Investigation Drainage Conditions (Culverts, Channels) in Forest Road of Makarood, Series 1

The role of forest as a source in sustainable development will happen when we have a multilateral view to the forest ecosystem. The most important subject is the existence of forest road with optimum density. Different elements affect forest road erosion, the most important of which is the runoff produced by rain, directly threatening the surface of forest roads. The purpose of this study is investigation of margin channels in 50 kilometers of forest road in series 1 of Makarood forestry plan from No 36 watershed of Kazemrood with approximate area of 2732 hectares by using topographic maps (1:25000) and HYFA, Excel, ARC GIS 9.2 software and GPS receiver to control the status of field drainage (culvert, channels). Also, the peak discharge with different return periods from 2, 5, 10, 25, 50, and 100 is determined by means of considering the intensity of rain, the runoff coefficient, the length of stream and steeping slop, topographical and hydrological and vegetation conditions in each sub-watershed. Results of this research indicate that from a total of 90 sub-watersheds, 5 forest roads which have been constructed in different routes, have 120 fracture points in the road slope, with only 70 culverts having been constructed in medium distance from 400 to 650 meters which carry out the drainage of the occurred runoffs. Also from about of 70 constructed culverts in these routes 90% have the capability of transferring the peak discharge with only 2-year interval, 70% transfer capability in 5-years interval, 50% transfer capability in 100-year period, 35% transfer capability in 50- and 25-year period and less than 30% have ability to transfer 100-year discharge.