Sediment Transport Investigations on the National Forests of Alabama
In recent years, increased concern and societal pressure have focused on environmental impacts of forest roads on soil erosion and water quality. Forest roads have been identified as the major contributor to sediment production from forested lands accounting for as much as 90 percent of all sediment produced from forest lands. This paper reports on two research studies on the National Forests of Alabama, which evaluate the effectiveness of sediment control alternatives from the forest road prism. Two of the most vulnerable components of the road prism, sideslopes and ditches, are considered in this work. Research evaluated the effectiveness of sediment control practices in mitigating sediment export. The first study, initiated in 1995, investigates the effect of three erosion control techniques on soil movement from cutslopes and fillslopes. Treatments consisting of a wood excelsior erosion mat, native species vegetation, and exotic species vegetation have been evaluated over the last 4 years. Treatments were detected to significantly affect sediment yield and runoff from the road sideslopes. The second study, initiated in 1997, evaluates the effect of selected techniques to control sediment movement in the forest turn-out ditch. The investigation compares sediment filtering and sediment export from the following selected treatments: sediment fence, settling basin, vegetation, and riprap.