Hosein Tavakoli Neko; Schahram Banedjschafie; Abbas Pourmeidani
Volume 31, Issue 1 , June 2024, , Pages 1-14
Abstract
Background and objectivesThe vast country of Iran, due to its location in the arid region of the earth and the lack of rainfall, has suffered from drought and groundwater depletion. The reduction of precipitation and soil moisture has a great effect on soil vegetation. The use of various types of moisture ...
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Background and objectivesThe vast country of Iran, due to its location in the arid region of the earth and the lack of rainfall, has suffered from drought and groundwater depletion. The reduction of precipitation and soil moisture has a great effect on soil vegetation. The use of various types of moisture absorbent materials that reduce water consumption and increase the time of plant access to water in the soil plays a big role in water conservation. Plantbac panels are made from cellulose waste and can be used to increase the water retention capacity of the soil in dry areas, especially in desert areas. MethodologyIn order to investigate the effect of Plantbac panels on the amount of water consumption and growth of Atriplex plant, the research was carried out in the area of Hesarsokh located ten kilometers north-east of Qom city for three years (2019-2021). The experiment was carried out as split plots in the form of randomized complete blocks including 12 plots in three replications. The main plot included irrigation treatments at intervals of 10 days (control) and 20 days, and the sub-plot included two treatments of using and not using Plantbac panels (control). To investigate the effect of Plantbac panels on seedling growth at the end of each growing season in each year, traits including: survival, height and crown diameter of the seedling were measured and compared with the control of the same treatment. Statistical analyzes including minimum and maximum traits, standard deviation, simple variance analysis of variables, compound analysis, comparison of averages with least significant difference (LSD) method for seedling height growth and crown diameter growth traits were performed. ResultsThere was no difference in seedling survival in the treatments of using Plantbac and control in irrigation with a 10 days interval. While in the treatment of Plantbac panels and the control, 5% of the seedlings were dried, and in the treatment of using the Plantbac panels, 21% and 40% of the seedlings were seen in the control. Combined variance analysis showed that the simple effects of using Plantbac panels, year and the interaction effect of irrigation in the year on the height growth of Atriplex were significant (P≤0.01). Also, the effect of irrigation treatments, the use of Plantbac panels, the mutual effect of irrigation in the year and the effect of the year had a significant difference in the diameter growth trait of the crown of Atriplex seedlings (P≤0.05). The comparison of the average traits showed that the Atriplex seedlings in the "3rd year × 20 days irrigation interval" had the highest height 6.32 cm, and in the "1st year × 20 days irrigation interval" with 9.75 cm, had the lowest height growth. Also, Atriplex seedlings had the highest crown diameter growth in the "3rd year × irrigation interval 10 days " with 22.11 cm growth, and the lowest crown diameter growth had in the "2nd year × 20 day interval irrigation" with 17.33 cm. ConclusionThe results of the research showed that the effect of Plantbac panels on the traits indicating the growth of Atriplex is effective. The use Plantbac panels reduces losses in the survival of Atriplex seedlings. In other words, the use of Plantbac panels can have an effect in reducing the losses of Atriplex seedlings in saline lands. Also, the height growth of Atriplex in the treatment of using Plantbac panels was higher than the control. The general results of the research showed that the use of Plantbac panels can have an effect in reducing the losses of Atriplex in saline lands. Also, the diameter and height growth of Atriplex in the following years of planting was higher than the first year, which can be due to the possibility of establishing and improving the soil conditions for plant growth in the following years after planting as a result of using Plantbac panels.
Reza Norouz Valashedi; Jaber Rahimi; Abbas Alipour
Volume 26, Issue 3 , September 2019, , Pages 640-649
Abstract
The main purpose of this study was to analyze the effective factors on farmers' participation in combating desertification plans in Iran. Thus, a number of farmers as a sample population were selected using Cochran’s formula and multi-stages sampling for selecting samples was done. A questionnaire ...
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The main purpose of this study was to analyze the effective factors on farmers' participation in combating desertification plans in Iran. Thus, a number of farmers as a sample population were selected using Cochran’s formula and multi-stages sampling for selecting samples was done. A questionnaire was used to collect data whose validity was confirmed by advisor and supervisor professors and some experts of desert organization. The reliability of the questionnaire was confirmed by computing Cronbach's alpha that was more than 0.75. Data were analyzed using SPSS and Expert choice 11 software and results showed that the population of the study had low literacy and income. They also had participated very few in education courses, whereas it was observed a significant positive relationship between variables such as literacy, income, and participation in education courses with the participation variable. Also, the correlation relationship between independent factors such as psychological, cultural, economic, education/extension and institution factors with the dependent variable of participation variable showed that except psychological factor, all of those factors had a significant relationship (sig level of 0.01) with participation variable. The results of the regression analysis also revealed that social/cultural and economic factors were the most important factors on the participation variable and explained 66% of participation changes. The model output indicated that rural communities showed significant interest in the city.
Mohammad Sadegh Kahkhakohan; Abolfazl Rajbar Fordoie; Seyed Hojat Mousavi; Abbasali vali
Volume 26, Issue 3 , September 2019, , Pages 754-771
Abstract
Drought and its effects is one of the world's major concerns. As one of the countries in the dry belt of the earth, Iran has always been and is facing environmental issues and natural hazards caused by drought. Therefore, this study aimed to monitor the aridity in Sistan and Baluchestan using remote ...
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Drought and its effects is one of the world's major concerns. As one of the countries in the dry belt of the earth, Iran has always been and is facing environmental issues and natural hazards caused by drought. Therefore, this study aimed to monitor the aridity in Sistan and Baluchestan using remote sensing data and geographic information system techniques for over a period of 15 years (2015-2000). In this regard, the MODIS satellite images from 2000 to 2015 were analyzed by applying the yearly Precipitation Condition Index (PCI) and Standardized Precipitation Index (SPI). Then, the drought changes were evaluated using supervised classification method and difference images. The results showed that the years 2007 and 2001 with an area of 157383.06 and 306.05 km2 had the highest and lowest levels of precipitation, and also with an area of 49511.1 and 69233.83 km2 had the minimum and maximum level of drought, respectively. The most severity change of drought has been in time for the 2002-2001 period and the place also belong to parts of Khash, Iranshahr and Sarbaz who takes 194302.93 km2 of the province. Finally, the general trend of changes in precipitation and drought is decreasing and increasing, respectively, requiring the major planning of resources conservation and risk and crisis management to rehabilitate and maintain the ecosystem of arid regions.
Mostafa Taleshi; Seyed Jafar Seyed Akhlaghi
Volume 26, Issue 2 , July 2019, , Pages 459-473
Abstract
Resilience is one of the strategies to reduce the vulnerability of communities in dealing with natural hazards. The present study examines the role of livelihood diversity as a strategic approach for adaptation and coping with drought risk in Hablehroud watershed. In this research, ...
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Resilience is one of the strategies to reduce the vulnerability of communities in dealing with natural hazards. The present study examines the role of livelihood diversity as a strategic approach for adaptation and coping with drought risk in Hablehroud watershed. In this research, the research method was quantitative and survey based, and descriptive, analytical and correlation methods were used. To this end, 9 villages from different areas of the province with different degrees of drought and development were selected by simple random sampling method. Then, based on the Cochran formula, 271 households were selected as the sample size. The validity of the questionnaire was confirmed through a panel of experts, and the reliability of the research tool was confirmed by a Cronbach's alpha of 0.842 at a very good level. The results showed that the level of resilience in the area was undesirable and lower than the average level, and the average of the human, social and physical capital index of the area was higher than the average value of the financial (economic) and natural capital. Based on the findings, adoption of a livelihood diversity strategy in promoting the resilience of rural households in Hablehroud area had a significant effect on drought risk.
Mohammad hosein parsamehr; zahra khoravani
Volume 24, Issue 1 , May 2017, , Pages 16-29
Abstract
This research was aimed to classify the drought in arid and semi arid regions of Isfahan province using TOPSIS technique. Four climatic elements including temperature, number of rainy days, annual rainfall and relative humidity were used for five meteorological stations during the 20-year period (1994-2013). ...
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This research was aimed to classify the drought in arid and semi arid regions of Isfahan province using TOPSIS technique. Four climatic elements including temperature, number of rainy days, annual rainfall and relative humidity were used for five meteorological stations during the 20-year period (1994-2013). For validation of the proposed method, the output of TOPSIS method was compared with the output of DPI, PNPI, RAI and SPI. For this purpose, Spearman's rank correlation coefficient was used between the quantified values of drought severity index and annual rainfall. The results showed that there was a strong correlation between the drought severity index and annual rainfall in the TOPSIS algorithm in all studied stations. Therefore, the validity of the model was approved. Generally, moisture fluctuations are high in the study area. In other words, drought is completely independent from station to station and from year to year, so that Nain and Isfahan had the highest (13 years) and lowest (7 years) number of drought years, respectively. In the TOPSIS algorithm, drought is closer to its real value since more parameters are used compared with previous simple methods. In this method, there is a systematic relationship between climatic elements in a year and other years, through which evaluation and ranking of drought is carried out. Finally, it could be concluded that the TOPSIS algorithm is a method capable of determining and ranking drought.
yousef safavi; Ali Ashraf Jafari; Mehrnaz Riasat
Volume 23, Issue 2 , September 2016, , Pages 254-244
Abstract
In this study, the effects of water stress on seedling growth characteristics were studied in Agropyron tauri and Agropyron repens. The experiments were conducted in the greenhouse of Fars Agricultural and Natural Resources Research and Education Center in 2010. Six Agropyron repens genotypes and ...
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In this study, the effects of water stress on seedling growth characteristics were studied in Agropyron tauri and Agropyron repens. The experiments were conducted in the greenhouse of Fars Agricultural and Natural Resources Research and Education Center in 2010. Six Agropyron repens genotypes and four Agropyron tauri genotypes were selected from the gene bank of Research Institute of Forests and Rangelands and were arranged in a factorial experiment in a completely randomized design with three replications. Factors A and B were the genotypes and drought levels, respectively. Drought stress levels were 100, 75, 50 and 25% of field capacity, and the measured characteristics were shoot length, root length, root/shoot ratio, seedling length, seedling fresh weight, seedling dry weight, dry weight/fresh weight ratio, and leaf area. There were statistically significant differences among drought treatments, genotypes, and interaction effects of accessions with land, in most of the above characteristics. Five drought resistance indices including stress susceptibility index (SSI), tolerance index (TOL), stress tolerance index (STI), mean productivity (MP), and geometric mean productivity (GMP) were calculated. By assigning the highest indices, the genotype A.tauri (99) showed the highest resistance in most of the traits tested.According to the obtained results, genotype A.tauri (99) as the best and genotypes A. repens (211), A. repens (217), A. repens (224), and A. repens (225) in the next rank could be recommended for rangeland improvement and reclamation in arid regions.
Sina Sarabi; Ali Heshmatpour; Choghi Bayram Komaki; Abolfazl Tahmasebi
Volume 22, Issue 2 , August 2015, , Pages 392-405
Abstract
Analysis of drought and factors affecting it using remote sensing data has a high potential to improve scientific knowledge about the properties of drought and the effects of this phenomenon on vegetation. The present study was aimed to investigate the relationship between satellite indices and the SPI ...
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Analysis of drought and factors affecting it using remote sensing data has a high potential to improve scientific knowledge about the properties of drought and the effects of this phenomenon on vegetation. The present study was aimed to investigate the relationship between satellite indices and the SPI index in northern rangeland of Golestan province. For this purpose, SPI index in one, three, and six month- moving averages was calculated and then zoning maps were prepared using kriging. Then, using MODIS images and the corrections, required for this type of sensor, made on the images, a vegetation map was prepared using the indices of NDVI, SAVI and VCI. In order to synchronize the climate data with satellite images, a 9 -year-old common time base was selected . Finally, in order to investigate the relationship between vegetation indices with the SPI indices correlation coefficient and linear regression were used. The results indicated a good correlation between satellite indices and SPI indices in the peak months of vegetation growth. In addition, correlation between vegetation cover indices and three and six-month moving average in non-growing season, and with a one-month moving average of SPI in growing season was higher.
Abolfazl Rahmatizadeh; Mohammad Jafary
Volume 21, Issue 3 , December 2014, , Pages 496-506
Abstract
Due to the population growth and human intervention in nature, desertification has increased drastically. The Masileh watershed is located in the southern highlands of central Alborz. In this study, vegetation condition, the volume of water entering the area, soil chemical characteristics, and ...
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Due to the population growth and human intervention in nature, desertification has increased drastically. The Masileh watershed is located in the southern highlands of central Alborz. In this study, vegetation condition, the volume of water entering the area, soil chemical characteristics, and agricultural production statistics of the region were examined and compared before and after the construction of dams during two periods with an interval of five years. Results showed that since the construction of 15- Khordad dam in 1995, the volume of water entering the Masileh plain has reached zero.The hydrograph study showed that the groundwater level of Masileh plain has dropped on average five meters/year. Due to the lack of flood entering and soil washing, the salt concentration of soil surface layers in most vegetation types has increased. Due to the lack of root access to water, the canopy cover percentage in halophyte vegetation types with shallow roots such as Aeloropus litoralis and Cyperus sp has been reduced up to 100%, and new species such as Halocnemum strobilaceum and Halostachys caspica have been replaced. In terms of agriculture, significant changes have occurred in the composition and type of agricultural crops. Our results clearly showed that the Masileh plain is turning from a productive agricultural area into a real desert.
Reza Bagheri; Sedegheh Mohammadi
Volume 19, Issue 2 , September 2012, , Pages 283-296
Abstract
This study was performed in order to determine spatial variations of drought in Kerman province by Standard Precipitation Index (SPI) and comparing interpolation methods of Kriging and inverse distance weight with powers of 1 to 5, over a thirty-year period (1970-71 to 2000-2001). According to the results ...
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This study was performed in order to determine spatial variations of drought in Kerman province by Standard Precipitation Index (SPI) and comparing interpolation methods of Kriging and inverse distance weight with powers of 1 to 5, over a thirty-year period (1970-71 to 2000-2001). According to the results during the study period (10-year intervals), maximum and minimum average amounts of SPI were respectively recorded for 1990-91 and 2000-2001. In all studied years, exponential model was determined to be the best variogram fitted to the spatial structure of data and the effective range of each station was a distance of almost 18.03 kilometers for all years except 1990-91 with an effective range of 5, 02 km. Cross validation techniques introduced Kriging as the best interpolation method for all years except 1990-91 in which IDW to the power of 5 was the best interpolation method. Spatial zoning map of SPI showed that moderate drought was recorded for southern parts of Kerman province such as Anbarabad and Jiroft in 1970-71 while in other parts of the province slight drought was observed except Rafsanjan. In 1980-81, slight drought was observed for most parts of the province while in Bam, Bardsir and east of Jiroft slight moisture was observed. In 1990-91, there was a slight drought was recorded for Kerman, Baft, Kahnooj and east of Jiroft. In 2000-2001, all parts of the province were at risk of drought as in the southern half of the province (Baft, Anbarabad and Kahnoj) moderate drought and in the northern half of the province(Kerman, Rafsanjan and Bardsir) slight drought were observed. Error maps showed considerable accuracy of interpolation, especially near the stations.
Omol banin Bazr afshan; Mohsen Mohseni saravi; Arash Malekian; Abalfazl Moeini
Volume 18, Issue 3 , September 2011, , Pages 395-407
Abstract
Drought is defined as the continuous and abnormal moisture deficit. The term of continuous means continuation of deficit and the term of abnormal means deviation of favorite index of natural condition from the mean. In every drought study four main characteristics are considered: severity, duration, ...
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Drought is defined as the continuous and abnormal moisture deficit. The term of continuous means continuation of deficit and the term of abnormal means deviation of favorite index of natural condition from the mean. In every drought study four main characteristics are considered: severity, duration, frequency or return period and areal extent. The objective of this investigation is mapping drought severity in Golestan province. For this purpose, Standardized Precipitation Index (SPI) was used for drought monitoring in some meteorological stations located in Golestan province. This index was computed in a period of 25 years precipitation data (1975-2000) at four different time scales including 6,9,12, and 24 months. Consequently, the most sever drought in 6 month time scale was observed in Saliantapeh station while the highest severity in 9, 12, and 24 time scales was observed in Polejadeh station. The aerial extent SPI values for the most severe drought condition in different time scales were classified in Golestan province using geostatical techniques. The results showed that the area affected by drought decreased with increasing drought duration and the condition of drought in the province had west-east direction
Abbas Kazempour; Ali ashraf Jafari; Mehrnaz Riasat
Volume 18, Issue 2 , September 2011, , Pages 307-321
Abstract
The genus of Elymus is of important grasses for forage production and soil and water conservation in Iran's rangelands.It has high preference value for livestock grazing because of the high production and high acceptability. Important species of this genus show different tolerances to drought.In order ...
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The genus of Elymus is of important grasses for forage production and soil and water conservation in Iran's rangelands.It has high preference value for livestock grazing because of the high production and high acceptability. Important species of this genus show different tolerances to drought.In order to determine the reactions of 14 accessions of Elymus hispidus and Elymus pertenuis to drought stress, a factorial experiment was conducted using completely randomized design with three replications in a standard germination test in 2008, Shiraz, Iran.Polyethylene glycol 6000 was used at 4 levels (0, -8/0, -9/0- and -1 MPa) as different osmotic potentials.Data were collected and analyzed for germination percentage, speed of germination, root length, shoot length, seedling length, root / shoot length ratio, seedling weight and seed vigor index.The results showed significant differences among accessions, drought effects and interaction effects of accessions* drought for all the traits.However, there were no significant differences between means of two species for all traits except seedling weight.In both species, all traits except root / shoot length ratio were decreased by increasing osmotic potential. In contrast, means of root / shoot length ratio was increased by drought stress.The effect of drought stress was higher on shoot length than those for root length, indicating that the sensitivity to drought stress of shoot length was more than root length.The results showed that some accessions within E. hispidus species as (Yasoj , Eghlid and Brojen) showed the maximum drought resistance in most of the seedling attributes. According to the results of Probit analysis, LD50 were estimated as -0.72 and -0.81 MP for E. hispidus and E. pertenuis, respectively.
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.
Shahram Khalighi Sigaroudi; Ali Sadeghi Sangdehi; Khaled Awsati; Usef GHavidel Rahimi
Volume 16, Issue 1 , December 2009, , Pages 44-54
Abstract
Annual rainfall data related to a 26 year period from a number of Mazandaran climatological stations were employed to analyze and model the precipitation toward a determination of drought as well as wet years. Results indicate the occurrence of different intensity drought phenomenon in all stations. ...
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Annual rainfall data related to a 26 year period from a number of Mazandaran climatological stations were employed to analyze and model the precipitation toward a determination of drought as well as wet years. Results indicate the occurrence of different intensity drought phenomenon in all stations. As regards the classification of the annual wet and dry years, normal precipitation among various alternate dry and wet years can be observed with the normal years having more stability and continuity as compared to wet and dry years. The Standardized precipitation Index (SPI) was recognized better and more accurate model compared to the other models because of more potential such as high sensitivity to precipitation variation and more punctual separating of drought and wet year classes in every events.
Tahereh Ensafi Moghadam; Amar Rafiei Emam
Volume 16, Issue 2 , December 2009, , Pages 274-292
Abstract
The present study firstly sets out the procedure for the generation of climatic files for localities with climatic records and secondly, The process of obtaining maps of the climatic zones for all of the localities in the Salt Lake Basin of Iran. For the generation of the climatic records such as rainfall ...
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The present study firstly sets out the procedure for the generation of climatic files for localities with climatic records and secondly, The process of obtaining maps of the climatic zones for all of the localities in the Salt Lake Basin of Iran. For the generation of the climatic records such as rainfall periods and intensity, provided by the 34 climatology stations for a total of 44 years data from (1957-2000), was used as a source of information. These data was then subjected to a statistical analysis, using SPI method for the calculation of the frequency, intensity and duration of drought process. Finally for the mapping drought zoning in all localities of the Salt Lake Basin for the long term period, the Inverse Distance Weighted Method(IDV) was used in the Arc view software environment. The results showed that the study area is very sensitive to climatic drought.
Jalal Abdolahi; Mohammad hasan Rahimian; Mohammad hosein Savaqebi
Volume 14, Issue 3 , January 2007, , Pages 289-301
Abstract
Today, various indices have been developed for monitoring of vegetation cover in different climatic condition, which cause variation in aspect and spectral reflectance. Therefore, an index can give different values in different conditions. In addition, sparse vegetation and soil background are the other ...
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Today, various indices have been developed for monitoring of vegetation cover in different climatic condition, which cause variation in aspect and spectral reflectance. Therefore, an index can give different values in different conditions. In addition, sparse vegetation and soil background are the other limitations. Hence, combination of some indices can provide sufficient real information in such areas. Contribution of each parameter can be obtained from a statistical method. However, there is no guarantee that the high correlation coefficients would get a good vegetation cover map. It depends on the originality of each predictor variable. The main objective of this study was to identify some probable limitations of Landsat ETM+ images for mapping of vegetation cover in arid and semi-arid zones, especially in drought conditions. In addition, it suggests a method for mapping of sparse vegetation cover in such areas. For this purpose, vegetation cover percentages were measured in two dry and rainy years (2000 and 2002) in the Nodoushan basin, Yazd, Iran. Afterwards, Landsat ETM+ images of two mentioned dates were acquired and different indices were derived. In addition, some environmental factor maps were generated and aligned with other variables (e.g. DEM, Slope and Aspect maps). These data were analyzed using a multiple linear regression method and built regression equations of the form: vegetation cover (%) =1X1+2X2+…+ for each year. Xi’s are independent variables (Satellite data bands, different indices and environmental factors) and’s are regression coefficients and is a constant. According to the equations, vegetation cover maps were generated using ILWIS software capabilities. Then, their accuracies were determined. Results show that the 2002 map (rainy year) is more reliable than the 2000 map (dry year). It was also found that if a drought was occurred in the arid zones, soil background would be dominant and therefore, vegetation indices would not be able to estimate vegetation cover confidently
Morteza Akbari; Hamid reza Karim zadeh; Reza Modares; Bahareh Chakoshi
Volume 14, Issue 2 , January 2007, , Pages 124-142
Abstract
Desertification is the ecologic and biologic reduction which may occur naturally or non naturally. Desertification process usually effects arid and semi arid region and reduce the land efficiency very rapidly. This study has been conducted to evaluate and classify desertification with the aim of geographic ...
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Desertification is the ecologic and biologic reduction which may occur naturally or non naturally. Desertification process usually effects arid and semi arid region and reduce the land efficiency very rapidly. This study has been conducted to evaluate and classify desertification with the aim of geographic information system and remote sensing techniques. In this study, TM data of 25 shahriver 1369(16 October 1990) and ETM+ data of 16 shahrivar 1380 (7 October 2001) were used. Geometric, radiometric and sun height angle correction were carried out on the images. Supervised and unsupervised classification were used for both two images and 9 land uses were classified and compare quantitatively due to geomorphology and desertification attributes. Each main and partial desertification factor was input to geographic information database and scaled to make the map of desertification severity based on recommended method for Iran and FAO map of desertification vulnerability. The result of desertification severity which shows desertification condition, velocity and potentiality, showed that natural desertification occurs in 35 % of area with different medium, high and very high desertification severity. Anthropogenic desertification includes 65 % of study area with high and very high condition. But in desertification vulnerability map, very high desertification vulnerability was determined in 20 % of area with simultaneous human and animal effect and high desertification vulnerability was determined on 80 % area with only animal effect. According to the map, for arid region of north of isfahan, it was identified that range land use change to agriculture, improve agricultural patterns, over grazing, incident economic condition and ground water over exploitation are the most important anthropogenic factor, and drought and soil and water salinity are the most important natural factors. Desertification trend is enhancing to north west of the study area which will make trouble for rangelands, residential and industrial areas.
Hamidreza Moradi; Mansur Rajabi; Manuchehr Faraj zadeh
Volume 14, Issue 1 , January 2007, , Pages 97-109
Abstract
Drought is the most complex and unknown natural disaster that affects human more than other natural disasters. Droughts occurred in Fars province in recent decades showed the importance of drought study in this region. In this research, standard precipitation index (SPI) was calculated based on monthly ...
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Drought is the most complex and unknown natural disaster that affects human more than other natural disasters. Droughts occurred in Fars province in recent decades showed the importance of drought study in this region. In this research, standard precipitation index (SPI) was calculated based on monthly rain of 26 stations in a period of 36 years (1963-1999). For investigation of spatial droughts changes in study area Kriging interpolate method were used. Then analyses were performed using linear regression model trend and Man-Kendal nonparametric test in studied stations. The results showed that the intensity of droughts in central parts of this province is more than other regions. The trends exist in all of studied stations except Chardangeh station.
Tahereh Ensafimoghadam
Volume 14, Issue 2 , January 2007, , Pages 271-288
Abstract
Of the many Climatic events that influence earth’s environmental fabric‚ drought is perhaps the one that is most linked with desertification(WMO‚1997).This Investigation is an effort for assessment of acceptability about many of Climatic current Drought Indices in reagent and ...
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Of the many Climatic events that influence earth’s environmental fabric‚ drought is perhaps the one that is most linked with desertification(WMO‚1997).This Investigation is an effort for assessment of acceptability about many of Climatic current Drought Indices in reagent and sample stations of Salt Lake Basin of Iran. These drought indices which are used in world active systems, are Percent of normal precipitation Index PNI, Deciles of precipitation Index DPI, Standardized precipitation Index SPI, and Z Score Index ZSI.The above mentioned indices were calculated first by average of monthly precipitation data for a 44 years period from 1957 to 2000 relate to 34 synoptic and climatological stations in their common time scales. Based on obtained results from one hypotheses, DPI and SPI indices in the contemporary with minimum occurrence, showed, extremely drought in the studied stations. These acceptability of indices in more than of other indices and according of this investigation,DPI index sit on the first place, SPI sit on the second place, ZSI index sit on the third place, and finally PNI Index, sit on the forth place. In next stage the Standardized Precipitation Index SPI, based on precipitation values from 34 monitoring stations around the Salt Lake Basin of Iran, is computed monthly and was performanced for climatic interpret and characteristic include assess drought relative frequency, intensity, expand and duration and calculated return period of the most intense drought and according to the point stations data, drew intense map. This investigation indicate the most intense drought in Salt Lake Basin of Iran belong to Hamadan(Nozheh) and the longest drought duration in Avaj ‚Dooshantappeh‚ and Kashan Stations with the highest relative frequency digit of drought (38/6%) and the lowest relative frequency digit of drought (18/1%) belong to Golpayegan. The most of severe year has occurred in 1973 and 1967 in 44 years period.
Mehdi Morovati Sharifabad; Jalal Barkhordari
Volume 9, Issue 3 , September 2001, , Pages 1023-1034
Shabanali Gholami
Volume 9, Issue 3 , September 2001, , Pages 1047-1064