Geomorphology
sayyad asghari; shiva safari; elham mollanouri
Abstract
Land displacement is known as one of the most obvious invisible effects of natural earthquake hazards. In the present study, the radar interferometric technique (SBAS) using the images of Sentinel 1 (2018 to 2021) was used to estimate the land subsidence, and the Landsat 8 image of 2018 was used to extract ...
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Land displacement is known as one of the most obvious invisible effects of natural earthquake hazards. In the present study, the radar interferometric technique (SBAS) using the images of Sentinel 1 (2018 to 2021) was used to estimate the land subsidence, and the Landsat 8 image of 2018 was used to extract the land use classes in a part of the Sarab county. Also, the data obtained from the regional water organization has been used to investigate the condition of underground water in connection with the subsidence caused by displacement. According to the findings and survey of the land use map of the study area, the subsidence can be seen in different places and it reaches 9 cm per year around the agricultural areas and pastures. Also, in some places, the rising rate is estimated up to 12 cm. Examining the condition of aquifers shows a drop in the level of underground water in most stations, especially a sudden drop since the beginning of 2018. Considering that the direct relationship between groundwater withdrawal and subsidence has been fully proven; But after the 5.9 magnitude earthquake in November 2018, sudden changes have occurred in the subsidence of the region. Therefore, it seems that the subsidence of the region is more affected by the earthquake.
Geomorphology
sayyad asghari; Elnaz Piroozi
Abstract
The danger of earthquakes causes irreparable damage to societies. Therefore, it is effective to prepare to deal with it by identifying vulnerable points. Ardabil City is not exempt from this rule due to the existence of many faults, seismic points, and non-compliance with standards. Based on this, the ...
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The danger of earthquakes causes irreparable damage to societies. Therefore, it is effective to prepare to deal with it by identifying vulnerable points. Ardabil City is not exempt from this rule due to the existence of many faults, seismic points, and non-compliance with standards. Based on this, the current research seeks to measure and evaluate the vulnerability of Ardabil City against the risk of earthquakes. For this purpose, first by examining research sources related to the subject, some of the most important factors affecting the occurrence of this phenomenon were prepared as independent variables. Valuation and standardization of the layers were done by using the fuzzy membership function and weighting of the criteria, using the CRITIC method. Finally, modeling was done using the MARCOS multi-criteria decision-making method. The results of the study showed, respectively; The factors of distance from the fault, land use, and distance from the earthquake center have the greatest influence on the occurrence of earthquakes in the region with the weight coefficient of 0.110, 0.104, and 0.102. In addition, according to the results of the research, 16.67% of the entire city of Ardabil has a high vulnerability potential and 30.27% has a relatively high vulnerability probability. Also, based on the results of the research, Ardabil city is at an average level in terms of the level of vulnerability to earthquake risk, the cities of Hir and Arallo are in the high vulnerability category and Somarin city is in the relatively high vulnerability zone. In addition, according to the findings of the research, 22.86 and 30.86 percent of the settlements and villages of Ardabil, respectively; In the area with high and relatively high vulnerability, 13.14% in the area with moderate vulnerability, and respectively; 22.28 and 10.86% are located in the area with relatively low and low earthquake vulnerability.
Geomorphology
Imanali Belvasi; sayyad asghari; Fariba Esfandiari Dorabad; Batool Zeynali
Abstract
Introduction
Morphological Assessment will be necessary to understand the current situation and the potential for possible river changes in the future. Natural factors such as floods, soil erosion, landslides and human factors such as land use change and sand removal from the riverbed affect the morphology. ...
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Introduction
Morphological Assessment will be necessary to understand the current situation and the potential for possible river changes in the future. Natural factors such as floods, soil erosion, landslides and human factors such as land use change and sand removal from the riverbed affect the morphology. River systems have always been of interest to humans as one of the most vital elements of the Earth's surface. Humans also change the face of the earth by changing their use, destroying natural resources, plowing the land in the direction of the slope, planting trees in the riverbeds. Any Manipulation into the riverbed will change the process of erosion and sedimentation along the river. Understanding the characteristics of flow and sediment is the basis for evaluating the behavior of rivers and deciding on engineering activities. Therefore, it is necessary to obtain the necessary information on how they work before starting engineering projects for rivers.
Data and Method
In this study, geological maps at a scale of 1: 100000 of the Geological Organization, topographic maps at a scale of 1: 50,000 digits of the Geographical Organization of the Armed Forces, Landsat satellite images, 2020 April, November 1995, Climatic data Temperature and precipitation (1399-1374) of Lorestan Meteorological Organization and Digital elevation model of 30 meters has been used. Arc GIS software was used for spatial analysis and ENVI software was used for processing satellite images. The normalized water difference index is the first index of water extraction in images and remote sensing data. In this indicator, two green and infrared bands are used. Positive values of this index indicate water and negative values indicate phenomena other than water. Researchers have proposed different methods for studying changes in river channels. The transect method is used to evaluate changes and displacements in river channels. In this method, lines with specific distances on both sides of the river route are drawn as baselines. These lines are constant for the time periods studied. River channel displacements relative to these lines are quantified. To further evaluate the Kahman River canal, the canal migration rate method was used. The Kahman river Canal was divided into two areas, mountainous areas and plain and agricultural areas, based on topography and land use.
Results and Discussion
To calculate the area to the right and left of the transects, the Kahman river channel was cut separately with a transect layer in 1995 and 2020. Calculation of changes in the area of transects shows that about 185.85 hectares of land adjacent to the Kahman river (1995-1999) have been eroded. On average, about 7.43 hectares of these lands have been destroyed annually. The maximum value of this index in transect 30 is calculated at 8.27 hectares. In order to better understand the changes and dynamics of the Kahman river Canal, the migration rate index (Rm) was also used. First, two fixed lines were drawn around the Kahman river channel. The area between the two was calculated using Arc GIS software functions. The average migration rate of Kahman river (1399-1374) was 2.51 meters per year. The lowest level of this index occurred in Trasket 49 at 0.18 meters per year. The mountain factor and stabilization operations along the river have been the most important reasons for its control and stabilization. The highest rate of migration occurred in transects 4, 32 and 30 at 4.80, 5.5 and 6.12, respectively. Shortcuts and land use changes have been the main reasons for the high rate of duct migration in these transects. The largest amount of lateral changes in the Kahman river route occurred in parts of the plain and agricultural areas, including transects 30 to 35. The most important factor was the high lateral changes of the Kahman river route in the plain area due to the high erosion of the coastal and floodplain materials. Most of the constituents of the bed and banks of the Kahman river in these periods are from fine to coarse sands.
Conclusion
Duct migration rate index showed that the average displacement of Kahman river canal (1374-1399) was 2.51 meters per year. The lowest value of this index was 0.18 meters per year and the maximum value was 6.12 meters per year. Calculation of changes in the area of transects showed that about 185.85 hectares of land adjacent to the Kahman River (1374-1399) has been destroyed. On average, about 7.43 hectares of these lands are lost every year. In the mountainous area, the effects of the mountains were the most important factor in determining the morphological changes of the Kahman River channel. The presence of erodible materials along the Kahman River in the plains and agricultural areas has increased the lateral migration of meanders and the width of the valley and floodplains adjacent to the river has increased significantly. Therefore, it can be said that the Kahman River has had more geometric changes in the plains and agricultural lands.
Geomorphology
sayyad asghari; delnya palizban; Hadi Emami; ehsan ghaleh
Abstract
Introduction Landslide is a term that encompasses a variety of amplitude motions and causes the movement of a mass of material in the slopes. And creep is classified. Natural slope instability is one of the geomorphological and geological phenomena that plays an effective role in deforming the ...
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Introduction Landslide is a term that encompasses a variety of amplitude motions and causes the movement of a mass of material in the slopes. And creep is classified. Natural slope instability is one of the geomorphological and geological phenomena that plays an effective role in deforming the earth's surface. Identifying areas with potential for landslides and their zoning is one of the key steps in managing environmental hazards and reducing the damage caused by this phenomenon, because this phenomenon causes financial and human costs, soil and land degradation and increased sediment production at the basin outlet. It becomes. Iran with its predominantly mountainous topography, high tectonic activity and seismicity, diverse geological and climatic conditions, has the most natural conditions to create a wide range of landslides. The purpose of this study is to zoning the risk of landslides on the Sarab-Nir road. In this research, two models of network analysis and fuzzy logic are examined and evaluated. It is hoped that eventually, by preparing a landslide risk zoning map, it will be of great help to planners and managers in order to reduce potential damages and find safer locations for development, construction and road construction. Methodology Sarab-Nir road is located between East Azarbaijan province and Ardabil province and is a communication route between these two provinces, whose geographical coordinates are 37 degrees and 94 minutes to 38 degrees and 03 minutes north latitude and 47 degrees and 53 minutes to 48 degrees and 01 minutes. It is east longitude. In this study, network analysis model was used to determine areas prone to fall and zoning. In order to better understand the causes of landslides and also to organize the research in the field, the study area was visited and 15 geographical points from different areas of the study area were recorded. The geographical location of the points prone to fall was also recorded with GPS. Then, according to the network analysis model, information layers were prepared in ArcGIS software. The information layers for landslide risk zoning are: fault, slope, slope direction, distance from road, and distance from waterway, land use, geology (lithology), precipitation, altitude and vegetation. The elevation file or digital model of the elevation of the area was prepared with an accuracy of 30 meters from the USGS site and the desired DEM is a digital file obtained from the ASTER sensor and according to this DEM, the information layer such as streams, slope and direction The slope was obtained. Results and Discussion Four maps have been developed to investigate landslide hazards, which are rainfall, slope, elevation and land use layers. After creating information layers in order to prepare the final landslide hazard map, fuzzy information layer maps were created. In this study, in order to determine the effect of different classes of criteria on landslide sensitivity zoning, the layers are based on the type of performance of each in the landslide event using fuzzy membership functions in the range of zero to 1 fuzzy. Were made. The results obtained from the information layers and finally the landslide hazard map show that altitudes of more than 2000 meters have the highest share of landslides, and altitudes of 1400 meters have been significant landslides due to the instability of the slopes against Climatic and environmental factors. Also, most of the landslides occurred at a distance of 3 to 6 km from the faults, which shows the importance of faults against landslides. About 40% of landslides occur in very high-risk classes. This indicates that the model has a high capability in predicting landslides. It is necessary to explain that most of the landslides occur in the area of Saein pass, which have very favourable conditions for the occurrence of range movements that start from 25 km of mirage and continue for a distance of 15 km of Nir. Conclusion Factors such as slope, precipitation and geology play a more important role in landslides than other factors. Slopes of 60 to 80% have the greatest impact on landslides, which are more pronounced at altitudes above 2000 meters. Therefore, altitudes above 2000 meters have the most landslides. Also, due to the direct relationship between altitude and climatic fluctuations in these altitudes, the amount of precipitation is higher and, of course, has a great impact on the occurrence of landslides. In these areas, vegetation is at a minimum and due to the cold region, the vegetation in these areas is very small, which prepares the conditions for landslides and due to the presence of sedimentary formations such as sandstone, Siltstone mudstone with tuff interbreeds in the area, the conditions for landslides have become more prone and because these formations lose their stability sooner and are strongly influenced by physicochemical factors, they are more prone to landslides than other formations. To be. According to the results, the low risk floor with the highest value, 405.44 square kilometers, occupies approximately 30.87 percent of the area, but the very high risk floor with 288.2 square kilometers and the high risk class with 23.23 square kilometers. , Occupy a total of 37.25% of the area of risk classes.
Geomorphology
Sayyed Asghari Saraskanrood
Abstract
The purpose of this study is analysis of affecting factors in pattern forming and channel dynamic in mountainous Intervals of Garangu River between Khorasanak villages in Hashtrood to input of river in Mianeh city. The pattern of research is comparative – deductive. materials of research are include ...
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The purpose of this study is analysis of affecting factors in pattern forming and channel dynamic in mountainous Intervals of Garangu River between Khorasanak villages in Hashtrood to input of river in Mianeh city. The pattern of research is comparative – deductive. materials of research are include of Topographic map, Geological map, flow Hydrological data, data provided from Dem and field data. In this research were used methods of River Power Analysis, River specific power, Sinuosity Index, Central angle, Route Sinuosity and longitudinal profile analysis in order to channel pattern and dynamic analysis. Results indicated that forming of channel pattern and dynamic in studied area was controlled by lithological features of sections. So channel dynamic in sections such as section 1 is impressed by lithological resistance of river bed and sides mainly bed deepening and it in sections such as section 10 is impressed by erodibility and loose formation mainly bed Widening that it was controlled by river lithological features strongly. The results of this study can be used to identify of interval Maximum River power and interval affected by river erosion.
Geomorphology
Sayyad Asghari Saraskanroud
Abstract
The purposes of this study are investigation of Shahr Chai river patterns, its stability and subsequently changes in the period of 2000-2013. For this purpose were used Landsat images, topography, geological maps and hydrological data. For study of river pattern and its changes was used Sinuosity and ...
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The purposes of this study are investigation of Shahr Chai river patterns, its stability and subsequently changes in the period of 2000-2013. For this purpose were used Landsat images, topography, geological maps and hydrological data. For study of river pattern and its changes was used Sinuosity and Meander Central Angle Indexes. Also for study of river stability was used by shear stress and RBS indexes. Results indicated that river pattern changes are very low. River stability analysis indicated that total shear stress rate is higher than critical shear stress. Results show that potential of river is high for creating of morphological changes in costal interval but decreasing of river flow has been caused that river changes be in lowest amount possible.
Climatology
MohammadHoseein Rezaei Moghaddam; Khalil Valizadeh Kamran; Mehdi Belvasi; Hoseein KheiriAstiyar; Sayad Asghari Saraskanroud
Volume 20, Issue 56 , August 2016, , Pages 127-148
Abstract
One of the most important procedures in the water sources studies is the estimation of the local distribution of precipitation in different time scales. The study of precipitation is a basic element in the water balance studies and is an important factor in the natural sources programs of each country. ...
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One of the most important procedures in the water sources studies is the estimation of the local distribution of precipitation in different time scales. The study of precipitation is a basic element in the water balance studies and is an important factor in the natural sources programs of each country. Also, because of the rain-evaluation stations deficiency and their discreteness, it is necessary to use a special model. Besides the interpolation of precipitation amounts of stations, this model should interpolate topography, moisture and the slope direction of precipitation. In this work, at first, some data were gathered, in one year. These data were connected with the precipitation and moisture of 9 synoptic stations and 31 rainevaluation stations. These stations were located in the Lorestan province. Second, using the least square method and with the help of Maple software, the relations between precipitation and moisture was extracted. Third, by using the Python programming language, these relations were linked into the GIS. Finally, by so doing, the digital precipitation modal was achieved. The results obtained from the digital precipitation model show that, the precipitation amounts are different from the measured data in the stations, from 0.02 to 11.6 mm. Also, to investigate the efficiency of the considered model, the data obtained from this model were compared with the precipitation data achieved from TRMM radar at 21 April 2010. The concluded result show that, the determination coefficients are 79 and 86% for the TRMM data and for the digital precipitation model, respectively
Mohammad hossein Rezayee Moghadam; Mohammad reza Servati; Sayyad Asghari Serkanrood
Volume 16, Issue 40 , September 2012, , Pages 119-139
Abstract
Researchers of river Geomorphology science are seeking new ways to check River Geomorphology and its pattern changes always. Fractal geometry is one of the new methods that can be used in Geomorphology of river science. The main importance of fractal geometry is presentation of the model and mathematical ...
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Researchers of river Geomorphology science are seeking new ways to check River Geomorphology and its pattern changes always. Fractal geometry is one of the new methods that can be used in Geomorphology of river science. The main importance of fractal geometry is presentation of the model and mathematical description for complex shapes that in nature can provide. The goal of this research is Fractal analysis of GezelOzanRiver changes between routes of Miyaneh to Zanjan. For this purpose was used satellite images of periods 2000, 2004 Sensor ETM + and 2007 sensor IRS. For Fractal analysis the studied route was divided into three periods that each period is different in terms of morphological characteristics. For determine of fractal dimensions was used from box-counting method. The survey results showed that the first interval (interval arterial) has had the highest changes and the second range (Mid-range Mountain) has had the lowest changes and third period (mountain range) has had an intermediate case.
