『Abstract
On the basis of the Manning equation and basic mass conservation
principles, we derive an expression for scaling the steady-state
width (W) of river channels as a function of discharge (Q), channel
slope (S), roughness (n), and width-to-depth ratio (α): W = [α(α+2)2/3]3/8Q3/8S-3/16n3/8.
We propose that channel width-to-depth ratio, in addition to roughness,
is a function of the material in which the channel is developed,
and that where a river is confined to a given material, width-to-depth
ratio and roughness can be assumed constant. Given these simplifications,
the expression emulates traditional width-discharge relationships
for rivers incising bedrock with uniformly concave fluvial long
profiles. More significantly, this relationship describes river
width trends in terrain with spatially nonuniform rock uplift
rates, where conventional discharge-based width scaling laws are
inadequate. We suggest that much of observed channel width variability
in river channels confined by bedrock is a simple consequence
of the tendency for water to flow faster in steeper reaches and
therefore occupy smaller channel cross sections. We demonstrate
that using conventional scaling relationships for channel width
can result in underestimation of stream-power variability in channels
incising bedrock and that our model improves estimates of spatial
patterns of bedrock incision rates.
Keywords: fluvial geomorphology; tectonic geomorphology; channel
width; river incision; landscape evolution.』
Introduction
Model
Methods
Model evaluation
Modeling river incision
Discussion
Conclusions
Acknowledgments
References cited