Fatemeh Gholami; Tayebeh Mesbahzadeh; Gholamreza Zehtabian
Volume 28, Issue 1 , April 2021, , Pages 11-20
Abstract
Drought and dust are some of the atmospheric hazards that have affected the western and southwestern regions of the country for many years due to various factors. The recent droughts have had a significant impact on the emergence and intensification of dust. Therefore, studies related to it are considered ...
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Drought and dust are some of the atmospheric hazards that have affected the western and southwestern regions of the country for many years due to various factors. The recent droughts have had a significant impact on the emergence and intensification of dust. Therefore, studies related to it are considered important. In the current study, temporal and spatial fluctuations of meteorological drought and dust in Khuzestan province were examined on a monthly, seasonal and annual time scale. Drought estimation was possible using standard precipitation-evapotranspiration index (SPEI) and estimation of dust occurrence based on phenomenon codes 07 and 09 with a field of view of less than one kilometer. To ensure the adaptation of drought to the abundance of dust, a Pearson correlation was established between the two phenomena. The results of correlation showed a direct and significant relationship between meteorological drought and the number of dusty days in the province. The most correlation is in February, July, June, August, and May. The highest level of significance is attributed to the winter and summer and then spring. Cross-correlation also showed that the events of the dust simultaneously and one month later are more affected by the drought.
Ammar Rafiee Emam; Gholamreza Zehtabian; Amir Houshang Ehsani
Volume 11, Issue 3 , August 2019, , Pages 323-342
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.
Leila Biabani; Gholamreza Zehtabian; Hasan Khosravi; Mahin Hanifepour
Volume 26, Issue 1 , June 2019, , Pages 158-17
Abstract
Managing the optimal use of water resources is one of the most important issues in sustainable development. Considering the importance of studying groundwater in the field of drinking, industry and agriculture, the study of water qualitative changes can be important for humankind. ...
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Managing the optimal use of water resources is one of the most important issues in sustainable development. Considering the importance of studying groundwater in the field of drinking, industry and agriculture, the study of water qualitative changes can be important for humankind. In this study, groundwater level depletion and electrical conductivity (EC) were used to investigate the quantitative and qualitative changes of groundwater in Karaj plain. The water level hydrographs were drown using Thiessen method based on the piezometric wells data and the groundwater depletion, the elevation contour line, and iso- electrical conductivity maps were provided using GIS. Quantitative changes were studied with reading of each well in different months in a 15-year period (2001-2016). The obtained results showed that the vast range of Karaj plain was depleted due to the lack of proper recharge as well as the over-exploration of groundwater. In addition, the relation between EC and anions and cations (such as Ca2+, Mg2+, K+, Cl-, Na+, SO42-, HCO3-) were determined. The calculated Standard Index of Annual Precipitation (SIAP) in five meteorological stations showed groundwater depletion due to rainfall reducing and drought. Electrical conductivity had direct relation with concentration of ions in all cases. According to the hydrographs, the average level of groundwater decreased to 1.02 m over 15 years and the groundwater level depletion consequently decreased the water quality.
Saeed Barkhori; Rasoul Mahdavi; Gholamreza Zehtabian; Hamid Gholami
Volume 25, Issue 2 , August 2018, , Pages 355-365
Abstract
The aim of this study was to investigate the temporal and spatial changes trend of groundwater quality for drinking purposes in Jiroft plain. The role of land use and geological formations in the groundwater quality was also investigated. In this study, the parameters of electrical ...
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The aim of this study was to investigate the temporal and spatial changes trend of groundwater quality for drinking purposes in Jiroft plain. The role of land use and geological formations in the groundwater quality was also investigated. In this study, the parameters of electrical conductivity, sodium adsorption ratio, pH, calcium, chlorine, magnesium, sodium, and sulfate were used and the zoning of qualitative data was done by the geostatistical method of Kriging in ArcGIS9.3 software; then, the classification of the region was done using Schoeller diagram. Results showed that in 2001, southern parts of the study area had a lower quality of groundwater but in 2014, northern parts had a lower quality. According to the results, the groundwater quality decreased overtime and the decreasing trend spread from the south to the center and the north of the region. Also, the land use map showed a low quality of groundwater in agricultural lands. The geology map showed a low quality of groundwater in central and southern parts. In general, it can be concluded that the water quality of the study area for drinking is decreased over time and influenced by land use and geological formations; thus, to improve the quality of groundwater resources the role of human factors (land use and agricultural activities) need be taken into account.
Mehdi Ganji; Gholamreza Zehtabian; Mohammad Jafary; Hasan Khosravi; Reyhaneh Masoudi
Volume 22, Issue 1 , June 2015, , Pages 12-20
Abstract
In many parts of arid and semi-arid regions of Iran, agricultural activities such as mismanagement of land as well as inappropriate irrigation systems have seriously led to land degradation and desertification. Therefore, it is necessary to do some researches in order to determine which region is suitable ...
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In many parts of arid and semi-arid regions of Iran, agricultural activities such as mismanagement of land as well as inappropriate irrigation systems have seriously led to land degradation and desertification. Therefore, it is necessary to do some researches in order to determine which region is suitable for agriculture or not and if the region is suitable, what type of agriculture management should be applied prevalently. To achieve this goal, a region in Arak Mighan playa (Savarabad watershed) was chosen. At first, different maps of region including soil map, elevation and land use maps were prepared by ArcGIS 10.1. Five land uses were recognized as treatments including garden lands, dry farming systems, irrigation lands, dry lands and rangelands. Soil samples were taken and soil factors including N, Ca, Mg, and Humus as well as degradation factors such as EC, SAR, pH, Na and Hco3 were measured at two depths of 0-30 cm and 30-60 cm. The analysis of factors was done by SPSS software and results showed that there were significant differences among treatments based on Duncan test. In addition, rangeland was identified as a favorable treatment in terms of EC, pH, SAR in the surface layer. According to the results, it was found that rangelands had ideal conditions and dry farming and dry lands were identified as the most unfavorable treatments.
Tayebeh Sohrabi; GHolamreza Zehtabian
Volume 19, Issue 1 , June 2012, , Pages 17-31
Abstract
Iran with its special geographical position mainly has an arid and semi-arid climate. The average annual rainfall in Iran is about 240 mm equivalent to one-fourth of the world average rainfall. In addition, irregular spatial and temporal distribution of rainfall has caused problems in natural resources ...
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Iran with its special geographical position mainly has an arid and semi-arid climate. The average annual rainfall in Iran is about 240 mm equivalent to one-fourth of the world average rainfall. In addition, irregular spatial and temporal distribution of rainfall has caused problems in natural resources and agriculture and annually huge amount of our water and soil resources are degraded. Since the advent of the farming activities until the present, human needs have been based upon farming activities. Considering the growing population and the social and economic developments, most of rangelands have been subject to rainfed cultivation. Therefore, to prevent further degradation of soil in these regions research should be conducted on agricultural lands and the exploitation methods. For this reason, Taleghan was selected as the study area. Map of the area, including soil maps, land types and the current land use were produced by GIS. After determining the main treatments, soil samples were taken in every part of the area and in agricultural area and soil factors were measured within two groups of soil improvement factors including nitrogen, phosphorus, potassium, humus and lime and soil degradation factors including acidity, sodium adsorption ratio (SAR) and salinity in two depths of 0-10 and >10 cm. These factors were studied in a split-plot design. The results showed significant differences among treatments. According to the results of soil improvement and degradation factors, orchards and rangelands are in an ideal condition and monoculture treatment decreases the performance of the products.
Gholam reza Zehtabian; Mehrnush Ghadimi; Ali Tavili; Jamal Bakhshi
Volume 17, Issue 3 , October 2010, , Pages 353-361
Abstract
This research was performed to investigate the relationship between environmental factors including water and plant composition. In other words, determining the most effective factors in distribution of vegetation types in Arak playa was the main aim of this study. To achieve this goal, the initial map ...
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This research was performed to investigate the relationship between environmental factors including water and plant composition. In other words, determining the most effective factors in distribution of vegetation types in Arak playa was the main aim of this study. To achieve this goal, the initial map of vegetation was provided and afterward water and vegetation sampling was done. Water parameters including K, Na, CL, Mg, %Na (exchangeable sodium percentage), Th, SAR, Co3, Hco3, So4, TDS (total hardness), EC, pH, and anions (sulfates, bicarbonates and chlorates) were measured. Multivariate data analysis techniques including principal component analysis (PCA) and canonical correspondence analysis (CCA) were used to analyze the collected data. The results showed that vegetation distribution pattern was mainly related to water characteristics such as Mg, TDS, Cl, anion, EC and Th. it can be concluded that according to habitat conditions, ecological needs and tolerance range of each plant species have significant relationship with water properties.
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.
Gholam reza Zehtabian; Anayat... Janfaza; Hossein Mohammad asgari; Mohammad javad Nematollahi
Volume 17, Issue 1 , September 2010, , Pages 61-73
Abstract
Ground Water quality change is due to mismanagement in use of groundwater resources. Main objective of this research was to investigate spatial variability of chemical properties of ground water. In this research chemical properties such as cation, anion, sulphate and carbonate were studied. Normality ...
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Ground Water quality change is due to mismanagement in use of groundwater resources. Main objective of this research was to investigate spatial variability of chemical properties of ground water. In this research chemical properties such as cation, anion, sulphate and carbonate were studied. Normality of data investigated based on Kolmogeraph- Smirnov test. Then, variogeraphy analysis was done in geostatistical methods. Accuracy assessment was investigated based on mean absolute error (MAE), residual mean square error (RMSE) and correlation coefficient (R). Results showed that geostatistical methods have more accuracy than determinestic methods. However, global polynomial interpolation was the best method for mapping cation. In addition, for the most parameters, Cokriging method was the best method for interpolation
Mitra Shirazi; Gholam reza Zehtabian; Hamid reza Matinfar
Volume 17, Issue 2 , September 2010, , Pages 256-275
Abstract
Recently there is a great deal of interest in the quantitative characterization of temporal and spatial vegetation patterns with remotely sensed data for the study of earth system science. One of important methods for extracting information from satellites image is use of indices. In this study for enhancement ...
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Recently there is a great deal of interest in the quantitative characterization of temporal and spatial vegetation patterns with remotely sensed data for the study of earth system science. One of important methods for extracting information from satellites image is use of indices. In this study for enhancement of land cover in region of northwest Tehran near Hashtgerd some indices such as BI, MIRV2, GREENNESS, TVI, VNIR, MND، NIR, OSAVI, RA, NDVI, IR1, MSI IPV ,MSAVI, SAVI, TSAVI, PD322 ,BI, INT1, INT2, PVI, SI1, SI2, SI3, GEMI, WDVI Are used. Most of study area covers by density of vegetation (such as irrigation farming and vegetation cover around streams) and bare lands. The results have shown that TSAVI, DVI, IPVI, RA, NIR, IR1 Indices have the most effective efficiency for vegetation enhancement and SI2, BI, TVI, PVI, INT1, SI3, SI2 indices have the most effective efficiency for salinity surface. This study addressed that all of vegetation indices except DVI have correlation more than 0.8 and DVI has correlation around 0.4 with others. Meanwhile all of salinity indices have more than 0.9 correlations with each other. As conclusion, this study has shown that IRS satellites image have high accuracy for providing land cover map by use of vegetation indices, also use of salinity indices having high capability for salinity surface can be used for providing salinity maps, meanwhile vegetation indices with high correlation can be used instead each other for providing vegetation maps.
Gholam reza Zahtabian; Mohammad Jafari; Fatemeh Movahedian; Maryam Naeemi
Volume 16, Issue 4 , January 2010, , Pages 468-480
Abstract
Nowadays, desertification as a great problems affect most of the countries in the world especially developing countries. Desertification phenomenon that occurs in arid, semi-arid and dry semi-wet regions will reduce the land potential. For evaluation and mapping of desertification many researches have ...
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Nowadays, desertification as a great problems affect most of the countries in the world especially developing countries. Desertification phenomenon that occurs in arid, semi-arid and dry semi-wet regions will reduce the land potential. For evaluation and mapping of desertification many researches have been conducted leading to regional and local models. In this study MEDALUS model because of easy style and data accessibility and also compatible with the effective indices on land degradation was applied for land degradation intensity mapping with emphasis on soil criterion in Hablerood catchment. So in this study, soil criterion and 6 indices including: EC, Rock fragment, depth and texture of soil, slope, and percentage of soil organic matter were assessed. At the first work units was prepared; in each work unit, one soil profile was dogged (10 profiles) and desired indices were measured in laboratory. Finally, sensitive map of region was extracted using assigned score to each index and geometric average of all indices. Data were analyzed by using spss software and analysis method of various one- way ANOVA. The results showed that, about 4.16 percent of the area is classified under low class and in the level of 0.05 there was no significant differences between indices, and the only significant difference was in the gravel percentage of soil surface in 0.01 levels.
Gholam reza Zehtabian; Jamal Bakhshi; Mehrnush Ghadimi; Nader Biroudian
Volume 15, Issue 4 , January 2009, , Pages 436-446
Abstract
As the recognition impact of a plant specie plantation in a specific area can determine the effects of that plant in other parts and areas of the country, the effects of Haloxylon plantation on the stand understory in desert lands of Ardestan were studied. Three areas of Haloxylon plantation and a reference ...
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As the recognition impact of a plant specie plantation in a specific area can determine the effects of that plant in other parts and areas of the country, the effects of Haloxylon plantation on the stand understory in desert lands of Ardestan were studied. Three areas of Haloxylon plantation and a reference site which were approximately similar in terms of altitude (height), slope, soil, and geomorphology have been selected. The necessary number of plots in each area was chosen on statistical base. In this study the plant density and crown closure of the understory species in the Haloxylon stand and also, the reference area were measured. Then, by using Dankan Test and Analysis of Variance through SPSS package the achieved data of the sampling were analyzed. The study conducted that there was a significant difference between the understory coverage of plantation areas and the reference site. It is concluded that the Haloxylon plantation caused a great deal of increasing in understory species number and composition.
Gholam reza Zehtabian; Marzeyeh Tayeb; Mahshid Souri
Volume 13, Issue 4 , February 2007, , Pages 368-384
Abstract
Salinity is one of the factores affecting the reduction of soil biological potential and vegetation and finally desertification. Water is the most limiting factor for cultivation in arid and semi arid regions. Due to shortage of surface water resources, the pressure is exerted on under ground water ...
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Salinity is one of the factores affecting the reduction of soil biological potential and vegetation and finally desertification. Water is the most limiting factor for cultivation in arid and semi arid regions. Due to shortage of surface water resources, the pressure is exerted on under ground water resources. Meanwhile, over –exploitation of underground water resources and neglecting technical points in exploitation have caused the level of underground water to be dropped. This water level drop in addition to other factors causes the quality of water resources to be changed leading to increasing of salinity. This research has been carried out in kabootarkhan plain, kerman province. In order to study factors salinizing underground water resources in this basin, some baseline data were gathered. Then, sampling of profiles of soil profiles were done in the four soil units (arable lands, ferdowsi, agriculture station and kabootakhan) in the basin in three replications. The laboratory results and existing data were analyzed using SPSS software according to the randomized split-pot design. The results show that in appendage plain of the basin, irrigation with saline water resources in addition to soil texture have caused salinity to be occurred and in clay flat, irrigation has caused salinity to be declined due to the good soil texture and existence of natural drainage.