Estimation of Design Flood Hydrograph for an Ungauged Watershed

Based on the physiographical features of the studied watershed of 102.5 km² in northern Ontario and the meteorological data of one nearby climatic station, through the combination of the regionalization of flood and the HEC-1 modeling, this article presents an approach that may be used to determine the desired peak flows for the ungauged watershed. The empirical equations used to determine the desired peak flows were developed by the Cumming Cockburn Ltd. (CCL) who has carried out the studies on flood regionalization by using flow data at 380 gauging stations in Ontario. CCL has proposed four methods to estimate peak flows, namely 1) regression method describing multiple linear relationships between flood flow and related parameters; 2) index flood frequency curve; 3) regional flood frequency curve and 4) isoline map for unit peak flow. The desired peak flows for studied watershed determined by CCL methods were used to calibrate the HEC-1 model for the rainfall-runoff simulation for this watershed which consists of 15 subwatersheds. Through slight adjustment in the CN number used in the HEC-1 model, the calibrated HEC-1 model could be used for rainfall-runoff simulation for this ungauged watershed. This approach could be recommended for hydrological design and watershed management for ungauged watersheds provided the analyses of flood regionalization could be conducted. In addition, comparing to the Bavaria forest region, Germany, some questions have been discussed in this article.     

西藏稀缺资料地区洪峰流量推求

洪峰流量是水利工程规划设计、工程建设和运营管理的重要依据,对水利工程的投资规模和安全运行有着重要的意义。西藏地区主要水文测站实测洪峰流量(Instantaneous Peak Flow,简称:IPF)资料稀缺,而按水位计算整编的日径流资料(Mean Daily Flow,简称:MDF)相对较多。通过构建实测资料时段的洪峰流量与对应日平均流量间的函数关系,基于长序列的日径流资料估算洪峰流量,延长洪峰流量序列,为设计洪水提供数据支撑。研究结果表明:(1)西藏地区主要水文测站IPF～MDF函数关系稳定,利用这种函数关系由实测MDF推求的IPF误差均在10%以内,且延长后的IPF序列频率分析计算结果更加合理;(2)对于实测MDF序列缺乏的测站,可以通过气象资料驱动HIMS系统水文模块(Hydro Informatic Modeling Systerm)拓展MDF序列,在此基础上推求IPF序列。基于HIMS系统水文模块对西藏三条典型河流(年楚河、拉萨河和尼洋河)的日径流序列进行了模拟,结果表明,模型对日径流整体过程与高流量值的模拟效果均良好。进而利用模型延长的MDF序列以及构建的IPF～MDF函数关系拓展了西藏三条典型河流2000年-2010年间的IPF序列。     

Comparison of Artificial Neural Network Methods with L-moments for Estimating Flood Flow at Ungauged Sites: the Case of East Mediterranean River Basin, Turkey

A regional flood frequency analysis based on the index flood method is applied using probability distributions commonly utilized for this purpose. The distribution parameters are calculated by the method of L-moments with the data of the annual flood peaks series recorded at gauging sections of 13 unregulated natural streams in the East Mediterranean River Basin in Turkey. The artificial neural networks (ANNs) models of (1) the multi-layer perceptrons (MLP) neural networks, (2) radial basis function based neural networks (RBNN), and (3) generalized regression neural networks (GRNN) are developed as alternatives to the L-moments method. Multiple-linear and multiple-nonlinear regression models (MLR and MNLR) are also used in the study. The L-moments analysis on these 13 annual flood peaks series indicates that the East Mediterranean River Basin is hydrologically homogeneous as a whole. Among the tried distributions which are the Generalized Logistic, Generalized Extreme Vaules, Generalized Normal, Pearson Type III, Wakeby, and Generalized Pareto, the Generalized Logistic and Generalized Extreme Values distributions pass the Z statistic goodness-of-fit test of the L-moments method for the East Mediterranean River Basin, the former performing yet better than the latter. Hence, as the outcome of the L-moments method applied by the Generalized Logistic distribution, two equations are developed to estimate flood peaks of any return periods for any un-gauged site in the study region. The ANNs, MLR and MNLR models are trained and tested using the data of these 13 gauged sites. The results show that the predicting performance of the MLP model is superior to the others. The application of the MLP model is performed by a special Matlab code, which yields logarithm of the flood peak, Ln(Q_T), versus a desired return period, T.     

Rating Curve Development at Ungauged River Sites using Variable Parameter Muskingum Discharge Routing Method

A physically based simplified discharge routing method, namely, the variable parameter Muskingum discharge-hydrograph (VPMD) routing method, having the capability of estimating the stage hydrographs simultaneously in channels with floodplains is presented herein. The upstream discharge hydrograph is routed using this VPMD method in different two-stage symmetrical trapezoidal compound cross section channel reaches. The performance of the VPMD method is evaluated by numerical experiments using the benchmark MIKE11 hydrodynamic model and the field data of the Tiber River in central Italy. The proposed method is capable of accurately routing the discharge hydrographs, corresponding stage hydrographs and synthesizing the normal rating curves at any downstream ungauged river site which is not affected by any downstream effects. This study can be helpful for various planning and management of river water resources in both the diagnostic and prognostic modes.     

Regional Models for the Estimation of Streamflow Series in Ungauged Basins

The assessment of water resources in a region usually must cope with a general lack of data, both in time (short observed series) as well as in space (ungauged basins). Such a lack of data is generally overcome by combining rainfall–runoff models with regionalization techniques in order to transfer information to sites without or with short available observed series. The present paper aims to analyze applicability and limitations of two regionalization procedures for estimating the parameters of simple rainfall–runoff models respectively based on a “two-step” and on a “one-step” approach, for the estimation of monthly streamflow series in ungauged basins. In particular, an application to a Sicilian river basin of multiple regression equations according to a “two-step” and a “one-step” approaches and of a “one-step” approach based on neural networks is reported. For the investigated region, results indicate that models based on the “one-step” approach appear to be robust and adequate for estimating the streamflows in ungauged basins.     

西江天河站洪水特性分析与洪峰预报方案研究

通过西江干流、珠江三角洲河口区的天河水文站的洪水特性分析，根据上游的高要站洪峰水位及石角、天河站同时水位，对天河站的峰水位及出现时间进行预报。对受潮汐顶托及网河交汇影响，不便用合成流量法来进行实时水文预报的站点，用相应水位法进行预报，也能取得较好的预报精度，且简单快捷，适用性强。     

Estimation of Parameters of a Conceptual Water Balance Model for Ungauged Catchments

The problem of parameter estimation constitutes the largest obstacle to successful application of conceptual catchment models in ungauged catchments. This paper investigates the usefulness of a conceptual water balance model for simulating river flow from catchments covering a wide variety of climatic and physiographic areas. The model is a 6-parameter water balance model which was applied to 26 seasonally snow covered catchments in central Sweden. The model was calibrated on a group of catchments and the calibrated parameter values related to physical catchment indices. The relationships were tested by comparing observed and simulated runoff records from 4 catchments that were not contained in the regression analysis. The results show that the model can be satisfactorily applied to ungauged basins in the study region. In order to test the physical relevance of the model to a wider set of conditions, the model was modified by excluding the snow routine part. The resulting model and the same technique were tested on 24 catchments taken from northern Belgium. The verification results were found to be satisfactory.     

Spatial Information-Based Back-Propagation Neural Network Modeling for Outflow Estimation of Ungauged Catchment

Rainfall–Runoff Models (RRMs) are standard tools for hydrologists to organize water resource planning and management. With the development of space-information technology and computing science in recent years, RRMs have improved to better simulate the rainfall–runoff process along with the spatial variation of simulated catchment, with the aim of precisely articulating the underlying relationship between input and output information. The Artificial Neural Network (ANN) model is suitable because it has various mathematical compositions capable of simulating a nonlinear structural system to establish the flow discharge in a catchment. For this reason, it has been successfully applied in RRMs modeling. In this study, the rainfall–runoff behavior of the gauge stations will be replicated in an ANN model. A Back-Propagation Neural network (BPN) was adopted to estimate an ungauged region’s outflow considering the temporal distribution of rainfall–runoff and the spatial distribution of the watershed environment. The nonlinear relationship among the physiographic factors, precipitation and outflow of the specific catchment was established to estimate the outflow of the sub-catchment where no flow gauge had been provided. The hazard preventive hourly model was mainly considered in this paper, and the model was also compared with the Instantaneous Unit Hydrograph (IUH) and Area Ratio Method (ARM) approaches. In validation tests in the middle and large catchments in Taiwan, the model performed well in providing forecast results. From the research work, it is revealed that the relevant spatial information can be obtained easily and precisely, which will help future studies on more related dimensions.     

Development of Design Hyetographs for Ungauged Sites Using an Approach Combining PCA,SOM and Kriging Methods

A design hyetograph represents the temporal distribution of rainfall intensity associated with a return period. The choice of the design hyetograph will have a significant influence on the shape and peak value of the hydrograph. Hence, the determination of design hyetographs is an important task in the hydrologic designs. In this paper, an approach is proposed to develop design hyetographs for ungauged sites. The proposed approach is composed of four steps: principal component analysis (PCA), self-organizing map (SOM)-based clustering, region delineation, and kriging-based construction. Firstly, PCA is applied to obtain the principal components of the design hyetographs. Then the transformed data resulting from PCA and the three geographic characters of the gauges are used as input data to the SOM, which is applied to group the rain gauges into specific clusters. Thirdly, the regions for these clusters are delineated and then the regions map is made. Finally, the design hyetographs for ungauged sites is constructed by using the kriging method. The proposed approach is applied to estimate the design hyetographs of ungauged sites in Taiwan. For comparison with the proposed approach, three other approaches are executed. Four gauges are treated as ungauged and the three approaches are used to construct the design hyetographs. The results show that accurate estimated design hyetographs can be obtained by the proposed approach. Cross-validation tests further have been performed to examine the stability and the accuracy of these approaches. Again, the results indicate that the proposed approach is more accurate and stable than the other approaches. Overall, the results demonstrate that the proposed approach is useful to develop design hyetographs for ungauged sites.     

黄河中游府谷站"03·7"洪峰流量合理性分析

从府谷水文站洪水过程测验控制情况、天桥电厂下泄流量推算和天桥电厂-府谷区间洪水加入等3个方面,对府谷站2003年7月30日洪峰测报是否偏大的问题进行了分析.结果表明,天桥电厂下泄洪峰估算定性偏小,府谷站洪峰测验过程控制良好,天桥-府谷区间产生了1800m3/s的洪峰直接加在天桥电厂下泄的洪峰上,使府谷站8时出现12800m3/s的洪峰是可信的;府谷水文站出现低水位大流量的现象主要是断面冲刷造成的.     

基于Copula函数的洪水峰量联合设计方法研究

为明晰洪水峰量联合设计的特点,以岗南水库洪水为例,基于Gumbel Copula函数,分析了AND、OR、Kendall、生存Kendall 4种重现期的优缺点,采用极大似然法、同频率法、条件最可能组合法3种方法计算了联合设计值。结果表明: ①AND和OR重现期在危险域和安全域的识别上存在局限性;相对而言,Kendall重现期更合理,但其安全域是无界的,这与实际不符;生存Kendall重现期则界定了有界的安全域,使得重现期的概念在逻辑上更科学合理。② 3种设计值计算方法的差别不大,但从简单实用角度出发,推荐采用同频率法计算设计值。③不同重现期标准的设计值差别比较明显,基于OR重现期计算的设计值总是最大的,生存Kendall、Kendall重现期设计值次之,AND重现期设计值最小。④推荐采用生存Kendall重现期进行两变量洪水设计,因其有比较严谨的理论基础,且设计结果兼顾了安全性与经济性。⑤两变量联合设计值与单变量设计值的差异受变量间相关性的影响较大,且变量相关性越弱,差异越大。研究显示,基于生存Kendall重现期、采用同频率法计算设计值是目前较为科学合理的洪水峰量联合设计途径。     

基于Copula函数的气候变化下洪水峰量联合分析

为研究气候变化对北江流域洪水特征发生频率的影响,采用分位数映射(Quantile Mapping,QM)后处理方法校正BCC_CSM1.1气候模式2种情景(RCP4.5和RCP8.5)下的气候数据,用于SWAT模型模拟历史(1965—2010年)和未来(2030—2064年、2065—2099年)的北江流域径流量,并采用单变量分析法和基于Copula函数的双变量联合分析法分别对各时期年最大洪峰流量Q和年最大7 d洪量W进行对比分析。结果表明:除RCP8.5下2065—2099年的W外,重现期(T≥50 a)越大,气候变化对Q和W的影响越大; RCP4.5下气候变化对Q和W的影响较RCP8.5下大;2种未来情景下,气候变化对Q的影响均大于对W的影响;对于同一重现期,双变量联合分析法推求的洪水特征设计值较单变量分析法的偏安全。该研究结合了气候变化和双变量联合分析,对变化环境下的洪水风险评价与管理具有一定的参考价值。     

近期黄河洪峰增值现象研究综述

对小浪底水库运用之前黄河干流洪峰增值现象的研究进行了回顾,对小浪底水库运用后洪峰增值的洪水场次进行了系统整理,并对近期黄河洪峰增值现象的研究成果进行了综述,指出了已有的河槽形态变化观点、"孤立波"和"水跃"观点、减阻观点、密度差观点、沙坝观点、扰动说等研究成果存在的问题,认为小浪底水库运用前后小浪底—花园口区间洪水洪峰增值机理是相同的,与洪水是否漫滩无关。另外,建议加测足够的野外资料,然后从理论上分析洪峰增值的机理。     

2010年黄河调水调沙期间花园口洪峰增大的成因

对2010年黄河调水调沙期间花园口站出现的洪峰增值现象进行了分析,结果表明:洪峰增大的主要原因是洪水运行过程中,铁谢-逯村间展宽河段内粗颗粒泥沙发生沉积,产生了一个临时的潜水沙坝,造成其上游的蓄水量增加,在水流的持续作用下,沙坝被冲开从而造成了逯村站流量的加大;在洪水波向下游运行的过程中,又产生了沿程河槽的冲刷,流速递增,从而造成了流量进一步加大.     

Estimation of Peak Flow Rates for Small Drainage Areas

Runoff plots are important for soil loss measurements, and increasing numbers of plots use automatic equipment. To choose equipment with appropriate capacities, the peak flow rate must be known. The peak flow rate is also an important parameter in the modified universal soil loss equation (MUSLE) which calculate the soil loss from upland slope. The available peak flow rate equations are primarily for the watershed scale, not for small drainage areas like runoff plot. This study’s purpose was to derive an equation suitable for the small drainage areas. A total of 149 runoff events on 5 runoff plots were used to develop a peak flow rate equation for the hillslope scale. All plots are located in the Tuanshangou catchment, Zizhou county, Shaanxi province, China. Dimensionless analyses were used to determine the equation form of linear regression analyses. The results revealed that the peak flow rate was significantly correlated with plot area, slope steepness, runoff depth, rainfall depth and the maximum 30-min rainfall intensity. Two equations were developed to estimate peak flow. The model efficiencies of both equations exceeded 0.9. The equations developed in this study represent an important complement to existing peak flow rate equations. These new equations will facilitate the design of soil conservation practices and/or the selection of flow-observation equipment for small drainage areas.     

Combined Effects of Parallel and Series Detention Basins for Flood Peak Reduction

A simple analytical method is proposed that allows a preliminary evaluation of the overall efficiency of a detention basin system for flood risk reduction in a specific target section. Solutions are provided both for parallel and series systems, under some simplifying assumptions concerning the linearity of detention basin, river network and watershed responses. Further, for the series configuration a regressive model is proposed for the computation of the overall efficiency, because of the complexity of analytical solution. A case study is also presented, where the overall efficiency of a system of nine detention basins is computed by means of both the analytical and the regressive model. Results are discussed to assess the different influence of detention basins in parallel or in a series system.     

利用简测法施测分析山区河流最大洪峰流量方法探讨

河流突发最大洪峰流量时,利用施测断面岸边1～3条测速垂线平均流速与断面平均流违的相关关系,分析其相关系数与误差,可较为精确地求得断面洪峰流量.     

汾河水库以洪峰推算洪量法预估入库洪水量

用水库上游水文测站报汛实测洪峰，通过实测洪峰值计算入库洪水量，在汛期水库调度中简单实用，易于被水库基层管理人员掌握。     

贵州暴雨洪水计算综述

简要阐述设计洪水的主要计算方法。对建国后贵州主要应用的《贵州省水文实用手册》、《中小流域雨洪计算综合法》、《贵州省暴雨洪水计算实用手册》及其修订本和其他一些有关成果 ,以暴雨资料计算设计洪水的方法进行了概述。文中系统介绍推介的贵州现阶段主要应用的暴雨洪水计算方法 ,以及在使用中解决几个具体问题的意见 ,对岩溶地区小流域和特小流域 ,及不透水复盖面积较大的流域等异常情况的暴雨洪水计算问题提出一些具体处理方法 ,可供进行设计洪水计算时参考。