Performance of a Retrofitted Medieval Stone Bridge under a Severe Flood

The very long absence of floods with a return period of more than about 100 years in the Vltava river basin dulled the vigilance of the state administration and self-government bodies. Flood safety measures were mostly related to once-in-a-hundred-years floods. When planning the engineering works before major repairs to the medieval Stone Bridge in Písek in the 1990s, an unpleasant but justified question was raised—what would happen to the Stone Bridge if an extremely powerful 500-year return period flood were to occur? The following case study deals with this question and provides a definitive answer to it. Works were carried out on the Stone Bridge, which was just a few years later exposed to the catastrophic flood that occurred in Bohemia in 2002.