GEOGRAPHY AND ENVIRONMENTAL HAZARDS
Year:2022 | Volume:11 | Issue:1|Papers Count:15

An 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, that is, basin asymmetry factor (AF), basin sinuosity index (S), basin shape index (BS), river longitudinal slope index (SL), bifurcation ratio (Rb), unevenness number (Rn), relative relief index (Bh), mountain front sinuosity (Smf), drainage density (Dd), hypsometry, drawing and analysis of erosion maps of formations, soils and land use to identify the relationship of tectonic activity with soil erosion in 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 low effect, so the soils are strong. Sub-channels 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 in the river route is low. The most erosion is along the river in the center and southeast of the basin. The basin is hypsometrically balanced and the topographic and geomorphic appearance of the studied basin is affected by tectonic activities, which results in high elevation and sloping of basin. The streams flow is almost irregular. Sub-streams also often enter the main stream at an acute angle. The drainage density of the canals is low and the soil is highly permeable, covered with dense vegetation and coarse-grained drainage.

Heavy metals are known to be the most dangerous environmental pollutants because they do not decomposed 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. Therefore, in order to control the quality of the environment, it is important to study the heavy elements in the soil. So far, many researchs have been done to identify contaminated areas and implement sustainable land use policies regarding 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. 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 uses and about 2×2 km in uncultivated lands. The concentration of total nickel and absorbable soil was measured by atomic absorption spectrometer. Statistical and geostatistical measures were performed by SPSS, Variowin and WINGSLIB software and contamination map was drawn with Surfer16 software. The results indicated that the concentration of nickel in various forms in the region does 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. Stream bank erosion is very important because entering a large part of the river sediments through erosion of the river bank changes some parts the river channel such as width and depth. It is also important as it affects the characteristics of river pattern and hazards that threaten people's lives and properties. The purpose of this study was to investigate the instability and morphometric changes of canal in Haji Arab river in Buin Zahra of Qazvin province. Rapid Geomorphic Assessment (RGA) was used for measuring the stability and morphometric changes in Haji Arab river. For this purpose 8 reaches were chosen. Indices of stability and instability along the bank stream were evaluated using cross-sectional mapping and field operations. The parameters of Channel Stability Index (CSI) were scored during the field works. The reaches were classified in terms of sensitivity to lateral erosion. The results show that the highly unstable stream banks belong to reaches of 7 and 8. Moreover, the distribution of data was determined using a Box Plot diagram. According to the relative score, it was found that the stream bank erosion and the vegetation of riparine are the most effective factors in the instability of the banks of Haji Arab river.

Mapping land degradation is essential for appropriate management. In this study, the potential of revised MEDALUS model and its integration with fuzzy logic in land degradation crisis mapping was 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. The results showed that 7% of the study area is classified as slight, 84% as moderate and 14% as severe degradation. Results also showed that 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 results indicate that the conversion of rangelands to agricultural land, overgrazing and drought are main factors of land degradation crisis in the study area.

Flooding is a natural phenomenon and the risk of its occurrance in urban areas is a global issue. Rapid urbanization and climate changes have increased the risk of urban flooding, leading to massive infrastructure and human losses. The aim of this study was geomorphological zoning of Shahinshahr River flood risk. Therefore, the HEC-RAS numerical model was used to simulate the flood. The geometric data was processed in GIS by 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 maximum flood discharge with different return periods were calculated whereby the river area was devided into 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 show that the flood zone in the 25-year return period includes 0.948  km2, 1.13 km2 in the 50-year return period, and 1.34 km2 of the lands along the Shahinshahr River in the 100-year return period. In the last reach, due to the reduction of the slope and the flow velocity, the flood zone has become wider than other periods.

In recent years, along with the increase in the population of urban areas, urban hazards have also increased. Sanandaj is one of the cities that have a high potential for the occurrence of hazards. Therefore, this study explored Sanandaj’s areas vulnerable to the risk of slope movements, floods, earthquakes, pollution, and traffic. According to the objectives, two integrated models of Fuzzy logic and the Analytic Hierarchy Process (AHP) were used and areas vulnerable to each of the mentioned hazards were identified. The results indicate that many of western parts and also the northern parts of Sanandaj city are prone to slope movements due to the high slope and height. Moreover, due to the existence of the Gheshlagh River in the eastern half of the city as well as the presence of low slope areas in its central part, many parts of the Sanandaj city have a great potential to cause floods. The assessment of the potentials 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. Regarding pollution and traffic, the central parts of Sanandaj city have a high potential for pollution and traffic due to high population density and the existence of various uses like transportation. The western and northern parts of Sanandaj are prone to large-scale movements and have a high potential for earthquake. 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. Moreover, the central parts of Sanandaj have a high potential of pollution and traffic.

Hazard management includes all actions that can prevent adverse events, and in case of occurance, can reduce its effects and provide the necessary readiness for quick relief and improvement of the situation. The important measures of risk management is paying attention to increasing individual readiness in dealing with risks. Considering the importance of the subject, this study examines the factors affecting individual readiness against flood occurrence. The applied research uses a mixed method. The data collection tool was a questionnaire and interview. The statistical population of the study was 3861 households living in the mountain villages in the flood of the city of Poldakhtar city, from among of which of 360 households of 30 flood-affected villages were selected as samples using Cochran formula and a simple random sampling. Data were analyzed using descriptive statistics and binary logistic regression model. The findings of the research on the factors affecting individual readiness against flooding indicate that individually sociological issues, socioeconomic status of families, the impact of society, and adaptability with risks, respectively, have the highest role in individual readiness for floods. Investigating the requirements and actions of readiness in case of floods also showed that improving local economy, improving local infrastructure, giving credits to increase readiness, government assistance, and increasing the livelihoods of households are the most prominent requirements for increasing the readiness in the face of the flood event.

Today, rainfall hazards create wide crisis in terms of military, security and social issues, because the tensions in rural and social destruction of the natural environment have led to violent conflicts. For analyzing the extreme rainy days in Iran, daily data of extreme rainy days in 235 synoptic stations in the period from 3/21/1961 to 03/20/2019 (21549 days) were used. Therefore, a database of a matrix of 21549×235 was created. Rows show time and columns show the stations. Using Euclidean distance and Ward linkage, extreme rainy days were classified into four regular rain clusters. The results showed that the first cluster (days with relatively heavy rain) with a frequency of 87% of the stations is widely distributed in Iran. The second cluster (semi-heavy rain) with 9 percent is limited to a few stations in the eastern coast of the Caspian Sea and the western side of the Zagros Mountains. The third cluster (heavy rain) with 3% of stations is 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, occurs only in Bandar Anzali station. It seems that the frequency of extreme rainy days in Iran tends to cluster and comply with topography and distance or proximity to the sea. The results of the present study showed that the stations located in western Iran have many rainy days due to their special geographical location in the Zagros Mountains and the influence of westerly winds.

The purpose of this study was to compare the statistical parameters of maximum annual precipitation in the watershed of Haraz River located in the central part of the Alborz Mountains. After reviewing the data of precipitation in Haraz watershed and considering lack of long-term statistics in the study area, Panjab-Haraz, Karsang-Haraz and Mahmoudabad-Haraz stations in different parts of the river from mountain to plain in 44-year statistical period from the water year of 1968-69 to 2011-2012 were selected. The annual precipitation frequency analysis of the selected stations was performed and the results of the Residual sum of squares (RSS) test were extracted by the method of ordinary moments and the maximum likelihood at this stage to be compared with the linear moments method. Residual sum of the squares in the linear moment method were also calculated by a computer program for the studied distributions. The results showed that in general, normal moment and maximum likelihood methods in selected stations have better fit and less RSS. The results of scoring and ranking the best selected method and distribution also showed that in all three selected stations, the maximum likelihood method with the minimum RSS was the best fit with the annual maximum precipitation data.

Dust is one of the natural hazards that occur mainly in arid and semi-arid areas of the world such as 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 is the first step in controling this phenomenon. Thus, this study tried to identify dust sources of Hamadan province using Aerosol Optical Depth (AOD) from the MODIS satellite images and numerical modeling to predict airflow from 2008 to the end of 2018. In the next step, using HYSPLIT model, the path of particles’ moves and their source were determined at three levels of 500, 1000 and 1500 meters for 48 hours before the storm for external sources and 18 hours for internal sources. The meteorological data of the model was obtained from a 0.5-degree GDAS. Finally, its movement from source to Hamadan urban area was monitored using GIS and Spatial Analysis Tools. The results showed that the origin of the dust phenomena in this city are three sources including internal parts the province (Famenin, Malayer and Razan county), outside the province (such as Kurdestan, Markazi, and Khuzestan province) and out of Iran (Western parts of Iraq, Syria, Jordan and northern Saudi Arabia). So, it is necessary to monitor the spatial patterns of dust sources in the western regions of Iran for different years. The combination of remote sensing data, Hysplit model, and field based data could well show dust transport corridors.

Trend variations in large-scale atmospheric systems like subtropical high pressure play a significant role in climate change. In this study, to achieve the objectives, mid-level atmospheric geopotential altitude data were employed based on the European Center Database of Atmospheric Medium-Term Forecasting. The data that 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 155 cells. Mann-Kendall trend test was used to explore the geopotential altitude trend on Iran. The results showed that the atmospheric geopotential altitude on Iran in June, July, and August has an increasing (positive) trend which is at the significant level of 1.96. The decreasing trend of geopotential altitude in the eastern and southeastern regions of Iran is remrkable. 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 abnormalities in climatic patterns of the regions. The study also showed that continuing subtropical pressure stack on top of ever-increasing trend in the region is significant.

Human settlements have faced different challenges due to various cultural, economic, and social factors and the threatening componants of the outbreak of COVID-19. Therefore, different models and systems are needed for management and planning. The study focused on the pathology of rural areas regarding the risk of corona virous in rural areas of Ijroud city. This applied used a descriptive-analytical method. The data was obtained from documentary reports. Data analysis was performed in the form of spatial and geographical statistics in ArcGIS/ GeoDA and SPSS. The results showed that there is a positive and significant relationship between corona and the level of services in these areas. On the other hand, most services are concentrated in more populated areas and less populated areas have much fewer services. It is clear that people of areas with fewer services go to areas that have more services, and given the infectious diseases will distribute more in transportations, this is a major factor in the prevalence of the disease in larger and more populous areas. Six rural areas that were the main focus of the disease were identified and preventive measures should be taken to provide services and restrictions on going to these areas.

Relying on key factors affecting physical resilience and using scenario planning approach, this study investigated the credible scenarios of increasing the physical resilience of Region 10 of Tehran against earthquakes to formulate and prioritize sustainable strategies for increasing the physical resilience of the study area on the horizon of the year 2025. The study used a descriptive-analytical method to answer the question: 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, at first, the subject was explicated using documentary method and review of literature, and then, relying on environmental dynamics, experimental data were extracted. The statistical population of the study includes 20 urban experts and the sampling method was purposeful method. 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 show that if District 10 of Tehran tends to increase physical resilience in case of earthquake damage, reliance on sustainable defense strategies is inevitable.

Most parts of Iran have special climatic conditions that are among the least rainy regions of the world as they are in the arid geographical belt and desert strip of the world. Therefore, drought is one of the most important natural hazards in Iran. The purpose of this study was to investigate the role of empowerment of villagers in dealing with drought and reducing its effects in rural areas of Sarpol-e Zahab County in the west of Kermanshah province. Therefore, it tried to answer the following question:  What is the relationship between economic and social empowerment of rural households and reducing the effects of drought in the study area? The applied research used a descriptive-analytical method. Questionnaire was used to collectg the required data. Due to the geographical extent of the region and a large number of rural settlements, from among the villages located in the political area of ​​Sarpol-e Zahab county that had 100 families and more, considering the natural location, 10 rural points were selected as a sample. At the household level, out of 1966 rural households based on census data (2016), 321 items were selected as a sample using Cochran's formula and questionnaires were distributed randomly. One-sample t-test, factor analysis, and path analysis were used to analyze the data. The results showed that from the perspective of residents, empowerment in economic and social dimensions have positive effects on reducing the effects of the drought disaster. The results of path analysis show that access to financial resources, improvement of the business environment, and local social capital respectively have the greatest impact on economic and social empowerment for reducing the effects of the drought disaster.

Complexity science is about a management that deals with variety and multiplicity and tries to avoid dominant issues. Therefore, whenever there is a system composed of different factors on different scales with inherent and inseparable dependence and interdependence of factors, we face complexity. Ecological and social systems, on the other hand, are systems which are related to people and nature, emphasizing that man not only cannot be separated from nature, but also must be part of it. Hence, the necessity was felt to address the issue of managing ecological and social complexities in conserving natural resources. This exploratory research applied a descriptive-analytical method and used library and documentary sources. In order to analyze data, DEMATE was used. The results indicated that among the factors affecting the management of ecological and social complexity, such factors as lack of systemic and comprehensive attitude, lack of discussion of environmental resources for 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 included in four propositions (f4) with a coefficient of 1.077 and active natural resources were identified  the most significant factors that affect the management of ecological and social complexities in preserving the natural resources of the villages of Lorestan province.