Derived flood frequency distribution and sensitivity analysis to variations in model parameters

2012 ◽  
Vol 43 (3) ◽  
pp. 249-261 ◽  
Author(s):  
Alejandra I. Vornetti ◽  
Rafael S. Seoane
Keyword(s):  
Frequency Distribution ◽  
Method Of Moments ◽  
Flood Frequency ◽  
Model Parameters ◽  
Unit Hydrograph ◽  
Frequency Distributions ◽  
New Model ◽  
Instantaneous Unit Hydrograph ◽  
Infiltration Parameters ◽  
Frequency Curves

In this paper we propose a new derived flood frequency distribution approach using the Nash instantaneous unit hydrograph (IUH) as the catchment's response model and analyze the sensitivity of flood frequency distributions to variations in the model parameters. We analyzed the effect of applying the Nash IUH to estimate peak flows in two basins in the province of Buenos Aires (Argentina). For the new flood frequency distribution, the Nash IUH parameters were estimated using the method of moments and a technique that relates the IUH parameters to the basin geomorphologic and hydraulic features. After applying the proposed derived flood frequency distributions to the basins, it is concluded that the new model (which includes the Nash IUH) yields similar results to those attained with a model developed by Raines and Valdés; the new model parameters can be estimated using a technique for ungauged basins. Also observed is a change in the shape of the flood frequency curves according to the IUH parameter estimation technique and to the set of infiltration parameters used.

scholarly journals Regional parent flood frequency distributions in Europe – Part 1: Is the GEV model suitable as a pan-European parent?

2014 ◽  
Vol 18 (11) ◽  
pp. 4381-4389 ◽  
Author(s):  
J. L. Salinas ◽  
A. Castellarin ◽  
A. Viglione ◽  
S. Kohnová ◽  
T. R. Kjeldsen
Keyword(s):  
Statistical Model ◽  
Frequency Distribution ◽  
Climatic Factors ◽  
Extreme Value ◽  
Flood Frequency ◽  
Generalized Extreme Value Distribution ◽  
Statistical Hypothesis ◽  
Generalized Extreme Value ◽  
Frequency Distributions ◽  
Hypothetical Scenario

Abstract. This study addresses the question of the existence of a parent flood frequency distribution on a European scale. A new database of L-moment ratios of flood annual maximum series (AMS) from 4105 catchments was compiled by joining 13 national data sets. Simple exploration of the database presents the generalized extreme value (GEV) distribution as a potential pan-European flood frequency distribution, being the three-parameter statistical model that with the closest resemblance to the estimated average of the sample L-moment ratios. Additional Monte Carlo simulations show that the variability in terms of sample skewness and kurtosis present in the data is larger than in a hypothetical scenario where all the samples were drawn from a GEV model. Overall, the generalized extreme value distribution fails to represent the kurtosis dispersion, especially for the longer sample lengths and medium to high skewness values, and therefore may be rejected in a statistical hypothesis testing framework as a single pan-European parent distribution for annual flood maxima. The results presented in this paper suggest that one single statistical model may not be able to fit the entire variety of flood processes present at a European scale, and presents an opportunity to further investigate the catchment and climatic factors controlling European flood regimes and their effects on the underlying flood frequency distributions.

Using Tolerance-Maps to Generate Frequency Distributions of Clearance for Pin-Hole Assemblies

2006 ◽  
Author(s):  
Gaurav Ameta ◽  
Joseph K. Davidson ◽  
Jami J. Shah
Keyword(s):  
Mathematical Model ◽  
Frequency Distribution ◽  
Probabilistic Representation ◽  
Frequency Distributions ◽  
New Model ◽  
Iso Standards ◽  
Material Condition ◽  
Geometric Tolerances ◽  
The Future

A new mathematical model for representing the geometric variations of lines is extended to include probabilistic representations of 1-D clearance which arise from multidimensional variations of an axis, a hole and a pin-hole assembly. The model is compatible with the ASME/ANSI/ISO Standards for geometric tolerances. Central to the new model is a Tolerance-Map (T-Map), a hypothetical volume of points that models the 3-D variations in location and orientation for a segment of a line (the axis), which can arise from tolerances on size, position, orientation, and form. Here it is extended to model the increase in yield that occurs when maximum material condition (MMC) is specified. The frequency distribution of 1-D clearance is decomposed into manufacturing bias, i.e. toward certain regions of a Tolerance-Map, and into a geometric bias that can be computed from the geometry of multidimensional T-Maps. Although the probabilistic representation in this paper is focused on geometric bias and manufacturing bias is presumed to be uniform, the method is robust enough to include manufacturing bias in the future. Geometric bias alone shows a greater likelihood of small clearances than large clearances between an assembled pin and hole.

scholarly journals On the quest for a pan-European flood frequency distribution: effect of scale and climate

2013 ◽  
Vol 10 (5) ◽  
pp. 6321-6358 ◽  
Author(s):  
J. L. Salinas ◽  
A. Castellarin ◽  
S. Kohnová ◽  
T. R. Kjeldsen
Keyword(s):  
Frequency Distribution ◽  
Flood Frequency ◽  
Mean Annual Precipitation ◽  
Annual Maximum ◽  
Catchment Scale ◽  
Gev Distribution ◽  
Frequency Distributions ◽  
Definition Of ◽  
Coefficient Of Skewness ◽  
Annual Maximum Series

Abstract. This study addresses the question of the existence of a parent flood frequency distribution on a European scale and aims to better understand the effect of catchment scale and climate on the statistical properties of regional flood frequency distributions. A new database of L-moment ratios of annual maximum series (AMS) of peak discharges from 4105 catchments was compiled by joining 13 national datasets. Using this database and additional Monte Carlo simulations, the Generalised Extreme Value (GEV) distribution appears as a potential pan-European flood frequency distribution, being the 3-parameter statistical model with the closest resemblance to the estimated average of the sample L-moment ratios, but failing to represent the kurtosis dispersion, especially for high skewness values. A more detailed investigation performed on a subset of the database (Austria, Italy and Slovakia, involving a total of 813 catchments with more than 25 yr of record length) confirms that the GEV distribution provides a better representation of the averaged sample L-moment ratios compared to the other distributions considered, for catchments with medium to high values of mean annual precipitation (MAP) independently of catchment area, while the 3-parameter Lognormal distribution is probably a more appropriate choice for dry (low MAP) intermediate-sized catchments, which presented higher skewness values. Sample L-moment ratios do not follow systematically any of the theoretical 2-parameter distributions. In particular, the averaged values of L-coefficient of skewness (L-Cs) are always larger than Gumbel's fixed L-Cs. The results presented in this paper contribute to progress towards the definition of a set of pan-European flood frequency distributions and to assess possible effects of environmental change on its properties.

scholarly journals Combining regional rainfall frequency analysis and rainfall-runoff modelling to derive frequency distributions of peak flows in ungauged basins: a proposal for Sicily region (Italy)

2017 ◽  
Vol 44 ◽  
pp. 15-22 ◽  
Author(s):  
Brunella Bonaccorso ◽  
Giuseppina Brigandì ◽  
Giuseppe Tito Aronica
Keyword(s):  
Monte Carlo ◽  
Frequency Analysis ◽  
Extreme Rainfall ◽  
Flood Frequency ◽  
Regional Frequency Analysis ◽  
Ungauged Basins ◽  
Rainfall Runoff ◽  
Frequency Distributions ◽  
Monte Carlo Approach ◽  
Frequency Curves

Abstract. In the present study an attempt is made to provide a general Monte Carlo approach for deriving flood frequency curves in ungauged basins in Sicily region (Italy). The proposed procedure consists of (i) a regional frequency analysis of extreme rainfall series, combined with Huff curves-based synthetic hyetographs, for design storms and (ii) a rainfall-runoff model, based on the Time-Area technique, to generate synthetic hydrographs. Validation of the procedure is carried out on four gauged river basins in Sicily region (Italy), where synthetic peak flow frequency curves, obtained by simulating 1000 flood events, are compared with observed values. Results of the application reveal that the proposed Monte Carlo approach is suitable to reproduce with reasonable accuracy the hydrologic response of the investigated basins. Given its relative simplicity, the developed procedure can be easily extended to poorly gauged or ungauged basins.

scholarly journals Climatic and basin factors affecting the flood frequency curve: PART I – A simple sensitivity analysis based on the continuous simulation approach

2000 ◽  
Vol 4 (3) ◽  
pp. 463-482 ◽  
Author(s):  
A. M. Hashemi ◽  
M. Franchini ◽  
P. E. O’Connell
Keyword(s):  
Time Series ◽  
Sensitivity Analysis ◽  
Flood Frequency ◽  
Model Parameters ◽  
Rainfall Runoff ◽  
Frequency Curve ◽  
Rainfall Runoff Model ◽  
Runoff Model ◽  
Insight Into ◽  
Frequency Curves

Abstract. Regionalized and at-site flood frequency curves exhibit considerable variability in their shapes, but the factors controlling the variability (other than sampling effects) are not well understood. An application of the Monte Carlo simulation-based derived distribution approach is presented in this two-part paper to explore the influence of climate, described by simulated rainfall and evapotranspiration time series, and basin factors on the flood frequency curve (ffc). The sensitivity analysis conducted in the paper should not be interpreted as reflecting possible climate changes, but the results can provide an indication of the changes to which the flood frequency curve might be sensitive. A single site Neyman Scott point process model of rainfall, with convective and stratiform cells (Cowpertwait, 1994; 1995), has been employed to generate synthetic rainfall inputs to a rainfall runoff model. The time series of the potential evapotranspiration (ETp) demand has been represented through an AR(n) model with seasonal component, while a simplified version of the ARNO rainfall-runoff model (Todini, 1996) has been employed to simulate the continuous discharge time series. All these models have been parameterised in a realistic manner using observed data and results from previous applications, to obtain ‘reference’ parameter sets for a synthetic case study. Subsequently, perturbations to the model parameters have been made one-at-a-time and the sensitivities of the generated annual maximum rainfall and flood frequency curves (unstandardised, and standardised by the mean) have been assessed. Overall, the sensitivity analysis described in this paper suggests that the soil moisture regime, and, in particular, the probability distribution of soil moisture content at the storm arrival time, can be considered as a unifying link between the perturbations to the several parameters and their effects on the standardised and unstandardised ffcs, thus revealing the physical mechanism through which their influence is exercised. However, perturbations to the parameters of the linear routing component affect only the unstandardised ffc. In Franchini et al. (2000), the sensitivity analysis of the model parameters has been assessed through an analysis of variance (ANOVA) of the results obtained from a formal experimental design, where all the parameters are allowed to vary simultaneously, thus providing deeper insight into the interactions between the different factors. This approach allows a wider range of climatic and basin conditions to be analysed and reinforces the results presented in this paper, which provide valuable new insight into the climatic and basin factors controlling the ffc. Keywords: stochastic rainfall model; rainfall runoff model; simulation; derived distribution; flood frequency; sensitivity analysis

scholarly journals Application of HEC-HMS programme for the reconstruction of a flood event in an uncontrolled basin / Zastosowanie programu HEC-HMS do odtworzenia wezbrania powodziowego w zlewni niekontrolowanej

2013 ◽  
Vol 18 (9) ◽  
pp. 13-20 ◽  
Author(s):  
Andrzej Wałęga
Keyword(s):  
Flood Event ◽  
Model Parameters ◽  
Army Corps ◽  
Army Corps Of Engineers ◽  
Unit Hydrograph ◽  
Ungauged Basin ◽  
Instantaneous Unit Hydrograph ◽  
Determination Of Parameters ◽  
Department Of The Army ◽  
Different Characteristics

Abstract The paper presents an assessment of the applicability of HEC-HMS programme to simulate a precipitation flood event in an ungauged basin. The programme has been developed by the Department of the Army Corps of Engineers and enables conducting hydrological calculations for basins with different characteristics and including a number of meteorological factors. The application of this model in Polish conditions was verified in the basin of the Stobnica River - a right tributary of the Wisłok River. The calculations were carried out for the flood event caused by a continuous rain, which occurred in April 1998. Four hydrological models were compared: geomorpho-climatic instantaneous unit hydrograph by Nash - GcIUH_Nash, Snyder's synthetic unit hydrograph with the determination of parameters by regression models - Snyder_reg and standard method - Snyder_ stand and Clark's instantaneous unit hydrograph - IUH_Clark, where the model parameters were optimized in the programme. The calculations revealed that the best simulation results were obtained with the Snyder_stand and Snyder_reg models. Further research should be directed to verifying the applicability of HEC- -HMS programme for hydrological analyses of much more extensive hydrometric material and basins with different characteristics.

The relationship between morphoclimatic characteristics and peak flows: A case study of the southern Alborz Basins, Iran

2010 ◽  
Vol 34 (2) ◽  
pp. 173-182 ◽  
Author(s):  
M. Mohseni Saravi ◽  
M. Abasizadeh ◽  
A. Malekian ◽  
A.A. Nazari Samani
Keyword(s):  
Stream Flow ◽  
Flood Frequency ◽  
Regional Frequency Analysis ◽  
Model Parameters ◽  
Frequency Distributions ◽  
Ungauged Sites ◽  
Annual Peak ◽  
Study Results ◽  
Flood Estimation ◽  
Water Response

Ideally, flood estimation in hydrological studies and applications requires recorded data, but this is missing or insufficient in many cases for a variety of reasons. Approaches to modelling the hydrologic response of ungauged basins may use physical characteristics of watersheds either to directly infer values for the parameters of hydrologic models or to establish regression relationships between watershed structure and model parameters. Most studies, however, are concentrated in humid hydroclimatic zones. In this study, a regional frequency analysis of annual peak maximum series of flood flows from rivers of the arid southern Alborz basins, Iran, was conducted, including identification of suitable regional flood frequency distributions. The peak stream flow for different data periods was estimated based on physiographic as well as climatic parameters. Because of the close relationship between elevation, stream flow regime and hydrological features, the development of a water response model first involved delimiting homogenous hydrological regions by using two-step cluster analysis. Equations were established for each region relating peak flow of different return periods and the basin parameters. The study results also revealed that the regional regression models developed in this study could be applied reasonably well at relatively similar ungauged sites, which is of potential interest in other water-stressed areas of the world, particularly given expected scenarios of population growth, development and climatic change.

scholarly journals Effects of runoff thresholds on flood frequency distributions

2008 ◽  
Vol 5 (2) ◽  
pp. 903-933 ◽  
Author(s):  
A. Gioia ◽  
V. Iacobellis ◽  
S. Manfreda ◽  
M. Fiorentino
Keyword(s):  
River Basin ◽  
Test Site ◽  
Flood Frequency ◽  
Model Parameters ◽  
Runoff Generation ◽  
Antecedent Soil Moisture ◽  
Frequency Distributions ◽  
Basin Scale ◽  
Modelling Assumptions ◽  
New Formulation

Abstract. Runoff generation during extreme floods usually occurs whenever rainfall forcing exceeds a given threshold. In many cases, different thresholds may be identified as responsible of the hydrological losses during ordinary events or extraordinary events at the basin scale. Such thresholds are shown to be related to the dynamics of soil saturation of the river basin and to account for the high skewness of their annual flood distributions. In basins where ordinary floods are mostly due to a small portion of the surface which is particularly prone to produce runoff, depending on permeability of a river basin and its antecedent soil moisture conditions, severe rainfall may exceed a basin-wide soil storage threshold and produce the so-called outlier events responsible of the high skewness of floods distributions. In this context, the derived theoretical model based on the concept of variable contributing area to peak flow proposed by Iacobellis and Fiorentino (2000) was generalized with the aim of incorporating such kind of dynamics in the description of the phenomena. The work produced a new formulation of the derived distribution where the two runoff components are explicitly considered. The present work was validated by using as test site a group of basins belonging to Southern Italy and characterized by flood distributions with high skewness. The application of the proposed model provided a good fitting to the observed distributions. Moreover, model parameters were found to be strongly related to physiographic basin characteristics giving consistency to the modelling assumptions.

scholarly journals Regional analysis of runoff thresholds behaviour in Southern Italy based on theoretically derived distributions

2011 ◽  
Vol 26 ◽  
pp. 139-144 ◽  
Author(s):  
M. Fiorentino ◽  
A. Gioia ◽  
V. Iacobellis ◽  
S. Manfreda
Keyword(s):  
Frequency Distribution ◽  
Southern Italy ◽  
Regional Analysis ◽  
Flood Frequency ◽  
Annual Maximum ◽  
Runoff Generation ◽  
Frequency Distributions

Abstract. The analysis of runoff thresholds and, more in general, the identification of main mechanisms of runoff generation controlling the flood frequency distribution is investigated, by means of theoretically derived flood frequency distributions, in the framework of regional analysis. Two nested theoretically-derived distributions are fitted to annual maximum flood series recorded in several basins of Southern Italy. Results are exploited in order to investigate heterogeneities and homogeneities and to obtain useful information for improving the available methods for regional analysis of flood frequency.

scholarly journals Runoff thresholds in derived flood frequency distributions

2008 ◽  
Vol 12 (6) ◽  
pp. 1295-1307 ◽  
Author(s):  
A. Gioia ◽  
V. Iacobellis ◽  
S. Manfreda ◽  
M. Fiorentino
Keyword(s):  
Source Area ◽  
Infiltration Rate ◽  
Flood Frequency ◽  
Model Parameters ◽  
Runoff Generation ◽  
Frequency Model ◽  
Frequency Distributions ◽  
Proposed Model ◽  
Basin Scale ◽  
New Formulation

Abstract. In general, different mechanisms may be identified as responsible of runoff generation during ordinary events or extraordinary events at the basin scale. In a simplified scheme these mechanisms may be represented by different runoff thresholds. In this context, the derived flood frequency model, based on the effect of partial contributing areas on peak flow, proposed by Iacobellis and Fiorentino (2000), was generalized by providing a new formulation of the derived distribution where two runoff components are explicitly considered. The model was tested on a group of basins in Southern Italy characterized by annual maximum flood distributions highly skewed. The application of the proposed model provided good results in terms of descriptive ability. Model parameters were also found to be well correlated with geomorphological basin descriptors. Two different threshold mechanisms, associated respectively to ordinary and extraordinary events, were identified. In fact, we found that ordinary floods are mostly due to rainfall events exceeding a threshold infiltration rate in a small source area, while the so-called outlier events, responsible of the high skewness of flood distributions, are triggered when severe rainfalls exceed a threshold storage in a large portion of the basin.

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