The River Arno Project
It is thought that the original plan to divert the river may have come from Leonardo in an effort to solve the conflict between Florence and Pisa through technology, and not war. Leonardo proposed the construction of one wide channel, deeper than the Arno itself, which when combined with a dam, would divert the entirety of the river away from Pisa and into the Stagno (marshland). The channel was intended to be eighty feet wide at its mouth, sixty-four feet wide at its end, thirty feet deep, and a mile long. Leonardo estimated that the construction of this channel would require the removal of over one million tons of earth and more than fifty thousand worker-days. In order to supplement for the tremendous workload, Leonardo designed various machines to aid in the digging and extraction of the earth, none of which were actually built.
We tested the effectiveness of Leonardo's engineering plan using our own model of the Arno. The results of this reconstruction in action can be seen in this video.
Unfortunately, due to the extraordinary cost and number of man hours needed for da Vinci's plan, the chief engineer of the project, Colombino, opted to use his own design.