radius of influence
Technical term used in fields such as hydrology, civil engineering, and environmental science to describe the distance over which an effect (e.g., drawdown from a well) is felt.
The radius of influence of this well is estimated to be about 500 meters.
影響圏 refers to a broader sphere or zone of influence, while 影響半径 specifically denotes the radial distance.
Compound of 影響 (influence) and 半径 (radius).