Excerpt
Vegetated filter strips protect water quality by reducing the amount of sediment that reaches streams. Silvicultural filter strips typically differ from agricultural filter strips in that ground cover is provided by forest litter, not grass or other low vegetation, and slopes are typically steeper. Relative to agricultural filter strips, there is less information on the capacity of silvicultural filter strips, or streamside management zones, to retain sediment mobilized during forest harvest and regeneration.
In this study, simulated runoff containing sediment ranging from colloidal-sized clay to sand-sized particles and aggregates was applied to forested filter strips in two conditions—undisturbed forest floor and forest floor removed by hand raking—across five slope classes (0 to 2%, 5% to 7%, 10% to 12%, 15% to 17%, and 20% to 22%) in the Piedmont of Georgia. We found that sediment retention ranged from 53% to 96% and averaged 72% across all slope classes and conditions. Larger particles (>20 μm [>0.00079 in] in diameter) were retained in the first 2 m (6.6 ft) of the filter strip because they settled out of runoff, whereas smaller particles (<2 μm [<0.000079 in] in diameter) did …
Footnotes
- Copyright 2007 by the Soil and Water Conservation Society
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