Assessment of Drainage System Standards of Forest Roads in Iran Using GIS

摘要

Forest roads should be constructed according to standards and particular attention needs to be given to forest roads in planning and management schemes to develop sustainable forest infrastructure. The creation of standards for drainage systems is one of the most important technical developments in forest road construction. Seri 1 of Darabkola forest has been located in the central part of the northern Alborz Mountains in basin 74 and in 15-kilometer distance of Sari in Iran and covers an area of 2,612 hectares. In this research slope and aspect maps of the Seri 1 of Darabkola forest were prepared using Arcview 3.1 and ArcGIS 9.1 to evaluate drainage. In addition, factors effecting road drainage were measured and evaluated: road width, cross and longitudinal slopes of roads, ranges of excavation and embankment slopes, longitudinal slope of ditches, and basal area of ditches at intervals of 1.5 kilometers of forest road and for each 40 meters of each section. Sample points of locations were taken using global positioning system (GPS) and a related map was prepared. Measurements of culverts were taken for diameter and distances apart from each other in the existing drainage system as well as locations that were also recorded using GPS. In addition, road routes were tracked and recorded using GPS to obtain the desired accuracy. Finally, the drainage system of the forest road was compared to the accepted standards. Results showed that there was significant difference between the current drainage system of Seri 1 of Darabkola forest roads and accepted standards, but in some cases evaluation of the existing drainage systems on these roads demonstrated that they were in accordance with accepted standards.