A methodology for the estimation of short duration design storms in South Africa using a regional approach based on L-moments

Smithers, J.; Schulze, R. E.

doi:10.1016/s0022-1694(00)00374-7

Cited by 74 publications

(54 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The GEV distribution is widely used for modelling hydro-climatological extremes (e.g. Alila, 1999;Smithers and Schulze, 2001;Castellarin et al, 2001;Kharin and Zwiers, 2005;Fowler and Ekström, 2009), and frequency analyses of precipitation extremes have also confirmed its applicability in central Europe (the Czech Republic - Kyselý and Picek, 2007a;Slovakia -Kohnová et al, 2006;Gaál et al, 2008b). The T -year growth factors (i.e.…”

Section: Estimation Of Growth Factors and Quantilesmentioning

confidence: 98%

Comparison of region-of-influence methods for estimating high quantiles of precipitation in a dense dataset in the Czech Republic

Gaál

Kyselý

2009

Hydrol. Earth Syst. Sci.

View full text Add to dashboard Cite

Abstract. In this paper, we implement the region-ofinfluence (ROI) approach for modelling probabilities of heavy 1-day and 5-day precipitation amounts in the Czech Republic. The pooling groups are constructed according to (i) the regional homogeneity criterion (assessed by a built-in regional homogeneity test), which requires that in a pooling group the distributions of extremes are identical after scaling by the at-site mean; and (ii) the 5T rule, which sets the minimum number of stations to be included in a pooling group for estimation of a quantile corresponding to return period T . The similarity of sites is evaluated in terms of climatological and geographical site characteristics. We carry out a series of sensitivity analyses by means of Monte Carlo simulations in order to explore the importance of the individual site attributes, including hybrid pooling schemes that combine both types of the site attributes with different relative weights.We conclude that in a dense network of precipitation stations in the Czech Republic (on average 1 station in a square of about 20×20 km), the actual distance between the sites plays the most important role in determining the similarity of probability distributions of heavy precipitation. There are, however, differences between the optimum pooling schemes depending on the duration of the precipitation events. While in the case of 1-day precipitation amounts the pooling scheme based on the geographical proximity of sites outperforms all hybrid schemes, for multi-day amounts the inclusion of climatological site characteristics (although with much lower weights compared to the geographical distance) enhances the performance of the pooling schemes. This finding is in agreement with the climatological expectation since multi-day heavy precipitation events are more closely linked Correspondence to: L. Gaál (ladislav.gaal@gmail.com) to some typical precipitation patterns over central Europe (related e.g. to the varied roles of Atlantic and Mediterranean influences) while the dependence of 1-day extremes on climatological characteristics such as mean annual precipitation is much weaker.The findings of the paper show a promising perspective for an application of the ROI methodology in evaluating outputs of regional climate models with high resolution: the pooling schemes might serve for defining weighting functions, and the large spatial variability in the grid-box estimates of high quantiles of precipitation amounts may efficiently be reduced.

show abstract

Section: Estimation Of Growth Factors and Quantilesmentioning

confidence: 98%

Comparison of region-of-influence methods for estimating high quantiles of precipitation in a dense dataset in the Czech Republic

Gaál

Kyselý

2009

Hydrol. Earth Syst. Sci.

View full text Add to dashboard Cite

show abstract

“…However, from the literature it is clear that the four distributions analysed here, Gumbel, GEV, LN3 and LP3, are indeed among those commonly used for frequency analyses of ERS (e.g. Table II on page A6.7 of Cunnane, 1989; and also Daud et al, 2002;Porras & Porras, 2001;Schaefer, 1990;Smithers & Schulze, 2001;Slimani & Lebel, 1987;SWW, 1990). In order to give an impression of the pdfs based on the 54-element recorded sample series at Florya, the histograms of these four distributions for 5-min and 24-h ERS, along with the pdfs, are plotted in Fig.…”

Section: Study Contextmentioning

confidence: 72%

Divergence criteria in extreme rainfall series frequency analyses

Haktanır

2003

Hydrological Sciences Journal

View full text Add to dashboard Cite

Extreme rainfall series (ERS) are treated as successive-duration events of from 5 min to 24 h in most parts of the world. In Turkey, as in European countries, the ERS of standard durations of 5, 10, 15, 30, 60 min, and 2, 3, 4, 5, 6, 8, 12, 18, 24 h are recorded, and these sample series are analysed to ultimately determine the depthduration-frequency (DDF) relationships. If a probability distribution function (pdf) is used for these ERS, the frequency curves in the form of graphical quantile functions may intersect each other at high return periods, due to possible data recording errors, and an extreme rainfall magnitude of a longer duration may turn out to be smaller than that of a shorter duration beyond some high return period. In this study: (a) the criteria of divergence of the quantile functions of various pdfs used in frequency analyses of ERS are depicted; (b) necessary and sufficient conditions for divergence of the quantile functions and ultimately of the DDF curves are analytically deduced; (c) scaling relationships between conventional statistics and rainstorm durations, and between probability-weighted moments and rainstorm durations, are investigated; (d) necessary adjustments to the parameters of four commonly-used pdfs are shown; and (e) a comprehensive example using rainfall data recorded at the Florya gauging station (Istanbul, Turkey) is presented.Key words extreme precipitation; frequency analysis of extreme rainfalls; depth-durationfrequency curves; divergence of quantile functions Critère de divergence dans des analyses fréquentielles de séries de pluies extrêmesRésumé Généralement, dans le monde, les séries de pluies extrêmes sont traitées comme des événements de durées successives allant de 5 min à 24 h. En Turquie, comme dans certains pays européens, les séries de pluies extrêmes sont enregistrées pour les durées standard de 5, 10, 15, 30 et 60 min, et 2, 3, 4, 5, 6, 8, 12 et 24 h; et ces séries d'échantillonnage sont analysées pour finalement déterminer les relations hauteur-durée-féquence (HDF). Si une fonction densité de probabilité (fdp) est utilisée pour ces séries de pluies extrêmes, les courbes de fréquences mises sous la forme graphique de fonctions de quantiles peuvent se couper pour les grandes périodes de retour, à cause d'éventuelles erreurs d'acquisition. Cela signifie que, au delà d'une certaine période de retour, la hauteur de pluie extrême pendant une longue durée peut apparaître plus faible que la hauteur correspondante pendant une durée plus courte. Dans cette étude: (a) le critère de divergence des fonctions de quantiles de diverses fdp utilisées en analyse fréquentielle de séries de pluies extrêmes est décrit; (b) les conditions nécessaires et suffisantes pour la divergence des fonctions de quantiles et donc des courbes HDF sont déduites analytiquement; (c) les relations d'échelles sont étudiées, entre les statistiques conventionnelles et les durées de pluie, et entre les moments de probabilité pondérée et les durées de pluie; (d) les nécessaires ajustements...

show abstract

“…We avoid using site statistics derived from the examined samples of extremes when forming the regions; this is in accord with the idea that testing regional homogeneity -which makes use of site statistics -should be independent on the process of forming the regions (cf Hosking and Wallis, 1997;Castellarin et al, 2001;Smithers and Schulze, 2001). The key issue of the ROI method is to decide on the number of similar sites that form the pooling group of any given site, i.e.…”

Section: Roicli3mentioning

confidence: 98%

Comparison of regional and at‐site approaches to modelling probabilities of heavy precipitation

Kyselý¹,

Gaál²,

Picek³

2011

Intl Journal of Climatology

View full text Add to dashboard Cite

Several approaches to estimating distributions of precipitation extremes are compared by means of simulation experiments, and their applications into observed data in the Czech Republic are evaluated. Regional frequency models, which take into account data in fixed or flexible 'regions' when fitting a distribution at any site, lead to estimates with much smaller errors compared to a single-site analysis, and efficiently reduce random and climatologically irrelevant variations in the estimates of the model parameters and high quantiles. The region-of-influence (ROI) methodology with a built-in regional homogeneity test is recognized as a useful approach, with the model based on proximity of sites outperforming the Hosking-Wallis regional frequency analysis. Comparison of estimates of the return period of a heavy precipitation event on 24 June 2009, which triggered a disastrous local flash flood, illustrates that the at-site analysis leads to unrealistic and extremely uncertain estimates that strongly depend on whether or not a single outlying observation is involved in the sample, while all regional methods yield return periods in the same order of several hundreds of years, notwithstanding whether the 2009 data are included in the sample. The ROI method may be found useful for modelling probabilities of other meteorological variables, extremes of which are strongly influenced by sampling variability, and may also represent an efficient tool for 'smoothing' random variations in the estimates of model parameters and high quantiles of precipitation in high-resolution regional climate model simulations.

show abstract

A methodology for the estimation of short duration design storms in South Africa using a regional approach based on L-moments

Cited by 74 publications

References 12 publications

Comparison of region-of-influence methods for estimating high quantiles of precipitation in a dense dataset in the Czech Republic

Comparison of region-of-influence methods for estimating high quantiles of precipitation in a dense dataset in the Czech Republic

Divergence criteria in extreme rainfall series frequency analyses

Comparison of regional and at‐site approaches to modelling probabilities of heavy precipitation

Contact Info

Product

Resources

About