@Nanook,
Yes, floods happened before. The thing is they are happening more and more often, as well as droughts and storms, more often and more intensely.
@arnst Let's start with an overall graph of deaths due to natural disasters from 1900 to current:
And then fires:
And then Storms:
Unfortunately I was not on the fly able to find flood data going back more than about 20 years but I think this is largely due to the fact that prior to dams, flooding along river basins was a seasonal occurrence. In fact, it is floods that brings silt down stream and makes productive farmland the rich soil that it is.
But with the exception of short term storms, and I really believe this is largely a reporting bias, until recently we didn't have Doppler radar and the link and a day of rain just wasn't worth recording, but with that exception everything else peaked between 1890 and 1930 and has been less than those peaks in current times.
Real Photo of Cars Piled Up After Floods in Spain?
Nur Ibrahim (Snopes.com)