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Hillslopes |
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| Hillslopes make up the landscape of much of
the semiarid region of the Southwestern United States. The hillslopes can be
described by their profile shape, length, and slope. Common hillslope shapes include
convex, concave, straight, or complex. Complex hillslopes are typically made up of
several segments with various shapes. Water induced soil erosion that drives
hillslope evolution is impacted by several factors, including topography, vegetation, and
soil surface characteristics. |
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| Vegetation and Bare Soil |
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| Vegetation, such as grass, protects the soil
. A landscape view of seemingly uninterrupted grassland does not reveal the bare spaces
between vegetation that provide flow paths for runoff. A
view from above reveals exposed, unprotected soil that is subject to erosion. |
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Just Add Water |
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| Water causes soil erosion. Soil particles
detached by the impact of raindrops or flowing water may be transported or deposited
downslope. Because flow rates change with time and position along the hillslope, soil
detachment, transport, and deposition change with time and space. Steeper sections of
hillslopes are subject to downcutting. Eroded material is deposited in response to a
reduction in slope. |
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| Kinematic Wave Equations |
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| Erosion/Sediment Yield Equations |
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A Mathematical Model
to Simulate Hillslope Erosion and Sediment Yield |
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| A mathematical model has been developed by
scientists at the USDA-ARS Southwest Watershed Research Center in Tucson, Arizona to
describe hillslope erosion processes. Given hillslope segment lengths, slopes, % canopy
cover, % surface ground cover, runoff volume, and a soil erodibility value, the model will
simulate erosion process along the hillslope and will return runoff volume, sediment
yield, interrill detachment, rill detachment, rill deposition, and the mean concentration
of sediment in the flow for each hillslope segment. Sediment
yield equations were developed for a single plane, and were extended to irregular slopes
by approximating the irregular slopes as a cascade of planes.
Increasing sediment concentration in the downslope
direction may indicate erosion along the hillslope. Deposition may be indicated by a
decrease in sediment concentration in the downslope direction. Constant sediment
concentration indicates an equilibrium.
Run the Model |
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Downloadable
References |
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Additional detail regarding the Hillslope
Erosion Model can be found in the following publications that are available in Adobe
Acrobat Reader PDF format:
To view these files in PDF you will need the Adobe
Acrobat Reader. If you don't have the reader, please follow the Adobe Acrobat Reader link.
Acrobat and the Acrobat logo are trademarks of Adobe Systems Incorporated.
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Modeling Erosion
on Hillslopes: Concepts, Theory, and Data (146 KB pdf
file)
by L. J. Lane, M. H. Nichols, and G. B. Paige
In: Proceedings of the International Congress on Modelling and Simulation (MODSIM'95) (ed.
by P. Binning, H. Bridgman, and B. Williams), November 27-30, 1995, Univ. of Newcastle,
Newcastle, NSW, Australia, Uniprint, Perth, Australia, pp. 1-7.
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Modelling Erosion
on Hillslopes (126 KB pdf file)
by L. J. Lane, E. D. Shirley, and V. P. Singh
Chapter 10 In: Modelling Geomorphological Systems (ed. by M. G. Anderson). John Wiley and
Sons, Chichester, 1988, pp. 287-308.
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A Sediment Yield
Equation From an Erosion Model (111 KB pdf file)
by E. D. Shirley and L. J. Lane
In: Hydrology and Water Resources in Arizona and the Southwest, 8, 90-96.10, 1978.
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Processes Controlling
Sediment Yield from Watersheds as Functions of Spatial Scale (249 KB pdf file)
by L. J. Lane, M. Hernandez, and M. H. Nichols
Journal of Environmental Modelling & Software, Vol. 12, No. 4, 1997, pp. 355-369.
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Watershed Erosion
and Sediment Yield Affecting Contaminant Transport (102
KB pdf file)
by L. J. Lane, T. Hakonson, and G. Foster
Proceedings of the Symposium on Environmental Research on Actinide Elements, November
1983, Hilton Head, SC, pp. 193-223.
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