Evaluation of road approaches to four different types of stream crossings in the Virginia Piedmont
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Erosion potential was estimated for road approaches during 4 phases of a timber harvesting scheduled for 23 stream crossings in the Virginia Piedmont. The objectives of this study were to: (1) examine four different types of stream crossing structures (steel bridges, pole bridges, standard culverts, and reenforced fords) in order to determine if the type of stream crossing affects erosion potential and (2) evaluate the potential erosion associated with the stream crossing approaches using the Water Erosion Prediction Project (WEPP) for forest roads and the forestry version of the Universal Soil Loss Equation (USLE). An unbalanced replication resulted in six replications of each crossing, except pole bridges (7) and fords (4). Results indicate that any of the stream crossings may be appropriate if located, installed, and maintained properly. However, we found that approaches associated with culverts had the potential for the highest soil loss rates as estimated by both WEPP (46.2 tons per acre per year) and USLE (85.8 tons per acre per year). Both of these models showed a general decrease in the potential for erosion from the during harvest phase to the postroad closure phase.