Geological term for the movement of sediment or rock material by natural agents such as water, wind, or ice.
河川の運搬作用によって、砂や礫が下流へ運ばれる。
Sand and gravel are carried downstream by the river's transportation action.
風の運搬作用で砂丘が形成される。
Dunes are formed by the transportation action of wind.
浸食作用 refers to erosion, the process of wearing away material, while 運搬作用 specifically refers to the subsequent movement of that material.
堆積作用 is the deposition of material after it has been transported, whereas 運搬作用 is the transport phase itself.
Compound of 運搬 (transport, carrying) and 作用 (action, effect), used as a technical term in geology.