The 1714 flash flood in the Bohemian-Moravian Highlands – Reconstructing a Catastrophe

Abstract

The flash flood that occurred at the end of July and beginning of August 1714 on the Sázava River in the Bohemian-Moravian Highlands (550–750 m above sea level) is probably the most important case of flooding in the Czech lands. The extremity of the flood is likely to be ranked among the most notable occurrences of extreme weather in history, even within the larger Central European context. In this study we have focused on the upper and middle parts of the Sázava catchment (approximately 2000 km2). The aim of our study was to check of the reliability of the flood data in 1714. The main question was whether we should confirm or reject the possible dominant role played by local fishponds, especially the large Dářko fishpond. The extraordinarily high water levels documented by the chronicles were viewed a bit suspiciously at first.The hydraulic evaluation of the flood peak discharges and a reconstructed hydrograph, together with an envelope curve of maximum floods, have confirmed the reliability of the data recorded during the 1714 flood. The contribution of the collapsed fishponds was evaluated as a minor source of flooding. Therefore, the hydrological modelling enabled an estimation of causative precipitation equal to approximately 100 mm/3–4 h as the main flood source. The estimated rainfall amount and peak discharge of 700–1000 m3/s in the catchment area of 1000 km2 are likely to be the main results of the study. We also present an overview of flash floods in Central Europe in 1714, a definition of the affected area on 31 July, the damage, fatalities and a possible scenario of the storm's track. Our results indicate that the 1714 flood represented a unique extreme in Czech territory. The only comparable event appears to be the 25 May 1872 flood at the Berounka and Blšanka catchment.