Ento-bunsui (circular tank diversion works)
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This is a system designed to distribute water evenly among rice farmers to avoid conflicts over water.
It is used to adjust the volume of water to be supplied downstream by letting water spurt with the syphon function and adapting the direction and width of the water flow that passes through the outlet.
One such system was built in 1957 and remains in place in the land improvement district on the Isawa Plain, Iwate Prefecture. This circular distributary head is a half-scale model of the real equipment used to supply water to the pond and rice paddies here.