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Rill erosion in natural and disturbed forests: 2. Modeling approaches
Wagenbrenner, J.W.; Robichaud, P.R.; Elliot, W.J. 2010.
Rill erosion in natural and disturbed forests: 2. Modeling approaches.
Water Resources Research, 46, W10507, doi:10.1029/2009WR008315. 12 p.
Keywords: rill erosion
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Abstract:
As forest management scenarios become more complex, the ability to more
accurately predict erosion from those scenarios becomes more important. In this second
part of a two.part study we report model parameters based on 66 simulated runoff
experiments in two disturbed forests in the northwestern U.S. The 5 disturbance classes
were natural, 10-month old and 2-week old low soil burn severity, high soil burn
severity, and logging skid trails. In these environments the erosion rates were clearly
detachment limited, and the rill erodibility parameters calculated from four hydraulic
variables increased by orders of magnitude. The soil shear stress based erodibility
parameter, Kr, was 1.5 × 10-6 s m-1 in the natural plots,
2.0 × 10-4 s m-1 in the high soil
burn severity plots, and 1.7 × 10-3 s m-1 in the skid trail plots; Kr values for the low soil
burn severity plots had negative sign. The erodibility value for the skid trail plots fell
within ranges reported for tilled agricultural fields and also for forest roads. The Kr values
decreased as erosion occurred in the plots and therefore should not be a constant
parameter. The stream power produced the largest R2 value (0.41) when hydraulic
predictors and the sediment flux were log.transformed, but none of the four hydraulic
variables (soil shear stress, stream power, unit stream power, and unit length shear force)
explained much of the variability in sediment flux rates across the five levels of
disturbance when evaluated in the linear form of the erosion models under consideration.
Moscow FSL publication no. 2010h
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