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This study presents a flood frequency analysis for the Vltava River catchment using a major profile in Prague. The estimates of peak discharges for the pre-instrumental period of 1118-1824 based on documentary sources were carried out using different approaches. 187 flood peak discharges derived for the pre-instrumental period augmented 150 records for the instrumental period of 1825-2013. Flood selection was based on Q10 criteria. Six flood-rich periods in total were identified for 1118-2013. Results of this study correspond with similar studies published earlier for some Central European catchments, except for the period around 1750. Presented results indicate that the territory of the present Czech Republic might have experienced in the past, extreme floods comparable, with regard to peak discharge (POTQ10) and frequency, to the flood events recorded recently. [ABSTRACT FROM AUTHOR]

The paper aims to reconstruct peak discharges of historic floods in an urbanized area of the historic city of Prague based on documentary sources from pre-instrumental and the early instrumental period (1481-1825). Approximately 20-30 maximum water levels are denoted by flood-marks, accounts describing or related at unchanged sites, or by early instrumental measurements. The challenge in this reconstruction is the identification and consideration of man-made floodplain modifications influencing the cross-section area and the hydraulic roughness. In order to overcome this problem, a simple approach to estimate peak discharges of historic floods has been developed and applied to the River Vltava. This approach includes a procedure for reconstructing the hydraulic parameters of the river channel and inundated floodplain, coupled with an approach for the verification of estimated peak discharge reliability. As a result of the different hydraulic characteristics associated with ice jam floods all winter-flood events are excluded to avoid their potential inclusion. We present 18 reconstructed discharge maxima. The validation of the technique by comparison with the recent gauged flood of 2002 reveals results of adequate accuracy. The comparison also shows that the flood event of 2002 was conspicuously greater than all calculated summer floods in 1481-1825. [ABSTRACT FROM AUTHOR]

There are concerns that recent climate change is altering the frequency and magnitude of river floods in an unprecedented way 1 . Historical studies have identified flood-rich periods in the past half millennium in various regions of Europe 2 . However, because of the low temporal resolution of existing datasets and the relatively low number of series, it has remained unclear whether Europe is currently in a flood-rich period from a long-term perspective. Here we analyse how recent decades compare with the flood history of Europe, using a new database composed of more than 100 high-resolution (sub-annual) historical flood series based on documentary evidence covering all major regions of Europe. We show that the past three decades were among the most flood-rich periods in Europe in the past 500 years, and that this period differs from other flood-rich periods in terms of its extent, air temperatures and flood seasonality. We identified nine flood-rich periods and associated regions. Among the periods richest in floods are 1560-1580 (western and central Europe), 1760-1800 (most of Europe), 1840-1870 (western and southern Europe) and 1990-2016 (western and central Europe). In most parts of Europe, previous flood-rich periods occurred during cooler-than-usual phases, but the current flood-rich period has been much warmer. Flood seasonality is also more pronounced in the recent period. For example, during previous flood and interflood periods, 41 per cent and 42 per cent of central European floods occurred in summer, respectively, compared with 55 per cent of floods in the recent period. The exceptional nature of the present-day flood-rich period calls for process-based tools for flood-risk assessment that capture the physical mechanisms involved, and management strategies that can incorporate the recent changes in risk.