河道单宽测流法探讨

对一种用固定垂线单宽测流法进行分析,这种方法是在建立垂线单宽流量和断面平均单宽流量关系的基础上,精简流速仪测流方法,达到规范规定的精简目的。     

浅谈流速仪在渠道测流时应注意的几个关键环节

用流速仪量水是灌区量水的基本方法,其测量成果对灌区量水精度有很大的影响.本文通过介绍流速仪测流时的工作原理,在测流时科学选择测流断面和垂线数目,采用平均分割法计算渠道断面流量,并分析其测流过程中产生误差的原因,提高流速仪测流时的精度,为渠道量水工作提供参考.     

雷达波自动测流系统设计与应用

人工方式水文测流工作效率低、时效性差、安全风险大、成本高。因此,开发无人值守自动测流系统十分必要。基于自动化控制理论开发了自动测流系统。系统以非接触式雷达波流速仪作为水面流速测验传感器,利用简易双轨缆道将雷达波流速仪移动到设定垂线水面上方施测水面流速,同时实时采集水位数据,实现了河道水位、流量的实时自动监测。该系统可全过程自动控制测流,具备较强的差错控制能力和良好的系统辅助管理能力,很好地解决了无人值守条件下中小河流、山区性暴涨暴落河流流量自动测验的难题。     

介绍一种明渠测流方法及其设备

1 基本方法 目前,在明渠流量测量中,广泛采用《速度一面积》法。实施这种测流方法的主要设备是流速仪。本文介绍的明渠测流法是借助于几台新型的小流速仪,将其固定在位于施测垂线处的半自动测杆上,测量水流速度。施测后,将测杆移至下一根测速垂线继续测     

数值积分法施测流量的改进

一、引言 在测流方法中，我们一般采用梯型法，此法要求有较多的垂线才能达到精度要求。应用数值积分法测流，可以用较少的测流垂线，比较准确地计算全断面流量，使测流历时大幅度缩短，精度相应提高。其优越性在抢测洪峰时尤为突出。 　　数值积分法测流首先认为单宽流量沿断面的分布是条平滑连续的曲线，断面流量为单宽流量沿水面宽的积分。其表达式为： 经过一定的数学推导可得出理论上精度较高的数值积分法流量计算公式。 　　然而在实际应用中，由于多数测流断面并非很规则，水流要受某些因素影响而发生变化，很难满足单宽流量沿断面分…     

S3-SVR雷达流量计在南宽坪水文站流量测验中的应用分析

S3-SVR型缆道雷达波测流设备采用美国ACI公司多普勒雷达波测速传感器(www.stalkerradar.com),以非接触方式测量水流表面流速,借助水文站现有过河缆道设施,测量每条垂线的水面流速,配套测流软件,计算断面流量。本文通过对S3-SVR型雷达流量计与常规流速仪测流进行比测试验,找出系数。目的是利用先进的测量技术,提高测验时效性,为防汛及实施水资源的统一调度和管理提供技术支持。同时也为该仪器在陕西省及商洛市的推广使用打好基础。     

ADCP在冬季测流中的应用

介绍了ADCP的优点及测量原理。用ADCP有效地解决了某水文站断面与河流流向不垂直及冬季测流的问题。结果表明:①如果不进行流量偏角修正,则流速仪法所测数据同ADCP法测得的数据接近;②流速仪法在测流过程中人为地将流速仪垂直了断面,如果再进行偏角修正,将造成流量偏小;③该站冬季测流时,若使用悬杆测流则不需要进行偏角修正,若采用铅鱼悬吊测流则应该测量流向偏角并对流速进行偏角修正。     

雷达测流仪比测分析

S3—SVRⅡ型无线遥控雷达波数字化测流系统是一种新型的非接触式河道流量测验系统,分析了雷达施测水面流速和流量的测验误差,并与转子流速仪进行了比测。结果表明:雷达测流系统误差可以控制在±1%以内,随机不确定度超出了规范要求,但雷达测流精度满足中小河流水文监测要求。     

利用多普勒流速仪进行明渠流量在线监测分析

使用流速仪用精测法施测明渠流量,各次流量的测速垂线固定,各条测速垂线的平均流速与断面平均流速建立相关关系,分析各条垂线流速的代表性,并进行误差计算,找出代表性最好,推算误差符合水文测验规范要求的垂线,在该垂线所在断面位置的河底,安装座底式多普勒流速仪（淘金者-SW型）,利用座底式多普勒流速仪进行明渠流量在线监测。     

垂向声学多普勒流速剖面仪自动测流系统警示标志应用

流量在线自动监测已成为实现水文监测现代化的关键,垂向声学多普勒流速剖面仪(VADCP)自动测流系统得到广泛推广应用,为保障V-ADCP自动测流系统可靠运行,结合江苏省水文水资源勘测局部分V-ADCP自动测流系统损坏和恢复应用的案例,探讨V-ADCP自动测流系统安装及运行过程中存在的短板问题,提出在测流断面安装浮球式警示标志的方案,为进一步提高V-ADCP在线测流系统运行稳定性提供保障。     

多路水深流速自动采集系统设计与应用

针对河工模型试验中多点流速自动测量的需要,设计了一种多点水深流速同步自动采集系统。系统由计算机通过RS485总线与多台水深流速仪相连,组成多点水深流速自动测量。水深流速仪能够自动测量当前水深,并根据测得的水深和规定的测量法则,如1点法、3点法、5点法等,自动对流速传感器进行垂线定位和流速采集。系统通过串行通信方式控制各台水深流速仪,实现各垂线流速的同步测量、数据传输、显示、保存和查询功能,并能自动生成需要的测量记录报表。该系统显著提高了模型试验断面流速测量的效率和水深测量与定位的精度。     

徐六泾站悬移质含沙量比测与精度分析

通过长江口徐六泾断面大规模的跨越不同水情的现场测流试验,发现利用声学多普勒流速剖面仪(AD-CP)信号推算垂线平均含沙量,与传统值相比,平均相对误差绝对值小于5%,且误差呈正态分布。因此,升级现有的徐六泾浮标测流系统(以ADCP取代现有的ADP),可以实现徐六泾断面的在线实时输沙率监测,填补长江口泥沙站网的空白,为长江口相关规划、设计、科研等提供基础资料。     

梯形透水潜坝附近水面线及透水率

为研究结构物的透水特性和水动力特性,利用PIV流场测量系统专用水槽物理模型试验与Flow3D数值模拟相结合的方法研究均匀开孔的梯形透水潜坝附近水面线及坝体透水率的变化规律。结果表明:潜坝附近壅水及水跌高度随透空率的增大而减小,不同透空率潜坝坝后水面均出现"逆坡现象"。相同断面平均流速条件下,水深越大,相对壅水高度越小;当水深大于2倍坝高时,坝体壅水效果逐渐消失。相同坝前远端水深条件下,随着断面平均流速增大,坝后水跌高度增大。最后利用数模计算结果经回归拟合得到透水率的综合计算公式,经验证该经验公式计算结果和实测值最大偏差不超过5%,具有一定的可靠性。     

大赉水文站测速垂线精简测点的分析探讨

利用2007年大赉水文站总计30次用三点法实测流量资料,通过对流量、垂线平均流速两个方面分析得知,大赉水文站测速垂线精简测点后,采用相对水深0.2、0.8测点测流与采用相对水深0.2、0.6、0.8测点测流,两种方法计算的流量对比,总的系统误差为-0.36%。并对两种测流方法进行了单次流量随机不确定度验证,符合《河流流量测验规范》精度要求。其意义在于缩短测流历时,把流量测验的重点投入到增加测验次数上,满足大洪水时期,水位变幅大,测次不足的问题。尤其在主汛期可及早报出流量,为防汛抗洪服务。     

流量实时监测代表垂线法应用探讨

代表垂线法具有提升水文监测技术手段和防汛测报的快速反应能力,提高通航河道监测效率,简化测验方法等特点。通过从流速仪精测法实测流量中筛选出代表垂线,对实测垂线平均流速与实际断面平均流速进行横向比较,经过误差分析,确定垂线的平均断面流速和实测断面平均流速之间相关关系。经数据检验后,结果满足《水文资料整编规范》标准要求。代表垂线法可以提高流量测验效率,缩短在中高水期间通航河道流量监测时间,实现流量实时监测,为防汛救灾指挥部门提供及时、准确的水情信息。     

水文测验中两种测速垂线精简算法比较研究

随着中小河流治理项目的推进,改革水文测验方式,探索测流方式方法技术创新势在必行。本研究依托南京信息工程大学学生水文测验教学实习过程中组织开展的2次测速垂线优化精简实验,收集了渔梁水文站2次多测速垂线流量测验数据,针对原精简算法在流量误差最小的寻优过程中可能删去最有代表性的垂线这一问题,设计了直接寻求流量误差最小的测速垂线组合的新算法,并深入分析了两种精简算法对流量误差的影响。结果表明:测站目前采用的常测法选取的13根固定垂线代表性较好,流量测验精度较高;对比原算法,新的垂线精简算法在相同垂线数目下,流量误差更小,测验精度更高;由新算法,特殊水情下单垂线测流可考虑将垂线位置布设在起点距84 m处;流量相对误差大小随着优选垂线数量的增加呈指数递减规律。本研究所提的垂线精简算法有助于提高实验的精度,可为基层水文站开展垂线精简分析工作,进行测流方式改革提供参考。     

Advantages of a mobile LSPIV method for measuring flood discharges and improving stage–discharge curves

This paper investigates the potential of fast flood discharge measurements conducted with a mobile LSPIV device. LSPIV discharge measurements were performed during two hydrological events on the Arc River, a gravel-bed river in the French Alps: a flood greater than the 10-year return period flood in May, 2008, and a reservoir flushing release in June, 2009. The mobile LSPIV device consists of a telescopic mast with a remotely controlled platform equipped with a video camera. The digital video camera acquired sequences of images of the surface flow velocities. Ground Reference Points (GRPs) were positioned using a total station, for further geometrical correction of the images. During the flood peak, surface flow velocities up to 7 m/s and large floating objects prevented any kind of intrusive flow measurements. For the computation of discharge, the velocity coefficient was derived from available vertical velocity profiles measured by current meter. The obtained value range (0.72–0.79) is consistent with previous observations at this site and smaller than the usual default value (0.85) or values observed for deeper river sections (0.90 typically). Practical recommendations are drawn. Estimating stream discharge in high flow conditions from LSPIV measurements entails a complex measurement process since many parameters (water level, surface velocities, bathymetry, velocity coefficient, etc.) are affected by uncertainties and can change during the experiment. Sensitivity tests, comparisons and theoretical considerations are reported to assess the dominant sources of error in such measurements. The multiplicative error induced by the velocity coefficient was confirmed to be a major source of error compared with estimated errors due to water level uncertainty, free-surface deformations, number of image pairs, absence or presence of artificial tracers, and cross-section bathymetry profiles. All these errors are estimated to range from 1% to 5% whereas the velocity coefficient variability may be 10%–15% according to the site and the flow characteristics. The analysis of 36 LSPIV sequences during both events allowed the assessment of the flood discharges with an overall uncertainty less than 10%. A simple hydraulic law based on the geometry of the three sills of the Pontamafrey gauging station was proposed instead of the existing curve that is fitted on available gauging data. The high flow LSPIV discharge measurements indicated that this new curve is more accurate for high discharges since they are evenly distributed in a ±10% interval around it. These results demonstrate the interest of the remote stream gauging techniques together with hydraulic analysis for improving stage–discharge relationships and reducing uncertainties associated with fast flood discharges.     

Estimating discharge in gravel‐bed river using non‐contact ground‐penetrating and surface‐velocity radars

Discharge measurement is a critical task for gravel‐bed channels. Under high‐flow conditions, the elevation of the riverbed changes significantly by intensive torrential flow. The stage–discharge relations commonly used for stream discharge estimation may no longer be adequate. The contact‐type velocity measuring is also subject to measurement errors and/or instrument failures by the high‐flow velocities, driftwood, stumps, and debris. This study developed a new real‐time method to estimate river discharge in gravel‐bed channels. A systematic measuring technology combining ground‐penetrating radar and surface‐velocity radar was employed. The rating curves representing the relations of water surface velocity to the channel cross‐sectional mean velocity and flow area were established. Stream discharge was then deduced from the resulting mean velocity and flow area. The proposed method was examined in a steep gravel‐bed reach of the Cho‐Shui River in central Taiwan. The estimated stream discharge during three flood events were compared to the prediction by using the stage–discharge relation and the index‐velocity method. The proposed method of this study is capable of computing reasonable values of discharge for an entire flood hydrograph, whereas the other two methods tend to produce large extrapolation errors. Moreover, when the computed discharge is used in 2D flood flow simulation, the proposed method demonstrates better performance than the commonly used stage–discharge and index‐velocity methods.     

基于Fluent的混凝土面板堆石坝渗流的数值模拟

针对修建在深覆盖层地基上的大坝的渗流控制问题,利用Fluent中的User-Defined Function(UDF)模块进行二次开发,通过C语言编写,加载到Fluent以及多孔介质模型的应用中,采用有限体积法进行基于Fluent的大坝渗流的数值模拟。通过对不透水地基上的均质坝渗流和有压地基渗流的模拟,验证了渗流模拟与试验相比具有相当高的吻合度,其中均质坝渗流模拟中浸润线求解的相对误差最大不超过1.19%;有压地基渗流模拟中流速相对误差在5%之内;渗流量和渗透压力相对误差均在1%上下。相较而言,UDF法模拟结果更加精确,说明UDF法具有更高的理论精度。应用UDF法对某水库混凝土面板堆石坝进行渗流模拟,得出了浸润面与流线图、水头分布等值线图,得到了很好的模拟结果。