نوع مقاله : مقاله کامل علمی پژوهشی
نویسندگان
1 دانشیار ، گروه جنگلداری، دانشگاه علوم کشاورزی و منابع طبیعی گرگان
2 دانشجوی دکتری مدیریت جنگل، دانشکده علوم جنگل، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان.
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Background and objectives: The climatic conditions governing the Hyrcanian forests and also the decrease in the income of forestry projects due to the cessation of forest exploitation caused the protection and maintenance of forest roads to be almost stopped and as a result, the deterioration of the roads especially in steep slopes. In this situation, the dense surface of the forest roads during heavy rains causes the production of runoff and the washing of loose and fine-grained materials, which leads to the formation of sediment.
Materials and methods: In this research, the effects of three treatments including type of open-top culverts, installing distance of open top culverts and amount of rainfall on road materials loss from steep sections (6-9%) were investigated and then the economic efficiency was evaluated. Open top culverts including grooved and ridged culverts and rubber culverts with three repetitions up to the depth of the road bed and at an angle of 40 degrees to the road axis and at distances of 30 and 60 meters from the top of the dome arches (where the runoff originates), parts of the network The roads of Dr. Bahramnia's forestry plan were installed and implemented. Several road segments with a length of 60 meter and without installation of open-top culvert were determined as control plots. The amount of sediment coming out of the drains after 3 rainfall events (27, 33 and 70 mm) was measured in the sampling traps. Then the amount of material wastage was calculated.
Results: The results showed that the type of open-top embankments, the installation distance and also the mutual effects between them did not have a significant effect on the amount of soil loss or surface materials of forest roads. The highest amount of top material loss was related to the control treatment and also the third rain event. The increase in the distance between the installation of the beams did not have any significant effect on the amount of material wastage, but in general, the amount of material wastage slightly increased with the increase of the installation distance of the beams. The average loss of materials at the installation distances of 30 meters and 60 meters was 183.5 and 184.9 grams per square meter for the furrow and ridge treatment, respectively, and 171.8 and 188.3 grams per square meter for the rubber treatment, respectively. The evaluation of the costs of construction, installation and implementation of the treatments showed that the groove and stack has a more favorable economic function than the rubber one.
Conclusion: Considering the similar performance of the two open culverts and also the cost-effectiveness of the groove and pile culverts, it is necessary to introduce this type of culvert to the executive bodies for the management of runoff and sediment in road segment of 6-9% in study area. Also, at both distances of 30 and 60 meters, the surface flow was directed outside the crossing width at the right time before it caused the washing and channelization of the road surface. Therefore, it is possible to increase the installation distance of the culverts to assess the runoff and sediment behavior.
کلیدواژهها [English]