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.
Ahmad Ahmadi; Karim Javanshir; Hasan Ahmadi; Valiolah Mozafarian
Volume 10, Issue 2 , September 2019, , Pages 169-192
Karim Mehrvarz Moghanlo; Sadat Feiz nia; Jafar Ghayomian; Hasan Ahmadi
Volume 12, Issue 4 , August 2019, , Pages 438-467
Mehdi jafari; Gholamreza Zehtabian; Hasan Ahmadi; Tayebeh mesbahzadeh; Ali Akbar Norouzi
Volume 26, Issue 1 , June 2019, , Pages 29-39
Abstract
Dust pollution is one of the most important environmental challenges in recent years in the Middle East and Iran. It is important to monitor and control the quality of dust particles in a wider range using the methods that are more cost effective and less costly. The present study aims to use numerical ...
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Dust pollution is one of the most important environmental challenges in recent years in the Middle East and Iran. It is important to monitor and control the quality of dust particles in a wider range using the methods that are more cost effective and less costly. The present study aims to use numerical detection and analysis to determine the resources of dusts and the route over Iran and Isfahan province in May 2013. In this research, HYSPLIT, NAAPS, COAMPS models and MODIS images were used. The detection of dust was determined based on the characteristics of the brightness temperature in the infrared thermal range of the Modis sensor and the temperature thresholds for distinguishing this event from desert lands and clouds. The HYSPLIT model was used to track the movement path of dust particles. Based on the results obtained from image processing and model output, North of Saudi Arabia and Southwest – Northeast direction are respectively the origin and main route of dust entry to Isfahan. The results of HYSPLIT model were compared with the results of the COAMPS and NAAPS models for the optical dust depth and surface dust concentration and the mass flow rate. The detection of the MODIS satellite images also acknowledges the creation of dust and moving it towards the center of Iran and the province of Isfahan.
Mohammadreza Rahdari; Hasan Ahmadi; Ali Tavili; Mohammad Jafari; Aliakbar Nazari Samani; mohammad khosroshahi; Shahrooz Sharifi
Volume 26, Issue 1 , June 2019, , Pages 226-240
Abstract
Due to vast desert area in Iran, wind regime studies are important for the railway safe design as well as aeolian sediment transport. In this study wind regime and sand drift potential (DP) were calculated with Fryberger method in nine meteorological stations located near to the Qom –Tehran railway ...
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Due to vast desert area in Iran, wind regime studies are important for the railway safe design as well as aeolian sediment transport. In this study wind regime and sand drift potential (DP) were calculated with Fryberger method in nine meteorological stations located near to the Qom –Tehran railway (178 km). For this reason, hourly wind speed and direction data were analyzed. Annual wind roses showed that West and Northwest winds were predominantly about 40%, 50%, 42% and 57% at the stations of Tehran, Shahriyar, Qom, and Imam Khomeini airport, respectively. The highest amount of sand drift potential was at the Imam Airport station (DP= 574, UDI=0.8) in the west and its lowest value was at Qom station (DP= 109, UDI= 0.47) in the south of the region. The drift potential (DP) for aeolian deposits was generally high (DP >400) in the Garmsar (DP= 481), Salafchegan (DP= 485), Saveh (DP= 552) and Imam Khomini airport (DP=574) climatological stations. DP was relatively moderate (200>DP>400) at the Shariyar and Kahak stations in the northwest and south of study area, respectively; and weak (DP<200) in the Tehran and Qom climatological stations. There was an increasing trend in the transport of sand when moving from Namakzar railway station to the Imam Khomeini railway station. Also field evaluations indicated the sensitivity of the Separ Rostam-Namakzar block to entry of sand, which was 21.3 kilometers long. Finally, it is suggested to railway directors of the Islamic Republic of Iran to proceed with the assessment of sand drift potential near railways station for control of sand deposition.
ali nazari; hamidreza abbasi; hasan ahmadi; mohammadreza rahdari
Volume 24, Issue 1 , May 2017, , Pages 210-223
Abstract
This research was aimed to modeling the height and distance of sand dunes in central deserts of Iran (Kashan Erg and Jen Erg) as well as their classification. Results of identifying sand dunes in the study areas showed that there were considerable variations in formation of sand dunes in central ...
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This research was aimed to modeling the height and distance of sand dunes in central deserts of Iran (Kashan Erg and Jen Erg) as well as their classification. Results of identifying sand dunes in the study areas showed that there were considerable variations in formation of sand dunes in central deserts of Iran. Quantitative modeling of height based on DEM (80 × 80m) showed that the average height of sand dunes in Kashen Erg and Jen Erg was 35m and 6.84m, respectively. The reduced height in Jen Reg was due to the 37% frequency of sand dunes area and regardless of these dunes, the average height was calculated to be 8.63 m in Jen Reg, of which 90% was in a height class less than 20 m. On the other hand, the frequency percentage variation of sand dunes height classes is higher in Kashan Erg, so that over 80% of Kashan Erg is in a height class less than 50m, while 87% of Jen Erg is in a height class less than 10m. In Kashan Erg, the height of sand dunes is low and gradually increases in the center of Erg, reaching to the highest height of sand dunes. Quantitative modeling of relations between the height and distance of dunes in Jen Erg indicated that the sand dunes activity was restricted to the upper part of the dunes. In Kashan ERG, the comparison of fixed, linear and compound dunes showed that the fixed dunes would be formed at a closer distance as compared with two other types.
Saeedeh Nateghi; Gholam reza Zehtabian; Hasan Ahmadi
Volume 19, Issue 4 , March 2013, , Pages 590-600
Abstract
Segzi plain is one of the most critical areas of the province in terms of the extent and severity of desertification process. This area has a special strategic position due to the industrial centers, Shahid Babaee airport, Shahid Beheshti International Airport, railroads, transit road of Bandar Abbas- ...
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Segzi plain is one of the most critical areas of the province in terms of the extent and severity of desertification process. This area has a special strategic position due to the industrial centers, Shahid Babaee airport, Shahid Beheshti International Airport, railroads, transit road of Bandar Abbas- Esfahan, agricultural centers and vicinity to historical city of Esfahan. Consequently, investigation on the main cause of desertification phenomenon is the main objective of this study. Therefore, the IMDPA model was used to study desertification intensity in Segzi plain. In this research, two criteria including geology – geomorphology and soil, consisting of seven indicators (sensitivity of the formation, land use, and slope based upon geology–geomorphology criterion, and soil texture, soil depth, percentage of stone and gravel, and EC based upon soil criterion) were studied. Desertification intensity map was generated by using geometric mean of criteria. With regard to the geometric mean of criteria, soil criterion, with a numerical value of 3.4, and geology – geomorphology criterion, with a numerical value of 3 were classified in severe desertification class. Finally, the severity of desertification (DS) was calculated to be 3.26 indicating that the region was in severe desertification class. Results showed that EC, with an average value of 3.75, was classified as very intense indicator and had the most impact on desertification of the region.
Sadat Feiznia; Hasan Ahmadi; Soheila Youneszadeh Jalili; Mohammad Ali Fatahi ardakani; Marzeiyeh Abbasi
Volume 19, Issue 2 , September 2012, , Pages 244-263
Abstract
Differences in particle size through downstream is a proper tool to understand evolution steps and river channel morphological changes, including sediment transport, channel migration context, the risk of floods and human activities. The present study investigated sediment deposits in upper rangelands ...
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Differences in particle size through downstream is a proper tool to understand evolution steps and river channel morphological changes, including sediment transport, channel migration context, the risk of floods and human activities. The present study investigated sediment deposits in upper rangelands of Tehran- Qazvin highway located in Khur-Sefidarak Basin, Tehran Province. Two main channels with Gravelly- sand bed as the main drainage channels were studied. The aim of this study was to investigate changes in particle size based upon sedimentology and its correlation with textural parameters including sorting, skewness, and kurtosis and calculating the approximate volume of sediments behind dams. These parameters were analyzed by sampling 66 samples from upstream to the downstream side of the Khor-Sefidarak channels. All natural factors (secondary branches and sediment sources) and non-natural factors (such as small dams) were effective in tissue changes on this system and the results indicated the continuity of sediment along the channels due to regular gradient of channel bed. Sediment particles through these two channels had a medium sorting. Sorting decreased toward downstream, because of facing secondary branches and increment of shared formation number and totally increased diversity in sediments. Results of bed sediment volume showed that the amounts of bed load sediment through Khor and Sefidarak branches were 271.6 and 246.3 cubic meters per year, respectively.
Ali Ehsani; Hosein Arzani; Mahdi Farahpur; Hassan Ahmadi; Mohammad Jafari; Mortezah Akbarzadeh
Volume 19, Issue 1 , June 2012, , Pages 1-16
Abstract
In this study, potential and actual evapotranspiration were estimated by Penman- Matis using climatic data of Saveh Station, and plant and soil characteristics were estimated by Cropwat 8.0 software. Our results showed that potential evapotranspiration in growing season was 6.16 times greater than the ...
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In this study, potential and actual evapotranspiration were estimated by Penman- Matis using climatic data of Saveh Station, and plant and soil characteristics were estimated by Cropwat 8.0 software. Our results showed that potential evapotranspiration in growing season was 6.16 times greater than the average of actual evapotranspiration. Actual evapotranspiration was 1.18 times greater than the average precipitation of growing season. It means that plant species have used the stored moisture for actual evapotranspiration. According to the estimation of actual evapotranspiration in a ten-year period, a model was provided for forage production as Ya= 74.30+ 2.698 (ETact). Accordingly, average forage production of the studied site was estimated as 257 kg/hec. It could be said that actual evapotranspiration as an index for climate yield is one of the fundamental factors in improving water use efficiency. Application of the mentioned climate index in different estimation models of long term forage production could be considered in order to determine the rangeland grazing capacity and developing rangeland insurance as a replacement for the usual methods of production.
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).
Hasan Ahmadi; Ali asghar Mohammadi
Volume 17, Issue 3 , October 2010, , Pages 340-352
Abstract
Since wind or water erosion is a phenomenon that causes waste of soil, it is necessary to combat soil erosion through soil conservation practices. Currently, some models have been developed to estimate erosion which should be examined with other existing models in different regions. In this study, ...
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Since wind or water erosion is a phenomenon that causes waste of soil, it is necessary to combat soil erosion through soil conservation practices. Currently, some models have been developed to estimate erosion which should be examined with other existing models in different regions. In this study, PSIAC and EPM models were evaluated in one of the sub watersheds of Hableh rood (Dehnamak) with effects of geomorphologic factors. First of all, using available information and producing required maps at the level of hydrologic units and sub-watersheds existing factors in the models were analyzed in the study area. With regards to lack of statistics and information of MPSIAC model, this model was not used, but to complete PSIAC model geomorphology map and geomorphology faces were produced. The results of sediment estimation using mentioned models indicated that two models of PSIAC with effect of geomorphology and EPM had same results to some extent. In conclusion, comprehensiveness and completeness of PSIAC model, PSIAC with effect of geomorphology factors is recommended to estimate sediment.
Mohammad hassan Sadeghi Ravesh; Hassan Ahmadi; Gholam reza Zehtabian; Mohammad Tahmores
Volume 17, Issue 1 , September 2010, , Pages 35-50
Abstract
With respect to importance of desertification issue and complication of this phenomenon because of interaction of different and numerous variables during the time, paying effective attention to the optimum alternatives is vital for prevention of de-desertification or rehabilitation and improvement of ...
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With respect to importance of desertification issue and complication of this phenomenon because of interaction of different and numerous variables during the time, paying effective attention to the optimum alternatives is vital for prevention of de-desertification or rehabilitation and improvement of degradation lands so the loss of limited capitals are prevented and efficiency of control and rehabilitation projects is enhanced. Study of research sources showed that unfortunately proposed alternatives are superficial and there are not any precedence in application of systematic methods such as Multiple Attribute Decision Making (MADM) for desertification issues. Therefore in this research AHP method has been used for offering the optimal alternatives for de-desertification. In this study the opinion of experts about alternatives and criteria were assessed by using Delphi method and Pirewise comparison and with application of EC software. Then final preference for the alternatives was obtained with synthesis and integration of the results. The ability of the model was assessed for offering de-desertification alternatives in Khezrabad region in Yazd province. On the basis of obtained results unsuitable land use alternative with weighted average of %22.9, vegetation cover development and reclamation with weighted average of %21.8 and modification of groundwater harvesting with weighted average of %19.1 were determined as the optimum de-desertification alternatives in the study area.