Erosion Control Practices in Managed Forested Watersheds PDF Download

Author: Kevin Charles Bold
Publisher:
ISBN:
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Languages : en
Pages : 230

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Book Description
The Clean Water Act mandates the implementation of approved best management practices (BMPs) in all states to control non point source pollution. Water control and revegetation BMPs are commonly used to control erosion and sedimentation from forest roads. The main objective of this study was to assess the adequacy of broad-based dip construction and vegetation establishment. In 2006, 19 gravel haul roads with broad-based dips in the Monongahela National Forest, West Virginia were examined to determine if they adhered to Forest specifications for cut depth and dip outslope. Data on the azimuth, contributing road lengths, slopes of the contributing lengths, landscape position of the dips, wheel track depths and soil texture of the road bed materials also were recorded to identify variables that explained variation in cut depth and dip outslope. Only about 22 percent of the dips met allowable cut depth specifications, and just over half of the dip slopes met the 2-5 percent outslope specifications. Cut depth was explained primarily by road geometry variables, suggesting that proper construction is important to ensure the dip impedes longitudinal drainage down the road while remaining traversable. Dip slope was affected by environmental and use variables, so maintenance during and following use is critical to ensure proper short- and long-term drainage. Vegetative growth along the entire cutbank of Forest Service road 973 within a managed watershed in the Left Fork of Clover Run on the Cheat District of the Monongahela National Forest in Tucker County, West Virginia was monitored from 2004 through 2006 using photograph analysis. Four sets of photographs were taken over the three years, two of which were taken in 2005 before and after timber harvesting. Percent vegetation establishment along the cutbank for each year was calculated to determine if there were significant differences in vegetative cover over time. Aspect and cutbank slope also were examined to determine if they influenced vegetation establishment. Cutbank slope was not a significant variable, but aspect was. South-facing aspects had significantly less vegetative cover than NE-, E-, WNW-, and NW-aspects. Timber felled onto the cutbank and poor initial seed establishment had a significant effect on vegetation establishment. Trees felled onto the cutbank and road can be deleterious to established vegetation, thus, trees slated for harvest that could impact the road prism should be removed before seeding, or directionally felled away from the road prism. Additionally, if vegetation on cutbanks is not established, soil should be mulched and vegetation coverage should be monitored.