USGS/Cascades Volcano Observatory, Vancouver, Washington
PROJECT:
Gravel Dunes
Summary of research observations at a gravel-bed river
--
Randal L. Dinehart, 1997,
Gravel Dunes:
Summary of research observations at a gravel-bed river
Just as wind-blown sand forms ripples and dunes, a flowing
river will create dunes of many sizes from sediment on the
streambed. Although most river bedforms are composed of silt and sand,
some rivers with gravel or cobble beds can also
create dune-shaped bedforms. The amount of force required to move
river gravel as bedforms may occur during storm
flows or floods.
When gravel dunes form in a riverbed, water flowing over the
bedforms changes velocity because of the extra roughness.
When gravel dunes migrate, they change the mean bed elevation
by scouring sediment or forming gravel bars.
To show how gravel dunes in flooding rivers eventually affect
river measurements by hydrographers, this document
describes detailed observations of streambed and velocity over
the gravel bed of the North Fork Toutle River, Mount St. Helens,
Washington.
URL for CVO HomePage is:
<http://vulcan.wr.usgs.gov/home.html>
URL for this page is:
<http://vulcan.wr.usgs.gov/Projects/GravelDunes/framework.html>
If you have questions or comments please contact:
<GS-CVO-WEB@usgs.gov>
12/11/02, Lyn Topinka