Regionalisation of physically-based water balance models in Belgium. Application to ungauged catchments

More than 60 catchments from Northern Belgium ranging in size from 16 to 3160 km² have been studied by means of a physically-based stochastic water balance model. The parameter values derived from calibration of the model were regionally mapped for the study region. Associations between model parameters and basin lithological characteristics were established and tested. The results show that the simple conceptual monthly water balance model with three parameters for actual evapotranspiration, slow and fast runoff is capable either to generate monthly streamflow at ungauged sites or to extend river flow at gauged sites. This allows a fairly accurate estimation of monthly discharges at any location within the region.     

Hydrologically Based Environmental Flow Methods Applied to Rivers in the Maritime Provinces (Canada)

The demand for water withdrawal continues to increase worldwide. These water withdrawals from rivers can affect fish habitat and aquatic life. As such, environmental flow assessment methods are used in order to protect rivers against excessive water withdrawals. The concept of environmental flow relates to the quantity of water required in rivers to sustain an acceptable level of living conditions for aquatic biota at various phases of their development. For many agencies, environmental flow methods are essential in environmental impact assessments and in the protection of important fisheries resources. The present study deals with the evaluation of hydrologically based environmental flow methods within the Maritime Province of Canada. In total, six hydrologically based environmental flow methods were compared using data from 52 hydrometric stations across the region. Some methods provided adequate environmental flow protection (e.g. 25% mean annual flow and Q₅₀ flow duration method); however, other methods did not provide adequate flow protection (e.g. Q₉₀ flow duration method and 7Q10 and 7Q2 low‐flow frequency). The 70% Q₅₀ method provided adequate flow protection only under good baseflow conditions and should be applied with extreme caution. The present study shows the importance of the hydrologic flow regime, particularly as it pertains to the baseflow component, as a significant determinant in the level of instream flow protection. © 2014 Her Majesty the Queen in Right of Canada. River Research and Applications © 2014 John Wiley & Sons, Ltd.     

基于改进区域化流量历时曲线的无资料 地区径流模拟

台湾成功大学游保杉教授等人创造性地采用区域化流量历时曲线率定法,利用所推求的区域化流量历时曲线作为水文模型的拟合目标,率定无资料地区的参数,实现了无资料地区径流模拟。作为该法应用的关键,区域化流量历时曲线精度直接关系到模型率定的精度。研究通过趋势拟合对推求的流量历时曲线在形态上进行校正且利用量级调整对曲线的量级大小进一步进行调整,逐步改进区域化流量历时曲线。以此,提高了区域化流量历时曲线率定法的精度,较好地实现了无资料地区日径流过程模拟。     

Generation of natural daily flow time‐series in regulated rivers using a non‐linear spatial interpolation technique

Daily streamflow time‐series data are often in demand in water resource assessment, water quality and river ecology studies. Such studies normally require daily time‐series representing the natural conditions in a catchment. The generation of these time‐series by means of deterministic physically based daily models is a time consuming approach. This paper describes more pragmatic alternative techniques for generating daily flow sequences using the available observed daily flow records at the neighbouring gauging stations. The daily time‐series representing natural flow conditions at any site of interest may be generated by means of a non‐linear spatial interpolation technique, which is based on 1‐day long‐term flow duration curves for each calendar month of the year. This technique is used to transfer the daily flow information from a source site(s) with data to the destination site where these discharge data are either insufficient or completely missing. The transfer process is based on the assumption that daily flows occurring simultaneously at sites located close to each other correspond to similar probabilities on their respective flow duration curves. Several methods by which to establish the required 1‐day long‐term flow duration curves representing the natural flow regime at the destination site are presented and the conversion of these curves into a complete continuous time‐series of daily discharges is illustrated with the examples from modified streams in South Africa. Copyright © 1999 John Wiley & Sons, Ltd.     

流域设计枯水流量分析计算方法

流域枯水流量的大小,主要依赖于流域蓄水量的补给;同时随着流域蓄水量的减少,枯水流量也不断衰减。流域枯水流量与河道通航、城乡供水、水电厂与火电厂设计(运行)和生态环境质量等密切相关。流域枯水流量虽不如洪涝和地震等自然灾害与人类的关系那么剧烈,但它可严重制约工农业生产的发展和人类生活质量的提高。本文详细介绍了流域设计枯水流量分析计算涵盖的枯水调查与资料收集、枯水流量资料的审查与处理、具有实测资料时设计枯水流量的计算、资料不足时设计枯水流量的估算、缺乏资料时设计枯水流量的确定以及设计枯水流量成果的分析论证等6部分内容,以供从事河道航运、城乡供水和环境保护等部门工程技术人员参考,以利于经济社会更好地发展。     

基于灰色关联法的喀斯特流域枯水影响因素分析

枯水和洪水是水文学中极值范畴,枯水研究的深度远远低于洪水.本研究利用灰色系统理论,通过SPSS软件进行计算分析,用量化的方法找到喀斯特流域影响枯水的优势因素.对进一步开展喀斯特流域枯水的研究及合理开发利用枯水资源提供了科学的依据,特别是对于我国经济相对落后的喀斯特地区将具有深远的意义.     

低Reynolds数横向排列双圆柱绕流的POD-Galerkin谱方法数值模拟

该文将恰当正交分解(POD)方法应用到低Reynolds数(Re)二维横向排列双圆柱绕流问题.采用Fluent数值模拟得到Re=90时的流场数据库,在此基础上采用snapshot的方法构造了POD基.基于此POD基,构造了求解二维不可压缩Navier-Stokes方程组的低维Galerkin谱方法.采用该低维数值模拟方法,再现了低Reynolds数横向排列双圆柱绕流的多种复杂流动模式,其结果与已有的高精度直接数值模拟的结果符合较好,而计算量却非常小,显示了POD方法的有效性和优越性.     

Estimation of geomorphically significant flows in alpine streams of the Rocky Mountains,Colorado (USA)

Streamflows recorded at 24 gauging stations in the Rocky Mountains of Colorado were analyzed to derive regional regression equations for estimating the natural flow duration and flood frequency in reaches where the natural flows are unknown or have been altered by diversion or regulation. The principal objective of this analysis is to determine whether the relatively high, infrequent, but geomorphically and ecologically important flows in the Rocky Mountains can be accurately estimated by regional flow duration equations. The region considered in this study is an area of relatively abundant runoff, and, consequently, intense water resources development. The specific streams analyzed here, however, are unaltered and remain nearly pristine. Regional flow duration equations are derived for two situations. When the mean annual discharge is known, flows ≧10% of the time can be estimated with an uncertainty of ±9% for the 10% exceedance flow, to ±11% for the 1.0% exceedance flow. When the mean annual discharge is unknown, the relatively high, infrequent flow can be estimated using the mean basin precipitation rate (in m³/s), and basin relief with an uncertainty of ±23% for the 10% exceedance flow to ±21% for the 1.0% exeedance flow. The uncertainty in estimated discharges using the equations derived in this analysis is substantially smaller than has been previously reported, especially for the geomorphically significant flows which are relatively large and infrequent. The improvement is due primarily to the quality of streamflow records analyzed and a well‐defined hydrologic region.     

低渗透油藏非线性渗流理论及数值模拟方法

针对低渗透油藏非线性渗流理论与数值模拟方法方面存在的大量问题,从毛细管模型出发,推导了低渗透油藏非线性渗流新模型,详细解释了新模型中特有的物理参数内涵;并由此建立了低渗透油藏非线性单相渗流理论,与相对渗透率引入渠道流假设一致,将单相非线性新模型推广到两相渗流中,建立了能够同时考虑启动压力梯度、非线性渗流弯曲段连续变化的数值模拟方法。根据所建立的低渗透油藏单相稳态和非稳态渗流理论以及数值模拟方法,开展了达西、拟启动压力梯度和非线性模型的油藏动态对比计算。结果表明:低渗透油藏主要受非线性渗流控制,仅井点的少数网格存在拟线性流动,非线性模型计算的结果介于达西和拟启动线性模型之间。     

弯曲复式河道水流特性数值模拟研究

为了解二维、三维模型在弯曲复式河道水流数值模拟中的应用情况,利用物理模型试验数据验证二维模型的计算结果,并对断面水面线进行了分析。可以看出,二维数模不适用于弯道水流的局部模拟,而适用于宏观水流流动的模拟。采用三维模型分析了弯曲复式河道中的二次流现象,结果表明,三维数模对于弯道水流的二次流、垂线流速分布模拟效果比较理想,可以得到弯曲河道水流运动的基本规律。     

低渗透油藏渗流的差分法数值模拟

针对低渗透问题，给出了无量纲化的渗流控制方程、初始条件以及边界条件，并使用差分方法进行数值模拟。计算结果使用Gringarten-Bourdet图版进行井底压力分析，给出了一种计算动边界位置的方法，并详细讨论了动边界变化情况。     

湟水上游河川径流丰枯分析

对湟水上游河川径流量丰枯变化、年内分配特征进行研究,应用条件概率分析连丰、连枯概率,和丰枯转移概率。研究丰枯变化趋势,为干旱半干旱地区水资源合理开发利用及防汛抗旱提供依据。     

珠江流域枯水期流量周期特征及影响因素分析

本文从珠江流域的枯水问题入手,重点分析了珠江流域几个主要控制站(梧州站、马口 三水站、博罗站)约50年的流量时间序列,并利用正规化周期回归模型提取了序列的周期,最后,对厄尔尼诺、太阳黑子、人类活动等对枯水径流的影响进行了分析,得到以下结论:珠江流域三个主要控制站点存在21年、11年的显著周期;厄尔尼诺现象的对枯水期流量的影响有滞后效应,总体而言,使珠江流域下游地区枯水期来水更枯,拉尼娜现象影响特征不明显;太阳黑子活动规律和枯水期流量变化特征相反,其周期和流量变化周期较为一致;人类活动对枯水的影响越来越大,使枯水期水资源供需矛盾加大。最后提出珠江流域枯水研究未来的发展方向。     

深沱孤礁泡漩水形成特性试验研究

泡漩水险滩是山区河流中典型的碍航险滩之一,由于泡漩水险滩的存在,山区河流不仅通航能力低,甚至发生海损事故.弄清泡漩水形成条件、产生原因以及影响泡水强度的主要因素,是消除泡漩隐患的前提.针对顺直河段深沱孤礁地形产生的泡漩水进行了32组概化模型试验.通过试验和理论分析,找出了深沱孤礁地形泡漩水产生的条件,分析了这种地形泡漩水产生的原因以及影响泡水强度的主要因素,并对各因素进行相关分析,得出了泡水高度与各因素之间的量化关系式.将泡高的计算值与实测值进行比较,结果发现二者吻合较好.     

水平管内螺旋流涡特性数值模拟

螺旋流是工程上常见的流动现象,具有增强湍流度、促进传热传质和提高对颗粒的携带能力等特性。该文采用雷诺应力湍流模型(RSM)对水平管内由短螺旋扭带起旋的螺旋流流动特性进行了数值模拟研究,通过激光多普勒测速仪(LDV)测速实验验证了数学模型的准确性和可靠性。结果表明,水平管内螺旋涡首先在扭带吸力面形成,且形成初期,涡量的大小受主涡影响较大,二次涡形成后,涡量大小主要受二次涡影响。在形成过程中二次涡增强了壁面附近的速度脉动,能够有效地增加介质的掺混。此外,由于二次螺旋涡的存在,使水平径向压力梯度增加,靠近壁面处的轴向速度减小,近壁处切向速度值增大1倍,且径向速度在螺旋流中不可忽略。     

低扬程泵装置流动特性及水力性能研究进展

综述近年来低扬程泵装置流动特性及水力性能方面的研究进展,分别从进出水流道、叶轮和整体泵装置等方面对目前研究成果进行分析,指出为了更真实地描述泵装置流动与性能研究,应树立从装置的角度去认识泵装置及其各过流部件的内、外特性的思想。目前需要在泵装置内部三维流动测量和低扬程泵装置选型方法两方面作重点研究。     

Hydrological simulation approaches for BMPs and LID practices in highly urbanized area and development of hydrological performance indicator system

Urbanization causes hydrological change and increases stormwater runoff volumes, leading to flooding, erosion, and the degradation of instream ecosystem health. Best management practices （BMPs）, like detention ponds and infiltration trenches, have been widely used to control flood runoff events for the past decade. However, low impact development （LID） options have been proposed as an alternative approach to better mimic the natural flow regime by using decentralized designs to control stormwater runoff at the source, rather than at a centralized location in the watershed. For highly urbanized areas, LID stormwater management practices such as bioretention cells and porous pavements can be used to retrofit existing infrastructure and reduce runoff volumes and peak flows. This paper describes a modeling approach to incorporate these LID practices and the two BMPs of detention ponds and infiltration trenches in an existing hydrological model to estimate the impacts of BMPs and LID practices on the surface runoff. The modeling approach has been used in a parking lot located in Lenexa, Kansas, USA, to predict hydrological performance of BMPs and LID practices. A performance indicator system including the flow duration curve, peak flow frequency exceedance curve, and runoff coefficient have been developed in an attempt to represent impacts of BMPs and LID practices on the entire spectrum of the runoff regime. Results demonstrate that use of these BMPs and LID practices leads to significant stormwater control for small rainfall events and less control for flood events.     

鼓泡塔内气液两相流动力特性数值模拟研究

利用CFD软件模拟的方法研究鼓泡塔内气液两相流动力特性,为鼓泡塔的设计提供依据。采用欧拉-欧拉双流体模型分别结合标准k-ε紊流模型和RNG k-ε紊流模型对鼓泡塔内气液两相流进行数值模拟,并使用Phase Coupled SIMPLE算法进行速度与压力耦合求解。比较鼓泡塔内轴截面(y=0)处不同高度液相速度和气相速度的变化情况,发现速度沿径向呈现出抛物线分布,沿水深方向越接近通气孔,速度越大,且气相速度整体大于液相速度。通过将z=0.28 m处的垂向液相速度与实验值比较,得出欧拉-欧拉双流体模型结合标准k-ε紊流模型模拟鼓泡塔气液两相流动力特性优于RNG k-ε模型,且发现上升力对模拟结果有显著的影响。     

利用表面过剩吸附模型研究低界面张力体系下油水两相渗流

利用表面过剩吸附理论,建立了表面活性剂在油层中的输运及吸附模型,并利用有限差分法将该模型与油水两相质量守恒方程进行了耦合求解。通过与实验结果的验证表明,表面过剩吸附模型的计算结果与实验结果符合地较好。应用此模型可以较好地研究表面活性剂在油层中的分布及其对油水两相渗流的影响。讨论了表面活性剂浓度及用量对活性剂分布及原油采出程度的影响,结果表明,表面活性剂注入浓度的影响与注入体积密切相关。