Farzad Heidari moorchekhortei; Mohammad Khosroshahi; Razieh Saboohi; Morteza Khodagholi; Leila Kashi Zenouzi
Volume 30, Issue 2 , September 2023, , Pages 196-213
Abstract
Background and objectivesResearch has been done on different materials to control and reduce wind erosion. Among them, we can mention the performance of agar gum biopolymer in reducing dust production at different concentrations of 0.5, 1.0, and 1.5%. Its results showed that the addition of biopolymer ...
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Background and objectivesResearch has been done on different materials to control and reduce wind erosion. Among them, we can mention the performance of agar gum biopolymer in reducing dust production at different concentrations of 0.5, 1.0, and 1.5%. Its results showed that the addition of biopolymer improves the water-holding capacity, increases the surface and compressive strength of the soil, and decreases dust production. In another study, agar gum biopolymer significantly improved soil mechanical properties. This study investigates the effect of polymer nuclei (M19) on controlling sand dunes. This research investigates the effect of nucleos (M19) mulch on reducing wind erosion and controlling sand dunes and dust. MethodologyThis research was carried out in Segazi Plain, a study and implementation priority due to its proximity to urban areas, military facilities, transportation, as well as industries and workshops located there, from the aspect of preventing wind erosion and desertification. After choosing the field, two plots of 500 square meters with the same conditions (an active hill with an area around it with natural and hand-planted vegetation) were selected. To determine the effect of soil cover, the area of each plot was determined by wooden stakes. In addition, the surrounding sand dunes were staked to measure their displacement. A pump sprayer mulched the measuring plot with nucleos (M19) mulch. Following the soil moisture changes, information including seedling survival and growth rate, soil cover's ability to control sand dune displacement, and compressive stress was examined during different months. Finally, the effectiveness of soil cover was compared with the control treatment using the T-test. Results The results of examining the changes in humidity and the effect of soil cover on it showed that the highest humidity in the area was after rain. No clear difference was observed between the drying process of the control plot and the mulched plot. It was also found that this mulch positively affects seedling growth rates. During the research period, the control sand dunes moved about 0.75 to 2.5 meters depending on the season and wind direction. In contrast, the mulched sand dunes remained stable. On the other hand, with time, the mulched field's surface became flaky, and signs of wear and tear were observed.ConclusionThe first point about using this polymer as a soil cover is its two phases during transportation and storage until mulching. In such a way, the two layers can be clearly distinguished. As a result, mixing is necessary for the uniformity of the polymer during the preparation of the final emulsion. This can be considered as one of the negative characteristics of the used polymer. This mulch positively affected soil moisture changes and increased soil moisture retention. On the other hand, the comparison of the growth of the seedlings in the mulched field and control also shows its effect on the growth of the seedlings. This soil cover's only positive and critical feature is its high flexibility after mulching in such a way that it is possible to drive on it with caution. Finally, after a year, cracks were first detected in the research field. Gradually, the number and depth of cracks increased, which caused the mulched field surface to become flaky. Following this complication, instability and signs of wear and tear were observed in the mulched area. However, no movement or change in location was observed in the mulched hill. It should be noted that with time, more destruction occurs on the surface of the mulched area. Following more flaking, the mulched surface may be destroyed, and hill erosion may begin. Considering these cases, mulching in this and similar areas is not recommended.
Mahin Hanifapour; Gholamreza Zehtabian; Hasan Ahmadi; Aliakbar Nazari Samani; Hassan Khosravi
Volume 29, Issue 2 , July 2022, , Pages 186-195
Abstract
Wind erosion and dust storms are one of the natural disasters that are increasingly facing the arid and desert areas of central Iran. Improper management in natural resources has also had a high impact on this phenomenon. One of the basic principles of controlling and combating ...
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Wind erosion and dust storms are one of the natural disasters that are increasingly facing the arid and desert areas of central Iran. Improper management in natural resources has also had a high impact on this phenomenon. One of the basic principles of controlling and combating wind erosion is to know the areas of sediment harvesting. The purpose of this study is to identify the areas of wind sediment harvesting in the facies of the Mallard region in the west of Tehran province. Based on topographic maps, satellite imagery, geological map, and field surveys, the geomorphologic facies map was prepared and then the sampling was done and analyzed in a GIS environment. The interpretation of the anemometer data using Windrose & Stormrose showed the wind direction of the dominant and eroding from the northwest. The results obtained from the study's Sandrose indicated that variation in wind direction is low to high, and Qazvin station (the station closest to the critical centers) had high variability and included multi-directional winds with sharp angles. The 83 samples of different facies of the study area are graded by the ASTM (Dry Sieve) method. The granulation results indicate the local origin of the harvest. The prioritization map of the critical centers of the region showed that 16.4% of the area is low intensity, 3.4% medium intensity, and 3% high intensity. Finally, it was found that saline clay with no vegetation cover or with little vegetation covered with saline in the plain had the highest percentage of particles sensitive to wind erosion.
Razieh Saboohi; Farzad Heidari Mourchekhorti; Morteza Khodagholi; Somayeh Salehpour
Volume 28, Issue 2 , June 2021, , Pages 280-295
Abstract
The use of polymers to control wind erosion has been considered in recent years. However, before recommending them as mulch, their effects on the environment and reduction of wind erosion should be investigated. In this paper, the effect of Imen Asia polymer in stabilizing quicksands and reducing wind ...
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The use of polymers to control wind erosion has been considered in recent years. However, before recommending them as mulch, their effects on the environment and reduction of wind erosion should be investigated. In this paper, the effect of Imen Asia polymer in stabilizing quicksands and reducing wind erosion in both laboratory and field sections in the Lower Jargooiyeh region was investigated. For this purpose, first, an emulsion of polymer in water with a ratio of one to three (one-part polymer in two parts water) was prepared and to investigate its effect on reducing erosion, a volume of emulsion containing 80, 100, and 120 kg of polymer in 25 m2 plots Sprayed with three repetitions. The results showed that the wind erosion threshold speed after mulching increased from 3.5 to more than 11 m / s in all treatments. The study of the environmental effects of the polymer showed that the concentration of mulch did not affect the germination of native plants and the lifestyle of insects and rodents in the area. The effect of polymer on the physical and chemical properties of soil, including changes in the number of toxic elements and heavy metals on the soil before and after mulching, also confirms that it does not have a negative effect on these properties. Economically, the cost of using this polymer per hectare was evaluated. Based on the net present value (NVP) of this material and its internal rate of return (IRR), the economics of using it and investing in the use of this polymer as mulch are justified. Due to the lack of harmful effects on the environment and the ability to reduce wind erosion and economical to oil mulch, the use of this polymer as mulch is recommended
Morteza Abtahi
Volume 26, Issue 3 , September 2019, , Pages 517-530
Abstract
Wind erosion and its consequences, such as dust storms and sand movement is one of the environmental problems in arid regions. There are several ways to combat wind erosion, among which biological reclamation using drought-tolerant species and psammophytes is the most sustainable method. The initial ...
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Wind erosion and its consequences, such as dust storms and sand movement is one of the environmental problems in arid regions. There are several ways to combat wind erosion, among which biological reclamation using drought-tolerant species and psammophytes is the most sustainable method. The initial establishment of these plants requires the use of sand stabilizers such as mulches. The mulch used in the past was the product of oil refineries and industries, which despite its merits such as strength and flexibility, had many environmental consequences. Therefore, researchers and scientists in the country decided to present an eco-friendly product that would replace the oil mulch. One of these products is polymer-cellulosic mulch, produced by the Department of Chemistry, Malek Ashtar University of Isfahan. This mulch was used in sand dunes of Kashan, during which the mulch resistance to environmental conditions, its effect on plant establishment, and soil moisture uptake and retention were investigated. The results showed that this mulch had no negative effect on plant establishment. Its resistance to wind erosion is very good for the first few months of spraying. However, over time and during the hot summer months, cracks appear that partially overshadow the mulch's stabilizing properties. The soil moisture content was about 4.5% higher in 10 t/h mulch as compared with control. In general, for the crust and cracks problems, this mulch cannot be a good alternative to petroleum mulch.
Hajar Ranjbar; Masoud Bazgir; Davod Namdar Khojasteh; Mahmoud Rostaminia
Volume 26, Issue 3 , September 2019, , Pages 675-688
Abstract
Dust storm phenomenon is one of the most damaging natural disasters in arid and semi-arid regions of the world especially in Iran caused problem on human health and environment. The main reason of dust storm event can be climate change, destruction of natural ecosystems, ...
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Dust storm phenomenon is one of the most damaging natural disasters in arid and semi-arid regions of the world especially in Iran caused problem on human health and environment. The main reason of dust storm event can be climate change, destruction of natural ecosystems, deforestation, and destruction of rangelands in Iran and neighbor countries like Iraq. Ilam province due to adjacent to vast deserts such as the Iraq Sahara is exposed to severe dust storm continuously. The aim of this study was to identify the critical points of dust sources in Ilam province. At first step, long-term climate data (8 synoptic weather stations), vegetation cover, and physiography of study area were collected. In the second step, soil sampling was carried out at 0-30 cm soil depths in some places in Ilam province and then these soil samples were transferred to the soil laboratory for chemical and physical analyses. In the third step, by using USEPA model, soil and the maps of climatic parameters were prepared and finally critical and high critical dust source points were mapped through integration of different maps in Ilam province. The results showed that the Bahram Abad area in the central Mehran and Abu-Ghoraib and Abu-Ghovayr areas in Musian part, Dehloran city were selected as high critical sources of dust storm in Ilam province due to the highest corresponding with dust storm identification criteria. This project could be useful for prevention and control of dust storm via identification and dust storm maps.
Hosein Golbabaie; Abolfazl Khalilpour; Alimohammad Tahmasebi Beyragani
Volume 11, Issue 3 , August 2019, , Pages 255-274
Mohammad Fayaz
Volume 12, Issue 1 , August 2019, , Pages 41-62
Ewsmaeel Rahbar; Mohammad Darvish
Volume 12, Issue 1 , August 2019, , Pages 63-72
rasoul mahdavi; azam ali eivazi dokhtak; hamid gholami; Alireza kamali
Volume 24, Issue 3 , October 2017, , Pages 610-622
ali Nazari; asghar tavakoli; hoda ghasemieh; naser mashhadi; mohammadreza rahdari
Volume 24, Issue 1 , May 2017, , Pages 67-79
Abstract
Wind erosion is one of the most important natural processes in arid and semi-arid areas, occurring as a result of erosive winds. Wind speed, frequency and duration should be considered in studies related to wind erosion. Kashan Erg is one of the most important sand dunes complexes in Iran. To study the ...
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Wind erosion is one of the most important natural processes in arid and semi-arid areas, occurring as a result of erosive winds. Wind speed, frequency and duration should be considered in studies related to wind erosion. Kashan Erg is one of the most important sand dunes complexes in Iran. To study the relationship between the wind characteristics (Uni- directional index, windness index, wind duration and frequency) with Erg morphology and also study the changes of sand flow rate in various regions, anemometers data were obtained from synoptic stations of Kashan, Ardestan, Jangalbani Badrod, Garmsar and Qom. Then, the interpolation map of sand transport and interpolation map of average and maximum wind in Kashan Erg were drawn using GIS software. Finally, the analysis results showed that the interpolation map of sand transport corroborated the results obtained from interpolation map of average wind, because sand transport rate and average wind speed were reduced from east to west of the Erg. Therefore, it is found that wind frequency and duration have more important role in the sand transport and morphology of the study area as compared with the wind speed. In addition, the comparison of Erg morphology and anemometer results in different stations showed that the spring and summer winds had the highest role in the Erg morphology.
Amir Hosein parsamehr; zahra khosrovani
Volume 23, Issue 4 , March 2017, , Pages 832-842
Abstract
In arid and desert regions, wind has an important role in soil erosion. The amount of wind energy and its direction variability have significant control on the morphology and maintenance of aeolian land forms. This research was aimed to analyze the erosive winds and investigate the discharge and sediment ...
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In arid and desert regions, wind has an important role in soil erosion. The amount of wind energy and its direction variability have significant control on the morphology and maintenance of aeolian land forms. This research was aimed to analyze the erosive winds and investigate the discharge and sediment transport in the study area. For this research, anemometric data of a duration period of 20 years (1994-2013) were analyzed. Wind rose and sand rose are one of the best methods to determine the wind erodibility. The results obtained from the analysis of wind rose data indicated that the direction of prevailing wind in the study area was NE, W and E. The results of sand rose for a wind speed threshold of 12 knots showed that the drift direction was from south – west towards north – east. The maximum and minimum amount of total sand drift potential was 105.3 and 594.7 in vector units, related to Kashan and Ardestan stations, respectively.
Mohammadreza Ekhtesasi; Asghar Zare chahouki
Volume 23, Issue 2 , September 2016, , Pages 264-255
Abstract
Estimating the amount of wind erosion in the plains of Iran is the most important requirement for planning and selecting appropriate methods of erosion control. Two approaches including IRIFR1 Model and wind erosion meter were used to measure and estimate the erosion and deposition potential in the Segzi ...
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Estimating the amount of wind erosion in the plains of Iran is the most important requirement for planning and selecting appropriate methods of erosion control. Two approaches including IRIFR1 Model and wind erosion meter were used to measure and estimate the erosion and deposition potential in the Segzi plain of Esfahan. Initially, different landforms of the Segzi plain including coarse grain plain, medium grain plain, and fine grain plain were detected. In order to measure the deposition potential, initially in each of the landforms per different wind speeds, the amount of soil erosion was measured within an hour using the wind erosion meter. The continuity of wind blowing for each wind speed class was estimated by analyzing the wind roses of East Isfahan station during the year. Finally, the erodibility rate of each landform was determined by integrating the multiplication of the continuity of each wind speed class and erodibility. In order to use the IRIFR1model, while visiting the desert, the scores of each index were given to the landforms and the deposition potential was estimated. The results showed that the amount of wind erosion of each studied landforms from coarse reg, average reg, fine reg and very fine reg were 2, 13.2, 21.3 and 74.1 ton/ha/yr, respectively. On the other hand, the values obtained from both models show differences of 5% to 30% in different landforms. The average amount of deposition obtained from IRIFR1 is about 11% less than the values obtained from wind erosion meter.
Ali Mohammad Ghaemi Nia
Volume 22, Issue 2 , August 2015, , Pages 356-372
Abstract
Due to the difficult field operations in desert regions, in order to measure wind erosion, the use of devices with a high-performance, resistant to environmental conditions and need less maintenance is required. The main objective of this research was to design, manufacture, and evaluation of EDST (Eight ...
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Due to the difficult field operations in desert regions, in order to measure wind erosion, the use of devices with a high-performance, resistant to environmental conditions and need less maintenance is required. The main objective of this research was to design, manufacture, and evaluation of EDST (Eight Directional Sand Trap)", so that it could be used in areas exposed to wind erosion and sedimentation. The device is made of two parts including the sediment catch from the soil surface to a height of 60 cm and sediment holding tanks for the eight geographical directions. According to the obtained results, the catching efficiency of this sand trap varied in different examined wind speeds (1, 2, 3, 4 and 5 ms-1);so that the most efficiency was equal to 47.3% at 4 ms-1. In addition, the device efficiency in determining the direction of sediment transport increased by increasing tunnel’s wind speed and reached to the highest value (61.8%) at 5 ms-1. The comparison of cumulative curve of sediment grading inside the sand trap and sediment source in the wind tunnel showed that the device was selective to diameter, so that the trapping of particles whose diameter was more 1 mm was done with an efficiency of 86%. However, it was inefficient in tapping the particles smaller than 1 mm.
Ahmad Pahlavanravi; Alireza Moghadamnia; Zohreh Hashemi; Mohammad reza Javadi; Abbas Miri
Volume 19, Issue 4 , March 2013, , Pages 624-639
Abstract
Many studies have been carried out to assess and prepare desertification map in the world. In order to assess the current situation of desertification intensity, a study was carried out in an area of 88350 hectares in Zahak region of sistan. In this study, at first, based on combining information extracted ...
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Many studies have been carried out to assess and prepare desertification map in the world. In order to assess the current situation of desertification intensity, a study was carried out in an area of 88350 hectares in Zahak region of sistan. In this study, at first, based on combining information extracted from topographic and geologic maps, aerial photos and field survey, the study area was divided into 11 geomorphologic faces and each face was considered as the main unit for evaluating the current situation of desertification. With regard to the analysis and combining FAO-UNEP and MICD models, as the most famous models of desertification intensity assessment in Iran and world, it was attempted to identify effective indices based on wind erosion to select the best ones. These indices were evaluated in a regional model of desertification assessment with regard to the numerical value of each index in each work unit and then in whole study area. Finally, the current situation of desertification intensity of the study area with emphasis on wind erosion criterion was estimated in four classes of insignificant and low, medium, intense and very intense. Results indicated that the study area with respect to desertification intensity was placed in the classes of medium (about 734.33 hectare (0.9 %)), intense (about 61473.38 hectare (73.6 %)), and very intense (about 21310.22 hectare (25.51 %)). Also, the weighted average of quantitative value (DS) was estimated to be 25.52 in the whole area indicating an intense desertification in the region.
Naser Mashhadi; Hasan Ahmadi
Volume 17, Issue 4 , November 2011, , Pages 499-517
Abstract
The results of wind dynamic are transport of soil or sediment particles and subsequently evolution of desert landforms according to the intensity of either erosion or sedimentation process.Geology, geomorphology and climatology conditions of the Khartouran region create a special situation on the closed ...
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The results of wind dynamic are transport of soil or sediment particles and subsequently evolution of desert landforms according to the intensity of either erosion or sedimentation process.Geology, geomorphology and climatology conditions of the Khartouran region create a special situation on the closed basin of Dasht-e-Kavir. It is evident that the ecosystem balance of the region is affected by anthropogenic exploitation and wind activity, so this area has a geoecological structure with special features. The Khartouran Erg is resulted of wind activity on sand sources. The study area is located on the southwest of Sabzevar city with a total area about 200000 hectares. The study was carried out based on topographic, geologic maps, satellite images, aerial photographs, field observation and sampling. Based on the information and data, the study area was divided into grid cells of 3 km × 3 km. Surface soil or sediment of corner points of each grid was sampled (214 points). The results of granolometry analysis of soil or sediment samples were presented in seven maps. These maps show grain size distribution and consequently determine sand supplement potential of each point in different wind velocities.The granulometry analysis of samples showed that particle size with a range of 0.063 to 0.150 mm (the most vulnerable sand particle size to wind erosion) comprised the most percentage of distribution. Based on the results it may be concluded that these regions were affected by wind erosion in the past more rather than of current time and Khartouran Erg is result of wind activity in the past. Currently, the rate of sand movement intensity and the balance between erosion and sedimentation are dominant factors in shaping geomorphologic facies (Aeolian landforms).
Abass Miri; Ahmad Pahlevanroy; Alireza Moghaddamnia
Volume 16, Issue 3 , December 2009, , Pages 329-342
Abstract
Occurrence of prolonged drought was commenced in Sistan region from 1999 caused by wetland dryness in Hamoun Lake and wind erosion. Severe wind erosion and dust storm cause huge damages to various aspects of the people's life in the study region and thus understanding of the impacts of soil erosion and ...
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Occurrence of prolonged drought was commenced in Sistan region from 1999 caused by wetland dryness in Hamoun Lake and wind erosion. Severe wind erosion and dust storm cause huge damages to various aspects of the people's life in the study region and thus understanding of the impacts of soil erosion and dust storms on human's lifefor making better decision is vital. The meteorological data of Sistan region and WRPLOT software were used to study wind erosion and draw wind rose in the study area. In addition, meteorological code numbers of 30 and 35 and the data of wind speed and direction as well as visibility were used to analyze dust storms datasets. The results show that prevailing wind has north to north west directions. It is found that droughts have increased the frequency of dust storms with mean dusty days, from 10 to 54 days in 1980 and 1999, respectively after drought occurrence. As above- mentioned, over period (1980-1999), there have been 324 dust storm days. The furthest horizontal visibility, between 1-5 km, took place in 2001, particularly in July, August, and September. It is found out that number of dust storm days which are recorded in summer season (June, July, August and September) is more than others. The length of dust storms in the region was between 3 to 110 hours. The frequency of dust storms occurred in more than 3 hours was fairly high. It can be concluded that wind erosion in the Sistan region has significantly increased after drought.
Hamid reza Azimzadeh; Mohammad reza Ekhtesasi; Hossein qoli Refahi; Hassan Rohipour; Manuchehr Gorji; Mohammad hasan Emtehani
Volume 16, Issue 1 , December 2009, , Pages 114-123
Abstract
Reducing the length of field along the wind path can be a major factor in providing protection against wind erosion. Therefore, the study of sediment transported by wind versus the field length and maximum transport capacity is necessary. As the wind passes over eroding soil surface, the quantity of ...
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Reducing the length of field along the wind path can be a major factor in providing protection against wind erosion. Therefore, the study of sediment transported by wind versus the field length and maximum transport capacity is necessary. As the wind passes over eroding soil surface, the quantity of sediment transported by wind increases until the wind stream becomes saturated. In the other word the mass transported is limited by the emission rate of materials from the soil surface to the air flow, known as transport limiting. The field length required for the wind to reach its maximum capacity depends on the wind velocity and the components of the soil surface. The field data were collected from 1.9ha fallow lands of Yazd-Ardakan plain. Big Spring No Eight (BSNE) samplers were set up to collect samples of horizontal sediment discharge passing through a point. Twelve events data were collected and analyzed started from May 2006 to may 2007. Two methods were adopted to determine the maximum transport capacity; 1) Fitting the mathematic equation of and 2) Direct measurement of transport capacity. Variance analysis and t-test paired data results showd that, there was no significant difference between the results of these two methods.
Ali Akbar Safdari; Zahra Mahmoodi; Hadi Memarian Khalilabad
Volume 15, Issue 3 , January 2008, , Pages 304-319
Abstract
In the wind erosion process, there are three areas: detachment area, transport area and deposition area. The prevention of sediments movement in the detachment area is a basic task. Knowing origin of sediments of sand dunes, the recognition of the detachment regions is necessary. In order to origin study ...
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In the wind erosion process, there are three areas: detachment area, transport area and deposition area. The prevention of sediments movement in the detachment area is a basic task. Knowing origin of sediments of sand dunes, the recognition of the detachment regions is necessary. In order to origin study of eolian sediments in the Mokhtaran plateau, step-by-step method (Ekhtesasi-Ahmadi) was used. This study is done at tow stages: direction finding and location finding. To direction finding of taking sector, firstly by questionnaire completion, local winds information were gathered. Then satellite image (ETM+, 2002) and field investigations, the erg morphological map was provided. By studying of wind regime and wind rose drawing, the erosive winds were recognized. After recognition of taking sector (surrounding pediments of sand dunes), the location finding phase was started. In this stage by geomorphologic studying of taking sector and sampling into facieses, the mineralogical and morphoscopical studies of sand dunes and taking sector sediments were done. At least, the study shows that KUPH (schist and phyllit), Colored melonged and other sensitive formations in the east and southeast areas are basic sources of eolian sediments for Mokhtaran erg, which deposited by water erosion in the different parts of Mokhtaran plateau. In consequence of east and southeast erosive winds, these sediments are taken and deposited around of DAGH. These sediments were displaced so much time by winds that have different directions inside of the erg (north and northwest winds) and formed pyramid sand dunes. Thus in order to preventing of wind erosion, the initial sources i.e. KUPH formation and surrounding pediments must have in mind.
Hadi Memarian Khalilabad; Ali akbar Safdari; Mohammad reza Ekhtesasi
Volume 15, Issue 1 , January 2008, , Pages 26-41
Abstract
In wind erosion process, there are three areas: source area, transport area, and deposition area. The prevention of sediments movement in the source area is a fundamental task. In stabilizing source sediments of sand dunes, recognition of the taking regions is essential. In order to study the in order ...
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In wind erosion process, there are three areas: source area, transport area, and deposition area. The prevention of sediments movement in the source area is a fundamental task. In stabilizing source sediments of sand dunes, recognition of the taking regions is essential. In order to study the in order to study the source of eolian sediments in the Fadisheh region, a step-by-step method (Ekhtesasi-Ahmadi) was used. This study was done in two stages: direction finding and location finding. First, information about the direction of local winds was gathered by questionnaire. Then satellite image (ETM+, 2002) and field investigations, the erg morphological map was determined. By studying wind regime and wind rose drawing, the erosive winds were recognized. After recognition of source sector (southeast and east sector), the location finding phase was started. In this stage by geomorphologic studying of the source sector and sampling into facieses, the mineralogical and morphoscopical studies of sand dunes and source sector sediments were done. Finally, paying attention to other evidences as the direction of Barkhan dunes (Southeast-Northwest), high intensity of energy for East winds, the existence of heavy minerals as Hematit, Chamosite, Edenite and Sphalerite in sand dune and source area soil samples, average median of sand dunes sediment samples (~210micron), symmetrical shape of sand dunes sediments frequency graph, was found that the source of eolian sediments are in the middle distance relative to sand dunes and are as follows: damaged Haloxylon forests, non vegetative area, unutilized lands in the southeast sector of the clay plains, Microlithic pediments and non vegetative lands in the margins of Kal-e-Shoor and Kal-e-Shoor River bed.
Naser Mirzamostafa; Davar Khalili; Mohammad jafar Nazemossadat; Gholam reza Hadarbadi
Volume 15, Issue 1 , January 2008, , Pages 85-69
Abstract
Zabol region is one of the places that is exposed to severe wind erosion, which is located in southeast Iran Due to the fact that, some stations like Zabol suffers from missing data (having five observations instead of eight), thus, the effects of missing data on prediction of wind speed and direction ...
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Zabol region is one of the places that is exposed to severe wind erosion, which is located in southeast Iran Due to the fact that, some stations like Zabol suffers from missing data (having five observations instead of eight), thus, the effects of missing data on prediction of wind speed and direction also needed to be considered. This study aim to determine the minimum years of data required in predicting hourly wind speed and direction, and predicts hourly wind speed and direction, also to verify suitability of Weibull distribution in predicting hourly wind speed and direction and finally to analyze the erosive winds in Zabol region. In this study, the regression coefficients (r) of probability of wind occurrence in various speeds for 16 cardinal directions in two different periods (1986- 1990 and 1986-1995) were separately calculated and compared. To predict hourly wind speed and direction by Weibull distribution, at first its scale and shape parameters (c and k) were determined using the least square method. Then, wind direction distribution, the ratio of maximum to minimum of wind speed, and the hours with maximum wind speed during any month were determined. Using these parameters along with generation of random numbers, the hourly wind speed and direction were simulated. The results indicated five years instead of ten years of data can be used to predict wind speed and direction with a confidence level at 99%. Weibull distribution provided best fit during the months that both the probability of calm periods or standard deviation of probability of wind occurrence in different directions were low. The maximum and minimum wind speed occurred at about 6:00 AM and 6:00 PM, respectively. The probability of occurrence of erosive winds (V≥8m/s) were maximum in June, July, August, and September. The analyses of wind data indicated that the most erosive winds were from North-Northwest, Northwest, and North. The wind speed and direction were predicted by Weibull distribution in the region with 99% accuracy. The results obtained from this research can help researchers and soil conservationists to predict and control wind erosion.
Ebrahim khalifeh; Mohammad reza Kavianpoor; Mojtabah Pakparvar; Sajad Vafaei
Volume 14, Issue 2 , January 2007, , Pages 204-221
Abstract
Wind erosion is one of the major problems in arid and semiarid regions, where the erosion and sand transport caused by wind can lead to serious problems for civilians live in those areas. The regions under wind erosion, includes the sources, transition and deposition areas. Amongst them, identification ...
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Wind erosion is one of the major problems in arid and semiarid regions, where the erosion and sand transport caused by wind can lead to serious problems for civilians live in those areas. The regions under wind erosion, includes the sources, transition and deposition areas. Amongst them, identification of the sources areas is significantly important, which affects our investigations, evaluation and control over wind erosion. It has been found that the application of Remote Sensing (RS) techniques and Geographical Information Systems (GIS) is considerably useful to find the sources of sand in wind erosion. In this study, a combination method based on Image Processing and Wind Analysis (IPWA) has been introduced and used to identify the sources of deposited sand in areas under wind erosion. The method is based on utilizing and composing of image processing techniques such as image enhancement, threshold, false color composition, filtering, and Spectral Profile Testing and Analysis. The results are compared with other investigations to validate the method. It was observed that the results of the present method are well comparable with those of previous researches which are highly based on field investigations. Without extensive field measurements, the method reduces the time and the cost of investigation and provides a basis for repeating the operation at any time and everywhere, which is required.
Ebrahim khalifeh; Mojtabah Pakparvar; Mohammad reza Kaviyanpoor
Volume 14, Issue 3 , January 2007, , Pages 403-420
Abstract
Active sand dunes particularly barkhans are serious threats for adjacent civilians live, agricultural lands and economic activities. Deployment quality and motion paths of these dunes are main targets in wind erosion studies in deposit regions. These targets need the active and inactive dunes to be identified. ...
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Active sand dunes particularly barkhans are serious threats for adjacent civilians live, agricultural lands and economic activities. Deployment quality and motion paths of these dunes are main targets in wind erosion studies in deposit regions. These targets need the active and inactive dunes to be identified. Edges and borders are evident characteristics of wind deposits and sand dunes. Inactive (old) dunes are more voluminous and smooth. Furthermore active dunes have distinct feature. Also temperature, humidity and plant cover variation lead to change surface and feature of inactive dunes. These changes can’t be observed in one band images. Therefore making uses of filters particularly non directional edges enhancement and band ratio techniques are main ideas to process the images of these dunes especially about their activity and displacement. In present research filter and band ratio techniques have been used and consequently, third band in Profile Testing and Spectral Analysis method (in this case study b5 of Landsat ETM+) and ratio of first and second bands (in this case study b62/b4) have been introduced respectively as appropriate band and ratio for these techniques to identify and separate active (new) and inactive (old) sand dunes.
Mohammad ali Meshkat; Mohammad reza Daneshvar; Mohammad reza Ekhtesasi; Kazem Dashtakian
Volume 13, Issue 1 , February 2006, , Pages 10-16
Abstract
Desertification is important for our country because it refer to land degradation in arid, semi-arid and arid sub - humid zones due to climatic and human agents. General and continuous study, local and exact investigation,and use of current quantitative models is necessary to better understanding of ...
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Desertification is important for our country because it refer to land degradation in arid, semi-arid and arid sub - humid zones due to climatic and human agents. General and continuous study, local and exact investigation,and use of current quantitative models is necessary to better understanding of land degradation process and desert development. In this research that is based on FAO/UNEP provisional methodology , some of the main desertification processes such as: vegetation destruction, wind erosion, and salinization were studied from two aspects:1) current status and 2) inherent risk. This area covers about 327700 hectars, extends to north of Yazd - Ardakan basin. Then, six maps were drawn for three processes and for two aspects which mentioned above, separately in 1:50000 scale, when the field observations and measurements were carried out. Finally two equal maps were provided by combination of six previous maps . Results of this investigation show that at the present time degrees of vegetation destruction, salinization, and wind erosion are ,, severe to very severe ,, ,,,medium to severe ,,, and,, slight to medium,, respectively . However, degrees of these processes from inherent risk aspect are ,, very severe ,, , ,, medium to severe,,, and,, medium to severe,, respectively. Although the FAO/UNEP methodology is the best model , however it has still some problems, such as: Non quantitative of some criteria; Non sensitivity of some indexes to slight changses ; Non measureable of some criteria; and Non equal the number of indexes in different processes.