Ento bunsui 円筒分水: Shimokuzawa diversion pond

円筒分水 (entō bunsui) えんとうぶんすい = cylindrical water diversion

An ento-bunsui is a structure that regulates a river or stream, diverting water towards multiple irrigation channels, which differ in size according to the size of the land they serve. The English word for 円筒分水 is practically non-existent. The best translation is probably “cylindrical water diversion”, but I’ve seen cylindrical water splitter, diversion cylinder, watershed cylinder,  cylindrical diversion, and others. I can find no evidence of similar devices outside of Japan.)

Kuji ento bunsui 久地円筒分水

For more photos of ento-bunsui throughout Japan, do a Google image search for 円筒分水.

Here’s the Shimokuzawa diversion pond 下九沢分水池 in Sagamihara-shi, Kanagawa (map)(source).

Read more about water infrastructure in Tokyo: ClearWater Nippon & splashing around Tokyo’s water infrastructure

Read more for information about the Shimokuzawa diversion pond: 春の円筒分水ツアー　（下九沢分水池～久地円筒分水へ） Spring of the cylindrical water diversion tour (to the watershed pond – lottery cylindrical diversion Shimokuzawa)

A map of all the identified ento bunsui in Japan (per entoubunsui.com):

Another version (unknown source):

See also:

• Takatsu-ku ento-bunsui walking map (Kawasaki) 円筒分水と久地不動尊コース
• 可視化された公平性 Fairness visualized: this post claims that ento bunsui were invented at the end of the Meiji era.