headwaters; source of a river
Refers to the upper reaches or origin of a river. Often used in geographical or poetic contexts.
The headwaters of that river are in a national park.
水上から下流まで、水質を調査した。
We surveyed the water quality from the source to the downstream area.
Standard kanji spelling for the reading みなかみ, meaning headwaters or source of a river.
Compound of 水 (み, water) and 上 (かみ, upper part). The reading みなかみ is a euphonically changed form of みのかみ.