1960-2015年洞庭湖水资源演变特征分析

洞庭湖是我国第二大淡水湖,也是长江流域重要的调蓄湖泊。由于受下垫面变化、人类活动和气候变化等的影响,洞庭湖流量、水位呈现新的变化趋势,研究洞庭湖水资源演变特征可为洞庭湖保护提供依据。采用Mann-Kendall突变检验方法对洞庭湖出口控制水文站城陵矶（七里山）及长江干流水文站枝城站、螺山站的1960-2015年流量、水位的年际和年内变化趋势进行分析。结果表明：洞庭湖上游长江枝城站在2000年以前径流量变化不大,但从2001年起呈现下降的趋势,水位呈现先上升后下降的趋势,洞庭湖出口城陵矶（七里山）站整体径流量呈现下降的趋势,而平均水位呈现上升的趋势,洞庭湖下游长江螺山站径流量整体上变化不显著,平均水位则呈现上升的趋势;三峡枢纽运行后,3个水文站汛期（4-10月）的径流量和水位均呈现下降趋势,枯水期（1-3月）则出现水位上升趋势;长江上水利工程尤其是三峡工程的修建,对洞庭湖水资源的调节影响明显。     

基于三维黏弹性边界的混凝土重力坝抗震性能分析

为进一步推动三维黏弹性人工边界在坝工抗震领域的研究和应用,更为方便地实现边界设置和波动输入方法与大型商业软件相结合,基于黏弹性边界基本理论及ANSYS有限元软件中的弹簧—阻尼单元,编制了三维黏弹性人工边界程序,该程序可有效求出边界结点的等效荷载,从而可以实现黏弹性边界单元的波动输入。然后,通过数值算例验证得出地表位移最大值接近入射波幅值的2倍,说明该程序的计算结果具有较高的精度。最后,将黏弹性边界单元及地震波入射方法应用到巴基斯坦玛尔水电站典型溢流坝段的抗震分析中,计算结果显示,在设计地震作用下坝体的动力响应峰值较固定边界下可减小20%~40%,说明考虑无限地基阻尼影响是很有必要的。     

隔水边界附近围岩渗透性变化时隧道涌水的渗流模型

根据各向同性岩石中隔水边界与水平方向的夹角,在岩石渗透性随深度呈负指数衰减条件下,分两种情况给出了二维稳定流隧道涌水量的解析解和数值解.分别对隔水边界距离和隧道埋深对隧道涌水强度的影响,以及岩体中上下水位的巨大差异进行了理论分析.此法可用于预测隧道涌水量,并给出了算例及关系曲线.     

三峡水库蓄水后重庆河段冲淤特性研究

三峡水库蓄水对重庆河段冲淤影响的研究具有重要的科学价值和应用前景。根据水沙连续原理和重庆河段输沙特点,考虑嘉陵江汇流和水沙变化特征,导出了重庆河段泥沙淤积比的公式,分析了不同时期河段冲淤变化特点,论证了重庆河段淤积比与嘉陵江汇流比和寸滩站流量有重要关系。三峡水库蓄水初期重庆河段冲淤特点与蓄水前基本一致,具有汛期淤积、非汛期冲刷的特点。试验性蓄水以来河段冲淤特性发生变化,汛后蓄水期和汛前消落期河段有冲有淤,总体发生淤积。汛期河道有冲有淤,淤积有所减轻,甚至发生冲刷。河道采砂对重庆主城区河段冲淤产生重要影响。     

AUTOMATIC DELINEATION OF FUNCTIONAL RIVER REACH BOUNDARIES FOR RIVER RESEARCH AND APPLICATIONS

The river reach is a pervasive term within contemporary river research and applications. Yet, despite its prevalence, there is a notable lack of consistency in its definition. This paper identifies the presence of two broad types of reach definition within the academic literature, operational and functional, and argues that a functional definition is more suitable for applications within river research and management. A range of sequence zonation algorithms that were originally derived for geological well‐log analysis were compared for their ability to automatically identify functional reach boundaries. An analysis of variance‐based global boundary hunting algorithm was identified as the most suitable. To demonstrate the potential practical applications of automatic reach delineation methods, two case studies where functional reach boundaries have been identified were described: first, in a sequence of predicted sediment transport capacities for use in a reach‐based sediment transport model; and second, in a sequence of RHS Habitat Quality Assessment scores for identification of lengths of channel in need of habitat restoration efforts. Finally, the paper discusses how this type of functional reach identification procedure might be applied in other areas of river research and applications and how a multivariate version of a statistical zonation algorithm might prove useful in facilitating integrated catchment management by identifying reach boundaries common across all variables of interest in the system. Copyright © 2011 John Wiley & Sons, Ltd.     

Estimation of discharge and its distribution in compound channels简

Results of research into a compound channel having width ratio(?)in excess of 11 are presented in the form of boundary shear distributions across the compound cross section.New relationship is derived between the percentage of shear carried by the flood plains(%)fp S and the percentage of area occupied by the flood plains(%)fp A.The equation so derived is taken as the basis to develop a new methodology to predict the stage discharge relationship specifically for wide compound channels using Darcy’s friction factor(f)for the main channel and flood plain regions.The methodology also is used for compound channels with smaller width ratios by applying the appropriate relation for%fp S derived earlier by different researchers and seems to work well.Next,as a corollary to the methodology,separate formulae are proposed to estimate flow distribution in main channel and flood plain regions.The proposed method and its corollary are tested for their validity against well-published small-scale data series of previous researchers along with some large-scale data series from EPSRC-FCF(A-Series)compound channel experiments and very good agreement is observed between the measured values and predicted values for total flow as well as zonal distribution of flow.The methodology is also applied to some compound river section data published in literature and is found to serve well the purpose of predicting flow in real world application.This new method gives the least RMS value of error for discharge prediction compared with some other well-known methods used for estimating stage-discharge relation in compound channels by considering all data sets.     

用边界拟合坐标下的有限差分法评价城市的地下水资源

本文给出了边界拟合坐标系下的二维地下的二维地下水流的基本方程，并且用该坐标系下的有限差分法对江苏某市的承压水和潜水资源进行评价。预测了１９９１－２０００年的地下水流场，边界拟合坐标下的ＡＤＩ法的计算结果和实测水位比较一致，表明该方法在地下水资源评价中有实际应用价值，尤其在处理边界几何形状复杂的地下水流问题时更为有效。     

Lattice Boltzmanm方法在计算流体力学中的应用

Lattice Boltzmanm方法(简称LBM)是一种基于分子运动论和统计力学理论的流体计算方法。详细分析了LBM的基本理论,系统介绍了曲线固体边界处理的新方法。与Navier-Stokes方程相比较,LBM在算法及复杂边界处理等方面更具有优势。该方法在多相流、多组分流、热传导、颗粒悬浮、紊流及微小流束等问题的模拟中已得到广泛应用。     

基于两类横缝接触模型的拱坝非线性动力响应研究

本文基于主、从接触面的接触边界方法，采用限制接触面切向滑移的弹簧单元，模拟切向完全约束的高拱坝横缝在地震动荷载作用下张开、闭合的非线性力学行为，并应用有限元隐式迭代方法求解结构的动力响应。为了适应拱坝计算，文中对基于接触边界的ABAQUS模型进行了功能扩展，包括引入弹簧单元约束切向滑移、嵌入有限元库水附加质量等。通过讨论接触边界与接触单元模型的有限单元格式，比较了两类接触模型的特点。分别采用该模型与基于接触单元法的ADAm88模型模拟某拱坝的动力响应，两者得到了基本一致的规律：结点位移与横缝开度吻合良好，动位移与开度时程反映出相同的动力响应周期，二者都反映出横缝张开引起的拱向拉应力释放和梁向应力的增加。通过计算验证了ABAQUS模型在拱坝动力计算方面的适用性，说明该模型适合作为一个扩展平台嵌入其他的本构、边界模型以全面模拟实际拱坝的动力特性。     

水沙变异对黄河三角洲湿地面积演变的影响

水沙过程是塑造湿地生态系统结构与功能的重要驱动力,控制着湿地的形成与演化。利用1976年-2014年近40年黄河三角洲湿地面积变化的遥感影像数据,系统分析湿地面积、湿地重心和南北区域湿地类型的动态变化进特征。研究结果显示:近40年来黄河三角洲人工湿地面积增加约1 000倍,自然湿地面积呈波动下降趋势,减少约41.9%;芦苇、滩涂、养殖及盐田湿地等典型湿地面积重心整体由西北向东南方向位移;南北部区域的湿地类型的演变出现呈现较为明显的差异特征,其中北部芦苇湿地、滩涂湿地面积呈减少趋势,南部芦苇湿地面积整体呈增加趋势,滩涂湿地面积先增加后减少。研究结果可为水沙变异条件下黄河三角洲湿地生态系统的保护与修复提供科学依据。