鄱阳湖低枯水位变化特征与成因探讨

近年来,鄱阳湖汛后水位消落过快,出现低水位的时间提前、枯水期延长、枯水位不断降低,给当地生产、生活、生态用水带来较大影响,引起社会广泛关注。从鄱阳湖区实测水文资料与地形资料的统计分析入手,结合流域用水及人类活动的影响状况,对鄱阳湖区低枯水位的出现规律、成因以及发展趋势进行了研究。结果表明,社会经济活动用水增长、河床变化、河湖采砂、三峡工程汛末蓄水等是鄱阳湖枯水期水位降低的主要原因。根据分析成果,提出了控制湖区低枯水位的措施建议。     

三峡水库运用后鄱阳湖区枯水情势及成因分析

鄱阳湖区枯水期的水资源情势变化与湖区供水安全、水环境及水生态环境保护密切相关。依据长系列实测降雨、径流、地形等资料,采用资料分析、水沙数学模型等手段,对近年来鄱阳湖区枯水情势、成因以及未来上游干支流水库调度运用后的枯水变化趋势进行了研究。结果表明,受三峡水库蓄水、天然降雨径流变化、江湖冲淤以及流域用水量增加等因素的影响,鄱阳湖区枯水位降低、枯水期提前、枯水历时加长的情况将呈常态化趋势。三峡及上游控制性水库运用后,蓄水期径流减少以及干流河道冲刷加大,将进一步加剧鄱阳湖区的枯水情势。     

赣江下游枯水期水位持续降低影响与分析

分析了2000年以来赣江下游枯水期水位变化情况,探讨了低枯水位持续走低对沿线城市用水安全、赣江防洪安全、抗旱灌溉、农村人饮安全、电网稳定等造成的不利影响,认为河床下切、入江泥沙减少、鄱阳湖枯水位提前等因素是枯水期低枯水位持续降低的原因,提出规范采沙市场、建立价格机制等建议,以保护赣江水沙资源。     

鄱阳湖低枯水位变化及趋势性分析研究

选取鄱阳湖水位代表站历年来的水位观测资料,分析湖区水位代表站低枯水位变化情况,采用Mann-Kendall非参数检验（M-K检验）、Kendall秩次相关检验（Kendall检验）、Spearman秩次相关检验（Spearman检验）、线性回归趋势检验（LRT检验）等4种方法分析研究鄱阳湖湖口、星子、都昌、棠荫、康山等5个水位站的低枯水位变化趋势.分析表明鄱阳湖湖区湖口、星子、都昌等站10月和11月平均水位均已出现趋势性降低变化.     

近期荆江河段护岸应急工程枯水平台高程探讨

针对林家垴护岸工程在施工过程中,实际枯期水位高过设计枯水位导致枯水平台和脚槽施工无法正常进行的情况,分析了2006年度和2009年度实施项目所采用的设计枯水位与三峡水库蓄水前设计枯水位的区别,研究了近期荆江河段各站枯水位的变化情况,指出三峡水库蓄水后荆江河段枝城至江口、江口至石首、石首至城陵矶新增护岸工程枯水平台可采取的应对措施。     

三峡水库蓄水后宜昌枯水位的时变特征及成因

三峡水库蓄水后,葛洲坝枢纽下游近坝河段内枝城枯水位降幅较小,但宜昌及宜都等位置枯水位降幅较大,且随时间变化显示出非均匀下降的特征。为揭示该现象成因,依据宜昌至枝城河段内枯水位、地形、河床组成等实测资料分析了各因素的时变特征,并采用分离变量法计算分析了枯水位非均匀下降的机理。结果表明:宜昌枯水位在2008年前降幅小且下降速度慢,2008年以后降幅增大且下降速度加快;宜都至枝城区间冲刷是引起宜昌枯水位下降的主导因素,宜都以上河床变形、枝城水位下降为次要因素;宜都以上河床粗化引起阻力调整,是导致2008年前宜昌枯水位降幅小的主要原因;2012年后,宜昌至枝城段河床变形和阻力调整余地都已不大,未来宜昌枯水位稳定性主要取决于枝城水位变幅。     

三峡水库运行初期坝下近坝段河道冲刷对河床糙率影响分析

三峡工程蓄水运行后,坝下河段出现较为剧烈的冲刷,但宜昌枯水位并未出现预期的大幅度下降.研究表明,宜昌枯水位稳定的主要原因之一是河床糙率增大.根据实测水文河道资料,分析了三峡水库运行初期坝下近坝段河道冲刷对河床糙率的影响,并进一步估算了河床糙率变化对宜昌枯水位的影响程度,认为河床粗化对宜昌枯水位下降有明显的补偿作用.     

三峡水库蓄水初期宜昌河道演变特点及趋势分析

在原型观测资料基础上,对三峡水库蓄水运行以来坝下游近坝宜昌河段河床冲淤演变特点进行了详细分析.结果表明,2003年以来,坝下游近坝宜昌河段经历了三峡水库不同的蓄水运行期,受多种因素的影响,河床冲淤变化呈现不同的演变特点,受宜昌河段冲淤影响,宜昌枯水位有时会出现下降或保持稳定不变的情况.近年来,由于坝下游长程河道冲刷带下移及宜昌以下枯水控制河段冲刷幅度加大,使宜昌枯水位又出现新一轮的下降.     

三峡工程对长江中下游鄱阳湖区防洪态势的影响分析

根据长江与鄱阳湖区洪水特点,针对三峡水库的综合调度方案,分析三峡工程运行对鄱阳湖区防洪与抗旱态蛰的影响。提出三峡工程的兴建不能一劳永逸地解决鄱阳湖区的防洪问题,应该继续加强鄱阳湖区的防洪与抗旱体系建设,保障鄱阳湖区经济社会的可持续发展。     

葛洲坝下游胭脂坝河床护底工程效果分析

自葛洲坝工程动工及运行以来,坝下游河段冲刷下切,致使宜昌枯水位逐步下降,因此,必须对河床实施工程保护,以遏制宜昌枯水位进一步下降。简要介绍了护底工程结构、工程布置及施工情况。结合实测数据和计算成果,分析了护底区域河床演变、糙率、水位的变化。结果表明,护底工程对河床有较好的保护效果,对遏制宜昌枯水位的下降亦有一定的作用。     

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.     

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．     

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.     

Statistical tools for thermal regime characterization at segment river scale: Case study of the Ste‐Marguerite River

Suitable thermal fish habitats are constrained by both maximum and minimum temperature tolerances. A multivariate and geostatistical approach was developed to estimate stream thermal characteristics at the river segment scale. Data from 22 temperature‐monitoring stations during summer 2007 were used to estimate monthly maximum temperature as well as thermal characteristics such as the number of events, the cumulative degree–days and the associated duration over specific temperature thresholds of 19 and 21°C. The probability of exceeding these temperature thresholds has also been interpolated. The methodology relies on the construction of a multivariate space using physiographic and hydrological characteristics of gauging stations as inputs in a canonical correlation analysis (CCA). A geostatistical interpolation technique, ordinary kriging, was subsequently used to perform interpolation in the physiographical space constructed using CCA. Results from this study were obtained for thermal characteristics estimated into two different interpolation spaces: (1) a 7 metrics space, and (2) an 8 metrics space. Cross‐validation technique has been performed and satisfactory results were obtained. Kriging thermal characteristics (magnitude and duration) into the 7 metric space for a 19°C threshold exceedance leads to best results with Relative Root Mean Square Error (RRMSE) ranging between 9.66 and 15.08%. The study shows that kriging in a multivariate space is a promising tool for water resources managers, especially in cases where risk mapping for lethal or sub‐lethal temperature thresholds may be required for a specific fish species. Copyright © 2010 John Wiley & Sons, Ltd.     

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。     

基于MIDAS软件探讨施工工序对深基坑稳定性的影响

基于武汉地铁名都站深基坑工程与水文地质勘察资料,建立了三维工程地质仿真计算模型。依据名都站深基坑开挖支护方案,利用有限元软件MIDAS的摩尔-库仑本构模型,对武汉地铁名都站深基坑施工过程中,不同施工工序下每步开挖之后,基坑的变形情况做仿真模拟计算,并对比分析其对基坑稳定性的影响。结果表明：基坑围护结构的变形情况与施工工序有很大的关系,施工工序越合理,上部土体变形越小,反之越大。因此,在基坑工程的施工过程中,要注重施工步骤的划分与合理安排,从而保证基坑工程的安全。研究成果为以后武汉地区基坑工程的施工设计提供了值得借鉴的经验。