Flood hydrograph attenuation induced by a reservoir system: analysis with a distributed rainfall‐runoff model     

Nicola Montaldo  Marco Mancini  Renzo Rosso 《水文研究》2004,18(3):545-563

Spatially distributed hydrologic models can be effectively utilized for flood event simulation over basins where a complex system of reservoirs affecting the natural flow regime is present. Flood peak attenuation through mountain reservoirs can, in fact, mitigate the impact of major floods in flood‐prone areas of the lower river valley. Assessment of this effect for a complex reservoir system is performed with a spatially distributed hydrologic model where the surface runoff formation and the hydraulic routing through each reservoir and the river system are performed at a fine spatial and time resolution. The Toce River basin is presented as a case study, because of the presence of 14 active hydroelectric dams that affect the natural flow regime. A recent extreme flood event is simulated using a multi‐realization kriging method for modelling the spatial distribution of rainfall. A sensitivity analysis of the key elements of the distributed hydrologic model is also performed. The flood hydrograph attenuation is assessed. Several possible reservoir storage conditions are used to characterize the initial condition of each reservoir. The results demonstrate how a distributed hydrologic model can contribute to defining strategies for reservoir management in flood mitigation. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

岩土材料塑性损伤模型及拱坝的变形局部化分析     

陈新  杨强  周维垣 《岩土力学》2007,28(5):865-870

常规的弹塑性模型难以模拟材料破坏时由于内部损伤累积引起的变形局部化带形成过程。将岩土材料抽象为含有孔洞的球形体胞单元的集合体,采用一个标量--孔洞体积百分比来刻划单元的损伤程度,基于细观损伤力学提出了一个适用于岩土材料的塑性损伤模型。将该模型通过用户子程序嵌入到大型有限元商业软件MRAC中,研究岩土材料的局部化剪切带形成过程。采用该模型,成功地对平面应力条件下岩土材料单轴受压和单轴受拉试件的局部化破坏分别进行了数值模拟。采用该模型,对拱坝在超水载作用下的变形局部化进行了研究,数值计算结果表明,上游坝踵处最先发生变形局部化现象。  相似文献   

高速公路连拱隧道开挖地表沉降研究     

孙少锐  吴继敏  魏继红 《岩土力学》2006,27(Z1):327-332

对隧道开挖引起的地表沉降模型进行总结,详细地调查和分析了金丽温高速公路红枫连拱隧道工程区的地质特征,系统研究了在偏压条件下连拱隧道开挖引起的地表沉降规律,对红枫隧道开挖引起的地表沉降进行研究,建立了偏压条件下连拱隧道分步开挖引起的地表沉降预测模型,对不同开挖工况下的差异沉降进行分析,证明该预测模型比较真实的反映了在偏压及浅埋条件下连拱隧道开挖引起的地表沉降规律,为浅埋连拱隧道开挖过程中防止地表过度变形提供理论基础。  相似文献   

地电影像技术在水利堤坝隐患探测中的应用     

魏月红  刘晓芳  崔元星 《煤田地质与勘探》2002,30(2):60-61

阐述了最新发展起来的物探方法——地电影像技术的原理及其应用在水利堤坝隐患探测中的地质—地球物理基础,并结合实例讨论了该领域的应用前景   相似文献   

土钉墙基坑支护中疏排桩抗滑效应研究   总被引：3，自引：0，他引：3  

金钢锋  屠毓敏  阮长青 《岩土力学》2005,26(4):577-579

在软粘土地基基坑支护中,当基坑开挖深度较深时,土钉墙的最危险圆弧滑动面往往入土较深,很难满足工程设计需要,为此可采用疏排桩以满足其整体稳定性要求。从土的塑性理论出发,利用土拱效应原理,分析了作用于疏排桩上的土压力。利用桩土相互作用的原理,研究了疏排桩在土钉墙基坑支护中的抗滑效应,并在深基坑支护中得到实际工程的验证。  相似文献   

Improvement of SWAT2000 modelling to assess the impact of dams and sluices on streamflow in the Huai River basin of China     

Gangsheng Wang  Jun Xia 《水文研究》2010,24(11):1455-1471

Hydrological simulation and assessment in a dam–sluice regulated river basin are a complex and challenging issue. In this article, an improved SWAT2000 modelling system was developed that incorporated the Shuffled complex evolution (SCE‐UA) optimization algorithm and the multi‐site and multi‐objective calibration strategy. The implication of multi‐objective is different for different types of outlets, i.e. streamflow for an ordinary outlet, inflow for a sluice, and water storage for a reservoir. Model parameters were redefined to improve model simulations. The surface runoff lag time (SURLAG) was extended as a spatially distributed parameter, and a correction coefficient was introduced to modify the saturated hydraulic conductivity. The modelling system was then applied to the Huai River basin of China under various climatic conditions, including a very dry year (1999), a dry year (1981), an average year (1971), and wet year (1991). In all, 26 dams and 35 sluices were considered, among which about 20 dams/sluices were used for model calibration. The impact assessment primarily focused on the very dry year (1999). The results indicated that the released water from large reservoirs was blocked in the river channels by sluices located downstream. In the very dry year, the dam–sluice operations could result in an increase of the runoff volume during the non‐flood season and a decrease in runoff during the flood season, but the changing magnitude during the non‐flood season was much greater. An important conclusion of this case study is that the sluices in the Sha‐Yin branch located in the north region and the dams in the southern mountainous region above the Wangjiaba Hydrological Station have played the most significant role in regulating the streamflow of the entire river basin. The methods addressed in this article can simulate hydrological regime in the river basins regulated by dams and sluices under different climatic conditions at the whole‐watershed scale. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

大跨连续钢桁拱桥动力系数影响因素研究     

蒲黔辉  魏召兰  李晓斌 《地震工程与工程振动》2011,31(6):123-128

以南京大胜关长江大桥为研究对象,建立其车桥耦合动力分析模型,采用逐步积分法求解动力方程,以动力系数作评判标准,讨论行车速度、阻尼比、行车方向、车辆数、吊杆布置方式等参数对动力性能的影响.结果表明:动力系数随行车速度的提高而增大;吊杆索力的动力系数与无应力索长成反比;随着阻尼比的增大,各构件动力系数均有所降低;同向行驶时...  相似文献   

周期径向荷载作用下圆弧格构拱动力稳定性分析     

赵洪金  刘超  孟昭博  吴敏哲 《地震工程与工程振动》2011,31(6):73-77

基于结构弹性稳定理论,根据能量法推导出以位移为基本未知量的圆弧格构拱总势能,从Hamilton原理出发,建立了考虑剪切变形的圆弧格构拱的动力稳定微分方程.利用Galerkin方法将其转化为二阶常微分Mathieu型参数共振方程,求得周期解所包围的动力不稳定区域,探讨了圆弧格构拱发生参数共振的动力稳定性问题,分析了缀条面...  相似文献   

一种求解地下结构顶板频率和振型的方法     

姚小彬  戚承志  陈国兴 《地震学刊》2011,(6):688-694

采用欧拉梁横向自由振动理论,发展了一种求解浅埋地下结构顶板频率和振型的方法。鉴于地下结构顶板频率求解问题的复杂性,首先将该问题假定为平面应变问题求解,推导出浅埋地下结构项板梁的自由振动方程;然后根据顶板梁的边界条件,得到了顶板梁的频率方程,从而得出了顶板梁的频率和振型;进一步得出了墙体转动刚度对顶板频率影响的规律,即转动刚度对顶板低频影响较小,对高频影响较大。还综合考虑土体刚度随埋深的变化和由于土体成拱引起的土体附加质量的变化,研究了结构顶板频率随埋深的变化。这些结果可以为地下结构的动力计算提供参考。  相似文献   

Changes in hydrology and sediment delivery of the Mekong River in the last 50 years: connection to damming,monsoon, and ENSO   总被引：1，自引：0，他引：1  

Zuo Xue  J. Paul Liu  Qian Ge 《地球表面变化过程与地形》2011,36(3):296-308

As the population and economy boom, more and more dams are being built in the Mekong River basin. Previous studies have revealed that Manwan Dam had little influence on the runoff–SSC (suspended sediment concentration) relationship, and the sediment load was relatively stable over the past 40 years. However, little is known at present on the relationship among monsoons, El Niño Southern Oscillation (ENSO), precipitation, runoff, and the impact of dams on the delta dynamics. A comprehensive hydropower GIS database covering the entire Mekong basin is presented in this study. Mann–Kendall trend analysis showed no significant change in precipitation and runoff over the past 50 years. Spectral analysis showed that the runoffs of the middle to lower reach of Mekong River are correlated with the Indian Monsoon, where as the East Asian Monsoon's influence is mainly on the lower reach. With another 200 new dams to be added to the basin in the next couple of decades, changes are expected in both hydrological regime and delta dynamics. On one hand, the runoff showed a closer connection with the regional precipitation and ENSO in the post‐dam period (1993–2005) than in the pre‐dam period (1950–1993). Such a relationship is expected to be even closer when more dams are completed. On the other hand, both daily maximum and minimum water levels on the delta plain have shown an abrupt drop since the end of 1994. This reduced water‐level gradient between the river and sea inevitably weakens the sediment discharge to the coast, which might intensify the ongoing coastal erosion on the eastern part of the delta plain. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献