USGS CMG InfoBank: Texture of Stream Beds

Source: Annenberg/CPB Resources - Earth Revealed - 19. Running Water I: Rivers, Erosion and Deposition

Keywords: "Dee Trent", river, stream, "water velocity", texture, gravel, boulder, mud, clay, "flow resistance", "Mississippi River"

Our transcription: The texture of a stream bed also influences stream velocity.

Roughness is a function of the materials over which it flows.

So if it's flowing over gravel and boulders, there'll be more resistance to the flow, and that will slow the river down.

If it's flowing over muds and clays, like along the lower part of the Mississippi River, there will be less resistance, and it will flow a little faster.