Wind erosion is one of the most important natural processes in semi arid, arid and hyper arid regions. This process occurs in conditions that wind has considerable speed and abundance in addition to existence of sensitive soil. Bafgh city is one of the arid regions of Central Iran has low rainfall and poor plant cover. Strong winds blowing on the surface of these non-coverage land causing soil erosion and other problems. Identify Storm prone areas could reduce its risks and losses. So identification and controlling of storm prone areas, the wind erosion threshold velocity should be determined in different facies foremost. In this study, the threshold velocity of each facies was measured by using of wind erosion meter (W.E. meter), and the iso-threshold velocity map of wind erosion was provided. For analyzing critical wind speed and aspect, the anemometers data of Bafgh synoptic station during 14 years statistical period was used. Grueling winds condition of this region was studied by Wind Rose (WRPLOT view 5.2.1) and SAND Rose (SAND Rosegragh 3.0) software. Results showed grueling winds blow from Northeast in 39 percent of the study area are fine grain plain facies with parabolic surfaces and Nebka, SAND dunes facies gardens and residential areas, and medium grain plain with medium reg and oued. The threshold velocity in these areas was 7 to 16 meters per second.

Background and Objectives: River sediments are the major component of the aquatic ecosystems and play an important role in the nutrients cycle and contaminants transformation in river systems.Sediment particles are transported in the forms of the suspended and bed sediment depending on the river flow regime and the size distribution of the particles. Sediments in the river are in equilibrium with the pore water and river flow. Therefore, the composition of sediments strongly affects water quality and the biological activities in the aquatic systems. Release of the organic and inorganic contaminants and nutrients from the sediments to the river flow is mainly influenced by the physical and chemical properties of the sediments. Thus, understanding of the basic physical and chemical properties of river sediments is essential for sustainable management of the watershed. The aim of this study was evaluate and compare the physical and chemical properties of the suspended and bed sediments of the ROZE-Chay river in the Urmia region.Materials and Methods: Total of the 19 bed sediments were collected along the river. Bed sediments were sampled from three parts of the river including up-stream (6 samples), mid-stream (6 samples) and down-stream (7 samples). In addition, six suspended sediments were sampled from the river during a flood event. Sediment samples were passed through a 2000 micron sieve and were analyzed for their basic physical and chemical properties. Hierarchical cluster analysis and principle component analysis were preformed for grouping the sediment samples and identifying the most effective properties of them.Results: Results indicated that the SAND and silt particles are very dominant in bed and suspended sediments, respectively. The average silt and very fine SAND content in bed sediments were 15.8 and 15.5 percents, while the silt and very fine SAND particles content in suspended sediments were 44 and 25 percent, respectively. However, bed sediment have coarse texture due to their higher SAND content in comparison with suspended sediments. The average values of organic matter and electrical conductivity of bed sediments were 1.7 and 2.5 times greater than the suspended samples. The organic matter content in up-stream bed sediments were higher than the middle and downstream parts, which may due to the discharge of the domestic sewage in this part of the watershed. Principle component and the hierarchical cluster analysis showed that the organic matter, EC and particle size distribution are the most effective properties of the sediments.Conclusion: Discharge of the domestic sewage to the river bed may has led to the accumulation of the organic matter and soluble salts in the bed sediments of the upstream part. As a result, the basic physical and chemical properties of the upstream bed sediments are different from the middle and downstream parts. Preventing the entry of the sewage into the river bed especially at the upstream part has an essential role in sustainable management of the ROZE-chay river ecosystem. Multivariate analysis of the sediment samples revealed that there was a significant difference between the properties of the suspended and bed sediments.

Land use surveys and investigations are a prerequisite for the study of watersheds, because regional planning is dependent on the awareness about land use type and future changes. As a result, modeling and predicting of land use is essential for land planning and management in the future of a country such as Iran, where land use is changing rapidly In this regard, in order to reveal the land use changes in the 15 years and modeling the changes for the next 20 years, the markovin transmission estimator was used with Landsat 7 and 8 Landsat satellite imagery data from the ROZE Chay basin of urmia. Based on the controlled classification algorithm with the maximum probability of land use as seven classes of land uses in this watershed were seven garden, irrigated farming, dry farming, grass land, residential area, water and salt marsh with a mean Kappa coefficient of 0. 88 and overall accuracy of 0. 9 for 2000 and 2015 were extracted. The changes of 15 years showed that the variation of water dependent uses in the region decreased during the mentioned time period (percentage reduction in the area of agricultural crops and gardens, 32. 51). The modeling of land use changes in the region with the markovin transmission estimator suggests that the use of gardens, arable and dry lands, villages and water resources will decrease, and the use of grass land and salt marsh will increase in the region (from 2020 to 2035 percent increase in area grass land 13. 11 and the percentage of dry farming 17. 56). The results indicate that soil and water resources are used improperly in the studied area, which requires comprehensive planning and management in the watershed.

In this research, the phenomenon of stress relaxation in unreinforced and reinforced SANDy soil with geotextile layer has been studied using a large-scale direct shear test. To investigate the effect of shear speed and soil density on the amount of resistance loss due to stress relaxation, two shear speeds of 0.5 and 5 mm/min and two relative densities of 35% and 60%, respectively, loose and medium density, have been used. All samples have been tested in direct shear test under vertical stress of 100 kPa. The results show that the amount of resistance loss due to stress relaxation depends on the shear stress level, soil density, presence of a geotextile layer in the soil and shear speed. In such a way that by increasing the level of shear stress and shear speed and by decreasing the density of SAND and also with the presence of a geotextile layer in soil, the amount of resistance loss due to stress relaxation increases.

Preparation of uniform and repeatable reconstituted SAND specimens of required density is a prerequisite for obtaining reliable results from experimental studies. Among different methods of reconstituted specimens, SAND pluviation technique is widely adopted by researchers because of its unique advantage. In this study, a new curtain traveling rainer (CTR) is developed for large model SAND bed preparation in experimental studies. CTR is a simple and low-cost system which is worked on the principle of air pluviation of SAND. It provides specimens with wide range of relative density of SAND bed (viz, 30%-90%) and very high degree of spatial uniformity of density distribution while reducing the time of preparation the specimens. A series of laboratory tests is carried out in order to study the performance of the proposed system and the effect of...

The phenomenon of liquefaction in loose and saturated SANDy soils is one of the most important hazards for engineering structures during an earthquake. In this phenomenon, the SAND changes its behavior rapidly from solid to viscous fluid, resulting in the instability of the ground. In this research, at first, SAND samples with liquefaction history collected from a site in Dorood, Lorestan, Iran. Samples obtained from depth of 1.8-2.7 and 2.7-3.5 m and in the laboratory, the parameters of maximum density, moisture content, friction angle and cohesion were determined. Then, in order to evaluate the effect of additive on the liquefaction potential, different percentages of clay from Dorood region added to the samples and tested. Finally, three-dimensional finite difference software (FLAC3D) used with inducing Dorood earthquake, to investigate liquefaction potential of stabilized samples by analyzing the u/σ ratio for models. The results showed that adding clay to the soil of this area reduce the friction angle, increase cohesion, and has a favorable effect on the liquefaction potential. Results of this investigation indicated that adding 3% clay to the liquefied Dorood SAND, would lead to decrease the liquefaction potential up to 39%.

The phenomenon of liquefaction in loose and saturated SANDy soils is one of the most important hazards for engineering structures during an earthquake. In this phenomenon, the SAND changes its behavior rapidly from solid to viscous fluid, resulting in the instability of the ground. In this research, at first, SAND samples with liquefaction history collected from a site in Dorood, Lorestan, Iran. Samples obtained from depth of 1. 8-2. 7 and 2. 7-3. 5 m and in the laboratory, the parameters of maximum density, moisture content, friction angle and cohesion were determined. Then, in order to evaluate the effect of additive on the liquefaction potential, different percentages of clay from Dorood region added to the samples and tested. Finally, three-dimensional finite difference software (FLAC3D) used with inducing Dorood earthquake, to investigate liquefaction potential of stabilized samples by analyzing the u/σ ratio for models. The results showed that adding clay to the soil of this area reduce the friction angle, increase cohesion, and has a favorable effect on the liquefaction potential. Results of this investigation indicated that adding 3% clay to the liquefied Dorood SAND, would lead to decrease the liquefaction potential up to 39%

This research describes the goals, design and implementation of a quasi natural gradient, laboratory scale, SAND tank (aquifer) model experiment. The model was used to study the transport of an inorganic tracer (Chloride) in groundwater, within a tropical aquifer (porous medium) material. Three-dimensional SAND tank (1.8 m × 0.3 m × 0.8 m) experiments were conducted to investigate contaminant transport and natural attenuation within the SAND tank. In all, 360 samples were collected during 24 sampling sessions, for the three days of the tracer experiments in the SAND Tank. The Owena SAND is a poorly graded SAND with 88.1 % SAND and 11.9 % gravel. Geotechnical properties including; coefficient of uniformity Cu = 2.53, coefficient of gradation Cz = 0.181, hydraulic conductivity K = 5.76 x 10-4 m/s, bulk density ρ = 1.9 Mg/m3, effective porosity ne = 0.215 and median grain diameter D50 = 0.55 mm, were determined. Other relevant hydraulic and solute transport parameters, such as dispersion coefficients and dispersivities were also established for the tropical soil.

Band e Rig Kashan is one the few large SAND zones of Iran with various SAND forms which is located at the south of salt lake. The area under study is a part of Band e Rig Kashan at south west of Maranjab with an area of 1.272 km2. In this study, thirty typical SAND hills were selected. The research method, based on field visits and sampling of SANDs in front head, tail, right and left arms of the understudy SAND hills was performed in the two time periods of August and March 2008, and by the use of grading technique, SAND particles were classified and their abundance were verified and analyzed.The aim of this research was review and study of seasonal changes of SAND particles diameter and their impact on the geometrical shape of SAND hills. The findings show that due to changes of direction, speed and frequency of wind during a year, changes occur on diameter afflection of SAND hills in main parts of SAND hill which leads to the changes of geometrical shape of forehead and right and left arms of SAND hill.