Assessment of extreme discharges of the Vltava River in Prague

Abstract

Damage of construction works due to flooding in 1997 and 2002 in the Czech Republic initiated investigations of structural failures and reassessment of available data for discharge extremes. In this study, hydrological data for 166 annual maximum discharges of the Vltava River in Prague since 1827 are analysed using various statistical methods. Moment characteristics of the measurements -the mean, standard deviation and skewness -are estimated and the enhancing effect of an exceptional observation in 2002 is detected. The annual maxima are described by two-or three-parameter lognormal distributions and the extreme value distributions of the type I and II. Standard statistical Kolmogorov and chi-square tests are applied to assess goodness of fit of the theoretical models. It appears that a two-parameter lognormal distribution may be the most suitable theoretical model. Assuming this distribution, extreme discharges corresponding to characteristic and design values are estimated. It is shown that the partial safety factor estimated from the measurements significantly differs from the recommended value of 1.5. The discharge in 2002 corresponds to an exceptionally long return period. It is concluded that statistical methods provide a valuable background for evaluation and prediction of discharges. However, the presented analysis should be further improved to include non-statistical aspects that influence discharges such as the effects of water management and deforestation.

Comparison of Three-Parameter Distributions in Controlled Catchments for a Stationary and Non-Stationary Data Series

“…The maximum peak flow of each year in the longest observation period consists of the sample series and is used in the annual maximum (AM) approach [4,5,[20][21][22][23][24][25]. The AM is still the most commonly used method in at-side FFA [12,20,24,26,27] and in non-stationary FFA in many countries [10,[16][17][18], including the Czech Republic and Poland.…”

“…In the hydrological literature [5,21,[26][27][28], traditional two-parameter distributions are most commonly studied. Despite the satisfactory results yielded by these distributions, the use of multi-parameter distributions could lead to more appropriate fits between simulated and observed data [11,15].…”

“…The research does not cover all the available stations in Poland, especially in the area of the Upper Odra basin [34]. Recently, in 2008, in the research area, studies of three-parameter Log-Normal and two-parameter distributions such as the Log-Normal, Gumbel, and Fechet distribution were used for the Vltava river, Prague station [26]. Later, only two-parameter distributions such as the Log-Normal, Log-Pearson III, Gumbel, and Fechet were tested.…”

Risk assessment of heritage structures endangered by fluvial floods

“…Gumbel and lognormal distributions are also widely used (see Holicky et al [13]). In general appropriate models should be selected on the basis of the statistical tests and experience with distributions of flows at other (similar) localities.…”