Papers on Geodesy and Gravity Tectonophysics
Geologic constraints on bedrock river incision using the stream power law
Article first published online: 20 SEP 2012
Copyright 1999 by the American Geophysical Union.
Journal of Geophysical Research: Solid Earth (1978–2012)
Volume 104, Issue B3, pages 4983–4993, 10 March 1999
How to Cite
1999), Geologic constraints on bedrock river incision using the stream power law, J. Geophys. Res., 104(B3), 4983–4993, doi:10.1029/98JB02139., and (
- Issue published online: 20 SEP 2012
- Article first published online: 20 SEP 2012
- Manuscript Accepted: 19 JUN 1998
- Manuscript Received: 9 JAN 1998
Denudation rate in unextended terranes is limited by the rate of bedrock channel incision, often modeled as work rate on the channel bed by water and sediment, or stream power. The latter can be generalized as KAmSn, where K represents the channel bed's resistance to lowering (whose variation with lithology is unknown), A is drainage area (a surrogate for discharge), S is local slope, and m and n are exponents whose values are debated. We address these uncertainties by simulating the lowering of ancient river profiles using the finite difference method. We vary m, n, and K to match the evolved profile as closely as possible to the corresponding modern river profile over a time period constrained by the age of the mapped paleoprofiles. We find at least two end-member incision laws, KA0.3–0.5S1 for Australian rivers with stable base levels and KfA0.1–0.2Sn for rivers in Kauai subject to abrupt base level change. The long-term lowering rate on the latter expression is a function of the frequency and magnitude of knickpoint erosion, characterized by Kf. Incision patterns from Japan and California could follow either expression. If they follow the first expression with m = 0.4, K varies from 10−7–10−6 m0.2/yr for granite and metamorphic rocks to 10−5–10−4 m0.2/yr for volcaniclastic rocks and 10−4–10−2 m0.2/yr for mudstones. This potentially large variation in K with lithology could drive strong variability in the rate of long-term landscape change, including denudation rate and sediment yield.