noun
natural damming of a river
Technical term used in geology and disaster prevention for a river blocked by a landslide, debris flow, or similar mass movement.
地震による河道閉塞が下流の洪水リスクを高めた。
The natural damming of the river caused by the earthquake increased the flood risk downstream.
Compound of 河道 (river channel) and 閉塞 (blockage, obstruction).