Site-Specific Erosivity Evaluation of a Sierra Nevada Forested Watershed Soil

Guerrant, D. G.; Miller, W. W.; Mahannah, C. N.; Narayanan, R.

Site-Specific Erosivity Evaluation of a Sierra Nevada Forested Watershed Soil

1991

Guerrant, D. G. | Miller, W. W. | Mahannah, C. N. | Narayanan, R.

Little quantitative site-specific infiltration, runoff, and erosion data for forested watershed soils of the Tahoe Basin are available. A Modular-type rainfall simulator was used to examine these variables for the Cagwin (mixed Typic Cryopsamment) soil series. Three slope (0–15, 15–30, >30%) and four plot conditions (undisturbed with natural duff, undisturbed without natural duff, disturbed without natural duff, and disturbed with natural duff removed) were studied. Infiltration and runoff data were incorporated into a modified Philip's model whereas erosion data were incorporated into a general nonlinear model. Data sets were analyzed via nonlinear regression for slope and plot interaction. Slope had negligible effect on infiltration and runoff but had a significant effect on erosion. Plot condition had significant effects on infiltration, runoff, and erosion. Final infiltration rates ranged from 4.7 to 6.1 cm h⁻¹, runoff ranged from 36 to 59% of the application rates, and cumulative interrill erosion ranged from 37.5 to 108.4 g m⁻² for a simulated design storm of 8 to 10 cm h⁻¹. The findings of this investigation were consistent with those of related quantitative investigations and indicate that the Cagwin soil has a low relative erosivity. Data from this study further suggest that previously applied models used to estimate potential erosion hazards of forested watershed soils may well result in over-estimation of erosion potential. A contribution of the Agric. Exp. Sin. (9-3-102-5006-637), Max C. Fleischmann College of Agriculture, University of Nevada, Reno.

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