drainage basin; river basin; watershed
Refers to the entire land area drained by a river and its tributaries. Common in geography, environmental, and news contexts.
Floods caused by heavy rain occur frequently in this river basin.
流域全体の水質を調査する必要がある。
It is necessary to investigate the water quality of the entire watershed.
The drainage basin of the Tone River extends across the Kanto region.
Many people live in the basin of this river.
Flooding occurred in the basin due to heavy rain.
Activities are being carried out to protect the environment of the drainage basin.