Next October the 14th is the 50th aniversary of the most terrible floods ever happened in Spain, that inundated the entire city of Valencia and its sorroundings.
In October the 13th of 1957 it rained the whole day. The 300mm precipation was about two thirds of the average rain in the area for the whole year.
The following night the very very small river Turia (average 14m3/second) was 3800m3/second (130,610ft3/second), wich is 6,5 times bigger than River Hudson in New York Bay or 50% more flow than River Danube in Budapest.
The waters reached the second floor in some parts of the city, destroying some bridges and many buildings, causing a great disaster. After the floods went the mud covered completely the city.
This is a common phenomenon every year in the Spanish Mediterranean coasts. It is called the "gota fría" and it happens when the Mediterranean waters reaches its highest temperatures of the year. Then huge storms enter the land and it rains very heavily.
47 big floods were registered in Valencia City betwen 1321 and 1957. When Romans founded the city the 138 b.c. had already reported floods.
Photo gallery from Levante newspaper Interesting article written by a historian