Executive SummaryThe Arno River Basin is located in Florence, Italy. In the last two thousand years there have been numerous floods encountered by this river. (Alessandro, 1993). The last flood encountered by the Arno river was that of 1966. It was also the most damaging flood ever recorded. While just over one hundred deaths were reported, the city of Florence suffered an economic loss of forty billion dollars. (Done, 2011). This loss was mainly due to the large-scale damage caused to the art and architecture around the city. Many of the pieces produced during the early and high Renaissance had been damaged, some permanently. Although flooding along the Arno River was relatively frequent, the city of Florence seemed unprepared for the 1966 flood. Several human errors can be attributed to the large-scale damage caused by the flood. Figure 1 showing the Arno River flowing through Florence. 2011). Historical documents, from Roman times to more recent years, have shown that floods along the Arno River are not uncommon. The most recent major floods along the Arno River occurred in 1117, 1333, 1557, 1666, 1844 and most recently, in 1966. (Alexander, 1993). On these dates, floods along the Arno River are very likely to occur every one hundred or two hundred years. The city of Florence has survived at least sixty-two floods along the Arno River in the last two thousand years. (Alessandro, 1993). The Arno flood of 1966 is the most recent of these floods. The Arno is a two hundred and forty-one kilometer long river that originates on Mount Falterona in Casentino, crosses Florence and flows into the Ligurian Sea near Pisa. Figure 2 illustrates the location and flow of the Arno River in Italy. Figure 2. Diagram showing the flow of the Arno River from (A) Monte Falternoa to (B) Pisa.2 The historic Arno River flood in Florence, Italy, began on November 3, 1966 and lasted until 8:00 p.m. of the following day. The flood itself had been the worst the city had seen since 1557, four hundred and nine years ago. Triggers of the flood The trigger of the flood was attributed to the heavy rains that began around midday on November 3 and lasted until the evening of the following day.