『Abstract
Stream power-based models of bedrock landscape development are
effective at producing synthetic topography with realistic fluvial-network
topology and three-dimensional topography, but they are difficult
to calibrate. This paper examines ways in which field observations,
geochronology, and digital elevation model (DEM) data can be used
to calibrate a bedrock landscape development model for a specific
study site. We first show how uplift rate, bedrock erodibility,
and landslide threshold slope are related to steady-state relief,
hypsometry, and drainage density for a wide range of synthetic
topographies produced by a stream power-based planform landscape
development model. Our results indicate that low uplift rates
and high erodibility result in low-relief, high drainage density,
fluvially dominated topography, and high uplift rates and low
erodibility leads to high-relief, low drainage density, mass wasting-dominated
topography. Topography made up of a combination of fluvial channels
and threshold slopes occurs for only a relatively narrow range
of model parameters. Using measured values for hypsometric integral,
drainage density, and relief, quantitative values of bedrock erodibility
can be further constrained, particularly if uplift rates are independently
known.
We applied these techniques to three sedimentary rock units in
the western Transverse Ranges in California that have experienced
similar climate, uplift, and incision histories. The 10Be
surface exposure dating and optically stimulated luminescence
(OSL) burial dating data indicated that incision of initially
low-relief topography there occurred during the last 〜60 k.y.
We estimated the relative dependence of drainage area and channel
slope on erosion rate in the stream power law from slope-area
data, and inferred values for bedrock erodibility ranging from
0.09 to 0.3 m(0.2〜0.4) k.y.-1 for the rock
types in this study area.
Keywords: landscape development; erosion; modeling; DEM; Cuyama
Basin』
Introduction
Previous bedrock landscape development model calibration
Modeling approach
Characterization of synthetic and real topography
Results: Synthetic landscape development
Model behavior and classification of model topography
Model calibration: Geological constraints
Surface exposure dating, burial dating, uplift rate, and
model calibration
10Be surface exposure dating
OSL burial dating
Application of geochronology to model calibration
Discussion
Values of K and relationship between K and U
Model calibration using real topography
Conclusions
Acknowledgments
References cited