A hundred-year flood has already happened
The next will be in a hundred years.
Extremely dangerous mistake. Hundred-year floods do not happen every hundred years. In reality, every year we have one chance in a hundred that AT LEAST ONE such flood will happen. Just like winning the lottery, which happens several times in a row, if you are lucky, also floods can be repeated immediately. In the Kłodzko Valley, catastrophic floods occurred in 1997 and in 1998. In the summer of 2010, in the Carpathian Mountains, the so-called hundred-year flood happened twice, in addition to two smaller floods!