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Ms. Sousan Heidari, Dr. Mostafa Karimi, Dr. Ghasem Azizi, Dr. Aliakbar Shamsipour,
Volume 9, Issue 4 (3-2023)
Volume 9, Issue 4 (3-2023)
Abstract
Explaining the spatial patterns of drought intensities in Iran
Abstract
Recognition of spatial patterns of drought plays an important role in monitoring, predicting, confronting, reducing vulnerability, and increasing adaptation to this hazard. This study aims to identify the spatial distribution and analyze the spatial patterns of annual, seasonal, and monthly drought intensities in Iran. For this purpose, the European center Medium-Range Weather Forecast (ECMWF) data for the period 1979-2021 and the ZSI index were used to extract the drought intensities. To achieve the research goal and explain the spatial pattern of the frequency of drought intensities (Extreme, severe, moderate, and weak), spatial statistical methods such as global Moran’s I, Anselin local Moran’s Index, and hot spots were used. The results of the global Moran’s I showed that with increasing intensity, the spatial distribution of drought events has become clustered. The spatial distribution of the local Moran’s Index and hot spots also confirms this. Very clear contrast was observed in the local clusters of high (low) occurrence as well as hot (cold) spots of severe (Extreme) yearly droughts in the south, southeast, and east. In autumn, weak to Extreme droughts show a southeast-northwest pattern. But in spring and winter, the spatial pattern of drought is very strong as opposed to severe and moderate drought. Despite the relatively high variability of maximum positive spatial Autocorrelation of severe and Extreme monthly droughts, their spatial pattern is almost similar. The spatial clusters of severe and very severe droughts in the northwest, northeast, and especially on the Caspian coast, are a serious warning for the management of water resources, especially for precipitation-based activities, such as agriculture.
Introduction
Drought or lack of precipitation over some time is the most widespread natural hazard on the earth compared to its long-term average. This risk negatively affects various sectors such as hydropower generation, health, industry, tourism, agriculture, livestock, environment, and economy. To reduce these negative or destructive effects, it must be determined how often drought occurs during the period and in which areas it is most severe. Doing so requires determining the characteristics of the drought. These characteristics include area, intensity, duration, and frequency of drought. Discovering the geographical focus, recognizing the pattern governing the frequency of occurrence and temporal-spatial distribution as well as changes in the dynamics of this hazard facilitate an important role in drought monitoring, early warning, forecasting, and dealing with these potential hazards; this information can be used to create a drought plan by providing analysts and decision-makers with ideas about drought, helping to reduce the negative and vulnerable effects and ultimately make it easier to protect or replace for greater adaptation. Many researchers have been led by these approaches to the use of statistical analysis. Numerous studies have been conducted in the study of climatic phenomena such as drought with space statistics techniques in various regions, including China, India, South Korea, and even Iran. Part of the domestic research on spatial patterns of drought is without the use of spatial statistics and a limited number of others who have used these analyzes have only studied the overall intensity of drought and have not studied the spatial patterns of different drought intensities. The main purpose of this study is to identify the distribution and spatial patterns of drought intensities in Iran using spatial analysis functions of spatial statistics based on the frequency of drought intensities (Extreme, severe, moderate, and weak) with yearly, seasonal and monthly multi-scale approach. Therefore, this study will answer the questions: a) What is the spatial distribution of drought intensity data in Iran? And b) What is the variability of spatial patterns of Iranian droughts at different time scales?
Material &Method
ERA5 monthly precipitation data for a period of 43 years from 1979 to 2021 were used for this study. an array of dimensions of 78×59×504 of data were formed in MATLAB software in which 78×59 is the number of nodes with a spatial resolution of 0.25 degrees and 504 represents the month. After creating the database, the ZSI index was used to calculate the severity of drought in annual, seasonal, and monthly comparisons. Finally, to achieve the research goal and explain the spatial pattern governing the frequency of drought intensities (Extreme, severe, moderate, and weak), spatial statistical methods such as global Moran’s I, Anselin local Moran I and hot spots was used.
Discussion of Results
Due to its ecological conditions, geographical location, and location in an arid and semi-arid region of the world, Iran is among the most vulnerable countries due to natural hazards, including drought. It has experienced many severe droughts in the last century. The occurrence of drought and its effects is one of the major challenges of water resources management in this century. The results of the Global Moran’s Index for all three annual, seasonal, and monthly scales showed a highly clustered pattern of drought events in the country. Spatial clustering of the occurrence of severe and Extreme yearly droughts in the eastern, southeastern, and southern regions is also an interesting result. These conditions are due to low precipitation and high spatial variation coefficient in these areas. This contrast of spatial clusters of drought intensities indicates the relationship between drought and temporal-spatial anomalies of precipitation so that with increasing precipitation, spatial variability of precipitation decreases, and consequently spatial homogeneity of precipitation increases. severe and moderate-intensity spots in the south-southeast in autumn and spring can be affected by fluctuations in the beginning and end of the monsoon season in South Asia due to the high variability of atmospheric circulation at the beginning and end of precipitation in these areas. Some studies have also shown the relationship between precipitation in these areas and the monsoon behavior of South Asia. Extreme drought events in winter and spring have had a positive spatial correlation pattern in the southwest, west, and northwest. However, precipitation at this time of year is concentrated in these areas. Warm clusters or concentrations of very severe drought events in the northern strip of the country, especially in the Caspian region, can be due to the high variability of precipitation at the beginning of the annual precipitation season (late summer and early autumn). Observations of these conditions in the northern strip indicate that an event with a high frequency of severe droughts, even in rainy areas, should not be unexpected. Spatial clusters of Extreme, severe, moderate, and weak drought every month using both local Moran and hot spots statistics show the fact that in Iran, the most severe droughts have occurred in the western, northwestern, and coastal areas of the Caspian Sea. However, the absence of severe droughts or spatial clusters has been the occurrence of low drought in the southeast and to some extent in the south. On a yearly scale, the south, southeast, and east have played a significant role in the spatial cluster of severe and extreme droughts. So that these areas of the country have had positive spatial solidarity. However, in these areas, negative spatial correlation prevailed in the autumn for severe drought. This may indicate an anomaly and a tendency to concentrate more precipitation in Iran, as well as many changes in seasonal and local precipitation regimes. According to the research results, a high incidence of severe and extreme drought on all three scales (monthly, seasonal and annual) even in the wettest climate of the country (northern Iran, especially the southern shores of the Caspian Sea) shows that High-intensity droughts can occur in all parts of the country, regardless of the weather conditions.
Keywords: Natural hazards, spatial patterns, Moran statistics, spatial autocorrelation, hot spots
Dr Mohammad Mahdi Hosseinzadeh, Dr Ali Reza Salehipor Milani, Mis Fateme Rezaian Zarandini,
Volume 10, Issue 1 (5-2023)
Volume 10, Issue 1 (5-2023)
Abstract
Introduction
A flood is a natural disaster caused by heavy rainfall, which causes casualties and damage to infrastructure and crops. Trend of floods in the world increasing due to climate change, changing rainfall patterns, rising sea levels in the future, and in addition, population growth and urban development and human settlements near river have caused floods to become a threat to humans. One of the most important and necessary tasks in catchments is to prepare flood risk maps and analyze them. In recent decades, researchers have been using remote sensing techniques and geographic information systems to obtain flood risk maps in an area. Due to the numerous floods that have occurred in the Neka river catchment, it is necessary to conduct a study entitled zoning of flood sensitivity in Neka river catchment for more effective management in this area.
Materials and methods
Study area: Neka river catchment area with an area of 1922
To study the flood zoning of the area using a multi-criteria decision model, 1: 25000 maps of the surveying organization and a digital elevation model with a resolution of 12.5 meters (Alos Palsar) were extracted. In order to study the flood risk in Neka river, 4 criteria of height, distance from the river, land use and slope have been used. In the present study, modeling and preparation of flood risk zoning map in 4 stage including descending valuation, normalization of each class, normalized index weight and integration of criteria has been done by the following linear weighting method. Performing linear weighting operations depends on the weighted average of a number of selected parameters in the opinion of the expert. According to the weight assigned to each criterion based on the expert opinion, each of the criteria was multiplied by the assigned weight and at the end the criteria were added together and the final zoning map was obtained.
Results and Discussion
In this study, using a multi-criteria decision-making system model, a flood risk zoning map in the Neka river catchment was prepared. According to the weight assigned to each criterion based on expert opinion, the final risk probability map has a value between 0.02 to 0.2, which is ultimately divided into 5 classes in terms of flood risk. Value range 0.02 to 0.06 component of very low risk zone, range 0.08 to 0.11 component of low-risk zone, range 0.11 to 0.13 component of medium-risk zone, range 0.13 to 0.16 component of high-risk zone, and finally domain 0.16 to 0.20 components of the area with very high risk potential have been obtained. According to the final divisions in the flood risk zoning map of the catchment area, a safe area means areas where the probability of flooding is very low and close to zero, and in contrast, the area with a high and very high risk potential for flooding has the probability of high-risk floods. According to the final flood risk zoning map, about 982
Conclusion
The results obtained from the model indicates that the highest risk of flooding points are located in the western parts of the Neka catchment area and the end of the catchment area that reach the city of Neka. According to the research findings, the most important factors in increasing the risk of floods were the slope in this area and the distance from the drainage network. According to the results of the model, a large area of the basin is a component of high risk zone, that means the Neka river watershed has a high potential for floods. Evidence and documented reports show that the Neka river Basin has experienced several floods in the last two decades. The major part of the occurrence of floods is due to the natural conditions of the basin, thus it is necessary to reduce flood damage by changing the locations of various land uses based on flood vulnerability maps. Using multi-criteria decision making method can be used to prepare flood risk zoning maps in basins that do not have hydrometric data; It is also a more cost-effective method in terms of time. One of the important issues in the final result of this model is due to the weight of the layers, which should be used by experts, who are familiar with the region and this method and adapt to field evidence.
Keyworlds: Flood, Multi-criteria decision making system(MCDA), Hazard zoning, Nekarod, Natural hazard.
Dr Abdolmajid Ahmadi, ,
Volume 10, Issue 1 (5-2023)
Volume 10, Issue 1 (5-2023)
Abstract
Extended abstract
Landslide risk zoning is one of the basic measures to deal with and reduce the effects of landslides. Vernesara watershed is one of the areas where many landslides have been observed in different parts of it. In this research, in order to zone the risk of landslides using the entropy index, first the ranges of landslides were determined, then the effective factors in the occurrence of range movements were prepared in the ArcGIS software environment, and a landslide susceptibility map of the studied area was prepared. . The prioritization of effective factors using Shannon's entropy index showed that the slope layers, land use, surface curvature, topographic humidity index and topographic position index had the greatest effect on the occurrence of landslides in the region. Also, zoning landslide sensitivity with the mentioned model and evaluating its accuracy using the ROC curve shows the very good accuracy of the model (79.6 percent) with a standard deviation of 0.0228 for the studied area. The zoning map shows that the low-risk areas cover only 13% of the area and more than 56% of the area is in the area with high risk of landslides, which indicates the high potential of the area in the occurrence of landslides. . Construction at a distance from fault lines, waterways and the steep Asmari Formation and safety of communication routes are the most important measures to reduce the amount of damage caused by landslides in Vernesara watershed.
Key words: natural hazards, landslide, entropy, folded Zagros.
Masoomeh Hashemi, Ezatallah Ghanavati, Ali Ahmadabadi, Oveis Torabi, Abdollah Mozafari,
Volume 10, Issue 2 (9-2023)
Volume 10, Issue 2 (9-2023)
Abstract
Introduction
Earthquakes as one of the most important natural disasters on earth, have always caused irreparable damage to human settlements in a short period of time. Severe earthquakes have led to the idea of developing an infrastructure plan to reduce the risks and damages caused by it. The urban water supply system is the most important critical infrastructure that is usually damaged by natural disasters, particularly earthquakes and floods; hence, the function of the pipelines of the water system determines the degree of resilience and design of the infrastructure against multiple natural and man-made hazards. Considering the inability to prevent earthquakes and the inability of experts to accurately predict the time it is necessary to know the status of earthquake-structure and seismicity in Tehran to determine the amount of earthquake risk in order to make the necessary planning for structural reinforcement. Theoretical and field studies of tectonic seismicity in the Tehran area show that this city is located on an earthquake-prone area around the active and important faults of Masha, north of Tehran, Rey and Kahrizak. The occurrence of 20 relatively severe earthquakes illustrates this claim. Regarding the location of faults in Tehran city, it is necessary to assess the vulnerability of Tehran water facilities.
Research Methodology
The present study is a practical-analytic one. Considering the severity of earthquake damages, it is necessary to conduct earthquake hazard zonation studies in different urban areas and to determine important indicators of damage assessment such as maximum ground acceleration, maximum ground speed, maximum ground displacement. Three indices were considered for mapping earthquake seismic zones and their integration into the GIS presented a seismic hazard map. In the analysis of earthquake risk, it is necessary to evaluate two indicators of risk and vulnerability. To prepare the general hazard power mapping the weights obtained from the ANP model were applied to the existing raster layers via the Raster Calculator command. In this way, the standardized layers are multiplied separately by their respective weights and finally overlapped. In order to evaluate the vulnerability, a series of evaluation indices are introduced and ANP techniques are used. The relative value of each index is then calculated using the multivariate approach using the SAW technique. In order to calculate the earthquake risk based on R = H * V relation, the values of these two components were multiplied. This calculation was performed in GIS software on the risk and vulnerability raster layer and the final result of this calculation was displayed on the map.
Description and interpretation of results
In this study, we tried to estimate the relative risk and risk of seismic hazard on the water supply lines in Tehran, using available data and scientific methods, and map the risk level. These lines should be prepared first by the amount of earthquake hazard risk and then by the risk map, to estimate the earthquake risk on the water supply network. first the earthquake risk then the status of the hazard lines should be calculated. The vulnerability of the water supply lines was calculated using the ANP model by multiplying the total potential hazard risk then substrate transfer network vulnerability risk map obtained transmission network. The highest risk was in the west and north of Tehran. The maps showed the risk potential and the vulnerability of the lines. These areas had high seismic potential and the density of the lines was higher in these areas. Water transmission facilities are at risk and earthquake hazards may be affected by damage to the transmission lines, drinking water to a large population will be difficult, as well as performing necessary zoning to prevent future expansion of the facility in place. These analyzes are a prelude to applying corrective techniques to pipelines to reduce their vulnerability and prevent newly created pipelines from locating in vulnerable areas. Since the results of this study are risk maps along the route of the water supply lines, so in order to prepare a risk control program, we can identify the high risk pipeline map and identify the pipeline vulnerability. And, depending on its location, provided an appropriate prevention and control plan for the conditions surrounding the pipeline environment.
Earthquakes as one of the most important natural disasters on earth, have always caused irreparable damage to human settlements in a short period of time. Severe earthquakes have led to the idea of developing an infrastructure plan to reduce the risks and damages caused by it. The urban water supply system is the most important critical infrastructure that is usually damaged by natural disasters, particularly earthquakes and floods; hence, the function of the pipelines of the water system determines the degree of resilience and design of the infrastructure against multiple natural and man-made hazards. Considering the inability to prevent earthquakes and the inability of experts to accurately predict the time it is necessary to know the status of earthquake-structure and seismicity in Tehran to determine the amount of earthquake risk in order to make the necessary planning for structural reinforcement. Theoretical and field studies of tectonic seismicity in the Tehran area show that this city is located on an earthquake-prone area around the active and important faults of Masha, north of Tehran, Rey and Kahrizak. The occurrence of 20 relatively severe earthquakes illustrates this claim. Regarding the location of faults in Tehran city, it is necessary to assess the vulnerability of Tehran water facilities.
Research Methodology
The present study is a practical-analytic one. Considering the severity of earthquake damages, it is necessary to conduct earthquake hazard zonation studies in different urban areas and to determine important indicators of damage assessment such as maximum ground acceleration, maximum ground speed, maximum ground displacement. Three indices were considered for mapping earthquake seismic zones and their integration into the GIS presented a seismic hazard map. In the analysis of earthquake risk, it is necessary to evaluate two indicators of risk and vulnerability. To prepare the general hazard power mapping the weights obtained from the ANP model were applied to the existing raster layers via the Raster Calculator command. In this way, the standardized layers are multiplied separately by their respective weights and finally overlapped. In order to evaluate the vulnerability, a series of evaluation indices are introduced and ANP techniques are used. The relative value of each index is then calculated using the multivariate approach using the SAW technique. In order to calculate the earthquake risk based on R = H * V relation, the values of these two components were multiplied. This calculation was performed in GIS software on the risk and vulnerability raster layer and the final result of this calculation was displayed on the map.
Description and interpretation of results
In this study, we tried to estimate the relative risk and risk of seismic hazard on the water supply lines in Tehran, using available data and scientific methods, and map the risk level. These lines should be prepared first by the amount of earthquake hazard risk and then by the risk map, to estimate the earthquake risk on the water supply network. first the earthquake risk then the status of the hazard lines should be calculated. The vulnerability of the water supply lines was calculated using the ANP model by multiplying the total potential hazard risk then substrate transfer network vulnerability risk map obtained transmission network. The highest risk was in the west and north of Tehran. The maps showed the risk potential and the vulnerability of the lines. These areas had high seismic potential and the density of the lines was higher in these areas. Water transmission facilities are at risk and earthquake hazards may be affected by damage to the transmission lines, drinking water to a large population will be difficult, as well as performing necessary zoning to prevent future expansion of the facility in place. These analyzes are a prelude to applying corrective techniques to pipelines to reduce their vulnerability and prevent newly created pipelines from locating in vulnerable areas. Since the results of this study are risk maps along the route of the water supply lines, so in order to prepare a risk control program, we can identify the high risk pipeline map and identify the pipeline vulnerability. And, depending on its location, provided an appropriate prevention and control plan for the conditions surrounding the pipeline environment.
Farzin Mahmoudi, Hamed Ghadermazi, Dr Leila Mafakheri,
Volume 10, Issue 3 (9-2023)
Volume 10, Issue 3 (9-2023)
Abstract
Introduction
Every year, natural hazards occur with great severity and sometimes they destroy people completely Today, science has proven that natural hazards cannot be avoided. He simply considered a natural event and did not pay attention to their complex causes. Most of these causes are attributed to a combination of socio-economic factors. But it is possible to reduce their consequences by carefully planning against such accidents. When these hazards and disasters have a human aspect and affect humans, human activity and human environment, they are introduced as crisis.
According to the statistics of the Food and Agriculture Organization of FAO, 5-15% of agricultural products are lost annually due to damage caused by frost and frost, this number reaches more than 40% for some sensitive garden products, especially almonds, pistachios and apricots. . The amount of damage caused by this complication in Iran is more than 500 million dollars. Rural settlements suffer the most damage after a drought. Thus, there is a significant relationship between the risk management of agricultural activities with most environmental components and natural disasters such as drought, flood, frost, etc. up to the 99% confidence level. In order to reduce the effects of natural hazards in rural areas, there are various strategies that can be used to manage the risk of natural hazards , diversification of agricultural productio, contract farming and increasing farmers' awareness of natural hazards.
Gardens are one of the most important sources of livelihood in rural areas in Tuysarkan city in Hamadan province. Tuysarkan city has 7600 hectares of garden lands, which includes 14% of all gardens in Hamadan province. Due to its geographical location, weather conditions and geological structure, this city is exposed to various natural hazards. Among them, we can mention drought, land subsidence, frost and earthquake. Identifying natural hazards in Tuiserkan city and the effects of these hazards, as well as the actions of the local community to reduce existing hazards, are among the most important goals of this research.
Research Method
In the current research, we tried to use different methods so that the subject can be better investigated from different angles of research. This research is applied in terms of purpose and based on a descriptive-analytical research plan and is considered analytical-exploratory in nature. The research data has been collected through questionnaires and official statistics of institutions such as Iran Water Resources Management Company and the country's Meteorological Organization. Data analysis has been done descriptively and analytically using Excel and GIS software.
Research Results
The results of the research show that the most important hazards in the field of horticulture in the central part of Tuiserkan are frost in the first place and drought and hail in the second and third places. Also, other results show that the most important risk that affects the livelihood and income of the local community is the annual frost of gardens, which has caused the migration of some family members, and the amount of income is also affected by this risk. Regarding the solutions proposed by the local community to reduce the effects of natural hazards on walnut orchards, providing financial facilities, using information technology, and planting cold-resistant species were among the most important solutions proposed by the local community. Regarding the analysis of open questions and conducted interviews, Netaj shows that the most important measures to reduce the effects of natural hazards (freezing, drought and hail) on walnut orchards are: heating the orchard environment, using resistant and using drip irrigation. Also, the evaluation of the analysis of local knowledge and the experience of the past regarding measures to reduce the effects of frost on walnut orchards shows that the actions of the past are not very popular with the current generation and they are doing the same thing that the past did. With this difference, the ancients believed more in luck and destiny than in practical action. Finally, from the point of view of the local community, the best measure to reduce the effects of frost on the walnut orchards in the central part of Tuiserkan is genetic modification of the orchards and cultivation of resistant species.
Every year, natural hazards occur with great severity and sometimes they destroy people completely Today, science has proven that natural hazards cannot be avoided. He simply considered a natural event and did not pay attention to their complex causes. Most of these causes are attributed to a combination of socio-economic factors. But it is possible to reduce their consequences by carefully planning against such accidents. When these hazards and disasters have a human aspect and affect humans, human activity and human environment, they are introduced as crisis.
According to the statistics of the Food and Agriculture Organization of FAO, 5-15% of agricultural products are lost annually due to damage caused by frost and frost, this number reaches more than 40% for some sensitive garden products, especially almonds, pistachios and apricots. . The amount of damage caused by this complication in Iran is more than 500 million dollars. Rural settlements suffer the most damage after a drought. Thus, there is a significant relationship between the risk management of agricultural activities with most environmental components and natural disasters such as drought, flood, frost, etc. up to the 99% confidence level. In order to reduce the effects of natural hazards in rural areas, there are various strategies that can be used to manage the risk of natural hazards , diversification of agricultural productio, contract farming and increasing farmers' awareness of natural hazards.
Gardens are one of the most important sources of livelihood in rural areas in Tuysarkan city in Hamadan province. Tuysarkan city has 7600 hectares of garden lands, which includes 14% of all gardens in Hamadan province. Due to its geographical location, weather conditions and geological structure, this city is exposed to various natural hazards. Among them, we can mention drought, land subsidence, frost and earthquake. Identifying natural hazards in Tuiserkan city and the effects of these hazards, as well as the actions of the local community to reduce existing hazards, are among the most important goals of this research.
Research Method
In the current research, we tried to use different methods so that the subject can be better investigated from different angles of research. This research is applied in terms of purpose and based on a descriptive-analytical research plan and is considered analytical-exploratory in nature. The research data has been collected through questionnaires and official statistics of institutions such as Iran Water Resources Management Company and the country's Meteorological Organization. Data analysis has been done descriptively and analytically using Excel and GIS software.
Research Results
The results of the research show that the most important hazards in the field of horticulture in the central part of Tuiserkan are frost in the first place and drought and hail in the second and third places. Also, other results show that the most important risk that affects the livelihood and income of the local community is the annual frost of gardens, which has caused the migration of some family members, and the amount of income is also affected by this risk. Regarding the solutions proposed by the local community to reduce the effects of natural hazards on walnut orchards, providing financial facilities, using information technology, and planting cold-resistant species were among the most important solutions proposed by the local community. Regarding the analysis of open questions and conducted interviews, Netaj shows that the most important measures to reduce the effects of natural hazards (freezing, drought and hail) on walnut orchards are: heating the orchard environment, using resistant and using drip irrigation. Also, the evaluation of the analysis of local knowledge and the experience of the past regarding measures to reduce the effects of frost on walnut orchards shows that the actions of the past are not very popular with the current generation and they are doing the same thing that the past did. With this difference, the ancients believed more in luck and destiny than in practical action. Finally, from the point of view of the local community, the best measure to reduce the effects of frost on the walnut orchards in the central part of Tuiserkan is genetic modification of the orchards and cultivation of resistant species.
Saeedeh Koohestani, Bijan Sayyafzadeh, Abdolreza Sarvghad Moghadam, Mahdi Sharifi,
Volume 10, Issue 4 (12-2023)
Volume 10, Issue 4 (12-2023)
Abstract
By increasing the number of process industrial plants because of societies necessity to their productions, a new branch of accidents caused by various occurred process failures and their effect on the societies and environment and economy has been introduced. Beside it, the increase of the accidents because of natural hazards effect on the industrial plants and their huge costs to the societies and governments and high vulnerability of plants and urbanized territory to the branch of the accidents, increased the attention to this type of accidents. However, in many parts of the world still do not pay attention seriously to this issue and by considering them as very low probability accidents, eliminate paying attention and accepting the responsibility of them while the frequency of such accidents is under growing! In this article according to the existing statistics, an evaluation and comparison of consequences of natural hazards that caused NaTech events has been done. The purpose of the NaTech events is process events that triggered because of natural hazards that are known as events with low probability and high consequences that can affect a wide area and cause huge accidents associated with domino effects. After introducing and categorizing NaTech events, a comparison of their distribution and consequences of these events in Iran and the world has been done according existing articles and researches. Researches shows opposite of the natural hazards and their effects on some structures and infrastructures, Natech events has not been paid under attention enough in Iran. While the variety of industrial plants and their structures in Iran is high, their existing condition and repairing and maintenance of them is not proper and according collected statistics in this article, the potential of NaTech events is also high in country. In the first step, to increase the preparedness for NaTech events, review of effective world experiences in this field is recommended. Recognition of past events and categorizing them and codification of data that should be included in safety reports and scenarios evaluation and considering the domino effects and review the recommendations in this field are parts of this step.
Dr. Habibollah Fasihi, Dr. Taher Parizadi,
Volume 10, Issue 4 (12-2023)
Volume 10, Issue 4 (12-2023)
Abstract
Urban planners consider historical fabric as the beating heart of cities. However, cities and specifically their historical fabrics are constantly under influence of natural and human-induced hazards. This study aimed to assess the vulnerability of Ferdowsi neighborhood as an example of Tehran’s historical fabric. The data was obtained from geographical information system (GIS) files and a survey, as well as historical contexts and documents were analyzed as part of this study. Ten municipal experts were also asked to provide a score of 1 to 5 for each of the 29 indicators compared to standard levels. The mean value of these scores was then used to evaluate the role of each parameter in the vulnerability of this neighborhood. Study findings indicate a high potential for the occurrence of natural and human-induced hazards in the study area. The abundance of unstable multistory buildings and derelict electricity and water networks, storage of flammables in warehouses, and lack of sewage network for half of the buildings were the most significant factors contributing to the vulnerability of this ancient fabric. Problems such as insecurity, drug abuse in public spaces, overcrowding and daytime congestion have also led to rapid relocation of neighborhood residents, who subsequently were replaced by commercial activities and warehouses. In conclusion, numerous problems are contributing to the vulnerability of historical fabric of this neighborhood and such problems are highly likely to be applied to other urban historical fabrics in Tehran.
Fahimeh Pourfarrashzadeh, Fariba Beyghipour Motlagh, Mortaza Gharachorlu,
Volume 11, Issue 1 (5-2024)
Volume 11, Issue 1 (5-2024)
Abstract
This study aimed to systematically explain the potential of the landslide occurrence to provide a prediction model of the possibility of this phenomenon in the Yamchi catchment in Ardebil province. In this regard, both approaches of discrete and continuous variables were used by means of overlay and logistic regression, respectively. Independent variables included elevation, slope, aspect, lithology, annual rainfall, roughness, general curvature, topographic wetness index, vegetation index, distance to fault, distance to stream and distance to road. The results, firstly, revealed the areas with high landslide potential by the matching layers of independent variables with the landslide layer in the geographical information system (GIS). These areas were in the middle elevation, high slopes, northern slope, high roughness, erodible formations, high rainfall, medium vegetation, surroundings of faults and rivers. Secondly, the results of the logistics regression model by providing a prediction equation of probability of landslide occurrence showed that the resulting model with pseudo r2 and ROC 0.22 and 0.86, respectively, had good power and efficiency to predict landslide through the catchment. In addition, the resulting beta coefficients for independent variables indicated that the importance of the variables was as follows: vegetation index distance to road, rain, lithology, distance to fault, elevation, topographic wetness index, roughness index, aspect, slope, and distance to river. In the end, the need to pay serious attention to the supporting and protection of vegetation cover of the mid -range and upstream of the catchment was determined because of unstable geomorphic conditions of these areas.
Mrs Samaneh Riahi, Dr Amir Safari, Dr Seyed Musa Hisseini, Dr Ali Ahmadabadi,
Volume 11, Issue 2 (8-2024)
Volume 11, Issue 2 (8-2024)
Abstract
In order to plan, manage and exploit water and land resources, awareness of the spatial variability of resources, as well as understanding the response behavior of the watershed in order to model physical processes, has an identical significant role. Due to its location in arid and semi-arid areas, special climatic and geomorphological conditions, Qom-Roud basin is prone to flash floods. Due to the lack of hydrometric and topographical data with high accuracy in the basin, the use of hydraulic models does not lead to accurate results of the hydraulic characteristics of floods. In such a situation, the methods based on the geomorphological features of the basin can be advantageous. In this article, Variable flood stage method (VFS) method is used, which combines the hydraulic characteristics of the river with the geomorphic characteristics of the basin in order to estimate the water depth in the river caused by floods with different return periods. The water depth was investigated for different return periods of two, five, ten, twenty-five, fifty and hundred years. In each period, the highest water depth was in the parts near the outlet and the lowest water depth was in the upstream parts of the river. The research illustrations there is a direct relationship between the depth of water and the area of the sub-basin. The results of this research can be used for basins without hydrometric and topographic statistics with high accuracy in order to estimate the peak speed and flood depth.
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