On the criteria of model performance evaluation for real-time flood forecasting     

Ke-Sheng?ChengEmail authorView author&#;s OrcID profile  Yi-Ting?Lien  Yii-Chen?Wu  Yuan-Fong?Su 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(5):1123-1146

Model performance evaluation for real-time flood forecasting has been conducted using various criteria. Although the coefficient of efficiency (CE) is most widely used, we demonstrate that a model achieving good model efficiency may actually be inferior to the naïve (or persistence) forecasting, if the flow series has a high lag-1 autocorrelation coefficient. We derived sample-dependent and AR model-dependent asymptotic relationships between the coefficient of efficiency and the coefficient of persistence (CP) which form the basis of a proposed CE–CP coupled model performance evaluation criterion. Considering the flow persistence and the model simplicity, the AR(2) model is suggested to be the benchmark model for performance evaluation of real-time flood forecasting models. We emphasize that performance evaluation of flood forecasting models using the proposed CE–CP coupled criterion should be carried out with respect to individual flood events. A single CE or CP value derived from a multi-event artifactual series by no means provides a multi-event overall evaluation and may actually disguise the real capability of the proposed model.  相似文献   

Impact of sensor measurement error on sensor positioning in water quality monitoring networks   总被引：1，自引：1，他引：0  

Seong-Hee?Kim  Mustafa?M.?Aral  Yongsoon?Eun  Jisu?J.?Park  Chuljin?ParkEmail authorView author&#;s OrcID profile 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(3):743-756

This paper studies the impact of sensor measurement error on designing a water quality monitoring network for a river system, and shows that robust sensor locations can be obtained when an optimization algorithm is combined with a statistical process control (SPC) method. Specifically, we develop a possible probabilistic model of sensor measurement error and the measurement error model is embedded into a simulation model of a river system. An optimization algorithm is used to find the optimal sensor locations that minimize the expected time until a spill detection in the presence of a constraint on the probability of detecting a spill. The experimental results show that the optimal sensor locations are highly sensitive to the variability of measurement error and false alarm rates are often unacceptably high. An SPC method is useful in finding thresholds that guarantee a false alarm rate no more than a pre-specified target level, and an optimization algorithm combined with the thresholds finds a robust sensor network.  相似文献   

Improving at-site flood frequency analysis with additional spatial information: a probabilistic regional envelope curve approach     

Daryl?LamEmail authorView author&#;s OrcID profile  Chris?Thompson  Jacky?Croke 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(8):2011-2031

Extreme flood events have detrimental effects on society, the economy and the environment. Widespread flooding across South East Queensland in 2011 and 2013 resulted in the loss of lives and significant cost to the economy. In this region, flood risk planning and the use of traditional flood frequency analysis (FFA) to estimate both the magnitude and frequency of the 1-in-100 year flood is severely limited by short gauging station records. On average, these records are 42 years in Eastern Australia and many have a poor representation of extreme flood events. The major aim of this study is to test the application of an alternative method to estimate flood frequency in the form of the Probabilistic Regional Envelope Curve (PREC) approach which integrates additional spatial information of extreme flood events. In order to better define and constrain a working definition of an extreme flood, an Australian Envelope Curve is also produced from available gauging station data. Results indicate that the PREC method shows significant changes to the larger recurrence intervals (≥100 years) in gauges with either too few, or too many, extreme flood events. A decision making process is provided to ascertain when this method is preferable for FFA.  相似文献   

Frequency based imputation of precipitation     

Fatih?DikbasEmail authorView author&#;s OrcID profile 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(9):2415-2434

Changing climate and precipitation patterns make the estimation of precipitation, which exhibits two-dimensional and sometimes chaotic behavior, more challenging. In recent decades, numerous data-driven methods have been developed and applied to estimate precipitation; however, these methods suffer from the use of one-dimensional approaches, lack generality, require the use of neighboring stations and have low sensitivity. This paper aims to implement the first generally applicable, highly sensitive two-dimensional data-driven model of precipitation. This model, named frequency based imputation (FBI), relies on non-continuous monthly precipitation time series data. It requires no determination of input parameters and no data preprocessing, and it provides multiple estimations (from the most to the least probable) of each missing data unit utilizing the series itself. A total of 34,330 monthly total precipitation observations from 70 stations in 21 basins within Turkey were used to assess the success of the method by removing and estimating observation series in annual increments. Comparisons with the expectation maximization and multiple linear regression models illustrate that the FBI method is superior in its estimation of monthly precipitation. This paper also provides a link to the software code for the FBI method.  相似文献   

考虑支座摩擦滑移及结构碰撞的非规则人字形桥梁地震响应分析          下载免费PDF全文

闫磊  李青宁  刘芳平  申纪伟  程龙飞  杨茂 《世界地震工程》2018,34(2):044-54

针对非规则人字形桥梁在地震作用下灾变严重的问题,以一座非规则人字形桥梁为研究对象,建立其空间分析模型,研究综合考虑支座摩擦滑移、结构碰撞对非规则人字形桥梁地震响应的影响。结果表明:邻梁间的碰撞作用可使得桥梁墩顶位移及内力相比不考虑时有所减小,但同时也使梁体产生了较大的加速度脉冲效应;当考虑支座摩擦滑移和结构碰撞时,固定墩墩顶位移和邻梁相对位移峰值有一定程度增大,然而对梁体加速度脉冲效应结果影响并无统一规律;纵向地震波作用下,非规则人字形桥梁不仅存在顺桥向的碰撞,横桥向的碰撞响应也不容忽视。非规则人字形桥梁进行抗震设计计算时应选取符合实际情况的计算模型,考虑支座摩擦滑移及结构间的碰撞。  相似文献   

落地通信基站机房地震易损性及震后功能失效概率评估          下载免费PDF全文

毛晨曦  李诗尧  张亮泉 《世界地震工程》2018,34(2):055-64

机房是移动通信基站的重要组成部分,其地震易损性将决定基站在震后的功能状态,即基站所辖范围内的移动通信服务在震后是否可以正常使用。在对我国北方某市典型落地通信基站机房进行实地考察的基础上,确定了影响机房地震后使用功能的重要设施（即基站板房、内部走线架、通信机柜和蓄电池组）;随后采用有限元软件ABAQUS分别建立了这些设施的数值模型,通过Pushover分析确定了每种设施的损伤模式、损伤水平评价指标及其数值;通过IDA分析得到了每种设施的抗震性能,并通过对IDA分析结果的统计得到了这些重要设施的地震易损性曲线;最后,给出了基于故障树模型的典型通信基站机房震后功能评估的方法。该工作将作为基本环节用于城市及地区移动通信系统的地震后功能状态评估与预测。  相似文献   

温州深软场地剪切波速实测误差及其对PGA影响研究          下载免费PDF全文

陈卓识  侯龙清  袁晓铭  李楠 《世界地震工程》2018,34(2):071-79

该研究在温州两个深软土层场地上完成了剪切波速测试误差专项实验,统计拟合了误差分布规律并研究了其对PGA的影响,得到结论:每米深度上的实测误差基本符合标准正态分布,温州地区深软场地的测试误差与我国其他几个地区覆盖土层较浅场地上的每米实测误差程度基本相同;两个场地上各深度的误差标准差大致相同,约为16%;实测误差对PGA影响明显,误差取1倍标准差时PGA的变化程度可能达到30%,取2倍标准差时可能高达45%;PGA的变化程度受输入地震动的频率特性制约,长周期频率成分对深软场地计算结果的影响明显。  相似文献   

设计反应谱标定方法的研究现状与讨论          下载免费PDF全文

蒋晓涵  薄景山    王竞  韩昕  郭晓云  赵培培  谭启迪 《世界地震工程》2018,34(4):038-48

设计反应谱及其标定方法的研究是工程抗震研究领域的基本问题之一。在现有研究成果的基础上,归纳和总结了设计反应谱及其标定方法的研究历史和现状;评述了研究进程中的若干节点问题;介绍了设计反应谱的标定原理和当前几种有代表性的设计反应谱的标定方法;分析了设计反应谱标定参数的影响因素。在此基础上,对设计反应谱及其标定方法研究中的强震资料积累问题、谱形状问题、标定参数的确定问题以及标定方法等问题进行了讨论并提出了改进和进一步研究的建议。  相似文献   

西藏典型单层混凝土砌块房屋打包带加固抗震试验研究          下载免费PDF全文

孙柏涛  黄佩蒂  姚新强  周强 《世界地震工程》2018,34(1):040-50

本文以振动台试验方式研究了打包带加固对西藏典型单层混凝土砌块房屋抗震性能的影响,同时考虑了结构平面布置、抗震设防及砌筑质量三个因素。选取3种西藏地区民居的经典户型制作了7个1∶3缩尺模型进行振动台试验,模型分别为3个无打包带加固模型、3个有打包带加固模型以及1个加固一半的模型。试验结果表明打包带加固墙体能明显提高墙体的整体性,减轻墙体震损;无打包带加固但砌筑质量好的单层民居抗震能力较好,基本满足当地9度设防的要求;高烈度下平面布置不规则的结构容易因扭转作用而发生破坏,圈梁、构造柱也在高烈度下发挥较大作用。打包带加固技术作为一种经济实用的加固技术可在西藏地区进行推广。  相似文献   

小跨高比带楼板半通缝连梁抗震性能有限元分析          下载免费PDF全文

张超  陈向上  于德湖 《世界地震工程》2018,34(1):051-62

为了缓解联肢剪力墙中小跨高比连梁发生低延性的剪切破坏,增强连梁的变形和耗能能力,可在单连梁中轴线位置设置半通缝并配置交叉斜筋,形成半通缝连梁。本文完成了的对7种连梁的模拟,分析了在小跨高比、低周反复荷载作用条件下不同类型带楼板连梁的承载力、变形能力、刚度退化和耗能能力以及不同跨高比、不同开缝位置对带楼板半通缝连梁抗震性能的影响。结果表明:楼板会使半通缝连梁的剪压比增大,延性下降;但相比于普通连梁和双连梁,半通缝连梁具有较好的变形能力和承载力,可在实际中推广。  相似文献