noun
alluvial fan; alluvial delta
A fan-shaped deposit of sediment formed where a river or stream flows from a steep gradient onto a flatter plain. In Japanese geography, 扇状地 is the standard term.
この扇状地は、川が山から平野に出るところにできた。
This alluvial fan formed where the river emerges from the mountains onto the plain.
扇状地
Alluvial fans are often used for orchards because of their good drainage.