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This paper describes an enormous flood that occurred in Bohemia in August 2002, which is considered to be one of the most disastrous to take place in the past 1000 years. Data on the catastrophic flood of July 1432 are also presented, derived from documentary records. The two floods are compared and analysed with respect to other heavy floods in Bohemia from the viewpoint of epigraphic and further documentary sources for the Vltava in Prague (water levels with respect to the relief of Bradac, the “Bearded Man”) and for the Elbe at Decn (flood marks cut into Castle Rock). Documentary evidence thus makes it possible to compile a chronology of the heaviest floods in Bohemia since the 12th century. However, the summer rain floods of July 1432 and August 2002 stand out as the greatest, while the case of September 1118 must be ranked near them. The concentration of four disastrous winter floods in the years 1784-1862 is also worthy of note, because it corresponds to the last stage of the Little Ice Age.

Historical hydrology can be defined as a research field occupying the interface between hydrology and history, with the objectives: to reconstruct temporal and spatial patterns of river flow and, in particular, extreme events (floods, ice phenomena, hydrological droughts) mainly for the period prior to the creation of national hydrological networks; and to investigate the vulnerability of past societies and economies to extreme hydrological events. It is a significant tool for the study of flood risk. Basic sources of documentary data on floods and methods of data collection and analysis are discussed. Research progress achieved in Europe in reconstructing past runoff conditions, hydrological and hydraulic analyses of historical floods, their meteorological causes, impacts and relation to climate change, as well as use of combined series of palaeofloods, instrumental and historical floods for reconstructing long-term flood records, is reviewed. Finally, the future research needs of historical hydrology are discussed.

This study focuses on two main rivers of Bohemia (Czech Republic): the Vltava and the Elbe. Flows are determined for the Elbe at Decin (discharges) and Litomerice (water stages), and for the Vltava at Prague (discharges). Extreme flows have an important socio—economic impact; hence modelling their occurrence accurately is crucial. We identify the meteorological causes for floods: (a) the winter type due to snowmelt, ice damming, and usually rain, and (b) the summer type due to continuous heavy rains. The amplitude and frequency of floods are analysed using extreme value theory, in a non-stationary context. This allows the determination of the trends of flood features during the instrumental period and their dependence on atmospheric circulation patterns.