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Volume 1, Issue 4 (1-2015)
The Iranian plateau formed by the active tectonics of the Alpine-Himalayan belt, is situated between the Eurasian and Arabian plates. The plateau is considered as one of the most seismically active regions in the world and is faced with different earthquakes each year. Active tectonic conditions, different faults and seismic sources and a large population in earthquake-prone areas makes it necessary to perform more considerations and scientific studies in order to analyze the seismic hazards and risks.
In this paper, different aspects and effects of the Iranian seismicity has been determined. In order to review the status of seismicity and distribution of earthquakes in Iran, we need first to consider the tectonic setting, structural environment and the active faults of the country. To date, there have been some different studies to divide the the seismotectonic setting of Iran into different seismic zones which are explained in this paper briefly. Moreover, the seismicity and most destructive past earthquakes in the Iranian plateau and distribution of earthquakes are shown.
One of the most important tools in studying earthquakes is to perform continuous recording and monitoring of the seismic event and ground motions which is implemented using seismic and strong motion networks. The systematic networks have been set up within the country and are working and responsible for data collection and monitoring of seismic events permanently. These networks including the Iranian Seismological Center (IRSC), broadband seismic network of the International Institute of Earthquake Engineering and Seismology (IIEES) and strong motion network of the Road and Housing and Urban Development Research Center (BHRC) are also introduced in the current study.
Given the high seismicity rate in Iran and rapid development and growing of the populated cities and buildings on seismic hazard prone areas, attention to seismic hazard and risk assessments has been become as a particular issue that should be addressed carefully. Therefore, seismic hazard analysis and estimation for the constructions of human structures has become an enforcement for which several seismic regulations and codes have been defined. In this regard, deterministic and probabilistic seismic hazard methods have been developed as the two most important techniques. The deterministic method is a conservative approach that is mostly used to determine the highest level of strong ground motion (acceleration) for a special site (such as dams and power plants). On the other hand, the probabilistic method provides probabilities of different strong ground motion levels considering different uncertainties and the useful life of a structure.
In addition, considering the level of seismic hazard in a region and its population can lead to risk assessment, vulnerability and resiliency of the human societies. Thus, parallel to seismic hazard and risk analysis, it is so important to conduct crisis management, reduce efforts and a continuing assessment of the situation in the country. In the present study, problems and challenges facing the crisis management, as well as urban distressed areas are mentioned.
Regarding the existence of constant threat of natural disasters, especially high risk of earthquakes, there is a serious need to conduct more scientific researches in various fields, including detailed research on various aspects of seismology in Iran, retrofitting of constructions, crisis management and disaster risk reduction. To achieve this purpose, we need a scientific network in Iran. There sould be several experts and organizations as the members of this network who are able to understand and control the earthquake effects on the society. Necessity of such a scientific network is due to that it is impossible to take efforts in order to reduce the earthquake risks without a holistic perspective and earthquake data completion.
In this regard, we need significant infrastructures in terms of human resources and technical cooperation to motivate a set of organizations, universities and research institutes. The responsible organizations such as geological survey of Iran, National Cartographic Center of Iran, meteorological organization, Institute of Geophysics of the University of Tehran, International Institute of Earthquake Engineering and Seismology, Road and Housing and Urban Development Research Center, National Disaster Management Organization, Red Crescent Society of the Islamic Republic of Iran, as well as universities and NGOs must work together to make it possible to review and integrate the existence potentials and to share the information and data of the earthquakes in Iran and define various response scenarios faceing natural disasters, especially earthquakes.
Volume 3, Issue 1 (4-2016)
In issues related to air pollution, the thickness of the boundary layer is known as the depth of the mixed layer because the pollution on the ground surface is mixed in this entire layer through turbulence processes. In most cases, the boundary of the area is clearly visible on big industrial cities. The depth of the mixed layer has an important effect in the concentration of air pollution which is dependent on the intensity and duration of solar radiation and wind speed. Usually after 2 to 3 hours from the time of maximum solar radiation, air temperature near the earth's surface reaches its maximum value. At this time convection of heat is formed in the air near the earth surface and transfers the heat from the surface to higher altitudes. These vertical movements will cause atmospheric turbulence and increase in instability. This is when the growth of the mixed layer reaches to its highest level. After sunset, night temperature inversion occurs near the surface. This temperature inversion is due to the rapid cooling of the Earth's surface. In such condition, the cold air layer is near the earth's surface and the warm air layer sits on top of it and air is in a stable condition. As a result, the accumulation of contamination, if there are sources of pollutants, will increase in the earth's near-surface layer. If the conditions remain steady during the day, the mixed layer will not have much growth and as a result, contamination in the shallow layer near the surface of the Earth reduces solar radiation.
Each year, thousands of gaseous pollutants and particulate matter are emitted in the metropolitan area of Tehran and due to the geographical and climatic conditions of Tehran, temperature inversion phenomenon is not something unexpected. By formation of the inversion layer, these pollutants will remain near the earth's surface for a long time which in turn will be the cause of a lot of heart and respiratory problems. Therefore, identifying the characteristics of this layer on polluted days is of particular importance to the health of the residents of this city.
In this research, the study area is Tehran which is in the foothills of the southern Alborz and between longitudes 51 ° 2 'to 51 degrees 36' east and latitude 35 degrees 34 minutes and 35 degrees 50 minutes northern. The height of the northernmost point of this city is 1800 and up to 1200 meters in the center and 1050 meters in the south.
To conduct this research, inversion data including temperature, wind, atmospheric pressure and humidity and vertical navigation radiosonde data at the Mehrabad weather station from January to 29 December 2013, were taken from the Meteorological Organization of country. Then the statistics of daily vertical scroll of atmosphere above the Mehrabad synoptic station was received from the University of Wyoming. Also, the hourly data of air pollutants including gaseous pollutants CO, N2O, O3, SO2 and particulate matter (PM10) were prepared from the air quality control center (AQCC) for the stations Aghdasiyeh, Geophysics, Poonak, Rey and District 11.
After receiving information about the vertical scroll of the atmosphere in Mehrabad station, in order to have a closer examination of the vertical profiles of potential temperature changes in the lower atmosphere, using daily data from the radiosonde to obtain potential temperature changes in height were measured. Then, in order to identify the days with high pollution levels (the unhealthy condition for sensitive groups) and days with good conditions, so that all stations under study were the same, based on a standard index of air pollution Table 1 was developed. In the end, 4 days with critical inversion of potential temperature, including two polluted days (February 6th and August 16th) and two clean days (9 February and 5 June) were detected. Then according to the proposed method of Hefter, the approximate height of the boundary layer was calculated for these 4 days.
In this study, it was observed that the boundary layer height in contaminated cold season of the year reached 1,200 meters in the morning hours while in the afternoon in the cold samples, it grew to 1900 meters. In the warmer months based on the height of critical inversion layer in the selected days it reached more than 6,000 meters. In pure samples of warm and cold seasons, the boundary layer height had significant growth to the extent that in the cold sample of the year it reached to 2,100 meters in the morning and 2,600 meters in the afternoon. On June 5, which is intended to represent the clean and pure heating season, boundary layer height was of 5300 meters in the morning hours which shows a 4,000-meters increase in comparison to its polluted counterpart. The point to be noted is that since the active track of potential temperature can be considered as a measure of air stability, in the critical inversion, for the case of polluted samples of morning hours that were irradiated with inversion, active track of the potential temperature was very high in them. Thus on days with radiated inversion (polluted days) we can say that border of boundary layer was based on the inverted layer. Also the methods used in these types of inversions are more efficient for the determining height of the boundary layer.
Volume 3, Issue 2 (5-2016)
One of the most important components of the extent of pollutants mixing and air quality at near the Earth's surface is the height of boundary layer. Many variables involved in determining the height of the boundary layer of atmosphere. Although all of the troposphere (the lower ~10km of the atmosphere) is affected by surface conditions, most of it has a relatively slow response time. The lower part of the troposphere that is affected on a shorter time scale is commonly defined as the Planetary Boundary Layer (PBL). The depth of the mixed layer has a significant effect on the concentration of air pollution, which itself is dependent on the intensity and duration of solar radiation and wind speed. According to Stull, one can describe the planetary boundary layer as “that part of the troposphere that is directly influenced by the presence of the earth’s surface, and responds to surface forcing with a timescale of about an hour or less.” Surface temperature has a strong relationship with height of the PBL. As the surface cycles between daytime radiation and nighttime cooling the amount of convection taking place changes. When the temperature gradient is steep, more convection takes place to dissipate thermal energy in the most efficient manner. In other words, the greater the temperature difference between the surface and the lower troposphere, the higher convective eddies must reach to alleviate the gradient. Relating this to Stull’s definition of turbulence, it can be concluded that the height of the PBL varies with surface temperature. In fact, the spatial range of the PBL can vary from less than one hundred meters to several kilometers. The strong relationship between convective turbulence and height of the PBL is sometimes used to define the boundary layer and call it the Convective Boundary Layer (CBL). Analogous to the Stull’s definition but focusing on turbulence, Lloyd et all describe CBL as “a layer of air typically of order 1km in depth, well mixed by turbulence maintained by buoyancy due to heating at the ground. It is bounded above by stably stratified, no turbulent air and grows through the day. In this study we aimed to analysis the status of ABL in 3 dust period days in Khuzestan province of Iran.
The Data were used in this study includes: The Daily data of dust concentration during 27Jan to 1 Feb 2015, the daily height of ABL also were used. The daily data of ABL were given from ECMWF with 1/8 degree spatial resolution. We used the Pearson correlation and synoptic analysis to assessment the condition of boundary layer at the mentioned days. For analysis the characteristic of ABL the climatic data of Wyoming University were used to assessment the thermodynamics of atmosphere. The spatial distribution of ABL height at the dusty day also were used for 12 UTC.
The results indicated there is the direct relationship between the ABL height and the concentration of dust in the mentioned days. So that in the days that the concentration of dust reaches maximum we fund that the height of ABL reaches maximum simultaneously and vis versa. The spatial distribution of ABL height shown that the height of ABL in the 29Jan reaches maximum that the maximum concentration of dust related to this day. And also the minimum concentration of dust observed in 27Jan and 1Feb that the in this day the height of ABL was minimum. The synoptic analysis also reveals that locating the low pressure system at the 500hp level that the Khuzestan province has been locating at the front of this system lead to transport the dust to study area.
In this study we reveal that the height of ABL in the dust days of Khuzestan has a totally revers behavior in compare to the air pollution days in Tehran. In the pollution days in Tehran the lowing of ABL height and inversion lead to intensify the concentration of pollution while in the dust days of Khuzestan the height of ABL were increased in compared with non-dusty days.
Volume 4, Issue 1 (4-2017)
Climate and weather conditions are among the most important factors in controlling our daily and even long-term activities. Since the emergence of human beings, the weather has been effective in our lives. Changes in precipitation and temperature, solar radiation and other climatic parameters, have had so much impact on people’s lives that as far back as the first periods of human lives, we have been witnessing the climate change, and these factors have determined the way of our lives. Since the old days, the scientists of criminology, sociology and psychology have considered the influence of nature and different circumstances on the crime and its rate. Hippocrates and Montesquieu were the oldest ones that studied about the impact of climate on effects and aggressive behavior. The main objectives of this research are as follows: Understanding the climatic regions of Kurdistan Province, and assessing the relationship between the climatic regions of the provinces and the aggression rate. From a psychological perspective, aggression is a behavior whose aim is to harm others or oneself with a conscious intent. The main idea of this study is to consider the theory that whether there is any connection between natural factors, especially the weather, and the mood, temperament and the aggression rate of people. For this purpose, and for climatic zoning of Kurdistan, we have used the surface data of all synoptic stations in Kurdistan as well as the stations around the province from their establishment until 2005 (25 stations). Using these data, 2068 cells (with approximate dimensions of 7/3 * 7/3 km²) in Kurdistan were appraised every day according to the Kriging interpolation. By applying the cluster analysis to these data, two main climatic zones were identified in Kurdistan. The hot-humid region was including the cities Bane, Marivan, Sarouabad, Sanandaj and Kamyaran, and the cold-dry region, was including the cities Saghez, Diwandareh, Bijar, Ghorveh and Dehgolan. Then in each of these regions, in the number of the samples which were obtained through Cochran formula (768 samples), the Buss and Perry questionnaires were distributed and collected. The new version of the Aggression Questionnaire, whose previous versions was hostile questionnaire, was revised by Buss and Perry (This is a self-report questionnaire that contains 29 words and four subscales).The prototype questionnaire has 52 questions, but a lot of weak questions of the questionnaire have been excluded using the factor analysis method, and it has turned into a questionnaire with 29 questions. Finally, the results of the questionnaires were analyzed through SPSS, using the t test for the independent groups. The results of this study indicate that the physical and verbal aggression rate and the level of anger and hostility among the residents of the cold regions of Kurdistan are higher than the residents of warmer regions. The results also showed that the level of aggression among the men is higher than women. The aggression among the men mostly appears in a physical form, while women make it in its verbal form. Also, in the hot-humid areas, the level of anger and hostility among the women is more than men. According to the data analysis, we can say that the results of this study are consistent with the findings of some researchers, though in some cases the results are not consistent with other researches. The assessment of the geographical environment has not concerned the scientists alone, and philosophers like Ibn Sina, Sociologists like Ibn Khaldun, and writers and thinkers such as Al-Jahiz have looked at geographical factors from other perspectives, and have examined its relationship with ethics and human behaviors. In conclusion, we can say that the results of this study are non-aligned with the results of the studies that have examined the effect of weather conditions on the temperament or real aggression. But the results of this study are consistent with the researches that have investigated the potential of aggression. Therefore, we can say that in a short period of time, warm weather conditions can predispose one to aggression, but to live in the warm climates, may raise people`s patience at the end, and make them able to control themselves at the occurrence of aggression. The results of this study indicate that in Kurdistan province, the extent of potential aggression is higher among the residents of the cold regions (Saghez, Diwandareh, Bijar, Ghorveh and Dehgolan) than the inhabitants of the tropic ones (Bane, Marivan, Sarouabad, Sanandaj, and Kamyaran). To justify these findings, we can say that freezing creates a sense of insecurity in people because we experimentally see that the residents of a cold region need to work constantly in order to keep their bodies warm. They need to have a secure plan for the winter, so that they can make enough food, fuel and clothing. This coherent planning makes them more active in comparison with the residents of the tropical regions. An unfavorable and difficult living environment emboldens people. The people who belong to these areas are pragmatic, and their approach to the environment is competitive or aggressive. In contrast, the people who live in the relatively warmer climate have usually less activity. The property of this kind of temperament is laziness and inertia. Working in hot places is unpleasant because it makes people sweat, and it makes them tired soon. Another finding of this study is that in the whole province, in both cold and warm climates, the aggression among men is more than women, and this difference is greater in cold areas. The men spend most of their time outside the houses, and because of this, the effect of climate is more on them, but women are living most of their time at home, and they can take advantage of the air conditioning equipment. Thus, they have a more relaxed and flexible temperament.
Volume 4, Issue 4 (1-2018)
Landslides are considered as natural disasters that lead to many deaths and severe property damages worldwide. Therefore, it is necessary to investigate the effective factors in order to make urgent planning and to present management solutions for the sensitive regions. Massive movement of materials, such as a landslide, is one of the problematic hillslope processes in Javanrood located in the northwest of folded Zagros, for this phenomenon leads to demolition of forest lands, farms, and pastures of the region. Moreover, it is considered as a threat for road traffic. The present study aims slope stability analyses and landslide hazard zonation applying the process-based model (Sinmap).
This research was done by both field and experimental methods. Research steps are summarized as following.
Geomorphologic, hydrologic and soil mechanic characteristics of slopes in the considered zone were the required information in this study. To obtain this information, at first, it was necessary to recognize sample slopes to measure the above- mentioned variables. Therefore, first of all, landslides distribution map was prepared in the considered area then, on this basin, sample slopes were selected to measure essential variables. Sample hillslopes were recognized as 12 hillslopes, 5 stable (lack of land sliding) and 7 unstable hillslopes (having land sliding mass). They were 1- 12 numbers. 1-5 hillslopes are stable and 6-12 unstable. After selecting sample hillslopes, necessary parameters were assessed as following:
Mechanical features of soil: soil sampling from each hillslope was done the mechanical features of soil, so 50 kg soil was removed from each slope, from 75 cm to 1cm depth. In order to sampling soft and coarse soils, a core cuter devise and shovel were used, respectively. Sampled soils were transferred to Kermanshah soil mechanic laboratory, Kermanshah provincial transport office and necessary parameters, including dry soil specific weight(γ d), wet soil specific weight (γt), hydraulic conductivity , soil internal friction angle(φ) ,soil cohesion , and soil porosity were determined by using direct shear test.
Determining the geometric parameters of slopes: except for using topography map, altitude numerical model (Dem) with a pixel size of 20 by 20 m and satellite images were used to determine morphology parameters and to identify various hillslope types. Applying GIS software, manual and laser tape measure, clinometer, slope geometry characteristics such as mean slope (beta), slope width (W), slope length (L) area, were extracted.
Model implementation
The model used in this study was Talebi (2008) model which was, in fact, an extended model of process-oriented (physically based) model, being a combination of geometry model, hydrology model (permanent condition) and infinite slope stability theory. After obtaining necessary parameters to get slope factor of security (F S) including laboratory, topography and hydrology parameters, Fs values for each slope were measured by Matlab software
Unstable slopes of the region mainly have the stability coefficient less than 1 which is classified as very high vulnerable class. They have low inner friction angle, less than 29 degrees, based on geo-mechanic properties of soil. Moreover, their gradient angle is more than 35 percent. In term of shape, most of them have concave profile curvature and convergent plan which lead to slower drainage, the increase of relative saturation saving of the soil, and the decrease of stability. The results of the landslide hazard zonation mapping indicate that the majority of the study area located in protection class includes 26 percent of the study area. The lowest percentage of study area belonging to middle stability and quasi-stable classes which constitute 9.2 and 6.2 precent of the study area respectively.
Volume 5, Issue 4 (3-2019)
Volume 6, Issue 2 (9-2019)
Drought is one of the most complex and unknown natural phenomena that causes a periodic water crisis in the affected areas. Increasing water demand on the one hand and the experience of droughts in the province in recent years have led to the water crisis. Knowing the drought is one of the requirements for water crisis management. The purpose of this study was to analyze the trend of the SPI drought index in Isfahan province using nonparametric Sen’s slope test, Pettitt’s change point test and Man-Kendall test. From the monthly climatic data of 10 synoptic stations with a length of 27 years (1990-2017) for time series The results of applying Mann–Kendall and Sen’s slope tests based on SPI Index for 9, 12, 18, 24 and 48 month time periods, shows drought trend is significantly increasing for all stations out of Ardestan, Esfahan and Shahreza stations. In Ardestan station, the drought trend is significantly decreasing for 9, 12, 18, 24 and 48 month time periods and in Isahan station, the drought trend is significantly decreasing for only 48 month time period, and in Shahreza statition, the drought trend is significantly increasingonly for only 18 month time period.
Despite all stations, the drought trend for one month time period, is significantly increasing just for Naein station.
In addition, applying Mann–Kendall test on monthly rainfall for all station shows downward but not significant trend.
Finally, applying Pettitt’s change point test based on SPI Index for 9, 12, 18, 24 and 48 month time periods indicates the existence of a significant change point. For same periods we observe no change point for the monthly rainfall in all stations.
In summation, considering the SPI drought index, about 59% of all stations show significant downward trend bases on Mann-Kendall test and 60% of all stations show significant slope based on Sen's slope test and 75% of all stations show significant change point based on Pettitt's test. In general, for drought analysis using different time periods for the SPI index, in a short time period. (such as 6 months) drought is more frequent but shorter, and as the period increases the duration of drought also increases but frequency decreases. All together, we are facing a water crisis in Isfahan province and we must manage water demand very urgently.
Volume 6, Issue 4 (2-2020)
Among the important challenges facing water resources of the country, one can mention the phenomenon of climate change and its impacts. The General Circulation Models (GCMs) can provide the best information about the response to increasing the concentration of greenhouse gases. Since the outputs of this model do not have sufficient time and space accuracy for studies on the effects of climate change, the output data of small general circulation models need to be quantitative. In this study, the SDSM statistical magnitudes and the CanemS2 model for climate change assessment, which are presented in the fifth report of the IPCC Comes under three scenarios RCP2.6, RCP4.5 and RCP8.5. The daily minimum temperature, maximum and precipitation rates of the synoptic station of Shahrekord (Cold mountain region) and Bandar Anzali (very humid and temperate climatic zone) are utilized and the parameters are for the period of 2040-2011, 2070-2070, and 2071-2099. Is. The results of the study show that the SDSM model has high accuracy and high efficiency in the climatic zone of very humid and temperate (Bandar Anzali) relative to the cold cliff (Shahrekord). However, the model has an acceptable ability to simulate the parameters in both areas. Under all three scenarios, RCP will experience the minimum and maximum temperature and precipitation in both climatic zones in all three times, but the cold climatic zone will be more affected by the climate change phenomenon.
Volume 8, Issue 2 (9-2021)
The daily cycle of radiant heating from sunrise and sunset leads to the daily cycle of tangible and hidden heat fluxes between the earth's surface and the atmosphere. These fluxes, which cannot directly reach the whole atmosphere, are confined to the shallow layer near the surface, called the boundary layer of the atmosphere. . The processes that take place in this layer are important in various aspects such as the dynamics of fluxes and atmospheric systems, surface radiation, the hydrological cycle, and air pollution research. The thickness of the boundary layer of the atmosphere varies with time and place, and its size varies from a few hundred meters to several kilometers on land under different conditions. This thickness depends on various factors such as the type of atmospheric systems and their structure, surface fluxes, steep vertical arrangement and wind direction and surface cover. The depth of the boundary layer can be calculated by different methods. This depth, which indicates the thickness of the turbulence zone near the surface, is usually called the depth of the mixed layer or the depth of the mixture. The methods used to determine the boundary layer of the atmosphere or the depth of the mixed layer are commonly used to investigate air pollution. Estimating the depth of the mixed layer is one of the most important parameters in the pollutant diffusion model. Therefore, the purpose of this study is to investigate the causes of monthly fluctuations in the height of the western border layer of the country with respect to the barley station above Kermanshah.
Materials and methods
Data on inversions of Kermanshah meteorological station during February and August 2012; Obtained from the Meteorological Organization of the country. Also, the data related to the vertical barley survey in this station, which were collected by radio sound, were used and the statistics of daily vertical barley survey above the Kermanshah synoptic station were obtained from the climatic database of the University of Wyoming. After obtaining information about vertical barley survey in Kermanshah station, Skew-T diagram, indicators and profile information of atmospheric conditions were drawn to recognize the dynamic and thermodynamic status of the atmosphere during the selected days in RAOB software environment. Then, in order to study the lower atmosphere more accurately, the changes in the vertical index of potential temperature, using daily radiosound data, the curves of potential temperature changes in terms of altitude were plotted. Then, using Huffer's computational method, days with critical inversion at potential temperature were found. Then, using geopotential height, wind and vertical ascent (omega) data, the synoptic causes of boundary layer depth fluctuations (mixed) and the effective factors were investigated.
Results and discussion
The main purpose of this study is to implement Hafter's proposed model to investigate the monthly fluctuations of the height of the boundary layer of Kermanshah station. The results of using Hafter method in estimating the depth of the mixed layer of the city and its daily changes for Kermanshah station in August and February 2012. In this regard, the effective factors in minimizing and maximizing the mixed layer in every two months (August and February), including: the synoptic situation in the study area on selected days, heat transfer, humidity, vertical arrangement and wind speed were investigated.
Conclusion
The results showed that in August, the depth of the layer during the month was between 3680 to 10292 meters. In this month, temperature subsidence, type of synoptic systems and vertical wind arrangement have directly played a significant role in the growth or weakening of the layer. Considering the comparison of the role of effective factors in maximizing and minimizing the depth of the boundary layer in August, it can be concluded that all factors have a positive role in maximizing the depth of the mixed layer; while the vertical wind arrangement plays an essential role in minimizing the layer depth in this month. In February, the depth of the mixed layer was about 2273 to 7017 meters and significant fluctuations in the values of the depth of the mixed layer were observed during the month. In this month, temperature subsidence, vertical wind arrangement and synoptic systems have been effective in changing the depth of the mixed layer. Comparing the results obtained from both months, it can be said that the amount of surface flux is higher in summer than in winter; thus, the average depth of the mixed layer in August has almost doubled to February. In general, it can be concluded that the depth fluctuations of the mixed layer in winter due to the passage of different systems and the occurrence of atmospheric instabilities, have more changes than in summer.
Volume 8, Issue 3 (12-2021)
Risk modeling of plant species diversity and extinction in Sorkheh_hesar National Park
Zahra Mosaffaei1, Ali Jahani2*, 3MohammadAli ZareChahouki, 4Hamid GoshtasbMeygoni, 5Vahid Etemad
1 Masters of Natural Resources Engineering, Environmental Sciences, College of Environment, Karaj
*2Associate Professor, Department of Natural Environment and Biodiversity, College of Environment, Karaj.
3 Professor, Department of Restoration of arid and mountainous regions, University of Tehran, Karaj
4 Associate Professor, Department of Natural Environment and Biodiversity, College of Environment, Karaj
5 Associate Professor, Department of Forestry and Forest Economics, University of Tehran, Karaj
Abstract
Full identification of hazards and prioritizing them for non-harm to nature is one of the first steps in natural resource management. Therefore, introducing a comprehensive system of evaluation, understanding, and evaluation is essential for controlling hazards. This study aimed to model and predict environmental hazards following increased degradation in natural environments by ANN. Thus, 600 soil and vegetation samples were collected from inhomogeneous ecological units. Soil samples were prepared by strip transect method according to soil depth in four profiles (5, 10, 15, 20 cm). Vegetation samples were also collected using a minimum level method using 2 2 square plots according to the type, density, and distribution of vegetation. Sampling was done in two safe zones and other uses were modeled using ANN in MATLAB environment. The optimal model of multilayer perceptron with two hidden layers, sigmoid tangent function and 19 neurons per layer and coefficient of determination of 0.90. The results of sensitivity analysis showed that soil moisture content would be effective in decreasing biodiversity and flood risk as well as increasing the risk of extinction of endemic species in the region, and then the apparent and true gravity and soil porosity and distance from the road play a key role in the degradation of cover. Vegetation has increased flooding and extinction risk. Therefore, it is recommended that measures related to soil and vegetation restoration in this park be taken to reduce future damages as soon as possible.
Keywords: Modeling, Artificial Neural Network, Environmental Hazards, National Park, Vegetation
Volume 8, Issue 4 (1-2021)
In this research, the most important synoptic patterns of widespread snowfall in the western half of Iran have been investigated. For this purpose, the data of current weather code and snow depth of 36 synoptic stations during the statistical period of 1371-1400, for the months of October to March, were received from the Meteorological Organization of the country. In order to investigate wide snowfalls, the days when more than 70% of the studied area saw snowfall at the same time were extracted as a wide day. In order to perform synoptic-dynamic analysis of wide snowfalls in the western half of Iran, the classification method using cluster analysis was used and maps of representative days were drawn, including atmospheric temperature, moisture flux, geopotential height, tovai, front formation, jet stream, omega index, and orbital and meridian wind data. Trend analysis was also performed using the Mann-Kendall test. The results showed that 4 models justify the widespread snowfall in the studied area in the best way. According to the results in all the models, at sea level, the collision of cold and dry air of northern latitudes with warm and humid air of southern latitudes has caused the formation of frontal fields in the western half of Iran. At the level of 500 hectopascals, the intensification of the meridional currents in the western winds caused the creation of closed centers and as a result the flow changed in the direction of the westerly winds, and the location of the western half of Iran in the east of Naveh Al-Aghti and Sardchal has provided the necessary conditions for air to rise. Also, there was no trend in the number of snow days in the western half of Iran at the significant levels tested. But; The number of snow days has been decreasing over time. In general, it can be concluded that due to the warming of the earth and climate change, the number of snowy days has decreased and these changes have led to a significant shortening of the snow season.
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