Elahe Khosrogerdi; Naser Mashahadi; Abolghasem Dadresi
Abstract
Desert pavement and playa crusts serve as resistant layers that protect underlying soil and sediment materials. When these protective layers are disrupted by human activities, the exposed fine particles become highly susceptible to wind erosion. This research aimed to evaluate the erodibility potential ...
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Desert pavement and playa crusts serve as resistant layers that protect underlying soil and sediment materials. When these protective layers are disrupted by human activities, the exposed fine particles become highly susceptible to wind erosion. This research aimed to evaluate the erodibility potential of three layers: sub-pavement soil in the pediment, sub-crust deposits, and playa crust. We assessed erodibility using soil texture characteristics, grain granulometry, and chemical properties including Electrical Conductivity (EC), Exchangeable Sodium Percentage (ESP), and Electrochemical Stability Index (ESI). Results indicate that the dominant granular category ranges between 250-500 microns in pediment samples, while playa samples exceed 500 microns. Particle size analysis reveals medium-to-fine sand in all pediment samples versus medium-to-coarse sand in playa samples, demonstrating finer particles in the pediment. Approximately 60% of all samples exhibited Sandy Clay Loam texture. Chemical analysis showed significantly higher mean values of EC, SAR, and ESP in playa crust compared to subsurface soil and deposits. The mean ESI values were 0.81 (playa crust), 0.67 (sub-crust deposits), and 0.10 (sub-pavement soil). Data analysis established the following wind erodibility sequence: sub-pavement soil > sub-crust deposits > playa crust.
Azam Beigi; Naser Mashahadi; Majid Karimpourreihan
Abstract
Mining activities are one of the most persistent causes of soil degradation due to the destabilization of the physicochemical structure of the soil. In this research, quantitative data of soil stability indicators were used to assess the effect of sodium sulfate extraction on soil properties and protective ...
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Mining activities are one of the most persistent causes of soil degradation due to the destabilization of the physicochemical structure of the soil. In this research, quantitative data of soil stability indicators were used to assess the effect of sodium sulfate extraction on soil properties and protective behavior of the earth's surface. The research method was based on tranformations in soil stability indicators, namely, acidity (pH), electrical conductivity (EC), exchangeable sodium percentage (ESP) and sodium absorption ratio (SAR), for natural surfaces (undisturbed topsoil), stripped topsoil layer (displaced soil layer) and sodium sulfate extraction layer. The results show that the concentration of exchangeable sodium percentage and the exchangeable calcium to magnesium ratio in the layer of displaced soil and the extraction layer of sulfate is reduced compared to the natural soil. While the organic matter content of soils does not change in all layers, and the value of electrical conductivity in the sulfate extraction layer is higher than all layers. The results of the soil stability data value show the instability of the displaced soil layer compared to the other two layers. Based on the presented results, it has been shown that the soil instability potential increases due to sodium sulfate extraction.
Farhad Hasani Dorabad; Naser Mashhadi; AmirReza Keshtkar
Abstract
The desert environment is aeolian, being dominated by the wind. The dynamics of wind erosion are driven by both natural processes, including climate and its fluctuations, and human activity. Separating the climatic and anthropogenic causes of wind erosion can improve the understanding of its driving ...
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The desert environment is aeolian, being dominated by the wind. The dynamics of wind erosion are driven by both natural processes, including climate and its fluctuations, and human activity. Separating the climatic and anthropogenic causes of wind erosion can improve the understanding of its driving mechanisms. The aim of current research is to evaluate the spatio-temporal dynamics of the aeolian process based on the sand dunes morphology and the analysis of the spatial correlation between wind erosion dynamics and climate fluctuations. Based on meteorological, remote sensing and field observations data, the impacts of climate fluctuations on the temporal and spatial changes of the aeolian process were evaluated according to the indicator of the creation and expansion of sand dunes .MODIS remote sensing data was used to study the sand dunes morphology. The temperature, precipitation, wind speed and other meteorological data used in this study were all derived from two synoptic stations of Qom and Kashan. The analysis of the elongation and form of the sand dunes as the wind direction indicator showed that the studied area is affected by the winds region of the Qom (northwest and west). The results of climate studies showed that over the last 27 years, the region has a rising temperature trend, while the average precipitation in the region has decreased in the same period. The relationship between drought conditions and aeolian process showed that the region experienced severe drought conditions more than normal or abnormally dry conditions during 1369 to 1395.
Naser Mashahadi
Abstract
The dynamics of human activities threaten the sustainability of global life-support systems. Analyze of anthropogenic transformation data play a central role in environmental problems evaluation. This study aims to analyze human activities in watershed. Studies and analyzes revealed that the anthropogenic ...
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The dynamics of human activities threaten the sustainability of global life-support systems. Analyze of anthropogenic transformation data play a central role in environmental problems evaluation. This study aims to analyze human activities in watershed. Studies and analyzes revealed that the anthropogenic transformation variables include the type, intensity and trend. Spatial and temporal patterns of the type of activity (land use), intensity and human intervention were studied using satellite images and field observation. The classification and land use map were done in two phases: The functional phase included the main land uses including agriculture, rangeland, urban and water resources, and the activity phase included ten types of land use. The study of the human interventions intensity in land use units was carried out based on the temporal extension of agricultural land development (agricultural land use), the rangeland condition assessment (rangeland land use) and the area extent of under influence (urban area and water resources). The results of land use studies identified that Rangeland lands cover 77.2 percent and agriculture, urban area and water resources land uses accounted for 21.5, 1.1 and 0.2 percent, respectively. The results of the intervention trend indicated that the trend continues from normal conditions to the replacement by technogenous structures. This trend has revealed growth of agricultural activity in rangeland and as well as the tremendous loss in cropland in uneven urban and industrial growth. The results of the study show the compatibility between the three variables of anthropogenic transformation; ie, the type, intensity and trend.
Asghar Tavakkoli Fard; Aliakbar Nazari Samani; Naser Mashhadi; Hoda Ghasemieh; Mojtaba Hodayi Arani
Abstract
Kashan Erg is one of the most important sand dunes complexes in Iran. It is included the most important various type of sand dunes in Iran. This study was performed to compare the granulometry of aeolian sediments in different sand dunes and also from plinth to crest of transverse dunes that located ...
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Kashan Erg is one of the most important sand dunes complexes in Iran. It is included the most important various type of sand dunes in Iran. This study was performed to compare the granulometry of aeolian sediments in different sand dunes and also from plinth to crest of transverse dunes that located in Kashan Erg’s north. In order to determining different statistical variables, aeolian sediment sampling was conducted in different sand dunes. Then, the sample’s granulometry test was done based on dry sieve analysis. Finally, statistical parameters such as mean diameter, Sorting, Skewness, Kurtosis, d10, and d90 were determined. The results showed that the mean diameter, Sorting, d10 and d90 parameters have significant differences at the 95% significance level between the stabilized sand dunes and active ones. Moreover, it was found that in transverse sand dunes, there are a significant difference at the 95% significance level between mean diameter and d90 parameters in bottom of the stoss side and lee side.
