共查询到20条相似文献，搜索用时 125 毫秒
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寸滩站作为长江上游重要控制站,承担着上游防汛和三峡蓄水的双重任务。基于三峡蓄水初期寸滩站水力学特性发生改变和该时段“高水位、低流量”现象,发现Q≤25 000 m3/s时,寸滩受顶托显著,Z—Q关系线发生“左偏”。在此变化条件下,分别研究了平水期、涨水期的水位、流量预报方法,即先由河道演算的流量查询预报综合线得到水位预报,进而通过水位反查报汛综合线（或绳套、临时关系线）获得流量预报。平水期,依适用条件采用落差指数或多元门限回归开展预报,成果基本能够满足防汛和蓄水需求;涨水期,以“嘉陵江2021年第3号洪水”寸滩预报为例,分析了洪水组成、Z—Q关系绳套化、洪峰水位流量错时出现、水库实时调度和下游顶托等多种因素,采用多源、多尺度水文气象耦合与预报调度一体化辅以主客观融合的人工校正技术实时预警预报,支撑长江上游水库群联合调度,降低寸滩水位约1～2.5 m。研究可为长江上游秋汛防洪和保障三峡蓄水提供支撑。 相似文献
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贾保国 《河北地质学院学报》1995,18(5):399-405
本文利用比较原理及两个Ｌｙａｐｕｎｏｖ函数ｖ（ｔ，ｘ），ｗ（ｔ，ｘ）研究了非自治系统解的最终有界性，对充分大的‖ｘ‖，只要求ｖ（１）（ｔ，ｘ）是常负的，ｗ（ｔ，ｘ）的构造也很简单。 相似文献
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河道水位流量预报方法研究 总被引：1，自引：0，他引：1
论述了加里宁-米尔加科夫洪水演进方法，通过“虚设下游断面”的概念和变特征河长演进的思路将其改进。结合洪水波的运动波近似值，建立了河道洪水流量和水位预报方法。将该方法用于小清河干流济南城区规划河段，得到了孟家节制闸处的洪水流量和水位变化过程，为河道的规划设计和防洪调度提供了决策依据。 相似文献
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等流时单元法是一种具有物理基础同时又非常简便的分布式流域汇流模型。若能应用于大流域,会显著提高大流域分布式水文模型的计算能力,可以扩展其在大流域分布式水文模型中的应用,降低其限制性。采用基于DEM的等流时单元法进行坡面汇流计算,即坡面汇流经河流两侧并入河道,河道汇流使用扩散波方程（USGS的河道汇流程序包SFR1）,将其推广到大流域分布式水文模型的应用之中。该方法与二维坡面汇流的扩散波数值方程相比较,能够节省计算时间。在伊通河中下游较大流域上试用结果表明,农安站计算与实测流量的最大相对拟合误差为13%,模型月流量Nash-Sutcliffe效率系数为0.9。等流时单元法用于大流域分布式水文模型的坡面汇流是可行的。 相似文献
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通过ｚ－τ变换，把（ｘ，ｚ，ｔ）域的波动方程变换为（ｘ，τ，ｔ）域的波动方程，以分离出波动方程中速度（或弹性系数）的变化项，并利用有限差分法来计算横向各向同位介质中的合成记录。差分格式采用二阶中心差商及一阶向前差商，边界条件为吸能边界。计算结果显示了横向各向同位介质中的ｑＰ、ｑＳＶ及ｑＳＨ波；在有界面的情形下，还较清楚地反映了反射波的存在。 相似文献
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二维横向各向同性介质中的差分法地震波正演 总被引：1，自引：0，他引：1
通过ｚ－τ变换，把（ｘ，ｚ，ｔ）域的波动方程变换为（ｘ，τ，ｔ）域的波动方程，以分离出波动方程中速度（或弹性系数）的变化项，并利用有限差分法来计算横向各向同性介质中的合成记录。差分格式采用二阶中心差商及一阶向前差商，边界条件为吸能边界。计算结果显示了横向各向同性介质中的ｑＰ、ｑＳＶ及ｑＳＨ波；在有界面的情形下，还较清楚地反映了反射波的存在。 相似文献
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Paula Etala 《Natural Hazards》2009,51(1):49-61
The ability of the SMARA storm surge numerical prediction system to reproduce local effects in estuarine and coastal winds was recently improved by considering one-way coupling of the air–sea momentum exchange through the wave stress, and best forecasting practices for downscaling. The inclusion of long period atmospheric pressure forcing in tide and tide/surge calculations corrected a systematic error in the surge, produced by the South Atlantic Ocean quasi-stationary pressure patterns. The maximum forecast range for the storm surge at Buenos Aires provided by the real-time use of water level observations is approximately 12 h. The best available water level prediction is the 6-h forecast (nowcast) based on the closest water level observations. The 24-h forecast from the numerical models slightly improves this nowcast. Although the numerical forecast accuracy degrades after the first 48 h, the improvement to the full range observation-based prediction is maintained at the inner Río de la Plata area and extends to the first 3 days at the intermediate navigation channels. 相似文献
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考虑渗流的主要影响因子,运用遗传神经网络建立了大坝渗流实时预报模型。该模型具有再学习能力,在应用过程中,可以用新的观测资料对模型不断地进行学习训练,且随着样本的积累,模型预报精度不断提高,预报速度很快,因而完全满足实时预报的需要。利用该模型对丰满大坝横向扬压力进行了建模预报,预报值与实测值基本吻合,预测精度高,证明该方法用于大坝渗流实时预报的有效性和实用性。 相似文献
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The propagation velocity of certain elastic waves (so-called surface waves) in vertically inhomogeneous materials is dispersive. The dispersion determination is however frequently ambiguous. To verify the signal analysis reliability and to estimate the dispersive character of the waves an algorithm for dispersive waveform calculation was designed. It is based on the summation of frequency components, with shifts corresponding to the velocity dispersion and distance. The knowledge of physical parameters of the medium is not required. The resulting waveform only contains an individual dispersive wave of the selected mode, thus being particularly suitable for testing of methodologies for dispersive wave analysis. 相似文献
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为精细化模拟明渠中水电站瞬变过程引发的涌浪, 克服以往低维模型无法细致刻画涌浪的横向和垂向运动、以及高维模型计算效率偏低等问题, 基于水位预测矫正法, 提出了一维-三维耦合的明渠瞬变流模拟方法。通过潮汐波浪运动、局部溃坝波和顺直明渠瞬变流算例验证了方法的有效性和准确性, 模拟结果与渐进理论解、商用软件模拟结果等吻合较好。将该方法应用在实际工程中, 计算了葛洲坝水利枢纽瞬变过程中库区的涌浪过程, 分析了瞬变过程的最大、最小涌浪波高和涌浪的衰减规律, 结果与频谱分析结果吻合较好, 说明了本方法能准确模拟实际的明渠瞬变流过程。 相似文献
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集合卡尔曼滤波（Ensemble Kalman Filter,EnKF）方法已广泛应用于地下水水流和污染物运移模拟相关问题的求解。但前人研究多建立在同化系统预报模型是准确的基础上,忽视了模型概化的不确定性。当模型概化不准确时,将导致预报偏差,可能带来错误的系统估计。因此,文章提出考虑模型预报偏差的迭代式集合卡尔曼滤波（Bias aware Ensemble Kalman Filter with Confirming Option,Bias-CEnKF）方法。以地下水水流数据同化为例,研究模型概化存在不确定条件下,边界条件、初始条件、源汇项概化不准确时新方法的有效性。结果表明,当预报模型概化不准确时,使用标准EnKF方法进行数据同化,可能会导致滤波发散,造成同化失败。Bias-CEnKF方法不仅保留了较好的同化性能,同时减小了参数、变量、偏差项非线性关系带来的不一致性。针对文章中4种情景,Bias-CEnKF同化获得的含水层渗透系数场以及水头场均接近真实场,且预报结果可靠。本研究进一步提升了模型概化不确定时EnKF方法的适用性,为实际野外复杂条件下地下水水流数据同化问题提供了可靠的方法。 相似文献
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突发型黄土滑坡灾前变形量小,加速阶段历时短,预警预报难度大。为探究该类滑坡失稳时间预测的新途径,降低滑坡造成的经济损失和人员伤亡,以2019年甘肃黑方台地区发生的4起滑坡为研究对象,基于改进的切线角模型确定滑坡变形阶段,提出以改进切线角为指标的简化累计计算方法;采用斜率模型（SLO模型）从滑坡各变形阶段起算进行失稳时间预测,从速度倒数变化趋势、滑坡成灾模式等方面分析预测结果差异。研究发现:（1）斜率模型在突发型黄土滑坡失稳时间预测方面具有一定的可行性,从80°切线角起算得到的预测精度最高;（2）以切线角为划分指标进行简化累计计算能降低数据波动对预测结果的影响,反映预测寿命变化趋势,提高预测精度;（3）速度倒数变化趋势呈“凹”型时提前预测概率大,速度倒数变化趋势呈“凸”型时滞后预测概率大,速度倒数变化趋势呈线性时模型预测精度较高;（4）该模型在黄土滑移崩塌型滑坡中的预测效果要优于静态液化型滑坡。 相似文献
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为解决低流速、受变动回水影响等较复杂监测环境下的流量在线监测问题,依据声学多普勒频移及雷达波测速的方法原理,结合新运粮河入滇池口监测断面复杂的水文监测条件实际,采用非接触式雷达波传感器与接触式水平ADCP传感器组合成一套完整的在线流量监测系统,实现河流水表面流速和水下指标流速的同步实时数据采集,再将同步采集的水表面流速和水下指标流速同时输入模型模拟监测断面流场、流速分布,再计算实时流量后,通过GPRS信道传送到中心站服务器,对数据进行分析处理、存储、转录、发布,实现WEB、手机APP远程实时流量、工作状态等查询功能。经近一年的运行,系统正常稳定。 相似文献
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A real-time flood-forecasting method coupled with the one-dimensional unsteady flow model was developed for the Danshuei River
system in northern Taiwan. Based on the flow at current time, the flow at new time is calculated to provide the water stage
forecasting during typhoons. Data, from two typhoons in 2000: Bilis and Nari, were used to validate and evaluate the model
capability. First, the developed model was applied to validate and evaluate with and without discharge corrections at the
Hsin-Hai Bridge in Tahan Stream, Chung-Cheng Bridge in Hsintien Stream, and Sir-Ho Bridge in the Keelung River. The results
indicate that the calculated water stage profiles approach the observed data. Moreover, the water stage forecasting hydrograph
with discharge correction is close to the observed water stage hydrograph and yields a better prediction than that without
discharge correction. The model was then used to quantify the difference in prediction between different methods of real-time
water stage correction. The model results reveal that water stages using the 1–6 h forecast with real-time stage correction
exhibits the best lead times. The accuracy for 1–3 h lead time is higher than that for 4–6 h lead time, suggesting that the
flash flood forecast in the river system is reasonably accurate for 1–3 h lead time only. The method developed is effective
for flash flood forecasting and can be adopted for flood forecasting in complicated river systems. 相似文献
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Esperanza Muñoz-Salinas C. S. Renschler D. Palacios L. M. Namikawa 《Natural Hazards》2008,45(2):309-320
In contrast to dramatic flow regime changes by less frequent large-scale volcanic eruptions, those caused by more frequent
small-scale processes in volcanic landscapes may also drastically change the direction and dynamics of flow in a drainage
system formed solely by fluvial processes. During such periods of channel morphology change, it is necessary to frequently
update channel flow parameters to assess preventive measures for civil protection purposes. Often aerial photography is impracticable,
since parts of the channels are covered by dense vegetation, while total station and laser topographic surveys are often too
slow and costly, particularly during a high frequency of events. This article introduces and validates a new methodology for
updating the representation of channel morphology in Digital Elevation Models (DEM) used specifically for assessing the dangers
of frequently occurring lahars along gorges in volcanic landscapes during eruptive and non-eruptive periods. The updating
of channel cross-sections was achieved by inserting more detailed representative profiles of homogeneous channel sectors in
DEMs derived from existing less detailed topographic maps. The channel profiles were surveyed along the thalweg in equidistant
points according to Universal Transverse Mercator (UTM) (x,y) coordinates and elevation derived from the existing DEM. The
proposed technique was applied at Tenenepanco-Huiloac Gorge on Popocatépetl volcano, Mexico, in an area affected by major
lahars during the volcano’s most recent eruptive period from 1994 to 2005. The proposed method can reduce the cost and person-hours
of a regular channel topographic survey dramatically and the enhanced DEM can determine volume parameters and flood zones
associated with the 1 July 1997 and 21 January 2001 lahars, respectively. In addition, the updated DEM with better channel
representation allowed a more realistic fluid flow and lahar simulation with the process-based TITAN2D model. 相似文献
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基于BP神经网络的泥石流平均流速预测 总被引：4，自引：0，他引：4
泥石流平均流速是泥石流防治工程中不可缺少的重要参数,准确地预测泥石流平均流速对于泥石流防治工程的设计是至关重要的。将BP神经网络应用于泥石流平均流速的预测:将泥石流平均流速的影响因素--泥沙平均粒径、泥深、沟床比降和泥石流密度作为BP神经网络的输入单元,通过对云南东川蒋家沟泥石流观测数据的训练与预测建立了泥石流平均流速的BP神经网络预测模型。将预测结果与东川公式和曼宁修正公式的计算结果进行对比:曼宁修正公式和东川公式预测结果最大误差分别为27%和7.3%,BP神经网络的预测结果最大误差仅为3.2%,BP神经网络的预测精度是最高的,可见此方法对泥石流平均流速预测具有适用性和准确性。最后应用此方法预测了乌东德水电站近坝库区内的3条泥石流的平均流速分别为12.8 m/s、11.3 m/s和13.0 m/s,为库区泥石流防治工程提供了可靠的参考数据。 相似文献