نشریه جغرافیا و مخاطرات محیطی
پیاپی 41 (بهار 1401)

A thorough assessment of tectonic activity, especially active tectonic movements and the resulting hazards, requires a thorough understanding of geomorphological processes. Many geomorphological features are very sensitive to active tectonic movements and change with them. The aim of this study was to use geomorphic indices (basin asymmetry index (Af), basin sinuosity index (S), basin shape index (BS), river longitudinal slope index (SL), branching ratio (Rb), unevenness number (Rn Relative basin protrusion (Bh), mountain frontal maze (Smf), drainage density (Dd), hypsometry), drawing and analysis of erosion maps of formations, soils and land use to know the relationship between tectonic activity With soil erosion, Karun catchment area (upstream of Shahid Abbaspour Dam). The results show that tectonic activity in erodible formations causes lateral erosion and as a result the soils are eroded, but in resistant formations the tectonic activity has little effect and the soils have almost their own strength. . Sub-canals also often enter the main stream at an acute angle. Karun River in the study basin is spread on soft and erodible formations such as Gurpi, Pabdeh, Aghajari, Gachsaran and Mishan and flows with less intensity. In this case, the erosion along the river is less, but the erosion is dominant. The most erosion is along the river in the center and southeast parts of the basin. The basin is hypsometrically balanced and the topographic and geomorphic appearance of the studied basin is affected by tectonic activities of zagros mountain range, which results in high elevation and tilt of the basin.

Heavy metals are known to be the most dangerous environmental pollutants because they do not decompose by physical processes and therefore remain for a long time and will be effective in biochemical cycles and ultimately in the human food chain, disrupting biological reactions and damaging organs. And they will even die. Therefore, in order to control the quality of the environment, it is important to study the heavy elements in the soil. So far, much research has been done to identify contaminated areas and implement sustainable land use policies with respect to the risk of contamination. In this study, the spatial distribution of nickel in surface soils (0-10 cm) in parts of Qom province with urban-industrial, agricultural and uncultivated land uses with an area of 883 Km2 was investigated. In this study, geostatistical tools (ordinary kriging) were used. Sampling was performed at 209 points on a grid with distances of about 1.5 × 1.5 km in agricultural and urban land use and about 2×2 km in uncultivated land use. Concentration of total nickel and absorbable soil was measured by atomic absorption spectrometer. Statistical and geostatistical studies were performed by SPSS, Variowin and WINGSLIB software and contamination map was drawn with Surfer16 software. The results showed that the concentration of nickel in any of the forms in the region did not show toxicity. But there were significant differences in land uses. Existing industries, parent materials, and nickel-rich basic and ultra-basic rocks, the use of phosphate fertilizers and sewage sludge may have increased nickel, and the direction of westerly winds has led to the transfer of nickel in the region.

Water flow is one of the earth processes that in addition to changing earth surface, affect human's life. Any change in channel properties affects other variables specially where human intervention disturbs the balance of the environment it can lead to hazards. Stream Bank erosion is very vital and important because stream bank erosion can result in loss of land, increased stream sediment load, diminishing water quality and aquatic habitat, threatens people's lives and property. Identifying and determining stable and unstable banks also determining their degree of stability can be a great way to manage fluvial environment. In this research the method of Rapid Geomorphic Assessment (RGA) has been used for investigate the stability and morphometric change in Haji arab river that located in south of Qazvin province. For this purpose 8 reaches were chosen. Field studies and mapping from all reaches were done. Based on channel stability index (CSI) that is one of the Rapid Geomorphic Assessment's (RGA) indicators. The parameters of this index (CSI) were scored during the field. In this research statistical analyzes such as correlation coefficient and Box & Plot diagram were used to determine the relationship between the parameters in the stream banks and data scatter. also relative score was used to determine the most effective factor in stability of stream banks, Results show that the highly unstable stream banks belong to reaches of 7, 8 and the most effective factor in the Haji arab river's bank ,based on Channel Stability Index(CSI) are stream bank erosion and riparian woody vegetation .

Mapping land degradation is essential for appropriate management. In present study, the potential of revised MEDALUS model and its integration with fuzzy logic in land degradation crisis mapping has been investigated in the Semirom County of Isfahan Province with more than 380 mm of rainfall. The study area has a semi-arid climate. Most of annual precipitation occurs in winter while less in summer. Altitude in the area is relatively high, ranging from 1707 to 4393 m, with the peaks in the Zagros Mountains. Due to large altitudinal range and human activity influences, there are a large number of vegetation types and a range of conditions in the rangelands. In recent years, grazing and other activities, such as the construction of the Hana Dam and land use changes, have degraded the existing rangelands, especially those around the agricultural lands in Semirom County. First, based on the characteristics of the study area, six desertification indicators including climate, soil, vegetation, groundwater, water erosion and management quality were selected. Then, 25 indices affecting the quality of each indicator were mapped and assigned a value between 0 and 1 using fuzzy logic option in GIS environment at pixel- size scale. According to the results, a 7% of the study area was classified as slight, 84% as moderate and 14% as severe degradation. Results also showed that the management, water erosion and vegetation indicators and the indices of the rangeland land use, vegetation resistance against erosion and rainfall were the most important factors with more than 70% effectiveness in the land degradation of the study area. The findings of this study indicate that the conversion of rangelands to agricultural land, overgrazing and drought are main factors of land degradation crisis in the study area.

Dynamic analysis of flood risk using HEC-RAS hydraulic model (Case study: Shahinshahr River, Isfahan Province)AbstractFlooding is a natural phenomenon and the risk of it occurring in urban areas is a global issue. Rapid urbanization and climate change have increased the risk of urban flooding, causing massive infrastructure and human losses. The aim of this study is geomorphological zoning of Shahinshahr River flood risk. Therefore, the HEC_RAS numerical model was used to simulate the flood and The geometric data was processed in the GIS by the HEC–GEORAS extension. The return periods of 25, 50 and 100 years of catchment area as well as its physiographic characteristics including area, length of main stream, CN curve number, concentration time, latency in the watershed were entered into the HEC-HMS software. Accordingly, the output results of maximum flood discharge with different return periods were calculated whereby river pattern reflect three reaches. Finally, manning's roughness coefficient was calculated for each reach that the Manning roughness coefficient was calculated using the Coon method. The results of studies show that the flood zone in the 25-year return period of 0.948 (km2) in the 50-year return period of 1.13 and in the 100-year return period of 1.34 (km2) of lands along the Shahin river. In the last reaches, due to the reduction of the slope and the reduction of the flow velocity, the flood zone has become wider than other periods.

In recent years, along with the increase in population of urban areas, urban hazards have also increased. One of the cities that has a high potential for the occurrence of hazards is the city of Sanandaj. Therefore, in this study, the vulnerable areas of Sanandaj against the risk of sloping movements, floods, earthquakes, pollution and traffic have been studied. According to the objectives, in this study, two integrated models of fuzzy logic and hierarchical analysis (AHP) have been used and vulnerable areas have been identified against each of the mentioned hazards. The results obtained from the study indicate that many parts of the west of Sanandaj city and also the northern areas of Sanandaj city are prone to slope movements due to the high slope and height. Also, due to the presence of Gheshlagh river in the eastern half of Sanandaj city and also the existence of low slopes in the inner areas of Sanandaj city, many parts of this city have a great potential to cause floods and flooding. Assessing the potential for earthquake vulnerability indicates that the western and central parts of Sanandaj have a high potential for vulnerability due to proximity to fault lines, high slope, lack of access to open space and high population density. In terms of pollution and traffic, the central parts of Sanandaj city has a high potential for pollution and traffic due to high population density and the existence of various uses, including transportation. According to the mentioned cases, the western and northern parts of Sanandaj are prone to large-scale movements and also have a high potential for earthquake vulnerability. The eastern parts of Sanandaj have a high potential for floods. The southern parts of Sanandaj are prone to floods and have a high potential for earthquakes.

The risk management includes all the actions that can be prevented from adverse events, or if incident, it can reduce its effects and provide readiness for quick relief and improvement of the situation. From important risk management measures, attention to increasing individual readiness is to face natural hazards. Considering the importance of the issue, the present study examines the factors affecting individual readiness against flood occurrence. The research is in terms of purpose, applied and method of doing it (qualitative and quantitative). The data-gathering tool was a questionnaire and interview with the villagers of the region. The statistical population of the study was 3861 households living in the mountainous villages in the flood of Poledokhtar Township, which is selected using the Cochran formula and by simple random sampling of 360 households from 30-flooded villages as a sample of research. Data analysis and data were analyzed using descriptive statistics and binary logistic regression regression and qualitative analysis. The findings of research in terms of factors affecting individual readiness against flooding indicate that among the four factors in this study, in order of factors: individual sociological, socioeconomic status of family, the impact of society and the adaptation to the highest role in individualization Equal to floods. The study of the requirements and actions of readiness in the face of floods also showed that the development of local economy, the development of local infrastructure, credentials for increasing preparation, government assistance and increasing the livelihood diversity strategies of households are the most prominent requirements and important measures to increase readiness are in the face of flood incident.

Today, rainfall hazards creates wide crisis in military, security and social, because the tensions in rural and social destruction of the natural environment have led to violent conflicts. To analysis the extreme rainy days in Iran, has been used daily data of extreme rainy day in 235 synoptic stations in the period from 1961/03/21 to 2019/03/20(21549 days). Therefore, this database is a matrix of size 21549×235. Rows are time and columns represent the stations. Using Euclidean distance and Ward linkage, extreme rainy days the country was in four regular rain cluster. The results showed that the first cluster (days with relatively heavy rain) with a frequency of 87% of stations, is widely distributed in Iran. The second cluster (Semi-heavy rain) with 9 percent, limited to a few stations in the eastern coast of the Caspian Sea and the western half of the Zagros Mountains. The third cluster (heavy rain) with 3% of stations located on the shore of the Caspian Sea and western Zagros mountains stations in Astara, Baboulsar, Noushahr, Ramsar, Rasht, Kouhrang and Yasouj. Finally, the fourth cluster (super heavy rain) with 1 percent, it occurs only in Bandar-Anzali station. It seems that the frequency of extreme rainy days in Iran tends to cluster and implant and complies with topography and distance or proximity to the sea.Among these, the role of rainfall hazards and their heterogeneous distribution, such as heavy rains and floods, is of particular importance in countries around the world, especially Iran. So that sometimes such events greatly affect the security and defense conditions of a country.

According to the objectives of the present study after reviewing the statistics and information of precipitation in Haraz watershed and due to the lack of long-term statistics in the study area, finally 3 stations of Panjab-Haraz,Karsang-Haraz and Mahmoudabad-Haraz in different parts of the river from mountain to plain in 44-year common statistical period from the water year of 1968-69 to 2011-2012 was selected for this study. After analyzing the changes in annual precipitation of the selected stations, the results of Residual sum of squares (R.S.S) test were extracted by the method of ordinary moments and the maximum likelihood were compared with the method of linear moments. Residual Sum of the Squares (R.S.S in the linear moment method were also calculated by a written computer program for the studied distributions .Based on the results of this study and using the scoring and ranking method, it is determined that in Panjab-Haraz station, the maximum likelihood method has the lowest R.S.S, with the total score of 6 has the best fit with the annual precipitation data and ordinary and linear moments methods with a total score of 15 are equally in the next ranks .At Karsang-Haraz station, the maximum likelihood method has a total score of 10 and the best fit with the annual precipitation data, followed by the ordinary moment method with a total score of 14 and the linear moment method with a total score of 15, respectively. At Mahmoudabad station the maximum likelihood method with obtaining a total score of 3 has been the best method selected at this station, followed by the ordinary moment and linear moment methods with a total score of 6 and 15, respectively.

Dust is one of the natural hazards that occur mainly in arid and semi-arid area of the world such as in Iran. In recent years, dust storms have been one of the most important air pollution crises in Hamadan province. Identifying the dust and sand sources, it is the first step in the management and control of this Phenomenon. Thus, in this paper, identification of dust sources in Hamadan province using Aerosol Optical Depth (AOD) from the MODIS satellite images and numerical modeling to predict airflow is discussed from 2008 through the end of 2018. In the next step, using the HYSPLIT model, the path of motion of particles and their source were determined at three levels of 500, 1000 and 1500 meters for 48 hours before the storm for outside sources and 18 hours for inside sources. The meteorological data of the model was obtained from a 0.5 degreess GDAS. Finally, its movement from source to Hamadan urban area was monitored by using GIS and Spatial Analysis Tools. The results showed that the origin of the entering dust phenomena in this city are from three sources including inside the province (Famenin, Malayer, and Razan county), outside the province (such as Kurdestan, Markazi, and Khuzestan province), and out of Iran (Western part of Iraq, Syria, Jordan and northern part of Saudi Arabia). So, it is necessary to monitor the spatial patterns of dust sources in the western region of Iran. In different years. In conclusion, the combination of remote sensing data, the Hysplit model, and field-based data could well show dust-affected corridors.

Given the importance of climate change in the structure of the Earth is trying to understand more about how climate change events for granted .Trend variations in large-scale atmospheric systems, such as subtropical high pressure, play a significant role in climate change. In this study, to achieve the objectives, mid-level atmospheric geopotential altitudedata were employedbased on the European Center Database of Atmospheric Medium-Term Forecasting. The data have a spatial resolution of 1 * 1 degree of curveand are collected on a daily average. The statistical period of the research ranges from 1980 to 2018 for Iran and included 266 cells. Mann-Kendall trend test was used to investigate the geopotential altitude trend on Iran. The results of the study indicate the height of the subtropical high pressure to the south of the Mediterranean, the Arabian Peninsula, Red Sea and around Iran. The results showed that the atmospheric geopotential altitudeon Iran in June, July and August has an increasing (positive) trend which is at the significant levelof 1.96.Indeed, the decreasing trend of geopotential altitude in the eastern and southeastern regions of Iran is worth considering. Moreover, in all the investigated months, Iranian atmosphere altitude in the central, western and northwestern regions had an upward trend, which is generally influenced by the high-pressure subtropical level. These changes cause anomalies in climatic patterns of regions. The survey also showed that continuing pressure subtropical the stack on top of ever increasing trend in the region is significant. Considering the large-scale atmospheric patterns associated with land surface changes of climate, where can be caused by climate change.

Human settlements have faced different challenges due to different cultural, economic, social factors, infrastructures and components threatening the outbreak of coronary heart disease and therefore need different models and systems for management and planning. This planning is more important in rural areas due to common beliefs and cultures, and lack of awareness and efficient management of this crisis will have irreparable consequences for these areas. The study focused on the pathology of rural areas from the risk of coronary heart disease in rural areas of Ijroud city. Applied research and research method is descriptive-analytical research. Research information was obtained in the form of documentary reports. Data analysis was performed in the form of spatial and geographical statistics in ArcGIS / GeoDA and SPSS. Documentary form was obtained. In rural areas, there is a positive and significant relationship between coronary heart disease and service levels in these areas. On the other hand, most services are concentrated in more populated areas and less populated areas have lower service levels. It is clear that areas with fewer services refer to areas that have these services for services, and given the nature of infectious diseases that are more prevalent in transportation and transportation routes, this is a major factor in the spread of the disease among areas. The village has become larger and more populous. In the study, 6 rural areas that were in the main focus of the disease were identified that management and preventive measures should be taken to provide services and restrictions on referral to these areas.

This study intends to rely on key factors affecting physical resilience and hiring the scenario planning approach investigate the credible scenarios of increasing the physical resilience of Tehran Region 10 against earthquakes to formulate and prioritize sustainable strategies in order to increase the physical resilience of the study area on the horizon of the year 1404. The methodology is descriptive-analytical and seeks to answer, what are the sustainable strategies that can ensure the physical resilience of the study area against the horizon of 1404? For this purpose, in order to provide a theoretical framework, first the subject is expressed using the documentary method, literature and theoretical foundations, and then, relying on environmental dynamics, experimental data are extracted. The statistical population of the study includes 20 urban experts and the sampling method is purposeful. As the first step, by determining the possible status of key factors and weighting them by experts, the necessary data were entered into ScenarioWizard and strong, weak and reliable scenarios were extracted from this software. At the next step, by analyzing the internal and external elements related to the physical resilience of the study sample, research strategies were presented in the form of SWOT and based on plausible scenarios. Finally, by the Strategic Planning Quantitative Matrix (QSPM) technique, sustainable strategies were enumerated and prioritized to increase the physical resilience. The results of this study demonstrate that if District 10 of Tehran tends to increase physical resilience in case of earthquake damage, reliance on sustainable defense strategies is inevitable

Much of Iran, due to its location in the arid geographical belt and desert strip of the world, has special climatic conditions that are among the least rainy regions in the world. Therefore, drought is one of the most important natural hazards in Iran. The purpose of this study is to investigate the role of empowerment of villagers in dealing with drought and reducing its effects in rural areas of Sarpol-e Zahab city in the west of Kermanshah province. The present research is an applied research and the method used is descriptive-analytical based on collecting the required data through a questionnaire. Due to the geographical extent of the region and the large number of rural settlements, among the villages located in the political area of ​​Sarpol-e Zahab city that had 100 families and more, considering the natural location, 10 rural points were selected as a sample. At the household analysis level, out of 1966 rural households based on census data (2011), 321 items were selected as a sample using the Cochran's formula and a questionnaire was distributed randomly. One-sample t-test, factor analysis and path were used to analyze the data. Findings showed that from the perspective of local residents, empowerment in economic (3.84) and social (3.60) dimensions has a positive effect on reducing the effects of the accident. The results of path analysis show that access to financial resources, improvement of space and business and local social capital with 0.49, 0.53 and 0.34, respectively, have the greatest impact on economic and social empowerment in order to reduce the effects of the drought disaster.

The science of complexity considers management that values ​​diversity and avoids dominant issues. Slowly Therefore, when there is a set consisting of many different factors, on different scales, with inherent and inseparable dependence and interdependence of factors on each other, we face complexity. Ecological and social systems, on the other hand, are systems related to people and nature, and emphasize that man not only cannot be separate from nature, but must be a part of it. Therefore, in the present study, it is felt necessary to address the issue of managing ecological and social complexities in the conservation of natural resources. This research is a descriptive-analytical research in terms of purpose and an exploratory research in terms of data collection, and is in the framework of library and documentary studies. On the other hand, Dimatel tool was used to analyze the information. The results showed that among the factors affecting the management of ecological and social complexity, the factors of lack of systemic and comprehensive attitude, the lack of discussion of environmental resources in land management And its legal status, institutional barriers, lack of an integrated system of exploitation of natural resources and control of unstable factors and lack of active participation and management interaction within the framework Factors included in the group of four propositions (f4) with a weight coefficient of 1.077 were identified as the most important factors affecting the management of ecological and social complexities in the conservation of natural resources in the villages of the province.