noun
raised river; elevated riverbed
A river whose bed has risen above the surrounding land due to sediment deposition, often contained by levees. A technical geographical term.
天井川は、堤防が決壊すると大きな被害をもたらすことがある。
A raised river can cause great damage if its levees break.
Compound of 天井 (ceiling) and 川 (river), referring to a riverbed elevated like a ceiling above the surrounding land.