This photo is a border of Aichi Prefecture and Gifu Prefecture and Mie Prefecture of Japan.
And Kiso-river, and Nagara-river, Ibi-river are called ”Kiso Sansen”.
"Chisui jinjya" shrine is a Shinto shrine dedicated to those who lost in the flood control work.
Many of the people who died in the construction of the three rivers is a Satsuma samurai in the Edo period.