Mohammad Khosroshahi; Zahra Saeedifar; Khosro Shahbazi; Samira Zandifar; Sakineh Lotfinasabasl; Azadeh Gohardoust; Fatemeh Dargahian; Maryam Naeemi; Tahereh Ensafi Moghadam; Leila Kashi Zenouzi; Zohreh Ebrahimi Khosefi; Morteza Khodagholi
Volume 30, Issue 4 , February 2024, , Pages 521-541
Abstract
Background and objectivesWind erosion and dust phenomenon are considered as one of the important processes of land degradation and a serious challenge in Iran. This phenomenon occurs due to the interaction between weather and terrestrial processes. The purpose of this research is to investigate and analyze ...
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Background and objectivesWind erosion and dust phenomenon are considered as one of the important processes of land degradation and a serious challenge in Iran. This phenomenon occurs due to the interaction between weather and terrestrial processes. The purpose of this research is to investigate and analyze the trend of temporal and spatial changes in the number of dusty days in Iran and to investigate the role of climate in its spread. MethodologyIn this research, after receiving hourly and daily statistics of dust events (through 148 synoptic and climatology stations) and parameters of precipitation, evaporation, temperature as key climatic elements (from 171 stations) in 22 provinces located in arid and semi-arid regions of Iran, The spread of dust was investigated and the correlation between climate and dust was determined. After calculating the number of dust days in Iran, the information was called in the GIS environment and a map of the spatial changes of the parameter of the number of dust days in the three decades of 1987-1996, 1997-2006, 2007-2016 was prepared. In the following, the spatial analysis of this parameter and its expansion over three decades were investigated. Next, the climate parameter that had the highest correlation with the number of dusty days was selected and after preparing a map of its spatial changes in the GIS software environment, the spatial compatibility of the desired parameter with the expansion of the number of dusty days was investigated. In the next step, after performing the homogeneity test on the dust occurrences, the partial square regression model was used to determine the contribution of the three mentioned climatic elements as independent variables and the number of dust days as a dependent variable. ResultsThe results showed that the number of dusty days and the area of its occurrence have increased in Iran, so that in the last decade under study (2007-2016) compared to the previous two decades, the dustiest event occurred in Iran. This increase has been more intense especially in the western and southwestern regions of the country, which were also affected by extra-local dust events. These dust events have spread to the central regions of the country with greater frequency. The homogeneity test in many provinces showed a common change point (year 2007-2008) in the number of dusty days, which could be related to the beginning of severe droughts and climate changes from this year in Iran. The study of climatic parameters (temperature, precipitation and evaporation) on changes in the number of dust days in Iran showed that during recent years, temperature had the highest significant correlation level (0.58) with the occurrence of dust. The temperature gradient map in the last decade (2007-2016) compared to the previous decade (1997-2006) also showed the increasing trend of temperature, especially in the western and southwestern regions as well as the southeastern regions of Iran. Modeling the effect of climatic parameters of temperature, precipitation and evaporation on the parameter of the number of dusty days showed that the contribution of the studied climatic parameters to the occurrence of dusty days is about 33% and other effects can be related to things such as human factors or soil characteristics, type of vegetation, solar radiation, etc. ConclusionIn general, the results of examining the trend of changes in the number of dust days and climatic indicators for nearly 3 decades indicate a significant increase in the number of dust days in most parts of Iran and the conditions for this increase have been provided and if the trend of changing these indicators in the coming years is according to the current trend, the risk of environmental problems in the country can be expected to increase.
Samira Zandifar; Maryam Naeimi; Zohre Ebrahimi Khosfi
Volume 27, Issue 1 , April 2020, , Pages 144-158
Abstract
The most important structural factor that contributes to desertification is the appearance of salt domes. Due to its solubility and also the effect it can have on the quality of water and soil resources in the surrounding areas, its study is of special importance in agricultural projects and natural ...
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The most important structural factor that contributes to desertification is the appearance of salt domes. Due to its solubility and also the effect it can have on the quality of water and soil resources in the surrounding areas, its study is of special importance in agricultural projects and natural resources because it will reduce soil fertility and expand deserts. In this study, it has been tried to determine the quality of surface and groundwater and also to study the factors of geology, morphology, salt dynamics, and tectonic fractures around the Dashti salt dome and its relationship in desertification. The thickness of the salt column in the Dashti salt dome has been estimated at approximately 2,800 meters, and salt glaciers are affected by the topography of the dome (northeastern-southwest) from both sides and laid on the surrounding rocks. For this reason, low sediment is constantly threatened with contamination. Examining the dynamics of the dome, it was found that the balance between the amount of supply and the lack of salt in the desired salt dome is always established and plays an active and permanent role in the expansion of the desert around it. The flow of groundwater in the aquifers of the region is mainly controlled by the permeability of tectonic joints and faults around the dome and confirms the effect of the dome on the salinity of groundwater. Close activity to the surface of the Dashti salt diapir before the orogeny of Zagros is an important and fundamental factor in the destruction of the Kangan anticline soils and the expansion of desertification.
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.