Road Erosion Estimation Equations Derived Using a WEPP Database

With the growing public use of the national forests, forest engineers, managers, and planners have had the challenge of maintaining extensive road networks, while minimizing the ecological impacts of those road systems on the environment. Properly spacing road drains for soils, topography, and slope conditions can reduce erosion from road surfaces, subsequently reducing sedimentation risk elsewhere. Knowledge about the amount of soil eroded and delivered from the road system is valuable when making decisions about road drainage design or redesign. The Water Erosion Prediction Project (WEPP) model, a process based erosion model that can be used to simulate low volume road erosion, was used to create a database of erosion estimates for 72,900 different road configurations, locations, and soil types. This database was then used to derive equations for low volume road erosion and runoff. A multivariate regression was used to derive equations for road soil loss, road runoff, and sediment yield. The resulting equations provided estimates of road soil loss and road runoff values within +/– 20% of the original database values. This approach was also attempted for sediment delivery across a buffer with less success. This is possibly due to complications from antecedent moisture conditions, vegetative cover, and sediment loading in runoff.