The Arno River Basin is located in Florence, Italy. Over the last two thousand years there have been numerous floods encountered by this River. (Alexander, 1993). The most recent flood encountered by the Arno River was the flood of 1966. This was also the most damaging flood recorded.
While just over one hundred deaths were declared, the city of Florence experienced an economic loss of forty billion dollars. (Done, 2011). This loss was primarily 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 eras had been damaged, some of them permanently.
Even though floods along the ...view middle of the document...
Figure 2. Diagram showing the flow of the River Arno from (A) Monte Falternoa to (B) Pisa.2
The historical Arno River flood in Florence, Italy began on November 3rd, 1966 and lasted until 8:00 p.m. the next day. The flood itself had been the worst seen in the city since 1557, four hundred and nine years earlier.
The trigger for the flood was attributed to the intense rainfall beginning around noon on November 3rd and lasting until the evening of the following day. Figure 3 illustrates the average, expected rainfall for each month in Florence. From this graph, it is evident that November anticipates the highest rainfall with approximately one hundred and eleven millimeters of rain. However, during the days of November 3rd and 4th, 1966, Florence received about four hundred and eighty millimeters of rain. This alone, accounts for a third of the annual rainfall in Florence.
Figure 3. Graph showing the average annual rainfall in Florence, Italy.3
Prior to the heavy rainfall, the latter days of October left the soils along the headwaters of the Arno River saturated with melting snow. (Hyndman et al., 2010). This contributed to the intensity of the floods since the saturation of the soils left them unable to absorb any of the rainfall or allow transport of the water into the groundwater table or other reservoirs. If the soils had not already been saturated with the melted snow, it most likely would have been able to act as a mediator by absorbing some of the rainfall and slowly directing the water to a nearby reservoir.
As previously mentioned, it is known with certainty that the city of Florence has been known to experience high intensity floods over the last two thousand years. (Alexander, 1993). Prior to 1966, the most recent, major floods occurred in 1117, 1333, 1557 and 1666 and 1844. However, there had been several instances where flooding along the Arno River had cost several people their lives and damaged numerous properties between these major flood periods. (Krech et al., 2003). In essence, the regions along the Arno River appear to be fated to undergo a major flash flood every other century with frequent minor flooding between these periods. This had been proved over a two thousand year period to the present day.
Knowing this, the regions along the Arno River appeared very unprepared for flash floods by the shear disruption of the floods alone. Two hydroelectric dams located upstream of Florence had not had their rivers dredged. (Krech et al., 2003). This significantly reduced the amount of water the dams were able to store and increased the flow of water downstream causing more destruction. In addition, the Penna hydroelectric dam, located forty eight kilometers upstream, had accumulated a significant amount of water behind the dam gates in the latter weeks of October, prior to the floods. (Krech et al., 2003). This water, coupled with the significant amount of precipitation which initiated the flood caused...