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Landscape Evolution Modeling Using the stream power incision
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Bedrock landscape development modeling: calibration using field study, geochronology and DEM analysis
DeLong, Stephen B. and Pelletier, Jon D. Department of Geosciences, University of Arizona, 1040 E 4th Street, Tucson AZ 85721, USA
Arnold, Lee Oxford Luminescence Research Group, School of Geography and the Environment, University of Oxford, Mansfield Rd, Oxford OX1 3TB, UK
Keywords: Landscape development; erosion; modeling; DEM; Cuyama Basin
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 are difficult to calibrate. This paper examines ways in which field observations, geochronology and 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 rate is 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. 10Be surface exposure dating and OSL burial dating data indicated that incision of initially low-relief topography there occurred during the last ~60 kyr. 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)kyr -1 for the rock types in our study area.