perennial river; permanent stream
Technical term in geography and hydrology for a river or stream that flows year-round. Rare in everyday conversation; more common in academic or environmental contexts.
The perennial rivers in this region maintain a stable flow throughout the year.
An intermittent or ephemeral river that flows only during certain seasons or after rainfall, contrasting with 恒常河川 which flows continuously.
Compound of 恒常 (constant, permanent) and 河川 (rivers). The exact historical derivation is uncertain; the term is a modern technical coinage.