year 11, Issue 4 (Winter 2021)
E.E.R. 2021, 11(4): 122-140 |
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Gholami Z, parsakhoo A, lotfalian M, rezaei motlagh A. Effect of Some Bioengineering Treatments on Sediment Yield from the Cut Slopes of Forest Roads. E.E.R. 2021; 11 (4) :122-140
URL: http://magazine.hormozgan.ac.ir/article-1-650-en.html
URL: http://magazine.hormozgan.ac.ir/article-1-650-en.html
Faculty of Forest Science, Gorgan University of Agricultural Sciences and Natural Resources , ghlamyzhrh@gmail.com
Abstract: (2161 Views)
1- Introduction
Soil is the most important foundation of any country's civilization, without which human life is endangered. Since man has lived on this planet, natural resources have undoubtedly been the most important source for satisfying his/her needs. With the increase in population, the amount of human use of natural resources has multiplied and more and more destruction is taking place in nature. Erosion is mong the most common phenomena that are seen in most parts of the world and Iran is the occurrence of erosion and instability of roadside slopes. Construction and maintenance of forest roads has been considered as a prominent feature of economic development for decades. In designing thes types of roads, in addition to paying attention to the main objectives, timber transportation and forestry objectives, maintenance of health and cleanliness of water outflows of a watershed against sediment should also be considered. Nowadays, the distribution of forest road network density for the implementation of forestry projects is an important issue that has been less considered by potential researchers as a potential source of sediment and runoff production. The upstream slope of the road is called the excavation trench, which is often located at the bottom of the side atmosphere. Side air can carry sediments produced from different parts of the road. Erosion of forest roads reduces the useful life of road constructions, increases the cost of protection and maintenance of vehicles and leads to the destruction of the environment of aquatic life. Many methods have been proposed to prevent soil erosion and stabilization in the walls/sides of forest roads. These methods generally include three biological methods, mechanical methods and biotechnical methods, each of which can be applied according to the existing conditions. The use of inanimate structures or biological structures is one of the most widely used methods to protect roads and maintain slope stability. So far, many bioengineering methods have been used to stabilize roadside walls and slopes in the world. The purpose of this study was to investigate the effect of some bioengineering treatments including installation of water absorption bags, dead leaves and cell stabilization (geocell) on the sedimentation rate of forest road trenches under rainfall and their efficiency and performance as protective mechanisms. In addition, in this research, by comparing the costs of preparation, installation, implementation and maintenance of each of the treatments used in stabilizing road trenches, the best treatment is determined. Conducting this study and similar studies can help us to gain the necessary knowledge and insight into the role of bioengineering treatments in the protection of forest areas and ultimately the correct and sustainable management of roads in forest areas.
2- Methodology
To investigate the effect of sedimentation on forest road trenches, bioengineering treatments of water absorption bags, dead leaves and cell stabilization methods were used. For this purpose, in the forest roads of a series of forestry plan of Dr. Bahramnia, the location of soil trenches prone to erosion and thrust was recorded with the help of GPS in the summer of 2020. Then 12 trenches, each with a minimum usable area of 30 square meters, were selected randomly and for each of the trenches, except for the control treatment, bioengineering treatments of water uptake bags, dead leaves and cell stabilization were performed. Trench status was monitored and rainfall and sediment data were collected after each rainfall during the two seasons of autumn and winter. Soil erosion and sediment delivery were examined by being trapped in the side atmosphere at the beginning and end of the treated and controlled trenches. Trapping involved digging a cylindrical pit 0.4 m in diameter and 0.6 m depth to collect sediment. A calibrated index was installed in the center of each to estimate the sediment height. Upon each visit, sediment height (meters) and sedimentation level (square meters) were measured to calculate sediment volume. To calculate the specific gravity of sediment, three soil samples were prepared at the end of each period by the ring method and were dried in an oven for 24 hours and then the weight of the samples was measured. Data analysis was performed in a randomized block design with two blocks of 4 treatments and 3 replications in SAS software.
3- Results
The results obtained from the analysis of variance of the effect of different treatments on reducing the amount of sediment from excavated trenches of forest roads showed that all the bioengineering treatments significantly reduced sediment (p<0.0001). Also, there was no significant difference between the amount of sediment obtained from the slopes treated with dead caper and the controlled slope. However, a significant difference was observed in the comparison of water and control bag absorption treatment at ٪5 probabilitylevel and in the comparison of cell stabilization and control treatment at probability level of ٪99. The amount of sediment from the dead treatments of water uptake bag and cell stabilization were 4787, 7309, 8798 g, respectively, compared to the controlled treatment condition.
4- Discussion & Conclusions
In the study of the effectiveness of different engineering treatments in different rainfall events, the results showed that the water absorption bag treatment is more efficient than the other two treatments: cell stabilization and dead leaf treatments. The reason for this is the hemp structure and water absorption properties of this type of treatment, which makes the rate of erosion and sediment production in the lateral atmosphere less than the other treatments. Another reason for the better performance of the water absorption bag in reducing sedimentation is that the treatment itself needs less digging and soil corrosion during execution and installation. Dead caper treatments, water uptake and cell stabilization treatments reduced soil loss at 20.30, 46.13 and 40.24, respectively. The reduction of soil loss in the mentioned treatments compared to the control treatment is due to the fact that each of these treatments acted as a retaining wall and reduced the water flow rate. In general, the study and monitoring of various treatments showed that the use of bioengineering treatments can have a significant effect on reducing the sedimentation rate of forest roads. Among the applied bioengineering treatments, water absorption bag treatment due to having hemp structure caused more water absorption and penetration in the soil. Erosion and sedimentation of forest road excavation walls were significantly reduced by increasing water uptake and reducing water flow.
Soil is the most important foundation of any country's civilization, without which human life is endangered. Since man has lived on this planet, natural resources have undoubtedly been the most important source for satisfying his/her needs. With the increase in population, the amount of human use of natural resources has multiplied and more and more destruction is taking place in nature. Erosion is mong the most common phenomena that are seen in most parts of the world and Iran is the occurrence of erosion and instability of roadside slopes. Construction and maintenance of forest roads has been considered as a prominent feature of economic development for decades. In designing thes types of roads, in addition to paying attention to the main objectives, timber transportation and forestry objectives, maintenance of health and cleanliness of water outflows of a watershed against sediment should also be considered. Nowadays, the distribution of forest road network density for the implementation of forestry projects is an important issue that has been less considered by potential researchers as a potential source of sediment and runoff production. The upstream slope of the road is called the excavation trench, which is often located at the bottom of the side atmosphere. Side air can carry sediments produced from different parts of the road. Erosion of forest roads reduces the useful life of road constructions, increases the cost of protection and maintenance of vehicles and leads to the destruction of the environment of aquatic life. Many methods have been proposed to prevent soil erosion and stabilization in the walls/sides of forest roads. These methods generally include three biological methods, mechanical methods and biotechnical methods, each of which can be applied according to the existing conditions. The use of inanimate structures or biological structures is one of the most widely used methods to protect roads and maintain slope stability. So far, many bioengineering methods have been used to stabilize roadside walls and slopes in the world. The purpose of this study was to investigate the effect of some bioengineering treatments including installation of water absorption bags, dead leaves and cell stabilization (geocell) on the sedimentation rate of forest road trenches under rainfall and their efficiency and performance as protective mechanisms. In addition, in this research, by comparing the costs of preparation, installation, implementation and maintenance of each of the treatments used in stabilizing road trenches, the best treatment is determined. Conducting this study and similar studies can help us to gain the necessary knowledge and insight into the role of bioengineering treatments in the protection of forest areas and ultimately the correct and sustainable management of roads in forest areas.
2- Methodology
To investigate the effect of sedimentation on forest road trenches, bioengineering treatments of water absorption bags, dead leaves and cell stabilization methods were used. For this purpose, in the forest roads of a series of forestry plan of Dr. Bahramnia, the location of soil trenches prone to erosion and thrust was recorded with the help of GPS in the summer of 2020. Then 12 trenches, each with a minimum usable area of 30 square meters, were selected randomly and for each of the trenches, except for the control treatment, bioengineering treatments of water uptake bags, dead leaves and cell stabilization were performed. Trench status was monitored and rainfall and sediment data were collected after each rainfall during the two seasons of autumn and winter. Soil erosion and sediment delivery were examined by being trapped in the side atmosphere at the beginning and end of the treated and controlled trenches. Trapping involved digging a cylindrical pit 0.4 m in diameter and 0.6 m depth to collect sediment. A calibrated index was installed in the center of each to estimate the sediment height. Upon each visit, sediment height (meters) and sedimentation level (square meters) were measured to calculate sediment volume. To calculate the specific gravity of sediment, three soil samples were prepared at the end of each period by the ring method and were dried in an oven for 24 hours and then the weight of the samples was measured. Data analysis was performed in a randomized block design with two blocks of 4 treatments and 3 replications in SAS software.
3- Results
The results obtained from the analysis of variance of the effect of different treatments on reducing the amount of sediment from excavated trenches of forest roads showed that all the bioengineering treatments significantly reduced sediment (p<0.0001). Also, there was no significant difference between the amount of sediment obtained from the slopes treated with dead caper and the controlled slope. However, a significant difference was observed in the comparison of water and control bag absorption treatment at ٪5 probabilitylevel and in the comparison of cell stabilization and control treatment at probability level of ٪99. The amount of sediment from the dead treatments of water uptake bag and cell stabilization were 4787, 7309, 8798 g, respectively, compared to the controlled treatment condition.
4- Discussion & Conclusions
In the study of the effectiveness of different engineering treatments in different rainfall events, the results showed that the water absorption bag treatment is more efficient than the other two treatments: cell stabilization and dead leaf treatments. The reason for this is the hemp structure and water absorption properties of this type of treatment, which makes the rate of erosion and sediment production in the lateral atmosphere less than the other treatments. Another reason for the better performance of the water absorption bag in reducing sedimentation is that the treatment itself needs less digging and soil corrosion during execution and installation. Dead caper treatments, water uptake and cell stabilization treatments reduced soil loss at 20.30, 46.13 and 40.24, respectively. The reduction of soil loss in the mentioned treatments compared to the control treatment is due to the fact that each of these treatments acted as a retaining wall and reduced the water flow rate. In general, the study and monitoring of various treatments showed that the use of bioengineering treatments can have a significant effect on reducing the sedimentation rate of forest roads. Among the applied bioengineering treatments, water absorption bag treatment due to having hemp structure caused more water absorption and penetration in the soil. Erosion and sedimentation of forest road excavation walls were significantly reduced by increasing water uptake and reducing water flow.
Received: 2021/06/28 | Published: 2021/12/22
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