservoirs and natural aquatic ecosystems,and estimation of net reservoir emissions

Carbon dioxide (CO₂) and methane (CH₄) diffusive emissions were measured during two field surveys in Queensland and Tasmania, Australia, using the floating chamber method. Bubbling and degassing emissions in 2010 were estimated in Koombooloomba Dam reservoir using only inverted funnels and gas concentrations, respectively. A total of 14 reservoirs and 16 rivers and lakes were sampled from 2006 to 2010. Spatial variation was substantial within each water body, as well as between them. The main drivers of diffusive emission variation were physiographic region and climate, with a clear demarcation being observed between diffusive emissions from tropical Queensland and temperate Tasmania, and between the humid West Coast Range (Tasmania) and dry Central Plateau (Tasmania). Higher CO₂ and CH₄ diffusive emissions were observed during the dry season, when long water residence times would promote organic matter degradation. Estimated total gross emissions, including diffusive, bubbling and degassing emissions, for Koombooloomba Dam reservoir were about 1.5 × 10⁶ t CO₂eq km² per year, or 24 × 10⁶ t CO₂eq per year. This corresponds to a plant emission factor of 3.18 kg CO₂eq MWh^?1. Using an estimate of terrestrial emissions derived from literature data for the Tully River catchment area, rough estimated net emissions from the catchment area are about 44 kt CO₂eq per year, or 5.83 kg CO₂eq MWh^?1, which is in the lower range of the studied reservoirs.     

掺MgO混凝土的宏细观试验研究

利用MgO膨胀剂的延迟微膨胀效应能显著提高大体积混凝土的力学性能,产生的预压应力还能有效提高大体积混凝土抵抗温度开裂的能力,但目前对其微观机理研究不多。采用宏观与微观相结合的方式,研究了不同活性指数、不同掺量的MgO混凝土的力学性能,利用SEM/EDS微观分析手段揭示了MgO对混凝土性能影响的作用机理。试验结果表明：MgO取代部分水泥掺入混凝土中,混凝土的力学性能降低;掺量为4%~5%时,活性指数为100s的MgO混凝土的膨胀率大于活性指数为50 s的MgO混凝土;MgO混凝土的膨胀特性与Ca,Si,Mg,Al等元素的分布情况有关,掺入的MgO将改变界面区Ca,Si,Mg元素的富集特性,Ca元素和Mg元素更易于在界面区富集,导致混凝土宏观力学性能的降低。