The canalization of the Yonne river - on which these boaters are crossing Joigny -was made possible in the 19th century following the widening of mobile dams known as 'needle weirs' to the entire width of the bed of a watercourse. Experienced in 1834 on the Yonne in Basseville, this innovation by the engineer Antoine Poirée was then extended to the canalization of many other rivers. Most of the canalization works on the Yonne began in 1861, following the building of a first weir and lock right after 1840.