In the fluvial process, rills erode and merge into large channels called:

Correct answer: Gullies. Rills deepen and join to form gullies, which are larger channels cut by running water.

Background: Fluvial processes are those caused by running water.

• Abrasion: Abrasion is erosion by rock fragments scraping a surface.
• Water channel: “Water channel” is not the standard term.
• None of these: “None of these” is incorrect because gullies is correct.

Did you know? Heavily gullied land is called badlands.

Memory trick: Rills → gullies → gorges.