overshot water wheel
A water wheel where water is fed from above, typically used in traditional mills and irrigation.
An overshot water wheel still remains at this old flour mill.
An undershot water wheel where water flows under the wheel, in contrast to 上掛け水車 where water is fed from above.
A breastshot water wheel where water hits the wheel at about axle height, intermediate between overshot and undershot.
Compound of 上掛け (うわがけ, 'overhead') + 水車 (すいしゃ, 'water wheel').