Ferdowsi University of MashhadJournal of Geography and Environmental Hazards2322-168213120240320Modeling Snowmelt Runoff by SRM Model and the Estimation of Degree-Day Factor using Net Radiation Satellite Images (Case Study: Kardeh Basin)Modeling Snowmelt Runoff by SRM Model and the Estimation of Degree-Day Factor using Net Radiation Satellite Images (Case Study: Kardeh Basin)1224298710.22067/geoeh.2022.78658.1280FARezaShahraki MojahedPhD Candidate in Irrigation and Drainage, Ferdowsi University of Mashhad, Mashhad, IranAminAlizadehProfessor in Water Engineering, Ferdowsi University of Mashhad, Mashhad, Iran0000-0002-9336-2750Seyyed HosseinSanaei-NejadProfessor in Climatology, Ferdowsi University of Mashhad, Mashhad, IranAlirezaFaridHosseiniAssociate Professor in Water Engineering, Ferdowsi University of Mashhad, Mashhad, Iran0000-0001-8175-7205AzarZarrinAssociate Professor in Climatology, Ferdowsi University of Mashhad, Mashhad, Iran0000-0002-4542-3176Journal Article20220907Snow studies drastically influences on managing water resources and preventing the dangers caused by floods. Moreover, the modeling of snow melt runoff is faced with the lack of snow density data in the basin due to many changes in the distribution of snow masses, and creating snow measurement stations at high altitudes are difficult and expensive work. Considering the issues, this study attempted to invent a new equation and use remote sensing techniques in a simpler and more physical way to determine the degree-day factor (α) and then the simulation was performed by defining its calculated values using classical and new methods along with the annual and seasonal values of the recession coefficient (k) for the snow-melt runoff model (SRM). The outcomes were evaluated and compared. In order to evaluate the performance of the model and its parameters, simulations were performed for the calibration and validation periods for the water years 2011-2012 and 2012-2013, respectively, and the MODIS snow cover product (MOD10A1) was used to estimate the snow-covered area and to estimate the radiation values. NEO net radiation product (CERES-NETFLUX-E) was used. The results showed that the best method for simulating runoff in the calibration period (2011-2012) was the new degree-day factor calculation method and the two values of the seasonal recession coefficient with the coefficient of determination of 0.72 and the volume difference of 4.17. In the validation period (2012-2013), the runoff simulation method with the new degree-day factor method and an annual recession coefficient with a coefficient of determination of 0.51 and the volume difference of 4.38 provided the best results in terms of assessment of the model accuracy criteria.Snow studies drastically influences on managing water resources and preventing the dangers caused by floods. Moreover, the modeling of snow melt runoff is faced with the lack of snow density data in the basin due to many changes in the distribution of snow masses, and creating snow measurement stations at high altitudes are difficult and expensive work. Considering the issues, this study attempted to invent a new equation and use remote sensing techniques in a simpler and more physical way to determine the degree-day factor (α) and then the simulation was performed by defining its calculated values using classical and new methods along with the annual and seasonal values of the recession coefficient (k) for the snow-melt runoff model (SRM). The outcomes were evaluated and compared. In order to evaluate the performance of the model and its parameters, simulations were performed for the calibration and validation periods for the water years 2011-2012 and 2012-2013, respectively, and the MODIS snow cover product (MOD10A1) was used to estimate the snow-covered area and to estimate the radiation values. NEO net radiation product (CERES-NETFLUX-E) was used. The results showed that the best method for simulating runoff in the calibration period (2011-2012) was the new degree-day factor calculation method and the two values of the seasonal recession coefficient with the coefficient of determination of 0.72 and the volume difference of 4.17. In the validation period (2012-2013), the runoff simulation method with the new degree-day factor method and an annual recession coefficient with a coefficient of determination of 0.51 and the volume difference of 4.38 provided the best results in terms of assessment of the model accuracy criteria.https://geoeh.um.ac.ir/article_42987_328170a8c1c0460e8710bd970dd0ec4f.pdfFerdowsi University of MashhadJournal of Geography and Environmental Hazards2322-168213120240320Investigating Flood Risk using SWAT and SIMHYD Models in Karganrud Drainage Basin, Talesh, IranInvestigating Flood Risk using SWAT and SIMHYD Models in Karganrud Drainage Basin, Talesh, Iran23464385710.22067/geoeh.2022.76374.1216FAMohammad HosseinRezaei MoghaddamProfessor in Geomorphology, University of Tabriz, Tabriz, Iran0000-0003-2626-4656KosarLoghmanniaMSC in Geomorphology, University of Tabriz, Tabriz, Iran0009-0001-7846-4425SadraKarimZadehAssistant Professor in Remote Sensing, University of Tabriz, Tabriz, Iran0000-0002-5645-0188AbdollahBehbodiPhD in Geomorphology, University of Tabriz, Tabriz, IranJournal Article20220423It is now easier to simulate catchments and take management measures to reduce flood damage with the development and expansion of hydrological tools. the SWAT model was used as a semi-distributive model and the SIMHYD model was used as an integrated model to estimate the runoff of the Karganrud Talesh catchment. For this purpose, observational data in the period 2006 to 2018 related to Talesh, Astara, Bandar Anzali synoptic stations and Hashtpar hydrometric station were obtained. In modeling by SWAT model, the coefficients N2 and R2 as the objective functions in the monthly flow calibration stage were 0.61 and 0.62, respectively, and in the validation stage were 0.67 and 0.70, respectively, indicating acceptable results in runoff peak simulation and the floods formed in this basin. Acceptable results were also obtained in the calibration and validation of the SIMHYD model. The coefficients N2 and R2 in the calibration stage were 0.710 and 0.8511, respectively, and in the validation stage were 0.625 and 0.9496, respectively. However, due to its semi-distributive nature, the SWAT model has a high accuracy in runoff simulation compared to the SIMHYD model, and the outputs obtained from both models showed this superiority in flood assessment and estimation, since this model simulates runoff well in the daily time period, while the SIMHYD model has satisfactory results in this basin by increasing the quality of data in the monthly time period.It is now easier to simulate catchments and take management measures to reduce flood damage with the development and expansion of hydrological tools. the SWAT model was used as a semi-distributive model and the SIMHYD model was used as an integrated model to estimate the runoff of the Karganrud Talesh catchment. For this purpose, observational data in the period 2006 to 2018 related to Talesh, Astara, Bandar Anzali synoptic stations and Hashtpar hydrometric station were obtained. In modeling by SWAT model, the coefficients N2 and R2 as the objective functions in the monthly flow calibration stage were 0.61 and 0.62, respectively, and in the validation stage were 0.67 and 0.70, respectively, indicating acceptable results in runoff peak simulation and the floods formed in this basin. Acceptable results were also obtained in the calibration and validation of the SIMHYD model. The coefficients N2 and R2 in the calibration stage were 0.710 and 0.8511, respectively, and in the validation stage were 0.625 and 0.9496, respectively. However, due to its semi-distributive nature, the SWAT model has a high accuracy in runoff simulation compared to the SIMHYD model, and the outputs obtained from both models showed this superiority in flood assessment and estimation, since this model simulates runoff well in the daily time period, while the SIMHYD model has satisfactory results in this basin by increasing the quality of data in the monthly time period.https://geoeh.um.ac.ir/article_43857_50a7d2b0a34ff60d996a9420699ba8b9.pdfFerdowsi University of MashhadJournal of Geography and Environmental Hazards2322-168213120240320Investigating the Impact of Bridge Structures on the River Floodplain using HEC-RAS and Arc-GIS Software (Case Study: Sarnagh Bridge on the Zola River)Investigating the Impact of Bridge Structures on the River Floodplain using HEC-RAS and Arc-GIS Software (Case Study: Sarnagh Bridge on the Zola River)47624385410.22067/geoeh.2022.75257.1175FAHassanHaji HosseinlouAssistant Professor in Geology, Islamic Azad University Khoy Branch, Khoy, Iran0000-0002-5596-8276VahidAghdamMSc Student in Water Science Engineering, Islamic Azad University Khoy Branch, Khoy, IranEbrahimValizadeghanAssistant professor in Water Science Engineering, Islamic Azad University Khoy Branch, Khoy, IranJournal Article20220217Zola River contains the most important fresh waters of West Azarbaijan province. The water surface of Urmia lake basin flows in this river. Sarnagh bridge is located on this river on the Sarnagh-Salmas road. Destructive flood event with high return time in river banks especially beside urban and rural residents cause many financial damages and life threats. So, exploring the river’s hydraulic behavior is essential. This study explored the Zola river bed and realm boundary and its floods bond affected by bridges structure. It studied the Zola River in Sarnagh road bridge position using HEC-RAS model. At first, using river 1:2000 scale topographic maps, ArcGIS software with HEC-Geo RAS extension, and HEC-RAS software, river discharge flow with 2, 5, 10, 25, 50, and 100 return time were analyzed for two scenarios. First scenario simulated the normal flow condition of the river and second one simulated the river flow, considering the effects of cross over structure of the bridge. The flow with 25 year return was used to model the design due to regional circumstances and controlled by 100 year return time flow, evaluating river bed extend before and after bridge structures. The results showed that narrow flow in bridge place causes flow reduction, flow reversal, deposition in upstream, as well as increase in the flow, erosion and foaming in the downstream of the bridge, which necessitates a bed stabilization structure.Zola River contains the most important fresh waters of West Azarbaijan province. The water surface of Urmia lake basin flows in this river. Sarnagh bridge is located on this river on the Sarnagh-Salmas road. Destructive flood event with high return time in river banks especially beside urban and rural residents cause many financial damages and life threats. So, exploring the river’s hydraulic behavior is essential. This study explored the Zola river bed and realm boundary and its floods bond affected by bridges structure. It studied the Zola River in Sarnagh road bridge position using HEC-RAS model. At first, using river 1:2000 scale topographic maps, ArcGIS software with HEC-Geo RAS extension, and HEC-RAS software, river discharge flow with 2, 5, 10, 25, 50, and 100 return time were analyzed for two scenarios. First scenario simulated the normal flow condition of the river and second one simulated the river flow, considering the effects of cross over structure of the bridge. The flow with 25 year return was used to model the design due to regional circumstances and controlled by 100 year return time flow, evaluating river bed extend before and after bridge structures. The results showed that narrow flow in bridge place causes flow reduction, flow reversal, deposition in upstream, as well as increase in the flow, erosion and foaming in the downstream of the bridge, which necessitates a bed stabilization structure.https://geoeh.um.ac.ir/article_43854_cc48bf2b2a320e7affeaa073fa2f4766.pdfFerdowsi University of MashhadJournal of Geography and Environmental Hazards2322-168213120240320Identifying and Measuring the Importance of Spatial Policy Indicators for Rural Flood Risk ManagementIdentifying and Measuring the Importance of Spatial Policy Indicators for Rural Flood Risk Management63864385910.22067/geoeh.2022.76633.1222FASeyed MohammadMousavi ParsaiePhD Candidate in Geography and Rural Planning, Tarbiat Modares University of Tehran, Tehran, Iran0000-0002-2548-0173MortezaTavakoliAssociate Professor, Department of Geography and Rural Planning, Tarbiat Modares University, Tehran, IranMahdiPourtaheriProfessor, Department of Geography and Rural Planning, Tarbiat Modares University, Tehran, IranJournal Article20220607Spatial policy regarding flood risk management is a series of actions that aims at achieving a logical solution for reducing the damages caused by floods and reducing the spread of floods. Spatial policies for flood risk management in villages are at the intersection of many management considerations, and thus, when formulating spatial policies for flood risk management, several indicators including environmental, economic, social-cultural, managerial-institutional and physical indicators should be considered. In this regard, this research examined the importance of each of the indicators in formulating the spatial policy of flood risk management in villages. According to the purpose of the research, which is identifying the importance of indicators in spatial policy making, the statistical population of the research consisted of experts, including academic faculty members specializing in this field, graduates and doctoral students defending their theses on the issues, and the people in charge. For this purpose, 70 participants were selected. From their point of view, the relevant questionnaire has a good level of validity and reliability with Cronbach's alpha coefficient of 0.97, which shows a very good level, considering the type of indicators and the number of samples. ANOVA, statistical tests, and Duncan's post hoc statistical test were used. The results indicated that the environmental index has the least importance with the value of 2.9484 in spectrum one along with the economic index with the value 1056/3. Social-cultural indicators with a value of 3.2381 and managerial-institutional indicators with a value of 3.3105 are close. The two indicators (social-cultural and managerial-institutional), due to their closeness to the significance of physical index (land use), were placed in the third spectrum. The only index that was separately placed in one spectrum and group is the physical index (land use). This indicator with the value of 3.4186 is in the third group and has the largest sub-set, which shows the greater importance of this index on spatial policy of flood risk management in villages.Spatial policy regarding flood risk management is a series of actions that aims at achieving a logical solution for reducing the damages caused by floods and reducing the spread of floods. Spatial policies for flood risk management in villages are at the intersection of many management considerations, and thus, when formulating spatial policies for flood risk management, several indicators including environmental, economic, social-cultural, managerial-institutional and physical indicators should be considered. In this regard, this research examined the importance of each of the indicators in formulating the spatial policy of flood risk management in villages. According to the purpose of the research, which is identifying the importance of indicators in spatial policy making, the statistical population of the research consisted of experts, including academic faculty members specializing in this field, graduates and doctoral students defending their theses on the issues, and the people in charge. For this purpose, 70 participants were selected. From their point of view, the relevant questionnaire has a good level of validity and reliability with Cronbach's alpha coefficient of 0.97, which shows a very good level, considering the type of indicators and the number of samples. ANOVA, statistical tests, and Duncan's post hoc statistical test were used. The results indicated that the environmental index has the least importance with the value of 2.9484 in spectrum one along with the economic index with the value 1056/3. Social-cultural indicators with a value of 3.2381 and managerial-institutional indicators with a value of 3.3105 are close. The two indicators (social-cultural and managerial-institutional), due to their closeness to the significance of physical index (land use), were placed in the third spectrum. The only index that was separately placed in one spectrum and group is the physical index (land use). This indicator with the value of 3.4186 is in the third group and has the largest sub-set, which shows the greater importance of this index on spatial policy of flood risk management in villages.https://geoeh.um.ac.ir/article_43859_8f921645a776c79989438af2d2808085.pdfFerdowsi University of MashhadJournal of Geography and Environmental Hazards2322-168213120240320Assessing the Vulnerability of Power Distribution Network to Natural Flood Hazards: A Case Study of the Behdan Watershed in Birjand CountyAssessing the Vulnerability of Power Distribution Network to Natural Flood Hazards: A Case Study of the Behdan Watershed in Birjand County871084393110.22067/geoeh.2023.81604.1348FAAliAshrafiAssistant Professor in Remote Sensing and Geographic information system, University of Birjand, Birjand, Iran0000-0002-7282-4776JavadMikanikiAssociate Professor in Rural Geography, University of Birjand, Birjand, IranMortezaDehghaniPhD in Watershed Management, General Directorate of Natural Resources of South Khorasan Province, Birjand, IranHasanSabeghiMA in Geography, University of Birjand, Birjand, IranJournal Article20230317According to the South Khorasan Province Electricity Distribution Company report, almost all the villages of the province are eqipped with electricity and related services. Since the density of settlements as well as industrial and service centers and consequently the electricity distribution network in the Shahroud watershed located in Birjand county is higher than other basins of the province, as well as, considering the damage caused to the masts and transmission beams of the electricity network in the past years, this study investigated the zoning of the vulnerability of the electricity distribution network against natural hazards in the Behdan watershed as a case to implement the model and estimate possible damages. To conduct this research, first, a map of the bases, the 20 kV network and other facilities of the electricity distribution company was prepared, topographical maps were used and matched with the electricity distribution network, and the effective lines were identified. Due to the absence of a hydrometric station in the studied area, the flood discharge of the studied basin was determined using the experimental-analytical method. In order to determine the flood zones, the transverse profile of the canals was first taken using the DGPS device. Using a photogrammetry drone, images were taken and, a digital elevation model was prepared. Then, the 100-year flood height model in each sub-basin was determined using Hec Ras software, and the flood area was determined using Hec Geo Ras extension in ArcGIS. Finally, the facilities related to the electricity distribution company exposed to flood damage and the possible costs caused by the flood were calculated for a representative basin.According to the South Khorasan Province Electricity Distribution Company report, almost all the villages of the province are eqipped with electricity and related services. Since the density of settlements as well as industrial and service centers and consequently the electricity distribution network in the Shahroud watershed located in Birjand county is higher than other basins of the province, as well as, considering the damage caused to the masts and transmission beams of the electricity network in the past years, this study investigated the zoning of the vulnerability of the electricity distribution network against natural hazards in the Behdan watershed as a case to implement the model and estimate possible damages. To conduct this research, first, a map of the bases, the 20 kV network and other facilities of the electricity distribution company was prepared, topographical maps were used and matched with the electricity distribution network, and the effective lines were identified. Due to the absence of a hydrometric station in the studied area, the flood discharge of the studied basin was determined using the experimental-analytical method. In order to determine the flood zones, the transverse profile of the canals was first taken using the DGPS device. Using a photogrammetry drone, images were taken and, a digital elevation model was prepared. Then, the 100-year flood height model in each sub-basin was determined using Hec Ras software, and the flood area was determined using Hec Geo Ras extension in ArcGIS. Finally, the facilities related to the electricity distribution company exposed to flood damage and the possible costs caused by the flood were calculated for a representative basin.https://geoeh.um.ac.ir/article_43931_899c617012fd3225c396958f91b21f84.pdfFerdowsi University of MashhadJournal of Geography and Environmental Hazards2322-168213120240320Spatial Analysis of Resilience of Urban Areas Against Earthquak (Case Study: Kermanshah City)Spatial Analysis of Resilience of Urban Areas Against Earthquak (Case Study: Kermanshah City)1091324350210.22067/geoeh.2023.80149.1317FAChnourMohammadiPhD Candidate in Geography and Urban Planning, University of Mohaghegh Ardabili, Ardabil, Iran0000-0003-4953-4241HosseinNazmfarProfessor in Geography and Urban Planning, University of Mohaghegh Ardabili, Ardabil, Iran0000-0002-5958-5256SayyadAsghari SaraskanroodProfessor in Natural Geography, University of Mohaghegh Ardabili, Ardabil, Iran0000-0002-5015-904XJournal Article20221219The expansion of the urban population to more than two-thirds of the world's population by 2050 on the one hand and the prediction of the growth of the risk of natural hazards in the future, on the other hand, necessitate the attention of managers, planners, and urban policy makers to the issue of greater resilience of societies in the face of natural hazard. The aim of this research was to analyze the spatial resilience of urban areas against earthquakes in Kermanshah. This study used a descriptive-analytical method. The statistical population consisted of the citizens of Kermanshah city, 385 people were selected as a statistical sample using Cochran's formula. For analyzing the data, one-sample t-test, Friedman, Kruskal Wallis, and CV method were used. The findings showed that the resilience of Kermanshah city in all indicators (awareness, knowledge, skills, attitude and social capital) is average. The attitude index is the most important regarding resilience and awareness, social capital, knowledge, and skill are respectively in the next ranks. The results of the Kruskal-Wallis test showed that there is a significant difference between the eight regions in Kermanshah metropolis in terms of all resilience indicators and that the status of the eight regions are not at the same level. Among the indicators, the highest inequality is related to the awareness index and the lowest is related to the social capital index. In general, the spatial analysis of resilience in Kermanshah city is average and there are differences between regions.The expansion of the urban population to more than two-thirds of the world's population by 2050 on the one hand and the prediction of the growth of the risk of natural hazards in the future, on the other hand, necessitate the attention of managers, planners, and urban policy makers to the issue of greater resilience of societies in the face of natural hazard. The aim of this research was to analyze the spatial resilience of urban areas against earthquakes in Kermanshah. This study used a descriptive-analytical method. The statistical population consisted of the citizens of Kermanshah city, 385 people were selected as a statistical sample using Cochran's formula. For analyzing the data, one-sample t-test, Friedman, Kruskal Wallis, and CV method were used. The findings showed that the resilience of Kermanshah city in all indicators (awareness, knowledge, skills, attitude and social capital) is average. The attitude index is the most important regarding resilience and awareness, social capital, knowledge, and skill are respectively in the next ranks. The results of the Kruskal-Wallis test showed that there is a significant difference between the eight regions in Kermanshah metropolis in terms of all resilience indicators and that the status of the eight regions are not at the same level. Among the indicators, the highest inequality is related to the awareness index and the lowest is related to the social capital index. In general, the spatial analysis of resilience in Kermanshah city is average and there are differences between regions.https://geoeh.um.ac.ir/article_43502_2a20ab109d1200c52d7bde56ad3e66e3.pdfFerdowsi University of MashhadJournal of Geography and Environmental Hazards2322-168213120240320Seismic Hazard Assessment of Badakhshan Region (Northeast Afghanistan)Seismic Hazard Assessment of Badakhshan Region (Northeast Afghanistan)1331504382610.22067/geoeh.2023.79118.1287FAKhadijehMohammadiPh.D in Geomorphological Hazards, Geography Colleg, University Of Tehran, Iran0000-0003-4698-3658EbrahimMoghimiProfessor of Physical Geography,Geomorphology, Geography Colleg, University of Tehran, Iran0000-0003-4698-3658MehdiZareProfessor of Eng Seismology IIEES, Tehran, IranMojtabaYamaniProfessor in Geomorphology, Geography Colleg, University of Tehran, Iran.0000-0002-2042-7365MasoudMojarabAssistant Professor, School of Mining Engineering, College of Engineering, University of Tehran, Iran0000-0003-4698-3658Journal Article20221117Badakhshan region, located in the northeast of Afghanistan, has a complex geology. A catalog from 2011-2021 was prepared using the data of the Middle Asia seismic catalog with updates (1909-2011) from the website of the American Geological Survey. Considering the last earthquake with a magnitude of 7.2 in 2015, the coefficients of b were calculated to the maximum value of 1.0 and the value of 7.9 on the surface and in the depth, the increase in the numerical values of a and b in the central half has been completely evident. The results indicated that the current trend is opposite to the direction of the main fault in North Badakhshan (north-south direction). The most frequent earthquakes M≥4 occurs at a depth of 150-70 km, earthquakes M≥5 at a depth of 150-300 km, and earthquakes ≥6 at a depth of 150-300 km occur in the east-west direction. This area is exactly where the Pamir Corridor plate meets the center of Badakhshan. This shows that at the end of the Pamir Corridor from east to west, ruptures are being created at depths of 0-150 km. Two east-west and east-south trends are evident. Regarding the shallow earthquakes related to the upper 50 km of the crust, the dominant mechanism is of the normal type, which indicates the stretching of the crust in this section. According to the deep mechanism of earthquakes, the direction of the tensile force is in the east-west direction. This issue further confirms the issue of continental collision and then subduction towards the south of Badakhshan. The innovation of this research is the identification of seismic trends that have rarely been researched in the studied area, and its application is identifying high-risk areas for construction.Badakhshan region, located in the northeast of Afghanistan, has a complex geology. A catalog from 2011-2021 was prepared using the data of the Middle Asia seismic catalog with updates (1909-2011) from the website of the American Geological Survey. Considering the last earthquake with a magnitude of 7.2 in 2015, the coefficients of b were calculated to the maximum value of 1.0 and the value of 7.9 on the surface and in the depth, the increase in the numerical values of a and b in the central half has been completely evident. The results indicated that the current trend is opposite to the direction of the main fault in North Badakhshan (north-south direction). The most frequent earthquakes M≥4 occurs at a depth of 150-70 km, earthquakes M≥5 at a depth of 150-300 km, and earthquakes ≥6 at a depth of 150-300 km occur in the east-west direction. This area is exactly where the Pamir Corridor plate meets the center of Badakhshan. This shows that at the end of the Pamir Corridor from east to west, ruptures are being created at depths of 0-150 km. Two east-west and east-south trends are evident. Regarding the shallow earthquakes related to the upper 50 km of the crust, the dominant mechanism is of the normal type, which indicates the stretching of the crust in this section. According to the deep mechanism of earthquakes, the direction of the tensile force is in the east-west direction. This issue further confirms the issue of continental collision and then subduction towards the south of Badakhshan. The innovation of this research is the identification of seismic trends that have rarely been researched in the studied area, and its application is identifying high-risk areas for construction.https://geoeh.um.ac.ir/article_43826_3969214cf75af11c1a013e4386787c54.pdfFerdowsi University of MashhadJournal of Geography and Environmental Hazards2322-168213120240320Investigating the Earthquake Cloud Precursor in the 2017 Azgeleh Earthquake in Kermanshah, IranInvestigating the Earthquake Cloud Precursor in the 2017 Azgeleh Earthquake in Kermanshah, Iran1511724385510.22067/geoeh.2022.75548.1186FAMostafaHeidariMA in Remote Sensing, Yazd University, Yazd, Iran0000-0002-5618-9522AhmadMazidiAssociate Professor in Climatology, Yazd University, Yazd, Iran0000-0003-4558-9907ImanRoustaAssociate Professor in Climatology, Yazd University, Yazd, Iran0000-0002-3694-6936Journal Article20220428The earthquake cloud is an ancient and visual precursor of an earthquake that sometimes is formed several days before the event, above the earthquake fault and often close to the epicenter. The most important characteristic of an earthquake cloud is that it emanates from the ground and remains in the sky for hours. This study aimed to find the major 2017 Azgeleh earthquake cloud by visual interpretation of Meteosat-8 satellite images. The characteristics of the cloud in question were then investigated using the same satellite products. By searching the infrared images, the Azgeleh earthquake cloud was found. The cloud was shown to have had a geological origin, and the formation of such a cloud was unusual in that region. The Azgeleh earthquake occurred near the High Zagros Fault (HZF), whereas its cloud had been formed 12 days earlier and about 700 km away from its epicenter, on other parts of the same fault, along a 160-km-long line. The study revealed that this high cloud consists of two parts: a high-pressure source and a tail diluted by the wind. Moreover, the moderate 2021 Sisakht earthquake cloud was found, which had been formed 6 days earlier and near the epicenter. Visually searching for earthquake clouds from the ground or space is a public scientific hobby, particularly among amateur meteorologists using satellite imagery. The formation of an earthquake cloud above a fault can be a warning of a possible impending earthquake on that fault, which, of course, requires further investigation.The earthquake cloud is an ancient and visual precursor of an earthquake that sometimes is formed several days before the event, above the earthquake fault and often close to the epicenter. The most important characteristic of an earthquake cloud is that it emanates from the ground and remains in the sky for hours. This study aimed to find the major 2017 Azgeleh earthquake cloud by visual interpretation of Meteosat-8 satellite images. The characteristics of the cloud in question were then investigated using the same satellite products. By searching the infrared images, the Azgeleh earthquake cloud was found. The cloud was shown to have had a geological origin, and the formation of such a cloud was unusual in that region. The Azgeleh earthquake occurred near the High Zagros Fault (HZF), whereas its cloud had been formed 12 days earlier and about 700 km away from its epicenter, on other parts of the same fault, along a 160-km-long line. The study revealed that this high cloud consists of two parts: a high-pressure source and a tail diluted by the wind. Moreover, the moderate 2021 Sisakht earthquake cloud was found, which had been formed 6 days earlier and near the epicenter. Visually searching for earthquake clouds from the ground or space is a public scientific hobby, particularly among amateur meteorologists using satellite imagery. The formation of an earthquake cloud above a fault can be a warning of a possible impending earthquake on that fault, which, of course, requires further investigation.https://geoeh.um.ac.ir/article_43855_5107915b16ea89bdc0dd279cc6686680.pdfFerdowsi University of MashhadJournal of Geography and Environmental Hazards2322-168213120240320Projection of Precipitation using CMIP6 Models Until the End of the 21st Century in the Northwest of IranProjection of Precipitation using CMIP6 Models Until the End of the 21st Century in the Northwest of Iran1731944385310.22067/geoeh.2022.76646.1223FABehroozSari SarrafProfessor in Climatology, Faculty of Planning and Environmental Sciences, University of Tabriz, Tabriz, Iran0000-0003-3923-0412HashemRostamzadehAssistant Professor in Climatology, Faculty of Planning and Environmental Sciences, University of Tabriz, Tabriz, IranNabiMohamadiPhD in Climatology, Faculty of Planning and Environmental Sciences, University of Tabriz, Tabriz, Iran0000-0003-1264-7381Journal Article20220417Precipitation is the main component of the hydrological cycle, which is very important in many studies, including those focusing on management of irrigation and drainage systems, crop performance, environmental issues, floods, droughts, etc. Therefore, this study eveluated seven GCMs models of Coupled Model Intercomparison Project phase 6 (CMIP6) regarding the simulation and projection of precipitation changes in the northwest of Iran under three scenarios of SSP in three periods (2021-2050, 2051-2080, 2081-2100) and compared them to the historical period (2014-1985). The trend of precipitation changes was calculated using Mann-Kendall test and Sen’s slope estimator. The Linear Scaling Bias Correction (LSBC) was used to downscaling the GCMs data and the validity of different models was evaluated using RMSE, MAE and R2 indices. The results of performance evaluation of CMIP6 models showed that among the studied models, MPI-ESM1-2-LR model with an average R2 of 0.86 and RMSE equal to 19.7 at the regional level were more accurate than other models in the simulation of precipitation. The results of projection also showed that precipitation according to SSP1-2.6 scenario will increase by 2.6% in the next three periods and on average in the end of 21st century and at most stations it is significant at the level of 0.01%. But according to SSP3-7.0 and SSP5-8.5 scenarios, the amount of precipitation will decrease by 14.5% and 3.6% in the end of 21st century, respectively, with the highest decrease being related to the rainy areas in the southwest of the region. In general, according to different scenarios, in most of the studied areas, the precipitation trend is decreasing until the end of 21st century, and it is necessary for officials and planners to adopt the required strategies to adapt to the resulting climate change.Precipitation is the main component of the hydrological cycle, which is very important in many studies, including those focusing on management of irrigation and drainage systems, crop performance, environmental issues, floods, droughts, etc. Therefore, this study eveluated seven GCMs models of Coupled Model Intercomparison Project phase 6 (CMIP6) regarding the simulation and projection of precipitation changes in the northwest of Iran under three scenarios of SSP in three periods (2021-2050, 2051-2080, 2081-2100) and compared them to the historical period (2014-1985). The trend of precipitation changes was calculated using Mann-Kendall test and Sen’s slope estimator. The Linear Scaling Bias Correction (LSBC) was used to downscaling the GCMs data and the validity of different models was evaluated using RMSE, MAE and R2 indices. The results of performance evaluation of CMIP6 models showed that among the studied models, MPI-ESM1-2-LR model with an average R2 of 0.86 and RMSE equal to 19.7 at the regional level were more accurate than other models in the simulation of precipitation. The results of projection also showed that precipitation according to SSP1-2.6 scenario will increase by 2.6% in the next three periods and on average in the end of 21st century and at most stations it is significant at the level of 0.01%. But according to SSP3-7.0 and SSP5-8.5 scenarios, the amount of precipitation will decrease by 14.5% and 3.6% in the end of 21st century, respectively, with the highest decrease being related to the rainy areas in the southwest of the region. In general, according to different scenarios, in most of the studied areas, the precipitation trend is decreasing until the end of 21st century, and it is necessary for officials and planners to adopt the required strategies to adapt to the resulting climate change.https://geoeh.um.ac.ir/article_43853_5ecb8385a9c516be58163f780a401eba.pdfFerdowsi University of MashhadJournal of Geography and Environmental Hazards2322-168213120240320Investigating the Atmospheric Structure of the Von Phenomenon at the Time of Forest Fires in Northern IranInvestigating the Atmospheric Structure of the Von Phenomenon at the Time of Forest Fires in Northern Iran1952164385810.22067/geoeh.2022.76403.1219FAFaramarzKhoshakhlaghAssociate Professor in Natural Geography,University of Tehran, Tehran, IranHasanHaji MohammadiPhD Candidate in Climatology,Tarbiat Modares University , Tehran, IranHoseinKoshkyPhD Candidate in Climatology, University of Tehran, Tehran, Iran0009-0005-2497-1500Journal Article20220511In order to investigate the atmospheric mechanisms governing the occurrence of the Von phenomenon at the time of forest fires in northern Iran, four types of data were used in the research. So, changes in parameters such as temperature, pressure and wind were investigated. Networked data from the National Environmental Prediction / Atmospheric Science Centers (NCEP/NCAR) and the European Center for Medium-Term Atmospheric Prediction (ECMWF) were then used to explain the structure of the atmosphere. Modis sensor images were used to study the surface temperature of the earth and suspended airborne particle model was used to track air masses. It was found that during the studied period, the event of January 25-31, 2007 was one of the strongest and most pervasive phones that occured in the region. The results showed that by forming a high pressure cell located in the south of the country and a low pressure cell in the wind protection part of Alborz mountain, it has created a strong pressure gradient and caused the south current to affect the northern regions of Iran. Accordingly, during a static-dynamic process, a wind turbine rotational current has been formed in the Alborz mountain range wind turbine. Moreover, by the ascent of the air mass on the Alborz mountain range, its moisture discharge, the passage of the air over the mountain, and its flow in the region and the heatless heat, the hot and dry air mass entered the region which had been accompanied by strong winds affecting fire-prone areas. With an increase in wind speed and a positive temperature drop, a sudden jump and increase in temperature had taken place. Trackings also showed that the main source of flow entering the region is in the northern part of the Persian Gulf and northeastern Africa.In order to investigate the atmospheric mechanisms governing the occurrence of the Von phenomenon at the time of forest fires in northern Iran, four types of data were used in the research. So, changes in parameters such as temperature, pressure and wind were investigated. Networked data from the National Environmental Prediction / Atmospheric Science Centers (NCEP/NCAR) and the European Center for Medium-Term Atmospheric Prediction (ECMWF) were then used to explain the structure of the atmosphere. Modis sensor images were used to study the surface temperature of the earth and suspended airborne particle model was used to track air masses. It was found that during the studied period, the event of January 25-31, 2007 was one of the strongest and most pervasive phones that occured in the region. The results showed that by forming a high pressure cell located in the south of the country and a low pressure cell in the wind protection part of Alborz mountain, it has created a strong pressure gradient and caused the south current to affect the northern regions of Iran. Accordingly, during a static-dynamic process, a wind turbine rotational current has been formed in the Alborz mountain range wind turbine. Moreover, by the ascent of the air mass on the Alborz mountain range, its moisture discharge, the passage of the air over the mountain, and its flow in the region and the heatless heat, the hot and dry air mass entered the region which had been accompanied by strong winds affecting fire-prone areas. With an increase in wind speed and a positive temperature drop, a sudden jump and increase in temperature had taken place. Trackings also showed that the main source of flow entering the region is in the northern part of the Persian Gulf and northeastern Africa.https://geoeh.um.ac.ir/article_43858_e4c38f2ce2a2c13df922f872c2e8c3e3.pdfFerdowsi University of MashhadJournal of Geography and Environmental Hazards2322-168213120240320Detection of Temperature Differences due to Urban and Suburban Land Use Changes (Case Study: Urmia City)Detection of Temperature Differences due to Urban and Suburban Land Use Changes (Case Study: Urmia City)2172424386010.22067/geoeh.2022.76651.1224FANasrin SadatBazmiPhD in Urban Climate, Islamic Azad University, Nour, Iran0009-0006-3649-7671ZahraHejaziZadehProfessor in Climatology, Kharazmi University, Tehran, IranParvizZeaiean FiruzabadiAssociate Professor of GIS and Remote Sensing, Kharazmi University,Tehran, IranGholamrezaJanbaz GhobadiAssociate Professor, Department of Geography, Islamic Azad University, Noor, IranJournal Article20220512The study aimed to explore land use changes and their relationship with the surface temperature using Landsat satellite images from 1990 to 2019. For this purpose, the urban land uses were classified and analyzed using 50 land sample positions from the visible composition of the Landsat images using the supervised classification algorithm in the GIS. The results showed that urban lands had undergone significant changes. The surface temperature of the different uses using the glow temperature algorithm showed that free lands at 33.5°C had the highest temperature, while the lowest average temperature at 25.4°C was for the use of gardens. In terms of temperature variability, the gardens at 7.5°C had the most variable average temperature, while the water agricultural zone at 2.1°C had the lowest level of temperature standard deviation. The results of correlation analysis between temperature difference and land use change showed that the correlation coefficient between temperature changes and urban areas was 0.86 and 0.82 in the irrigated agricultural zone. Regarding the use of gardens, waste lands, and marsh areas, the correlation between periodic land use changes and temperature changes was more than 0.8, which is significant at the reliability of 0.95. But at the level of rangelands, rain fed agriculture and water zone, the correlation or significant connection were not observed at the level of confidence.The study aimed to explore land use changes and their relationship with the surface temperature using Landsat satellite images from 1990 to 2019. For this purpose, the urban land uses were classified and analyzed using 50 land sample positions from the visible composition of the Landsat images using the supervised classification algorithm in the GIS. The results showed that urban lands had undergone significant changes. The surface temperature of the different uses using the glow temperature algorithm showed that free lands at 33.5°C had the highest temperature, while the lowest average temperature at 25.4°C was for the use of gardens. In terms of temperature variability, the gardens at 7.5°C had the most variable average temperature, while the water agricultural zone at 2.1°C had the lowest level of temperature standard deviation. The results of correlation analysis between temperature difference and land use change showed that the correlation coefficient between temperature changes and urban areas was 0.86 and 0.82 in the irrigated agricultural zone. Regarding the use of gardens, waste lands, and marsh areas, the correlation between periodic land use changes and temperature changes was more than 0.8, which is significant at the reliability of 0.95. But at the level of rangelands, rain fed agriculture and water zone, the correlation or significant connection were not observed at the level of confidence.https://geoeh.um.ac.ir/article_43860_24974eb25c5b3369d7fe2ae216d6f572.pdfFerdowsi University of MashhadJournal of Geography and Environmental Hazards2322-168213120240320Multidecadal Investigation of Integrated Surface Ultra-Violet Radiation and its Consistency with Total Column Ozone and CloudinessMultidecadal Investigation of Integrated Surface Ultra-Violet Radiation and its Consistency with Total Column Ozone and Cloudiness2432644385610.22067/geoeh.2022.76097.1211FAHaniyehBaziyarpurPhD Candidate in Agrometeorology, Bu-Ali Sina University, Hamedan, Iran0000-0002-9665-3430Ali AkbarSabziparvarProfessor in Meteorology, Bu-Ali Sina University, Hamedan, Iran0000-0002-0370-309XJournal Article20220407Solar radiation that reaches the Earth's surface has a significant impact on human health, agricultural productivity, terrestrial, aquatic ecosystems, and air quality. The difficulties from shortage of experimental field data motivate the researchers to rely on other database such as satellites and reanalysis radiation data. In the present work, the integrated daily solar ultraviolet-visible radiation (total integral of ultraviolet-visible radiation from 200 to 440 nm) was extracted from the ERA5 reanalysis database during the historical period of 1979-2020. Moreover, Total Column Ozone (TCO), and the Percentage of Cloudiness (CF) were obtained from the same database. The study area was divided into eight clusters by Analytic Hierarchy Process (AHP) method and trend analysis was performed using Mann-Kendall test. Results indicated that mean annual integrated UV-VIS 200-440 radiation of north and northwest of the country has experienced a positive trend during the last four decades, but no significant trend was detected for other parts of the country. The study of the TCO also showed that in all eight clusters, the TCO trend during 1979 to 2000 has experienced a significant decreasing trend, but has increased from 2001 onward. The linear regression equations between UV-VIS200-440 with TCO and CF were also constructed for all time scales (monthly, seasonal, annual) and the corresponding coefficients of correlation were calculated accordingly. The maximum annual correlation (r) was found between UV-VIS200-440 and the cloudiness (0.81). However, the highest r between UV-VIS200-440 and the TCO was 0.25. This result highlights that the variation in cloudiness plays more important role on determination of surface UV radiation than the changes in ozone concentration. This study did not investigated the influence of aerosol optical depth on UV radiation. This issue demands further investigation for evaluating the impact of aerosols on incoming surface UV radiation reaching the ground.Solar radiation that reaches the Earth's surface has a significant impact on human health, agricultural productivity, terrestrial, aquatic ecosystems, and air quality. The difficulties from shortage of experimental field data motivate the researchers to rely on other database such as satellites and reanalysis radiation data. In the present work, the integrated daily solar ultraviolet-visible radiation (total integral of ultraviolet-visible radiation from 200 to 440 nm) was extracted from the ERA5 reanalysis database during the historical period of 1979-2020. Moreover, Total Column Ozone (TCO), and the Percentage of Cloudiness (CF) were obtained from the same database. The study area was divided into eight clusters by Analytic Hierarchy Process (AHP) method and trend analysis was performed using Mann-Kendall test. Results indicated that mean annual integrated UV-VIS 200-440 radiation of north and northwest of the country has experienced a positive trend during the last four decades, but no significant trend was detected for other parts of the country. The study of the TCO also showed that in all eight clusters, the TCO trend during 1979 to 2000 has experienced a significant decreasing trend, but has increased from 2001 onward. The linear regression equations between UV-VIS200-440 with TCO and CF were also constructed for all time scales (monthly, seasonal, annual) and the corresponding coefficients of correlation were calculated accordingly. The maximum annual correlation (r) was found between UV-VIS200-440 and the cloudiness (0.81). However, the highest r between UV-VIS200-440 and the TCO was 0.25. This result highlights that the variation in cloudiness plays more important role on determination of surface UV radiation than the changes in ozone concentration. This study did not investigated the influence of aerosol optical depth on UV radiation. This issue demands further investigation for evaluating the impact of aerosols on incoming surface UV radiation reaching the ground.https://geoeh.um.ac.ir/article_43856_bc18cd01dacdd62719e6b4d59248c5e1.pdfFerdowsi University of MashhadJournal of Geography and Environmental Hazards2322-168213120240320Detecting Changes in Iran's Climate Zones over the Period 1965-2015Detecting Changes in Iran's Climate Zones over the Period 1965-20152652924386210.22067/geoeh.2022.77275.1246FAHengamehShiravandExpert of National Center for Climate and Drought Crisis Management, Tehran, IranZarrinTahanExpert of National Center for Climate and Drought Crisis Management, Tehran, IranSeyed AsaadHosseiniExpert of Meteorology, Saghez Meteorological Office, Saghez, Iran0000-0002-0393-6950Journal Article20220620The purpose of this study was to investigate the changes in Iran's climate zones during the periods 1965-1975, 1976-1985, 1986 -1955, 1996-2005, 2006-2015. For this purpose, the weather data (minimum, maximum, average), humidity (minimum, maximum, average), rainfall, wind and sunshine for 411 synoptic stations during the period 1965 to 2015 were collected and analyzed by the Iran’s Meteorological Organization. Moreover, the Asafzari database was also used in two sections. The first section was formed with the help of 1434 stations from the beginning of 1961 to 2004 and the second section from 2004 to 2015 with the help of 960 stations. At first, factors influencing the climate of Iran were analyzed using factor analysis and then clustered using cluster analysis. In order to validate the identified areas, Silhouette Index (SI) was used. The results showed that most of the spatial variations during the five periods studied were very hot and dry (very low rainfall and high temperature), warm and dry (low rainfall and high temperatures), and cold and dry (low rainfall and low temperature) so that each of these three areas, for example, the cold and dry (low rainfall and low temperature) areas, reduces. On the contrary, the size of the two other areas increased. This dimension of change in the first and second period has been quite evident. The results of the silhouette analysis also showed that more than 92 percent of the Iran’s zones were located right in their group, which indicates the high validity of the identified areas.The purpose of this study was to investigate the changes in Iran's climate zones during the periods 1965-1975, 1976-1985, 1986 -1955, 1996-2005, 2006-2015. For this purpose, the weather data (minimum, maximum, average), humidity (minimum, maximum, average), rainfall, wind and sunshine for 411 synoptic stations during the period 1965 to 2015 were collected and analyzed by the Iran’s Meteorological Organization. Moreover, the Asafzari database was also used in two sections. The first section was formed with the help of 1434 stations from the beginning of 1961 to 2004 and the second section from 2004 to 2015 with the help of 960 stations. At first, factors influencing the climate of Iran were analyzed using factor analysis and then clustered using cluster analysis. In order to validate the identified areas, Silhouette Index (SI) was used. The results showed that most of the spatial variations during the five periods studied were very hot and dry (very low rainfall and high temperature), warm and dry (low rainfall and high temperatures), and cold and dry (low rainfall and low temperature) so that each of these three areas, for example, the cold and dry (low rainfall and low temperature) areas, reduces. On the contrary, the size of the two other areas increased. This dimension of change in the first and second period has been quite evident. The results of the silhouette analysis also showed that more than 92 percent of the Iran’s zones were located right in their group, which indicates the high validity of the identified areas.https://geoeh.um.ac.ir/article_43862_d4aa28edb4a7e60bf8a800ef24c26eb3.pdfFerdowsi University of MashhadJournal of Geography and Environmental Hazards2322-168213120240320Investigating the Impact of the Spread of the Corona Virus on the Acquisition Functions of Borders in Southwest AsiaInvestigating the Impact of the Spread of the Corona Virus on the Acquisition Functions of Borders in Southwest Asia2933164386310.22067/geoeh.2022.77567.1254FAShaghayeghBaradaran MotieMA Student in Political Geography, Ferdowsi University of Mashhad, Mashhad, IranMohsenJanparvarAssistant Professor in Political Geography, Ferdowsi University of Mashhad, Mashhad, IranAliMohammadPourAssistant Professor in Political Geography, MalekAshtae University of Tehran, Tehran, Iran0000-0001-7791-8184Journal Article20220721Globalization and entering the age of information and communication have caused geographic spaces to be mixed and the spatial links to be expanded to a significant extent. This increase has boosted significantly the communication functions of borders. However, with the spread of the corona virus, extensive changes were made, the links between geographical spaces were transformed, and the communication function of borders was greatly affected. Accordingly, in the current research, which was carried out using a descriptive and analytical method, an attempt was made to see what effects the spread of the corona virus had on the communication function of borders in Southwest Asia. The results showed that the spread of the corona virus has had a wide impact on the acquired functions of borders in such a way that it has greatly affected the communication function of borders in Southwest Asia and reduced the links between spaces to a great extent that in some cases it has been replaced by a barrier function. On the other hand, the nation-building, legitimizing and even economic functions of borders have been highlighted after the spread of the Covid-19. Although the virus disease was controlled and subsided to some extent, it seems that human societies will face many such diseases and problems in the future, which is necessary to pay attention to its impact. The results of this study can provide the basis for countries’ preparation and reduce the insecurities and challenges caused by such problems to a significant extent.Globalization and entering the age of information and communication have caused geographic spaces to be mixed and the spatial links to be expanded to a significant extent. This increase has boosted significantly the communication functions of borders. However, with the spread of the corona virus, extensive changes were made, the links between geographical spaces were transformed, and the communication function of borders was greatly affected. Accordingly, in the current research, which was carried out using a descriptive and analytical method, an attempt was made to see what effects the spread of the corona virus had on the communication function of borders in Southwest Asia. The results showed that the spread of the corona virus has had a wide impact on the acquired functions of borders in such a way that it has greatly affected the communication function of borders in Southwest Asia and reduced the links between spaces to a great extent that in some cases it has been replaced by a barrier function. On the other hand, the nation-building, legitimizing and even economic functions of borders have been highlighted after the spread of the Covid-19. Although the virus disease was controlled and subsided to some extent, it seems that human societies will face many such diseases and problems in the future, which is necessary to pay attention to its impact. The results of this study can provide the basis for countries’ preparation and reduce the insecurities and challenges caused by such problems to a significant extent.https://geoeh.um.ac.ir/article_43863_69d0353e88f579cded20ed0c14345371.pdfFerdowsi University of MashhadJournal of Geography and Environmental Hazards2322-168213120240320The Morphodynamics of Sand Dunes and Wind Patterns (Case Study: New and Young Arg in Southeast of Qom)The Morphodynamics of Sand Dunes and Wind Patterns (Case Study: New and Young Arg in Southeast of Qom)3173384386110.22067/geoeh.2022.76706.1227FANaserMashhadiAssistant Professor in Geomorphology (Wind Erosion), University of Tehran, Tehra, Iran0000-0002-9253-5971Journal Article20220515The study of dunes morphology provides a valuable tool for investigating wind systems and the identification of sand sources (removal region). The wind direction is the primary factor controlling the dune shape and elongation. In deserts jubject to wind from different directions and with comparable magnitude, dunes are formed having different morphologies. The sand dunes are either perpendicular or parallel to the wind direction. The purpose of this study was to analyze the morphology of sand dunes under bimodal winds using conventional models. Observations showed that the linear (seif) dunes formation are due to the elongation of a barchan horn. These dunes are created by a bimodal wind regime with a strong peak from the result of northwest and west winds and a weaker peak from the east winds with a divergence angle of 135°. Sinuous crest lines of seif dune grow directly by west and east winds. The study showed that the evolution trend of the sand dunes of the region, under the strong northwest wind, first shield dune transforms into a dihedral barchans. At this stage, wind erosion on the back of the sand pile (shield dune) leads to the formation of a crest perpendicular to the wind direction and then to the formation of a slip face downwind. According to the effect of the magnitude and change of direction in the Westerly and Easterly winds, the western wing of barchan begins to extend and turns into a dentate seif dune.The study of dunes morphology provides a valuable tool for investigating wind systems and the identification of sand sources (removal region). The wind direction is the primary factor controlling the dune shape and elongation. In deserts jubject to wind from different directions and with comparable magnitude, dunes are formed having different morphologies. The sand dunes are either perpendicular or parallel to the wind direction. The purpose of this study was to analyze the morphology of sand dunes under bimodal winds using conventional models. Observations showed that the linear (seif) dunes formation are due to the elongation of a barchan horn. These dunes are created by a bimodal wind regime with a strong peak from the result of northwest and west winds and a weaker peak from the east winds with a divergence angle of 135°. Sinuous crest lines of seif dune grow directly by west and east winds. The study showed that the evolution trend of the sand dunes of the region, under the strong northwest wind, first shield dune transforms into a dihedral barchans. At this stage, wind erosion on the back of the sand pile (shield dune) leads to the formation of a crest perpendicular to the wind direction and then to the formation of a slip face downwind. According to the effect of the magnitude and change of direction in the Westerly and Easterly winds, the western wing of barchan begins to extend and turns into a dentate seif dune.https://geoeh.um.ac.ir/article_43861_81c5e25ca82fea62f9752fd589ccf200.pdf