It is pretty hard to find the answer to this question on the web. Most of the history of the flood centers around the damage done to Florence's works of art, but there was also a tragic human toll to the flood. Channel 4 from England has a website devoted to history, and in the section called "Cities and disaster" we found this:
"At least 30 people died, and 50,000 families were made homeless. There was a food shortage, 15,000 wrecked cars were strewn about the streets and 6,000 shops went out of business.
Estimates suggest that 14,000 movable works of art were damaged, plus three or four million books and manuscripts."
The whole article is only about a page long, but it is an excellent primer on the flood.