مجله مخاطرات محیط طبیعی
پیاپی 21 (پاییز 1398)

Iran is one of the top 10 countries facing natural hazards in the world. One of the basic approaches is to reduce the above-mentioned hazards, to identify the factors involved in hazard and risk zoning. The present study also explores the geomorphologic hydro-wind hazards on the Shahdad-Nehbandan road northwest of the Lut World Heritage, in order to achieve such a goal. In this way, the field was first identified with hazardous points and was marketed with the help of GPS. Then, the effective factors in the occurrence of the desired hazards were identified and the experts were weighed using the fuzzy set and the layers were overlaid using the ANP model. The results of the flood hazard zonation analysis showed that about 219 km of road length is moderate to very high, and the sand-zone hazard map illustrates the fact that more than 252 km of roads are exposed to windblown hazards. This fact highlights the emphasis on planning and environmental studies in the communication axis as one of the most important axes for achieving the Lut World Heritage and its eye-catching geomorphologic complications.

Due to water crisis and extreme volume of groundwater extraction throughout Iran, vulnerability assessment of aquifers and water sources management has become one of the essential need of environmental research in Iran. Through various pollutant, nitrate as one of the chemical water pollution index considered from ages. Chadegan aquifer, as one of the main Gavkhoni basins, was selected to study the environmental factors affecting groundwater pollution by nitrate, since the majority of the Chadegan aquifer is subject to a very high degree of human impact. The main goals of this study are 1) to get a better understanding of salinity distribution in the aquifer during last two decades, 2) to find out salinity and nitrate distribution in the Chadegan aquifer and 3) to figure the relative contribution of several environmental parameters (including land use) that are often used in groundwater vulnerability assessment, using principal components analysis (PCA). In this study, at the first, rate of sampling points for each DRASTIC layer and land use determined and then the relative contribution of several environmental parameters affecting groundwater quality of Chadegan obtained using the multivariate principal component analysis. This study showed that salinity level of groundwater vary from 250 to 408 µS/cm. Consistent increasing salinity level of groundwater during last two decades (from 308/5 µS/cm in 1995 to 359/2 in 2016) and presence of higher level of salinity in northern and southern part of the study area in 1995, 2010, 2013 and 2016 compare to central part of the area count as two considerable results of the present study. Concentration of nitrate between 15 and 37 mg/l in 2016 and interaction between intrinsic vulnerability and land use affecting groundwater risk pollution by nitrate in northern and southern parts of the study area take into account as the main findings of this study.

The rivers have been known from the past to this day as the most populous areas of the planet. The expansion of urbanization and the increase of human needs have created a balance between rivers and disruptions in the river system. One of the most important river hazards is the erosion of the river bank. It causes many economic, social and environmental damages every year. The present research is based on fieldwork and modeling of erosion of the river Bank. Therefore, it seeks to identify sensitive areas of the Bank erosion and estimate the extent of erosion. For this purpose, the NBS index and BSTEM model has been used to identify and estimate the erosion of the Kwtar River in Mahabad. A route of 3 km was selected from the Kwtar River. Morphological characteristics of five cross sections for NBS index and three intervals for BSTEM model were taken. Rosgen’s proposed seven parameters for assessing the near bank stress (NBS) index. In this research, three parameters were used for the estimation of bank erosion. Two parameters and the highest efficiency in the identification of river bank erosion was cauterized. While the parameter was somewhat contradictory to reality. Then using the BSTEM model, simulation of normal and flood flow and its consequences on the Toe Erosion and Bank Stability were studied. The BSTEM model evaluates the stability of the edges with the safety factor (FS). The main cause of the erosion of the Toe is due to hydraulic currents and the main cause of instability and fracture failure due to the geotechnical characteristics and the underlying hydraulic flow along the sides Toe Bank of the Kawtar River. As the rate increased, the amount of foot erosion and the fracture failure rate were increased.

Worn-Out urban textures have many problems in the physical, environmental, social and economic fields that have caused a lot of limitation for residents that live in these textures. In the presence of worn-out tissues, due to population growth and urbanization, natural disasters such as earthquakes can cause heavy losses and losses in such places. The need to reduce the vulnerability of cities and especially the worn-out structures against this phenomenon is considered as one of the main goals of urban planning and other related urban areas. Considering that the earthquake vulnerability is one of the most important challenges facing cities in Iran and is the subject of zoning of seismic risk and assessment of the vulnerability of cities to earthquakes in geographic and urban planning issues, this study attempts to measure the magnitude. The vulnerability of the corrosive tissues of Kashan city has been evaluated and solutions to this problem have been proposed. In this research, existing data from different organizations have been analyzed and evaluated using the fuzzy and fuzzy membership in the GIS environment. The results show that Kashan city with 754.3 hectare of worn out texture, located in different places of the city, the most used residential property with low quality, historical texture, ruined lands, long life of buildings and narrow and narrow streets exposed to greater vulnerability due to Earthquakes are more than other urban areas Among the worn-out tissues, the center of the city with the most and the Lather or lowest is the vulnerability.

Flooding is one of the major environmental hazards within the last century that widespread around the globe. Flooding is often thought of as a result of heavy rainfall, but different geomorphic and hydrologic systems have a different response to the precipitation. The main goal of the research is studying of flooding in the Maroon Catchment that severe flooding has been inflicted great losses in the agricultural, residential and deaths sectors over the past years. Usually, after any heavy rainfall, flooding will be expected. Maroon Catchment has located in the in the Kohgiluyeh and Boyer-Ahmad province, between 30° 40´ to 31° 20´ of northern latitudes and 50° 5´ to 51°10´ of eastern longitudes. To evaluate the various effective hydro geomorphologic parameters on flooding in the basin, we specified 18 different variable, but according to cluster analysis and multivariable regression models, effective parameters on the flood in the region were summarized in 6 factors includes: area, perimeter, and width of the equivalent rectangular, the total length of the drainage network, the length of the basin and average flow length. After choosing variable, standardization of them and using different methods, sub-catchment were separated. According to, sub-catchment divide to four homogeneous groups, each group contain some sub-catchment as follows: group 1 includes 1, 2, 3, 4, 7, 8, 9, 17, 10, 20sub-catchments; group 2 includes 5, 6, 11, 14, 16 sub-catchments, group 3 includes 12, 13, 15, 19sub-catchments, and group 4 include 18sub-catchment. On the basis of the parameters and also analysis of them, we were observed that the sub-catchment of the 1 group had severe floods, the 2 group with medium floods, the 3 group with low floods and the 4 group with the intensity of floods.

In this work, the role of the Persian trough and low-level jet (LLJ) in the north wind (Shamal) intensification were studied as the main cause of extensive dust storm (EDS) formation in the warm period of western Iran. In this regard, visibility reduction criteria of less than 1000m and the code of 06 (as a dust event) in more than 50 percent of the stations were refined in 21 stations in the west of Iran (Khuzestan, Ilam, and Kermanshah provinces) during 2000-2009. From a total of 346 dusty days, 28 specks of dust with duration of 1 to 12 days were detected, of which 20 are related to the warm period of the year (especially in the months of June and July). Further, the pressure patterns, potential vorticity and temperature, divergent field, wind vector and vertical profiles using NCEP/NCAR data and ERA-Interim data with 2.5 and 0.125 degrees resolution, respectively, in the range of 10N Up to 60N and 20E to 75E were extracted at all atmospheric levels. The results showed that the warm period dust storms in western Iran were related to the low-level pressure gradient in the Persian trough, which although it is a source of low-pressure monsoon, the strengthening of this low-pressure is due to the local and topographic factors of the western windward of Zagros. The deepening of this system by strengthening the northern wind is the cause of the formation of dust storms in western Iran. In addition, EDS rarely extend beyond 1000m due to the limitation of strong winds to low levels. The speed of these winds often exceeds 50 km/h. The severe nocturnal inversion, which generally extends at 400-450m height, causes an intense wind speed gradient, and developed a Jetstream, often overnight, at 250-350m height, that affected by the Blackheads heating system.

This research investigates the contamination of trace elements, nitrate, nitrite, ammonium and corrosive potential in the groundwater of south and southwest of Sirjan city, Kerman province, Iran. Therefore, 115 groundwater samples were collected for Hydrochemical analysis from Sirjan city area, Kheirabad salt playa area, Chahderaz plain, Golegohar mining area, Ghatarbaneh-Eynolbaghar plains and Marg salt playa in July 2016. In descending order, the mean values of minor ions and trace elements are such as: NO3 > B > NH4 > As > Mn > Ba > Cr > NO2 > Cu > Pb > Cd. Generally, the concentration of elements and ions in the groundwater of Chahderaz plain and Marg salt playa is above the maximum admissible concentration (MAC) values for drinking water according to WHO. Also, Cd, B and As have concentration more than MAC in total groundwater samples. Chromium in all of the groundwater samples except in Sirjan city samples have concentrations more than maximum admissible concentration. Moreover, Pb in groundwater of Kheirabad salt playa and Chahderaz plain shows a groundwater contamination. While concentrations of Cu, Ba, NO2, and Sb in all of the area are less than MAC. The evaluation indices showed spots in a high-risk level observed in Golegohar mining area, Chahdereaz plain, KH1, and KH2 from Kheirabad playa and KM1 and KM7 from Marg playa area. Finally, according to Langelier Saturation Index (LSI), most of the groundwater samples are corrosive in this area. Therefore, in the processing plant, corrosive process control of groundwater should be accompanied.

Impacts on over one-third of the world population, human and social causes of desertification remain identifying desertification drivers in the Sistan region in the southeast of Iran. We have evaluated managerial drivers that specifically contribute to the Sistan desertification. For this purpose, we followed a three-step survey with questionnaires prepared for each step of the survey. The three-step survey included: i) Identifying overall contributing factors ii) organizing candidate factors in 8 categories and iii) identifying and ranking the main factors based on their important role in desertification. The questionnaires were prepared and data were collected in collaboration with managers, experts, and administrators involved in combating desertification at the provincial level. Based on correlation statistics and multivariate analyses, the average contribution (%) of group to land degradation and desertification of the Sistan region, Desert management issues exhibited the highest fraction (33.47%), followed by Weakness of laws and regulation (15.43%), deficit studies and knowledge (13.76%), Farmland mismanagement (10.81%), soil issues (8.0%), unsuitable farmer's customs (6. 6%), water mismanagement (6.1%) while the contribution from the rest, Animal husbandry is 5.81 percent. also, more than 46 factors out of 72 resulted as significant in affecting land degradation and desertification in the Sistan region. Among them, the most important were Lack of integrated Hamoun watershed management, absolute responsible in combating desertification to FRWO, no allocating water to Ecological targets, no coordinating in combat desertification between stakeholders, deficit holistic plan for combat Desertification. Results contribute to the development of a deeper conception among decision-makers, experts and regional administrators appropriate tools for assessing the effectiveness of land management practices for contrasting land degradation and desertification.

Water and food security are serious challenges in climate change studies. the purpose of this study is to investigate the effects of climate change on water requirements of apple during the growing season. For this purpose, the ECMWF database has been used for observation data of Semirom and Urmia stations during the 20-year period (1996-2001).To check this quantity in the next 20 years, the daily  Downscaling dynamic data of the CORDEX project with a precision of 44% * 44% for the output of the ICHEC-EC-EARTH model under the two lines of 4.5 and 8.5 (RCP) was used for the period (2017-2037). In order to reduce the errors in the model estimates, the post-processing action of the estimated events was fulfilled. Then, minimum temperature data, maximum temperature, relative humidity, wind speed and radiation, potential evapotranspiration have been calculated using Penman-Monteith FAO method, which is more accurate than other models, and using the non-parametric Man-Kendall test and the Sen’s Slope estimator nonparametric Method in the confidence range, 95% evapotranspiration was determined. In the end, the water requirement was also examined during the growing season of apples. The results showed that evapotranspiration in both stations is increasing during the growing season. The ETo increase in the growing season of the apple tree stations was predicted from the base period for the trajectory of 4.5 and 8.5 for the Semirom 4.14.7 and 7.99.7, respectively, and for Orumiye Station, 26.5 and 11.8, respectively, and however, this increasing process will raise the apple's need for water. The highest amount of evaporation and water requirement in the observed and estimated data has occurred in the bud break periods, growth fruits. At this stage, the lowest effective rainfall and the highest average temperature have occurred but generally, the percentage of upcoming changes of germination stage was more than other stages.

Statistical analysis shows that the long-term occurrence of dust Khuzestan province last 60 years has been faced with the phenomenon of dust. However, dust storms with coverage of more than 50 percent and minimum 2-day duration over the past two decades have become an uninvited guest. Two conditions for the occurrence of dust storms are: the presence of dust, the presence of substrates and the presence of fine particles with a small diameter and a large volume of dust forming the source; and the another synoptic-dynamic conditions as the driving force and the transfer of dust particles from the source regions to other areas. In this regard, the aim of this study is to analyze the general pattern of dust in Khuzestan province in the warm period of the year. For this purpose, data from 20 synoptic stations from the Meteorological Organization have been extracted. Then, by performing cluster analysis, identification of effective patterns on Khuzestan dust has been investigated. The results showed that five patterns were identified in determining the patterns of dust storms in the warm year, including 1) Gang low pressure thermal. 2) Gang Low-pressure, low-pressure Eastern Europe, high-pressure North-East Europe. 3) Gang Low pressure, high pressure in Europe. 4) The massive pressure of Europe, the high pressure of Kazakhstan. 5) Polar warhead high pressure, low pressure, Iceland low pressure. The results showed that the synchronous mechanisms of the dust occurrence in the first to fourth patterns, Gang low pressure thermal, which is formed during the hot season of the year with extreme warmth and heat in southern Asia, played a major role in the dust situation on Khuzestan. By placing high strength Azores in the middle of the atmosphere, the pressure difference conditions between the two high pressure and low-pressure centers have accelerated the flow velocity from higher levels to the lower levels of the atmosphere. Consequently, in conditions of lack of moisture on Khuzestan and through the passage of compressive systems from the ground and areas susceptible to dusty, dust was transported to the Khuzestan area.

Infrastructures such as water, sewage, electricity, gas and etc. are some of the crucial living conditions of neighborhoods in cities. The deficiency of the performance in any part of the facility disrupts the life of the neighborhood. Therefore, measuring the vulnerability of urban facilities and their current status are the first steps in reducing urban vulnerability. The purpose of this study is applying the fundamental knowledge of vulnerability assessment in practical and quantitative approach to assessing the vulnerability of the facility against earthquake in two categories of objective and managerial indicators (each of which has sub-indicators weighed in the Delphi-AHP method and their maps are generated in the GIS software) in the scale of the Ghodghun neighborhood of Borujerd. The results of field studies and interviews with relevant authorities indicate that after 12 years since the beginning of the reconstruction process, 27% of sewage pipes, 35% of urban water pipes, 80% of electrical wires, 24% of wooden beams, 51% Of gas pipes replaced, while due to the lack of systematic seismic standards and the facility disaster management plans, has led to a slight decrease in the facility vulnerability. The vulnerability assessment results of the facility in the objective indicators show that all five indicators of sewage pipes, urban water, electricity, gas, and telecommunication have a number higher than 3 out of 5; and in management indicators of 6 The index, the existence of standard and planning indicators above 4, the indicators of congestion and utilities in the range of 2-3 out of 5 have been evaluated. In total, the vulnerability number of the facility in the two categories of objective and managerial indicators is 3.47 and 2.805, out of 0-5 range, which, in the weighted combination facility vulnerability, is estimated 3.2496 which evaluated a Medium upward.

Although the Urmia Lake is the largest domestic lake in Iran, the second largest saline lake in the world, and the world's 20th largest lake, and is weather-balanced for the region's climate, it has been declining in recent decades. There are several reasons to become dry this lake. In this paper, due to the complexity of the problem, system dynamics is used as a suitable methodology for modeling the reasons for drying Urmia Lake. According to Sterman's methodology, the boundary of the problem was first studied. Key variables and their historical behavior were studied at this stage. Then, the dynamic hypothesis of the problem was formulated by using the subsystem diagram, circular causal graphs and accumulation flow map. After simulating and testing the model, some of the possible ways were evaluated that lake can be recovery. Based on the results of this study, it seems that two main factors in decrease lake water are reducing the input of surface waters to the lake and damping. Therefore, supplying the Lake right of water and limiting the construction of dams can be two ways to stop the process of drying Urmia Lake. However, the dynamics within the problem, they can apply any solution with many complications and side effects.

The geological position and faults of Iran have caused earthquakes in the country throughout history. Assessing the seismic hazard of Tehran as the capital and its suburbs due to direct impact on the city of Tehran is very important from the viewpoint of earthquakes and the risks and possible damage caused by possible earthquakes to rehabilitate the more dangerous and vulnerable areas, as well as the creation of suitable facilities for the time of crisis... The hashtgerd range has high seismic activity due to its geographic proximity to Tehran. This is due to the construction of Hashtgerd new town, which has caused the extraordinary increase of human and urban densities in recent years to reduce the need of the region for more accurate and more rigorous surveying of seismicity. Risks make it special. In this research, using the conventional method of probabilistic seismic hazard analysis, the study area is located at 250 km radius of seismic studies and the estimated seismic riskiness of the area was estimated by analyzing the results. According to the study, the north and east of the region have higher fault densities. Also, according to the iso-acceleration map for a return period of 475 years, the maximum values are in the northern and northeastern strips as discrete zones and also in the southwest of Hashtgerd city in Najmabad area. The southern margin of the Alborz province generally has relatively less accelerated areas. The Hashtgerd city in the high danger zone ranges from 0.38 g to 46 g. Also, the map for the return period of 2475 years indicates that the maximum values are in the south of Hashtgerd, and Hashtgerd is in the range with an acceleration range greater than 0.68-0.85g.

Today, the path to sustainable development is to pay attention to the industries that, while maintaining the principles of the environment, while maintaining the principles of the environment, improve the lives of the people of society and do not pose serious risks for the future generation. In this regard, the environmental impact assessment Is an appropriate tool for achieving sustainable development goals that identify and predicts the environmental impacts of a project or different projects on the environmental components (physical, biological, socio-economic, and cultural). The purpose of this study was to identify and predict the effects of construction of yasuj cement factory in the city of Yasuj. In this descriptive-analytical study, the present state of the environment in the region was studied. Then, by reviewing the project's technical resources, we aimed to identify the most important phases of exploitation and construction. Finally, the Iranian Leopold Matrix method and RIAM were selected to evaluate the environmental impacts of the Yaman-e-Jam Cement factory. The results of the RIAM matrix analysis showed that the most negative effects were related to air quality, soil erosion, noise pollution, quality of agricultural products, landscapes and landscapes of the village, employment and unemployment, and in contrast to the positive the most significant impacts of rural development plans, services and transportation are property values. Therefore, the implementation of the project has many socio-economic benefits for the village and surrounding areas. Also according to the results of the Leopold matrix, the most environmental damage involved in the exploitation phase is related to the socioeconomic and cultural sectors and in the biological and physical building stage, therefore, since the most negative effects created in the classification of the weak group the project was fully approved. But corrective actions must be taken into consideration until the environmental effects of the plant increase.

Radon gas is one of the main causes of lung cancer, the release of this gas in water resources can lead to major environmental hazards. The purpose of this study was to measure the concentration of radon gas in groundwater of the Jiroft plain and determine its relationship with active faults in the region. In this regard, 40 samples of wells water were collected from Jiroft plain and the RAD7 was used to calculate the concentration of dissolved radon gas in them. According to the results, 67% of wells have more than the limit of radon concentration in the studied area. The zoning map of the radon gas concentration was prepared By performing an interpolation operation. The study area was classified into four classes: very high, high, medium and low in terms of radon gas concentration. So that the area is about 54,000 hectares are in a high and very high concentration range. While the Jiroft city is in the high concentration of radon gas. In order to determine the relationship between the high concentrations of radon gas and faults in the region, the weights of evidence method were used. The results of this method indicate that there is a high correlation between high and very high concentrations of radon gas and main faults. The greatest association was found in 1000 meters of faults and this association will be reduced by Getting away from the faults.