The effect of traffic on forest road surface erosion (Case study: Kohmian forest- Azadshahr)

Sediment production is one of the most consequences of forest road construction. Soil erosion and its consequences is one of the major environmental problems. Erosion of unpaved roads occurs when soil particles are loosened and carried from the road into the drainage system and rivers. So estimating the amount of sediment delivered from forest roads is an important issue. In this study the effect of traffic on sediment and runoff yield was assessed using a rainfall simulator. Setting up the simulator with 1×1 plot, rainfall simulation was conducted during a 30 minute period and the resulted rain fall was collected in the outlet of plot. The results showed significant difference between run off and sediment yield of two traffic classes. Sediment delivered from the road surface with high and low traffic classes were 166.41 and 36.75 g/m2, respectively whereas run off rates for roads with high and low traffic classes were 49.1 and 22.1 lit/ m2. Significant effect of traffic on run off and sediment yield shows the importance of considering standard materials in road construction and maintenance. Considering the impact of traffic on amount of sediment and runoff, is elemental in planning, construction, and maintenance of forest roads.