Search published articles
Volume 1, Issue 1 (4-2014)
Although environmental hazards occur because of natural factors, however, political economy, controlling the sociospatial relations and conditions, also affect centrally the increase or decrease of physical and social vulnerability caused by hazards. In this regard, present paper has put the spotlight on “explaining the role of spatial distribution of social stratification in vulnerability to environmental hazards in the city of Tehran”. This is based on Political Ecology Approach which emphasizes the domination of prosperous social strata on the urban natural-ecological endowments and utilities and marginalizes low-income and inferior social strata. So, the recognition of social strata inhabitation across the city is significant for the analysis of social inequalities and their effects on the vulnerability of environmental and human hazards. The concentration of middle to high class and working and inferior classes has also caused the range of social inequality to increase in the metropolitan of Tehran and this trend per se has transformed Tehran to the spatial reflection of the contrast between poverty and wealth to the greatest extent in the country. Hence, regarding the fundamental role of social stratification and class structure and its evolution in explaining the dynamics of socio-economical relations in the dominant society and the process of urban space production and reproduction, explaining the role of spatial distribution of social stratification in vulnerability to environmental hazards in the city of Tehran is significant and necessary. Vulnerability to environmental hazards has been studied from the physical, biological perspectives, social construction perspective and contingency perspective. The present paper emphasizes the effects of social construction on the production of vulnerability. Scientists think radical and critical geography of space is a kind of social production. They believe that not only urban space, but also the entire space has a social structure and nobody can analyze it thoroughly regardless to the society’s work on the space. Thus in a world under the Capitalist System, urban space represents a reflection of the control and domination of superior social strata (owners of power, wealth and high status, or the owners of political, economic and socio-cultural assets) in its functional zones. This has been appeared in the recent decades, within the literature of hazards and catastrophes and based on “an approach of vulnerability” which has been rested on Political Ecology. The mentioned approach has been concentrated on a series of socio-spatial conditions and political economy which shapes the hazards and catastrophes. Some of the effective social conditions in shaping the hazards and catastrophes and their amounts of vulnerability depend on the racial, ethnic and class characteristics. Racial, class, ethnic and political economy analyses, which dominate their social ties, are considered as part of understanding knowledge system of hazards and catastrophes. Since this causes detecting the role of political economy of inequalities and racial, class and ethical processes and the marginalization caused by it, in the emergence of hazards and exacerbation of catastrophes and crises impacts. To use job structure means to emphasize concrete class structures, according to which an image of social inequality can be offered. Thus in present study, for structure determination and main composition of social stratification in Iran and Tehran “Structure Determination and Composition of Social Strata Model” was used. According to this model and with the use of data from matrix tables, major occupational groups and occupational situation have been classified in 5 classes superior strata, traditional middle strata, new middle strata, working and inferior strata and farmers. The data were prepared and analyzed by ArcGIS and Ms Excel softwaares. During the last century, uneven development process of the country was in favor of the Tehran and superior strata and powerful institutions located in this city. Regarding the processes and relations emerged from political economy of space and political ecology of Tehran, social strata inhabitation of Tehran has been in compliance with environmental capacities raised from topographic and microclimatic distinctions and ecological endowments. The findings of present paper also indicate physical and social vulnerability changes caused by probable hazards related to the general pattern of social strata inhabitation in north-south geographical direction. Spatial distribution of populated blocks in 1996, for which more than 30% of their inhabitants were “senior managers and experts” and “manufacturing jobs employees and laborers”, indicates the above mentioned issue and clearly show the poverty (old poor neighborhoods) and wealth (expensive and rich neighborhoods) spatial centers. In addition, according to the supporting studies on Tehran Comprehensive Plan, most of old urban tissues are in central and southern regions. Also according to the International Seismological Research Agency (JICA), the mentioned regions would be the most vulnerable in the Tehran probable earthquakes. Therefore, it can be said that findings and results of the present study indicate the determining place of political economy of space and urban political ecology and also the fundamental role of social stratification and class structure for recognition, analysis, explanation and understanding of the urban development challenges and problems. Hence, this is impossible to reduce social and physical vulnerabilities caused by natural and human hazards, particularly in the poor neighborhoods, regardless of political economy of space mechanisms and reduction of the gap and even urban development.
Volume 1, Issue 4 (1-2015)
Tectonic geomorphology is part of Earth Sciences, which deal with study of the interaction of tectonic and geomorphology. In other words it studies the effective tectonic processes in forming and changing the landforms. Geomorphic and morphometric indicators are suitable tools to the morphotectonic analysis for different areas. These indicators are used as the base tool to identify and recognition of tectonic deformation or estimates of the relative instability of tectonic activity in a particular region. Some of geomorphic indicators has been widely used, then the results of research projects are used to obtain comprehensive information about active tectonics. Full assessment of contemporary tectonics and tectonic activities, especially the young tectonic and its hazards need to Full understanding of geomorphologic processes speed and made for this purpose, geomorphological methods play an important role in this context.
This research uses a descriptive-analytical approach, using library studies and aims at determininge the activity of Neotectonic in 7 Watersheds of Tehran metropolis (from west to east: Kan, Vesk, Farahzad, Darakeh, Velenjak, Darband and Darabad). In the first step, using topographic and geological maps of under the studied area, faults, drainage networks and watersheds are identified, then to evaluation the indicators of Mountain Front sinuosity (Smf), the main river sinuosity (S), the drainage watershed asymmetry (Af), rivers density index (D), hypsometric integral (HI), the ratio of the watershed shape (BS), the ratio of valley floor width to valley height (Vf), river longitudinal gradient index (SL) and Index active Tectonic(IAT) have been determined. Survey of these indicators by topographic and geologic maps and Google Earth images of the under studied area using software of Google Earth, Arc GIS and Global Mapper are derived and calculated. In the following, parameters and how they are calculated are given:
-Mountain Front sinuosity is the result from equation (1):
Smf = Lmf / Ls (1)
In the equation (1), Smf is index of sinuosity Mountain Front. Lmf is the front along the foothills and mountains of the specified slope failure and Ls: straight line along the front of the mountain.
- The main river sinuosity index is as follows: S = C / V. In this formula, S is main river sinuosity. C: along of the river. V: valley along of the straight line.
- Rivers density index, drainage density is obtained from the formula:
µ=
Li is length in kilometers of drainage Watershed, A is area in square kilometers, μ is total drainage watershed in terms of kilometers per square kilometer.
- Hypsometric integral is an indicator which represents the distribution of surface heights variation from equation (2) is obtained:
HI= H - Hmin / H max – H min (2)
In this equation Hi is hypsometric integral, Hmin and Hmax respectively are the minimum and maximum height and H is the height of watershed.
- The ratio of width to height of the valley floor is another geomorphologic parameters to investigate the tectonic forces in the region .This index is obtained from the equation (3):
VF = (3)
VF, represents the relationship of the valley floor width to valley height, VFW: the valley, Eld and Erd to the height of the left and right and Esc is valley floor elevation valley.
- The ratio of the area ratio of the area and the equation (4) is obtained:
BS= Bl / BW (4)
-BS; the shape of the watershed; Bl; length dividers watershed of water to the bottom of the watershed outlet and BW: width of the flat portion of the watershed.
-The longitudinal gradient index (SL) for a range of drainage path is calculated and determined by the relationship: SL = (ΔH / Δ L) * L. In this regard, SL: the longitudinal gradient index, ΔH: height difference between two points measured, ΔL: during the interval and L: total length of the specified channel to assess where the index to the highest point of the canal.
The classification provided for indicators Sl, Smf, Vf, Bs, Af by Homduni et al (2008), this indicator is obtained based on the amount of 1, 2, 3 classified in three classes. Index of active tectonic (Iat) Geomorphic indicators by means of different classes Calculated based on the value of (S /n) is divided into four classes, That the division are characterized by class 1 with very high activity Neotectonic, Class 2 with high Neotectonic activity, Class 3 with medium Neotectonic activities and and Class 4 with low Neotectonic activity. In this classification of Class1 have the highest and Class 3 have the lowest Neotectonic activities (Table11).
On the basis of Iat indicator Neotectonic activities in the under studied area were assessment and results were is in table (13). Based on the data in Table (13) , watersheds of Kan and Darband hava a high Neotectonic activities and located in Class 2 and watersheds of Vesk, Frahzad, Darakeh, Velenjak and Darabad have a medium Neotectonics activities and and located in Class 2, and Neotectonic activities are a high relative tectonic activity in all watersheds. Geomorphic indicators are reflecting activities in the metropolitan Tehran watersheds can say that tectonically active watershed has not yet reached stability and tectonic activity are relatively high. Geomorphologic indicators drainage watershed asymmetry, the main river sinuosity, the valley floor width to height ratio of density of rivers and valleys, structural geology and tectonic activity in the7watersheds of Tehran metropolis better show it.
The results show that Tehran metropolis Watersheds have a high relative tectonic activity in all watersheds, because of the proximity to the major faults (such as Mosha- Fasham and North Tehran faults) and minor faults, tectonic activity exists. Finally it can be stated that, due to the presence of multiple faults and background seismicity and tectonic activity in Tehran metropolis and its watersheds, occurrence of earthquakes in the study area is not unexpected and this issue requires serious consideration and management.
Volume 2, Issue 2 (7-2015)
With the development of economy and social services, increased need to reduce risks, control risks and other important measures in order to provide program management and follow-up plans vulnerability, Having the right information and understanding the current situation in the field is essential for prevention and planning measures, Therefore, research on risk reduction and knowledge of threats in the Arangeh region is essential, as one of the areas tourist attraction regions in Karaj's catchment area.
Geomorphology of River studies landforms and processes of river and predict changes using models and field studies and laboratory. And new analytical tools and techniques, growing and expanding with the help of river engineering.
This eventually leads to gain new capabilities in the field of river management, landscape restoration, risks and geomorphological studies ancient river.
In most cases geomorphological processes that are created by river systems, are causing environmental hazards of natural and human environments. In this paper, we have investigated the risks of geomorphic processes, especially risks of flooding and river flooding and is calculated for the maximum flood discharge for subarea also. In this article, it has been found that most of the flood will be calculated based on the map of the geomorphology of the area and the discharge sub basin. The purpose of this study, is assessing damages caused by the flood risks in the area. It is obvious that the results of this study will enable the pre-crisis phase of the crisis management system and can help to tourism and physical planning in the area.
Arangeh basin is an area of 10,090 hectares and a maximum height of 3665, at least 1637 m and average height of 2689 m. Arangeh area have an annual precipitation about 785 mm. Arangeh watershed is located within the northern city of Karaj, 15 km Karaj Branch, Karaj Dam east side of the river and inferiors (Amir Kabir).
In this study, to analyze the flood in the basin, a variety of sources are used including surveys of library data and documents, topographic base map scale of 1: 25,000 geological map of 1: 100000 taken from the ground geological, climatic data obtained from meteorological Organization, hydrological data obtained from regional water Alborz Landsat satellite image.Also field visits, the use of GPS and GIS software Arc GIS Version 10 was main parts of the survey.
The calculated concentration time by Krpych method to estimate the flood of data base, then estimate is based on a regional analysis of runoff and peak discharge of flood.
According to Hydrogeomorphic properties basin unit (sub-21) has the maximum flood discharge which is mostly covered by alluvium and located on the ground impermeable siltstone, waterways due to morphological features steep, mountainous dominant morphology, concentration time low basin, poverty and lack of vegetation (about 15 and 50 cubic meters per second in the 50 and 100-year return period). Other sub-basin with high flood discharge of sub No. 3, 5,7,9,12,14 and 16 are in Central, East, North, East and South of the basin villages.
Many parts of the Arangeh basin has slopes of more than 60%, which is an important factor in the effect of runoff, reducing the time of concentration, poor soil and vegetation and is an important factor aggravating flood risk and erosion. The presence of vegetation in these areas can have an important effect in obstructing runoff, reduce the rate of runoff, reducing flooding and consequently the reduction of soil erosion. We can largely control the flood basin watershed management practices and proper management range in the above units.
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)
Resilience are concepts that are finding increasing currency in several fields of research as well as in various policy and practitioner communities engaged in global environmental change science, climate change, sustainability science, disaster risk-reduction and famine interventions (Vogel, et.al, 2007). Where the risk is a probability of damage, injury, liability, loss, or any other negative occurrence that is caused by external or internal vulnerabilities, and that may be avoided through preemptive action (Benson, et.al, 2004). Among natural disasters, earthquakes, due to the unpredictable nature of these events, are one of the most destructive. Iran is one of the most earthquake-prone countries in the world that its cities most affected by this phenomenon. Among the cities of Iran, Tehran, as the country's first metropolis, due to dense population, poor physical development, structural density, and lack of standards, is potentially facing a serious threat. The purpose of this study is to investigate the spatial flexibility of Tehran over the region 12 after the earthquake incidence.
The present study is dealt with the data preparing and analysis using geospatial methods. The several geospatial data such as Peak Ground Acceleration (AGA) map, urban structure, infrastructure and population collected from Tehran Disaster Management Center were provided and analysis based some GIS known algorithms. In other to urban spatial resilience zonation the AHP (analytical Hierarchy Process) was implemented to generation risk map. Finally OWA (Ordered Weighted Average) method was implemented in order to Production spatial flexibility map of earthquake incidence over the District 12 of Tehran. AHP model uses of priorities straight experts, but OWA provides of control the level of compensation and risk-taking in a decision. Using the conceptual of fuzzy quantifier with OWA makes the qualitative data analysis enter to decision.
According to flexibility of the final map with fuzzy operator (All) equivalent to the operator MIN, the worst result Was obtained and resulting the highest risk and lowest flexibility respectively (Districts Nos. 2,12,7,8 and 11).By taking all the criteria of a criterion without compensation by other criteria as "non-risk" is obtained .
Map obtained with fuzzy operator (Half) has the high potential to provide suitable options, because in addition to integration criteria the importance of each parameter based on the weight given to the criteria are considered. In this map Districts Nos.2.6 and 8 (Baharestan, Emamzadeyahya and Sanglajedarkhangah) respectively were most Risk to earthquakes and therefore less flexibility to the earthquake. The map obtained with the fuzzy operator "Atleast one" is equivalent to MAX operator districts Nos. 2,12,7 and 8 (Baharestan ,DarvazehGhar of Shush,Abshardardar and Sanglajedarkhangah) respectively were most Risk to earthquakes and therefore less flexibility to the earthquake.
The fuzzy conceptual map quantifier showed that districts Nos. 2 and 12 (Baharestan and DarvazehGhar of Shush) were most vulnerable and therefore less flexibility to the earthquake as final results.
Volume 3, Issue 2 (5-2016)
Risk is an inevitable part of life, every day people are somehow at risk. Different risks in various forms and perspectives have different functions. Kurdistan province, with various heights and relatively good rainfall, It results the country's cold spots. Since most of seasonal rainfall occurs in winter, Snow cover is often the domain and passes it hillsides. One of the concerns of people in the mountainous area is a snow avalanche phenomenon. Sudden loss of massive snow is avalanche snow that may include rocks, soil, plants or ice. It seems that the name of the snow avalanche adopted from the eleventh month of the solar year. The possibility of snow in mountainous areas during this month of year is more than other months. Snow avalanches every year around the world, especially in alpine impose huge human and financial losses. Statistics and local evidence also show that the province of Kurdistan expect or accept to soil erosion and destruction of infrastructure and natural resources had a casualty. Actually, this is the most vital reason why zoning area danger avalanche was conducted in this study.
First, avalanche pathways was recognised and selected as a field visit by department of urban development The purpose of the visit was to extract the geography’s coordinates of the avalanche. The Background of the study shows some of the land criteria are more important than others. For this purpose we performed a literature survey to explore indicators that had a significant impact on avalanche snow like such as; slope, aspect, elevation, convexity and concavity, distance to roads and land. To facilitate greater accuracy, all criteria were used in geographic information system (GIS) for mapping. Thereafter, produced map can be categorised into four classes of low, moderate, high and very high. In the next step. Analytic hierarchy process (AHP) and Analytic Network Process (ANP) model were used for weighting and ranking all criteria (slope, aspect, elevation, convexity and concavity, distance to roads and land use) by using pairwise comparisons with judgments that represent the dominance of one element over another with respect to a property that they share. The Analytic Hierarchy Process (AHP) is a method for decision making which includes qualitative factors. In this method, ratio scales are obtained from ordinal scales which are derived from individual judgments for qualitative factors using the pairwise comparison matrix. The Analytic Network Process (ANP) is a more general form and extension of Analytical Hierarchy Process also uses a pairwise comparison matrix to obtain ratio scales. The difference between these two methods appears in modelling the problem and computing the final priorities for the criteria from ratio scales previously obtained. The ANP feedback approach replaces hierarchies with networks, and emphasizes interdependent relationships among all decision criteria were used in this study).
Based on the resultant Maps, AHP and ANP had a good overlap with visited points and with high accuracy lay in areas of high risk and very high risk. According to the map provided by Analytic Hierarchy Process from the total number of 30 hillsides, thirteen of them lay in very high risk and seventeen of them in the area of high risk. Thereafter, resultant maps of Analytic network Process shows from the total number of 30 hillsides twelve of them lay in very high risk area and eighteen of them in the high risk area.
The results of (AHP) indicates that from the total area of Kurdistan province, about 1049.7 square kilometres is classified in the low risk area, 11.392 square kilometres in moderate, 14.341 in the high risk area and 2009.1 square kilometres in very high risk area, respectively . In view of the process of the network as map about 978 square kilometres is in low risk area, 10245 square kilometres in moderate risk area, 15410 square kilometres in the high danger area and 2158 square kilometres is located in very high danger area. Therefore, we can use ground data for snow avalanche zoning areas along with Analytic Hierarchy Process and Analytic Network in zoning areas avalanche risk which is applicable. Weather parameters like snow, wind and temperature have an important role in terms of snow avalanche. Decreasing rainfall from west to east of study area. The number of freezing and snowing days indicates the critical situation for snow avalanche in the highlands and the pathways. More prevailing wind direction in the cities are in the Southern west, Southern and in area with high elevation blowing from western direction. Looking at the range of high and very high can be seen, mostly in the North and South and North East which show the impact of prevailing wind upon snow and putting snow in hillsides that can produce snow avalanches
. The hillsides show most of avalanche dangers are at west, northwest and south of Kurdistan thus they are compatible with rainy areas. To build any recreation centred including, winter sports, road construction and expansion, snow avalanche risk areas should be considered. Now pathways don’t have any risk signs warning about avalanches. The warning signs of avalanche at the pathways are essential.In the hierarchical model 198 villages lay at low-risk areas and 20 villages in the area were extremely dangerous. Also in the network model 184 villages in low-risk areas and 23 villages in the area were very dangerous.
Volume 4, Issue 1 (4-2017)
One of the geomorphologic issues that many human activities affect is the landslides. Natural factors and human activities on the other hand, these events are triggered. Landslide one of the most active hazards are natural processes that lead to erosion and changes in the landscape. Iran is a predominantly mountainous topography, seismic activity and high landslide, diverse climatic and geological conditions of natural conditions for a wide range of slip is important. Located in second place in the sector of industry, population of 1695094 people, proximity to major faults of Tabriz and occurrence Landslides of different city of Tabriz, the city has become one of the most dangerous cities in the environmental hazards, especially landslide. In these circumstances and completed a comprehensive review and a detailed zoning of land for landslide susceptibility seems absolutely necessary. The purpose of the present paper, the occurrence of landslide susceptibility assessment and mapping potential occurrence of landslides in the city of Tabriz in this range.
This research of the type applied- development research and of the research method is descriptive - analytic. In this study, using a variety of sources including satellite imagery, aerial photography, global positioning system (GPS) and field studies landslide occurred in the study area were identified and these data were analyzed using the software ILWIS and use of library studies and expert opinions should identify the criteria and sub-criteria and range were classified. Then, using fuzzy TOPSIS model, the importance of the criteria and sub-criteria specified in pixel units and finally combining fuzzy-TOPSIS model and overlapping functions in ARC / GIS final map was extracted.
Geomorphologic and lithology conditions of the city with its mountainous location where the trigger landslides. The final results indicate that over 30% of the areas of the city of Tabriz are medium to high risk that this areas of land in the north and northeast is sparse. The accuracy of the final map and the map of the distribution of faults and the accuracy of the study proved to be that hazardous zones roughly corresponding to the final map lapses occurred. So we can conclude that the method and the model presented in this paper is an effective method for landslide hazard zonation within the cities.
Volume 5, Issue 1 (6-2018)
Land use and land cover (LUC) change associated with climatic and geomorphologic conditions of the area have an accelerating impact on the land degradation. Natural as well as human-induced land use land cover change (LUCC) has significant impacts on regional soil degradation, including soil erosion, soil acidification, nutrient leaching, and organic matter depletion. Since the last century, soil erosion accelerated by human activities has become a serious environmental problem. It has a manifold environmental impact by negatively affecting water supply, reservoir storage capacity, agricultural productivity, and freshwater ecology of the region. In recent years, many researchers have highlighted the environmental consequences of soil erosion.
Soil erosion estimation at a regional scale is influenced by the complexity of the soil erosion process and the availability of data describing the soil erosion factors. In the last decade, regional and national level assessments of soil erosion were carried out using different approaches, ranging from indicator or factor-based approaches to process-based models. However, the revised universal soil loss (RUSLE) and its modifications are still widely used because of its simplicity and a greater availability of input parameters.
Gharesou basin is one of the sub-basins of Gharesou, it suffered from severe erosion in some areas over the past years. This erosion has occurred for different reasons and one of them is land use change and weak management of water and soil resources. The purpose of this research is to investigate the effects of land-cover changes on the potential of soil erosion in Gharesou Basin, a sub-basin of Gorganrood, in Golestan province. For this, we have employed RUSLE Model and used landsat satellite images from the sensors of TM, ETM, and OLI for 1985, 2000, and 2015. The potential soil erosion in this study was estimated using RUSLE model, which can be described using following equation:
A = R × K × LS × C × P
where A is amount of soil erosion calculated in tons per hectare per year, R is rainfall factor , K is soil erodibility factor , L is slope length factor, S is slope steepness factor, C is cover and management factor, and P is erosion control practice factor. To run the RUSLE model in GIS, first, rainfall raster layer, soil, slope, Digital Elevation Model, and also layers of soil protection range were created. Each of the involved factors was calculated in separate units in the basin level. In this research, Gharesou basin was analyzed based on raster network data with 30 meters cell size, because, from one hand it's small
enough to show heterogeneity of the basin and on the other hand, it matches pixel dimensions of landsat satellite images.
The results of land-cover changes have revealed a decrease in dense forest areas, low forest areas and the mixture of orchard, forest and pastures in a thirty years period. According to the results of RUSLE, changes of the classes indicate a general trend to the soil loss in the basin. Therefore, Gharesou basin is a basin with increasing soil erosion potential. In the plain and coastal plain areas of the basin, that is the mainly cultivated area, the amount of erosion is different from the other areas, and soil loss process is decreasing. It's due to the changes of cultivation method from traditional to modern, increase of irrigated farming area, choosing more environmentally friendly plants, and also, increase in the area of cities and villages from 7.14 percent to 29.04 percent during 30 years. In the study classes, for output of RUSLE model, in every 3 years of study, the maximum area relates to the classes of 100 to 200 Ton per year that is more seen in the mountainous regions. In these regions, all factors except vegetation are toward soil loss. Also, during 30 years, the amount of dense vegetation decreased from 34.56 to 31.55. In fact the only factor in protecting soil in (prone to erosion) areas has given its place to less effective vegetation, so, the area of this region has increased and Gharesou basin is in danger of soil loss in mountainous and forest parts. Also, areas with more than 200 Ton in hectare, with the lowest amount, have had a tangible increase during 30 year of study and its amount has increased from 11.74 to 12.50. These areas are usually located in mountainous parts with no vegetation. Also, the average of soil erosion potential estimated in Gharesou basin for 1985, 2000 and 2015 is 102.02, 103.11, and 103.76 (ton per hectare per year). This amount was found in the sub-basins too and except the sub-basin 4 located in coastal plain areas of the basin, with farming use, the amount of other sub-basins is increasing. According to the results of study, mountainous parts of Gharesou basin, has the most damage due to the accumulation of involved factors in the potential increase of soil loss. So, the necessity of watershed management is observed. Also modification of cultivation pattern and soil conservation training in farming lands of foothills and hillsides are required.
Keywords: RUSLE Model, soil erosion, Gharesou, Remote Sensing, land-cover changes
Volume 7, Issue 3 (11-2020)
In this research, two categories of data were used: the first group is data on climatic elements or unstable elements.
The annual climatic layers of the region were used for a 30-year statistical period of 2016- 2016. Measurement data on the temperature of surface temperature was obtained from a MODIS sensor in a 17-year statistical period (2000-2016). The second group of data layers and information on the ground factors or factors were stable. The layers of these variables included:
- The digital elevation layer of the area with a precision spacing of 30 meters from this layer was used as the elevation layer of the area.
2. The slope of the region, in percent, which is the layer derivative of the digital elevation model and derived from the same specifications of the DEM layer.
3. The surface layer of the surface layer that was taken from the MODIS surface coating product
4. Layer of vegetation on the surface of the earth, which was also taken from the 1 kilogram MODIS vegetation cover
5. Soil layer that was prepared by the country's water and soil organization
The rainfall factor is the most important and most important factor in determining the areas susceptible to becoming dusty. The weight of this factor in determining and identifying areas susceptible to dusty cores was equal to 239%. Vegetation factor, which was prepared using the NDVI indicator of the MODIS product, was the second factor in the development of dust-prone areas with a weight of 199.99. Relative humidity factor is the third factor or component that influences the determination of suitable areas to become the local focus of dust. The weight of this factor is equal to 0.15. The wind speed factor is in the fourth place in terms of determining the areas susceptible to dust. The relative weight of this factor is estimated at 116.0. As shown in Table 14, slope and elevation factors are the least important factors that can play a role in the production and development of dusty centers. The weight of these factors in identifying areas susceptible to formation of dusts is 0.024 and 032.2, 0 is detected. The calculated incompatibility index for this weighing is as high as 4.8, as shown in Table 15, which indicates that the contradiction between the offered weights of indices relative to each other is less than the allowed threshold (12).
Neutbay expressed the highest concentration of areas susceptible to dust mites in the eastern region, especially the northeast of the province, which includes the cities of Azna and Aligudarz. There are also parts of this category in the southern regions of the study area, including the cities of Poldokhtar and Rumshagan. In the central regions of the province as well as in the northwest of the province including the Khorramabad, Delfan, Dynasty and Dorood districts this class is not observed. In the southern parts of the city of Kohdasht, small parts of the floor of the potential centers of dust are also observed. This flooring has the most risk of becoming a dusty focus. The power source of many of the province's dusty incidents can also be said to be areas where some of them are currently potential sources of dust. Since they have played a major role in the identification and detection of these areas, rainfall and vegetation cover, these areas are exactly in line with parts of the province, which, firstly, have a mean rainfall of less than 250 mm, and the density of vegetation is less than 2 / 0 (NDVI index), which represents a very poor vegetation and, in fact, a lack of viable vegetation. In terms of land use, these areas, or inferior land, or very rangelands, are very weak.
Volume 8, Issue 2 (9-2021)
Air pollution, as one of the most important environmental hazards in urban areas, is closely related to weather conditions. Today, pollution in metropolitan areas has become an important issue that requires the study and presentation of practical solutions to improve living conditions in this area. Therefore, understanding the relationship between synoptic systems and air pollutants helps a lot in how to solve environmental problems and future planning. Therefore, in this study, compression algorithms of carbon monoxide emission and transfer from domestic and foreign sources were analyzed. For this purpose, GEOS-5 / GMAO / NASA satellite images were used. The results showed that the highest amount of pollution from the seasonal point of view is related to the cold and early morning seasons and the lowest is related to the early afternoon and hot season of the year. And Khuzestan are densely populated carbon monoxide cores. Low pressures of the eastern Mediterranean play an important role in reducing pollutants in the southwest of the country and in the south of the country, under the influence of atmospheric currents from the topographic cut of Bandar Abbas, air streams polluted with carbon monoxide are able to penetrate into the interior to the southern half of Kerman. Increased by low pressure systems in Afghanistan and Pakistan. The Zagros Mountains also play an important role in preventing the entry of pollutants produced by western neighbors into Iran. In summer, Iran is polluted by carbon monoxide carriers by monsoon currents from central and southern Africa to Iran and has caused a lot of pollution
Volume 8, Issue 4 (1-2021)
Introduction: Assessing the vulnerability and pollution of the aquifer is necessary for the management, development and allocation of land use, quality monitoring, prevention and protection of groundwater pollution. The purpose of this research is to identify and analyze the qualitative vulnerability of the Mashhad plain aquifer in order to monitor and manage underground water resources and prevent its future pollution.
Methodology: Mashhad plain is located in the northeast of Iran between Binaloud and Hezarmasjed mountains and in the watershed of the Kasfroud river, and its area is 2527 square kilometers. In this research, the vulnerability of the Mashhad Plain aquifer was evaluated with DRASTIC and SI models, and ArcGIS was used to analyze the parameters and prepare the vulnerability map. DRASTIC model is one of the overlap and index methods. In this method, the seven measurable parameters for the hydrogeological system include the depth of the groundwater level(D), net recharge(R), aquifer environment(A), soil environment(S), topography(T), Impact of the unsaturated Zone(I) and hydraulic conductivity(C) is used. The ratings for the sub-layers of each criterion vary from one to ten depending on their impact on the vulnerability potential. In SI method, five parameters of groundwater depth(D), net recharge (R), aquifer lithology(A), topography(T) and landuse(LU) are used for aquifer vulnerability. After preparing the SI model layers and weighting each of the layer classes using the functions available in the ArcGIS, the sensitivity index is obtained from the weighted sum of the mentioned parameters.
Conclusion: Study area is divided into four zones with very low vulnerability(21.85%), low(32.09%), medium to low(31.05%) and medium to high vulnerability(14.59%). Also, based on the results of the SI model, the study area is divided into five areas with very low vulnerability(0.4%), low(24.63%), medium to low(23.98%), medium to high(18.71%) and high vulnerability(32.25%). In general, the vulnerability of the aquifer increases from the southeast to the northwest.For verification, statistical method and calculation of correlation coefficient between vulnerability maps and TDS layer was used in TerrSet software and the results showed that both DRASTIC and SI models have high accuracy in zoning the vulnerability of Mashhad plain aquifer, so that the correlation coefficient of vulnerability maps with index The quality of TDS in Drastic model is (0.996) and in SI model (0.995); Therefore, the results of the following research can be used in environmental assessments and analysis of various pollutions and can be used as a basis for management decisions.
Volume 9, Issue 2 (9-2022)
Space-based quantification of anthropogenic CO2 emissions in an urban area using “bottom-up” method
(Case study: Isfahan Metropolitan)
Abstract
Increasing consumption of fossil fuels in urban areas emits enormous amounts of greenhouse gases into the atmosphere. Therefore, the study of carbon dioxide (CO2) emissions from urban areas has become an important research topic. The main purpose of this study is space-based quantification of carbon dioxide emissions driving from fossil fuel combustion in different source sectors in Isfahan. To achieve it, in the present study, the "bottom-up" method was used to quantify the carbon dioxide gas emission based on its production sources sectors. In this method, the amount of emission was measured distinctly for different sources of energy consumption and consequently the spatial distribution map the CO2 emission was generated. The results of this study revealed that the total amount of carbon dioxide emissions driving from fossil fuels is 13855525 tons per year in Isfahan. Separately stationary sectors of power plant, housing and commercial and mobile sources including road and railroad and existing agricultural machinery were responsible for emitting 50.61, 21.78, 17.18, 4.92, 4.37, and 1.14% of CO2, respectively. In conclusion, through applying the bottom-up method and CO2 emission distribution mapping based on different source sectors, mitigation measures can be applied more efficiently in urban planning.
Key words: Greenhouse gas (GHG), Fossil fuel combustion, Mobile and stationary source of energy consumption, climate change, Mitigation strategies
Volume 9, Issue 4 (3-2023)
One of the most important issues that has always affected the Iranian climate and has left many socio-economic consequences and financial losses climate change is. On the other hand Sea level pressure is one of the most important climatic elements that can affect other climatic elements such as temperature, humidity and wind. The study aimed to evaluate CMIP5 models based on CORDEX and Verdai dynamics Seasonal pressure anomalies in Iran among CMIP5 models based on CORDEX project dynamic models BCC-CSM, HadGEM2-ES, GFDL and MIROC model HADGEM2-ES had a higher level of correlation and efficiency than other models.
The data of 36 synoptic milestones during the statistical period (1960-2005), the data of the HadGEM2-ES model were applied by using the CORDEX model and the RCPs scenarios for the two historical periods (1960-2005) and predicted during Three periods of near future (2040-2011), middle future (2070-2041) and distant future (2099-2071) were used. Six methods R2, MAE, MBE RMSE, t-Jacovides and t-Jacovides / R2 ratio were used to evaluate the model performance. The results showed that the model has good performance in low altitude areas. Seasonal anomalies in all seasons, scenarios and time periods studied are positive and winter shows the maximum pressure anomalies between seasons.
The maximum seasonal pressure anomaly of Iran in all seasons, scenarios and periods studied corresponds to the altitudes, including its epicenter in the Alborz and Zagros heights and high geographical offerings and the minimum pressure anomaly corresponding to low and low areas such as Khuzestan plain and The southern coast of the country.
Volume 10, Issue 4 (12-2023)
Abstract
Ecological resilience is a concept that implies the reversibility of ecological structures and functions against the shocks experienced. The northern zone of Tehran, as the most important ecological support of this city, has undergone many land-use changes in recent decades. The present study has analyzed the role of land-use change in the ecological resilience of green infrastructure (as one of the pillars of ecological structure) in District 1 of Tehran Municipality. This study is an applied one in terms of purpose and is considered a descriptive-analytical one in terms of the method used. In this study Landsat satellite data (1976-2021) were used to detect the changes of interest, and landscape metrics were used to analyze the ecological resilience conditions. Based on the results of this study period, the Number of Patches (NP) has significantly increased and the Class Area (CA) has decreased during the period covered by this study. These changes indicate the fragmentation process and loss of structural cohesion of the green patches. The measurement results for the connectivity metrics (ENN and GYRATE) also showed a small connectivity between the green patches in the area. In addition, the results for CONTAG (Contagion Landscape metrics) measure indicated that, due to low connectivity, the transmission rate is low. Therefore, it can be said that the green infrastructure of the region has lost its structural cohesion in the face of land-use change, and as a result, the expected ecological functions and services have also failed. According to the results, the green infrastructure of the study area is vulnerable to land-use changes and their ecological resilience has been significantly reduced.
Volume 11, Issue 1 (5-2024)
Flash floods are one of the most dangerous natural events and often cause loss of life and damage to infrastructure and the environment. This research investigated the occurrence of the most intense continuous monthly floods (October-March) from 1989 to 2021. Precipitation data from 115 synoptic stations were selected. Then, the total rainfall of 1 to 9 days was sorted according to intensity. Using Minitab statistical software and the Andersen-Darling index, heavy rains were extracted based on the 95th percentile. Then, based on the criteria of the highest and lowest number of rainy days, the highest and lowest accumulated rainfall, the wettest and driest months were determined. Considering the three criteria of intensity, continuity, and rainfall coverage, the strongest storms in the wettest months were selected. The data used for synoptic analysis include the average sea level pressure data, the height and vertical component of the wind at 500 hPa, the wind and humidity field specific to the pressure levels 925, 850, and 700 hPa, and the horizontal moisture flux values specific to the pressure level 925, 850 and 700 hPa. The probability of the occurrence of atmospheric rivers was identified by the moisture flux extracted from the specific, meridional, and meridional wind components. The results showed that the storms of October 27-31, 2015, November 5-7, 1994, December 12-16, 1991, January 11-15, 2004, February 3-9, 1993, and March 13-15, 1996 were the strongest in the wettest months. During the storms of October, November, February, and March, moisture has been transported from the southwest of the Red Sea by atmospheric rivers to the western, southwestern, southern, and southeastern regions of Iran.
| Page 1 from 1 |
© 2024 CC BY-NC 4.0 | Journal of Spatial Analysis Environmental hazarts
Designed & Developed by : Yektaweb