Sediment deposition from forest roads at stream crossings as influenced by road characteristics.
Recent controversies associated with ditched forest roads and stream crossings in the Pacific Northwest have focused national attention on sediment production and best management practices (BMPs) at stream crossings. Few studies have quantified soil erosion rates at stream crossings as influenced by road characteristics and compared them to modeled rates. Soil erosion rates were measured and modeled from forest roads that represented a range of road classes (permanent high standard to temporary low standard). Forty road approaches were identified in the Piedmont and Mountain regions of Virginia and categorized into four general road classes. Road attributes were characterized at each crossing (BMPs used, road width, grade, gravel, cover, cut and fill slope ratios, ditch characteristics, etc.). At each stream crossing, conveyor belts were installed as water-control devices across the road to divert sediment from the stream crossing approach into silt fence sediment traps. Sediment pins were installed adjacent to the silt fence to allow periodic measurement of sediment depths. Additionally, erosion potentials for approaches were modeled with the Universal Soil Loss Equation (USLE) as modified for forestry and compared to actual sediment deposition near the stream. Data presented represents <1 year of sediment measurements from the stream crossings.