Changes in erosion from gravel surfaced forest roads through time

Abstract

Annual erosion rates were measured for 2 years at experimental road plots in Western Oregon. Sediment production was compared between years on 16 plots with graded road treads, and bare cutslopes and ditches. Sediment production declined in the second year by 72%, indicating a substantial decline in sediment availability. The relative influences of precipitation, vegetation regrowth and surface armoring were examined. Precipitation differences between years were assessed by comparing annual erosion from 6 plots with vegetation removed from cutslopes and ditches before each transport season. Although precipitation and rainfall erosivity increased, erosion from these control plots did not vary significantly between years. Vegetation became established late in the second year following the most significant sediment transport events. The 10 percent vegetation coverage in the roadside ditch may account for less than 40 percent of the observed decline in erosion. Graded road surface plots declined to background levels in the second year due to surface armoring. Armoring of graded cutslopes and ditches was observed to be an important process resulting in surface stability and may account for more than half of the decline in erosion rates observed in the second year.

Citation

Black, Thomas; Luce, Charles. 1999. Changes in erosion from gravel surfaced forest roads through time. In: Sessions, John; Chung, Woodam, eds. Proceedings of the International Mountain Logging and 10th Pacific Northwest Skyline Symposium; 1999 March 28- April 1, Corvallis, OR. Corvallis, OR: Oregon State University, Department of Forest Engineering. p. 204-218.