Efficacy of buffer zones in disconnecting roads and streams in the coastal plain
Established forest BMPs rely heavily on the forest floor to disconnect upslope activities from stream systems. Optimizing the buffer length required to negate the storm runoff contribution of upslope activities has been a point of interest for soil scientist, hydrologist, and conservation professionals for the last century. Minimum buffer lengths have been recommended or mandated throughout the U.S; however, a gap exists in the understanding of the effectiveness of these practices in controlling sediment movement and minimizing risks of sediment delivery to forest streams. The fundamental question that has not yet been answered is, “Do current management practices disconnect forest road sediment and water?” This paper reports findings of investigations to assess sediment travel distances downslope of forest roads in the Coastal Plain of Alabama, relate sediment travel distances to BMP recommendations, and describe deposition patterns within buffer zones. Sediment deposition depths and lengths within buffers from randomly selected National Forest roads were measured downslope of road lead-off ditch structures. The mean distance sediment was tracked across the forest floor was 27 meters. Sediment transport distances were less than 30 m for 45 percent of sites evaluated in National Forests in Alabama. This paper also presents special issues related to the connectivity and the role of the forest buffer in minimizing the connection of forest roads and streams in this sensitive region.