Mohammad Darvish
Volume 10, Issue 3 , September 2019, , Pages 301-320
Farshad Soleimani Sardoo; Ali Azareh
Volume 26, Issue 1 , June 2019, , Pages 131-142
Abstract
Over the past few decades, there have been many global efforts to combating and mitigating desertification, and one of the most important actions is the United Nations Convention on the combating desertification. The present study aimed to assess the severity of desertification and identify the most ...
Read More
Over the past few decades, there have been many global efforts to combating and mitigating desertification, and one of the most important actions is the United Nations Convention on the combating desertification. The present study aimed to assess the severity of desertification and identify the most important factors affecting land degradation in the Jazmurian basin. In this study, the IMDPA model was used to assess the desertification severity. Due to the time and cost limitations, two criteria for water and climate were selected. At first, by determining the geometric mean of the indices and then the criteria, the total desertification was calculated and the quantitative value of the indices and criteria and the final desertification were divided into four classes: low, moderate, severe and very severe. Then, using GIS, the desertification intensity map of the area was drawn up in the study periods. The results showed that in the study area, the water criterion was dominant and classified with a weighted mean of 3.2 in the sever class. Subsequently, the climate criterion with a weighted mean of 2.4 was in the next rank. The results indicated that the most important desertification indices in the study area were groundwater drop, electric conductivity of water, precipitation, TRANSO Drought Index, Drought Continuity Index and SPI index.
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 ...
Read More
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.
Mehdi Ahmadian; Moloud Sadat chavoshian; Mohammad Darvish
Volume 22, Issue 1 , June 2015, , Pages 109-120
Abstract
In recent years, the depletion of groundwater resources has been increased by the population explosionand the development of agriculture and industry. In this study, the geo-statistical methods were used to study the spatial and temporal variations in groundwater level in Kaboudrahang-Famenin plain. ...
Read More
In recent years, the depletion of groundwater resources has been increased by the population explosionand the development of agriculture and industry. In this study, the geo-statistical methods were used to study the spatial and temporal variations in groundwater level in Kaboudrahang-Famenin plain. For this purpose, available data of region including information about piezometers and monitoring wells were collected and then, database was composed. Next, the control of data accuracy was carried out. For comparison of geo-statistical methods, the variograms were plotted respectively and the different interpolation methods such as kriging (simple model), cokriging and Inverse Distance Weight with powers 1 to 5 (IDW) and radial basis functions (Thin Plate Radial Function, Inverse Multi Quadratic and Multi Quadratic) for groundwater zoning were used. The best interpolation method was selected by using two criteria, Root Mean Square (RMSE) and General Standard Deviation (GSD), and finally the zoning map of groundwater level was drawn in Arc-GIS software. The results of spatial statistical analysis indicated that the best variogram models for groundwater level data in the first period (1989), in the middle period (1993&1999) and the last period (2006) were spherical, circular and pentaspherical models, respectively.Evaluation of various interpolation methods with using "cross validation criteria" showed that in the investigation period, cokriging had the lowest estimation error compared with other interpolation methods. Thus, Cokriging was the most suitable interpolation method. The results of interpolated digital maps during the study period showed that the maximum fall of water table in 17 years was recorded to be 55 meters for central east region of plain. This shows the dramatic reduction in groundwater reserves of the region, which would not lead to industrial and agricultural sustainable development.
masoud masoudi; maryam vahedi; alireza nematollahi; seyed rashid fallah shamsi
Volume 22, Issue 4 , March 2015, , Pages 802-820
Abstract
This research was aimed to present a new model to determine the areas with higher degradation risk through considering various indicators of land degradation and desertification aspects or criteria, namely, natural, human and trend of degradation. For this purpose, two areas were selected in the north ...
Read More
This research was aimed to present a new model to determine the areas with higher degradation risk through considering various indicators of land degradation and desertification aspects or criteria, namely, natural, human and trend of degradation. For this purpose, two areas were selected in the north (Sepidan) and south of the province (Lamerd). These two areas were selected because of their differences in climatic conditions. The final land degradation risk map was produced by overlaying all three natural, human and trend of degradation layers in comparison with the current status of degradation in GIS. The areas under risk were classified into subclasses with different probability level to show a statistical picture of risk in future. In this study, the percentage of risk probability was evaluated according to the trend and potential of degradation. The results showed that the dominant risk class in Sepidan was moderate, in Lamerd the dominant risk class of natural factors was moderate, and in other cases, the dominant risk class was low or no risk. In addition, the comparison of risk assessment in both areas based on the weighted average indicates that the degradation risk of human factors, current degradation trend and finally land degradation risk in Sepidan is sever as compared with Lamerd. In general, degradation risk in Sepidan with a semi humid to humid climate condition is more sever than that of Lamerd with a dry climate.
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 ...
Read More
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.
Fatemeh Sharifani; Mohammad Jafari; Hossein Azarnivand; Hamid reza Abbasi; Mahshid Sori
Volume 13, Issue 4 , February 2007, , Pages 359-367
Abstract
This paper investigates the effects of plant growth on soil quality in Sagzi plain of Isfahan in order to evaluate the effects of agriculture on desertification processes in dry lands. Inappropriate crop management is the most effective factor which is related to soil and water ...
Read More
This paper investigates the effects of plant growth on soil quality in Sagzi plain of Isfahan in order to evaluate the effects of agriculture on desertification processes in dry lands. Inappropriate crop management is the most effective factor which is related to soil and water salinization and this is one of the important processes of desertification. Is agriculture a positive or negative factor for reclamation of saline soils? To find an answer for this question, some improved and degraded factors of desertification in Sagzi plain of Isfahan were considered. Among those common agricultural products, which of them is more effective and which of them is less effective in soil reclamation? Treatments of Medicago, Wheat and Barley were selected and compared with derelict land that was independent variable in this experiment. In order to investigate the effects of those products, soils were considered that were allocated to cultivation of these products successively at least for 5 years. Then sampling was selected in every treatment with 5 reduplication, from the depth of 0-3, 30-60, 60-90, 90-120, 120-150 centimeter. The saline features and CaCo3, EC, OM,K+, Mg2+,Ca2+, Na+, Caso4, Cl-, SAR, HCo3-, So42- investigated in every treatments. Dunkan test was applied for comparison of soil features. The results of variance analysis showed that there is significant different between treatments in different depths. Dunkan is test showed that according to the overall scores for each factor, derelict lands are least decent treatment while Weat annual agro technical lands are the most suitable one. Then this is better that agricultural products that are appropriated with condition is cultivated.