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Modeling rangeland watershed erosion processes
Elliot, W.J. 2000.
Modeling rangeland watershed erosion processes.
In: Flug, Marshall; Frevert, Donald; Watkins, Jr., David W., eds.
Proceedings from the Conference on Watershed Management & Operations Management 2000; 2000 June 20-24; Fort Collins, CO.
Reston, VA: American Society of Civil Engineers: 9 p.
Keywords: watershed
Links:
Available to purchase: PDF (101 kB) ASCE
Abstract:
Most common soil erosion models were developed for agricultural conditions and then modified for rangeland,
forest, and other applications. Rill and interrill
erosion generally dominate upland agricultural erosion on recently tilled fields. In
rangelands, soil is not tilled, rainfall is sporadic, infiltration is high, and the soil
surface is covered by vegetation residues and sometimes rocks. Recent research has
shown that as rangeland plant species change from the tall grass species that once
dominated many plant communities, to short grass species through overgrazing, the
hydraulic conductivity of the soil decreases and runoff increases. The net impact of
the rangeland surface and plant changes is that upland erosion may be low, and the
dominant source of sediment from rangelands may be from channels.
This paper describes a study in southeastern Colorado on sedimentation from
rangeland watersheds. The observed rates are compared to predicted erosion rates
from a locally developed erosion model, RUSLE, the WEPP model with typical
rangeland vegetation and soil scenarios, and the rangeland predictions from the Forest
Service WEPP interface and database. The local regression model and the Forest
Service WEPP interface best predicted sedimentation from small rangeland watersheds.
RUSLE overpredicted sediment yields by a factor of 3, and the WEPP
rangeland predictions were 1/6 the observed sediment yields. In a sensitivity analysis
with the FS WEPP interface, as cover increases, differences in runoff and erosion between soils decreases.
Moscow FSL publication no. 2000d
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