Journal of Geophysical Research: Earth Surface

Cover image for Vol. 121 Issue 10

Impact Factor: 3.318

ISI Journal Citation Reports © Ranking: 2015: 27/184 (Geosciences Multidisciplinary)

Online ISSN: 2169-9011

Associated Title(s): Journal of Geophysical Research

Bedrock topography influences erosion rate

Even small bumps in a river’s bedrock can change how sediment grains erode bedrock, a new modeling study shows. Observations have indicated that bumpy bedrock erodes more quickly, but most previous models of bedrock erosion assumed approximately planar beds.

To create a more realistic model of bedrock erosion, Huda and Small included bumps several centimeters high, spaced approximately 50 centimeters apart. As sediment grains flow along with the water, they hit the bumps, transferring energy to the bed and increasing erosion.
The authors found that erosion by moving sediment grains occurred 10 to 1000 times faster in the model with bumpy bedrock topography than in a planar bed model, depending on the size of sediment particles.

In addition, in their model, erosion increases with river stage, suggesting that the greatest erosion should occur during floods. In models with planar beds, erosion was at maximum at low to medium stages. The results show that even small bumps can make a big difference in how sediment erodes bedrock, indicating that it is important to include bedrock topography in models of erosion.

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