Showing 5 results for Sand Dune
H. Majdi, M. Karimian- Eghbal, H. R. Karimzadeh, A. Jalalian,
Volume 10, Issue 3 (10-2006)
Abstract
Stabilizng sand dunes has been one of the main challenges in the arid regions. So far, different kinds of mulches have been used extensively for sand dune stabilization. This study was carried out to determine the optimum composition, concentration and thickness of clay mulch for sand dune stabilization. For this purpose two soil samples from clay flats of a playa with different amount of salinity from Ardestan area were used to make clay mulches. A sand dune sample was selected as bed for applying the mulch. To select the right ingredient and treatments, clay samples were mixed with sand and different amount of water, and sprayed on sand dune bed. In addition, wheat straw was added to some mixture to test its effect on stability of the mulch. Treatments with lowest crack and highest penetration of mulch in sand bed were selected for the experiment in this study. Mulch treatments contained (1): 250g sand dune + 250g clay + 25g straw (2) 250g clay + 25g straw (3) 250g sand + 250g clay (4) 250g clay (5) 125g sand + 125g clay and (6) 125g clay. All treatments were mixed with 500ml water. The experimental design was a CRD with a 6(mulch) * 2(thickness)* 2 EC factorial method with 3 replications. The results showed that clay mulch were resistant to wind erosion, but erosion took place when they had been bombarded with sandblast. The mulches with straw showed the highest resistance to erosion as compared to other treatments. With increasing the number of mulch layers, resistant to erosion also increased. The added stability of mulch was due to the increase in mulch thickness and also increases in clay and silt content. The overall result of this study shows that the mulch with two layers and higher mixture of clay and sands was the best treatment for the stabilization of sand dunes.
H. Rezaei, Gh. R. Lashkaripour, M. Ghafori, N. Hafezi Moghadas,
Volume 18, Issue 70 (3-2015)
Abstract
Fine-grained materials of Clayey Loess deposits of Gorgan region were mixed with sand dune in the lab with various rations and their shear behavior was measured and evaluated by direct shear test. The result of the study showed that the increase of fine-grained clay in sand dune was directly related to the adhesion force and inversely to the internal friction angle. The increase or reduction in shear strength was affected by the fine-grain percentage. Dry condition and saturation of the test and sand dune had a less influence on shear parameters but in the mixed samples in dry condition and saturation, shear parameters revealed a considerable difference. The results of this study can be used in sand stabilization, erosion prevention, slope stability, embankment construction, compaction increase, and environmental pollution, and dust and water channels avoidance.
F. Imani, M. Moradi, R. Basiri,
Volume 20, Issue 77 (11-2016)
Abstract
This study was done to evaluate the effect of afforestation in sand dunes at the vicinity of Shush, because of the importance of soil protection and wind erosion in sand dunes, also sand dunes afforestation as an effective and long lasting fixation mechanism. The study site was covered by petroleum mulch about 20 years ago and afforested by Prosopis juliflora. To study the effects of afforestation on sand dunes, two 10 ha afforested sites (25-50 and 75-100 percent canopy coverage) and control were selected. In each of studied site 15 plots were established and soil physiochemical properties were determined. Our result indicated that afforestation caused soil texture to change from sandy to sandy-loam. Also, soil phosphorus, potassium, organic carbon and nitrogen increased in 0-5 cm soil depth by afforestation that could be because of nutrient absorption from soil depth and returning to the surface by litter fall compared to the control. This study revealed that 25-50 percent canopy coverage resulted in better soil physiochemical properties compared to control site. In conclusion, sand dunes afforestation not only resulted in sand dunes fixation but also soil fertility and long lasting fixation.
G. H. Zoraghi, K. Shabani Goraji, M. R. Noura, A. R. Rashki,
Volume 23, Issue 2 (9-2019)
Abstract
Creating a mulch layer on the sand dunes surface has long been applied to reduce their mobility. However, application of oil mulch in some countries, in addition to high costs, has many environmental problems. In this research, the hydrated lime slurry was used as a protective cover on the sand dunes. The slurry was prepared in three treatments with 3, 5 and 7% lime and sprayed uniformly on 2×5 m plots on the sand dunes surface. The average thickness of different types of mulch was measured by a caliper and then their abrasions were calculated in two-month intervals for three calcareous and controlling treatments at three locations. Statistical analysis was performed by using SPSS and the Excel software. The results showed that the 3% lime slurry layer had no resistance to wind abrasion and was comparable to the controlling sites. The results obtained for the 5 and 7% lime slurry mulch layers indicated that the increase in lime percentage raised the mulch resistance against the wind abrasion. The 7% lime slurry layer with a 6.3 mm thickness showed the highest abrasion resistance in the natural conditions.
A.r. Nourafar, A. Pahlavanravi, M. Nohtani, V. Rahdari,
Volume 26, Issue 1 (5-2022)
Abstract
Wind erosion is one of the most important natural processes in arid and semi-arid regions. Sistan plain has a hyper-arid climate and is one of the windy regions of the country. Due to the soil characteristics of the Sistan plain, wind erosion is very intense in this region. In this study, the relationships between some soil's physical and chemical properties and wind erosion were investigated in different land cover in a part of the central region of Sistan in 2018. A map of land cover in five classes was prepared using the results of field studies and the classification of satellite images. Fifty soil samples at a depth of 10 cm were collected to investigate the physical and chemical soil properties and the wind erosion threshold was determined at each location using a portable wind tunnel device. Also, the relationship between physical and chemical soil properties including soil texture, soil moisture, specific apparent weight, EC, SAR, ESP, Na+, k+, with the speed of wind erosion threshold was investigated. According to the results, the highest and the lowest threshold speed were 8.2 and 3.8 m s-1 and occurred in agricultural lands and hilly lands, respectively. The results of this study indicated that the velocity of wind erosion threshold in different lands adjacent to sandy areas is less than the average of that cover. Also, the soil texture, EC, and SAR have the most significant effect on soil wind erodibility at P <0.05 in the study area.
