Flood, war and economy. Leonardo da Vinci and the plan to divert the Arno River

This chapter explores the connections between Leonardo da Vinci and hydraulic works on the Arno, in particular the failed war scheme to divert the river in 1503–1504. Through observations of this river, the artist developed a number of studies on flooding, examining bridge projects, dams, channels, canals and levees connected with the Arno. Leonardo's activity for Cesare Borgia (1502), and then for Pier Soderini (1503–1504) in the context of plans to divert the river near Pisa, points up the relationship among hydraulic engineering, observations on nature and the measurement of terrain. Drawings and writings in Leonardo's corpus, such as the Windsor drawings (ca. 1503), which describe Leonardo's project for the ‘gran canale’, can be related to his studies on the Arno, to protect Florence from flooding. This chapter thus points up the relationship among control, transport, regulation and measurement in peacetime and in wartime, to prevent flooding or, inversely, to cause flooding against an enemy or deny that enemy access to the sea. Leonardo's ideas may not have been realised, but his thinking echoed into the sixteenth century, influencing the extensive river works in Tuscany undertaken by Grand Duke Cosimo I de’ Medici (1519–1574) and his successors. The essay has been peer-reviewed double blind