Search published articles
Showing 27 results for Tehran
Mohammad Ali Saghafi, Abbas Ali Aliakbari Bidokhti,
Volume 1, Issue 1 (4-2014)
Volume 1, Issue 1 (4-2014)
Abstract
Nowadays air pollution in large cities such as Tehran have dramatic effects on public health, hence study of the way air pollutions varies with meteorological parameters appears to be important. One important aspect of sustainability of large cities such as Tehran, is controlling the emissions of pollutants as the meteorological (climatic) conditions are becoming more acute in terms of air pollution and temperature rise. In this paper some recent records of near surface meteorological parameters as well as some pollutants records are examine to observe how they change daily, monthly and annually and how they are correlated. Considering the variations of winds and temperature (extracted from a 2D sonic anemometer at 10 m at the Institute of Geophysics, Tehran University in the northern part of central Tehran, with one minute intervals) and hurly data of CO and PM10 concentrations for the same station for 2007, their relations were investigated. Also using upper air meteorological data (at 00.00 and 12.00 UTC) from Mehrabad Airport station, the stability of the atmosphere during this period was analysed. Here the buoyancy frequencies that are measure of stability of air column were calculated. For averaging of winds two methods based on the real wind vectors and wind unit vectors were used. By correlations between the pollutants concentrations and meteorological parameters, their relationships were considered. Based on the probability distributions of winds for 2007, it was found that most of the time wind speeds were in the range of 0.5 and 2 m/s. Hence most of the time due to this weak wind there was a condition of air pollution accumulations over the city and only local winds could move the polluted air over the area. Annual cycle of variations of mean surface winds had small amplitude that appears to be due to high mountain ranges that surround the city from north and east. The annual cycle of CO variations showed a peak in autumn and winter while PM10 amounts showed a trough in winter and spring. The higher values of CO in winter seems to be due to the surface temperature inversions and improper burnings of the fuel of vehicles as well as the domestic heating systems. This was indicated in the correlations between temperature and CO concentration. In annual cycle the correlation between CO and PM10 concentrations was about 0.4 which increased to 0.7 for spring time. This may indicate that in this season the sources of these two are similar and one of them may be used to estimate the others is the sources are not changed. There are two maxima in the daily variations of CO which coincides with minima of wind in morning and evening transition times. In this study it was found that due to calm meteorological conditions (often od local origin, called mountain breezes) over the city air pollution problem is a serious problem requiring more emission control. Also trend factors as the pollutant sources (traffic) and the depth of the atmospheric surface layer are important. It is particularly noticeable that during the midday as the depth of the mixed layer increases, the air pollution concentration is reduced substantially. At night surface drainage flow from north of the city and surface radiation cooling creates near surface inversions that can limit mixing and ventilation of the polluted air from the area leading to higher values of gaseous pollutant over the city. Also lager stability in the air over the city at higher levels in autumn and winter is due to subsidence inversions as a result of the prevailing meteorological conditions of high pressure systems over this area in these months. Such conditions seem to have increased the creation of more acute conditions for air pollution over the city. For a more resilient city in terms of air pollution, some mitigation need to be undertaken in the face of climate change effects that are deteriorating the atmosphere of the city.
Tajeddin Karami,
Volume 1, Issue 1 (4-2014)
Volume 1, Issue 1 (4-2014)
Abstract
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.
Moosa Kamanroodi Kojuri,
Volume 1, Issue 2 (7-2014)
Volume 1, Issue 2 (7-2014)
Abstract
Illegal sale of extra building density (footages) and building violations all are being considered as the most important measures regarding urban management rent issues in Tehran, between 1991-2001. This in turn, intensifies the occurrence of building violations and instability regarding to Tehran’s spatial organization during the mentioned decade. This study aims to investigate the type, rate and spatial distribution of building violations and spatial-physical changes in districts of Tehran metropolis. The objective of this paper is to identify and explain the types of urban management functions and their resulting consequences in Tehran metropolis. The distribution pattern of building violations and some of their impacts are the major outcome of this research. This research based on its objective, possesses applied nature at strategic level. This study is based on spatial-structural and analytical approach. The under study area are all constructions in 22 districts of Tehran metropolis. It further supports the application of documentation. Data analysis demands descriptive statistic as well as GIS technique. This study suggests that 59% of all the issued construction permissions are associated with zone 1-5 followed by 67% which pertains to zones 1-7 between 1993-2002. These northern zones possess large holdings, good location, comparative advantage and very beneficial vertical density. About 117028 building licenses contain extra building footage problems. Total area of these violations occurrences has been amounted up to 32710210 meters. The distribution of the extra building footages associated with different zones represents a sharp but regular gradient with north-south direction. Moreover, this study suggests most of the governmental institutions committed violations associated with illegal land possessions as well as construction of illegal land uses in the area of public lands during 1990 decade. In addition, 249 illegal constructions pertaining to public institutions were identified by 2002 out of which 137 (55%) were visited by Tehran's municipalities.
The statistics associated with Tehran's building violations which referred to variance number 1 of 100 municipality law represents a high magnitude and level of violations occurrence during 2000 decade. The total area deal with these building violations inspected by these commissions has been amounted to be 2810559 and 1565644 square meters in 2001 and 2008 respectively. However, some of these types of violations informally resolved without ever referred to this corresponding municipality commissions. Most of these violations are associated with land use changes (56.98%). This is followed by violations pertaining to extra density footages. It is argued that 3.5 violation cases registered against each issued construction license between 1997-2008 in Tehran metropolis. Generally, the issuances of building permits and sale of extra construction density and footages were dealt with market demand and geared toward gaining its resulting rents. These measures and actions were contradicted with Tehran's master plan principles. These violations possess a sharp gradient with north-south directions in Tehran's south and north economic-social basins. These activities are harmful to public interests and simultaneously very beneficial to very small inclusive private group which possess capital and lands. This in turn, is associated with lack of a master plan and subsequent spatial equalization, imbalanced land uses per capita and services and cons equally. Tehran's unsustainable physical development, For instance, Tehran's residential per capita in 1991, 1996, and 2001 has been amounted to be 20.35, 22.51 and 23.88 square meters respectively. This amount is associated with 17.37% growth rate unit during 1990 decade. However, Tehran's residential per capita in 1996 and 2001 have been underestimated and amounted to be 17.8 and 12.8% respectively compared with 1995 estimation (27.39 square meters). Tehran's existing commercial per capita in 2001 (2.05 square meters) compared with previous estimation of 1996 (0.87 square meters) shows 136.44% growth. This has been resulted from change in existing residential unit in central part of Tehran. Tehran's military per capita land use in 2001 (7.50 square meters) compared with the previous estimation of 2006 (1.5 square meters) shows 400.87% growth as well.
Ali Saei, Seyed Ali Badri, Nasrin Kazemi, Fayezh Tajik,
Volume 1, Issue 3 (10-2014)
Volume 1, Issue 3 (10-2014)
Abstract
Various community groups can play important role in disaster management. Countries with different segments of people directly participate in activities to reduce the risk. Therefore, regarding the role of women's participation in disaster management process and as a part of human society will have an important role in this process, identify and analyze the factors affecting women's presence is essential. However, the central role of women in families and communities remains unknown in most parts of the world specially in planning and managing the disaster. The purpose of this study is to identify and understand the different capabilities of women to participate actively in the cycle of disaster management and providing strategies for increasing women's participation in the prevention, preparedness, response and recovery of probable disasters. This study is an original and practical research. According to the theoretical research, a questionnaire was designed in four parts and it was completed through sampling. The sample population is women living in 22 districts of Tehran. This study implies that there is the low participation rate of women in disaster management among citizens of Tehran. To complete the data, proportional sampling was used and data were analyzed using factor analysis. Using this method, the data and the variables were summarized and the most effective factors were set in the partnership. These factors include disaster management, cultural factors and gender, fatalism, a feeling of power and confidence that the results of the factor analysis was performed using four dimensions. Based on tradition of social research and the findings of previous empirical research on women's participation in disaster management and the factors influencing voluntary participation, contextual condition of social variables (including socio-economic condition, occupation, marital status, number of children and age), as well as religious and fatalistic attitude would studied and evaluated the factors influencing the motivation and willingness to participate as a volunteer in the field of disaster management. The findings show that KMO value was equivalent to 0.74 in four factors of disaster management and the total values of the sector were defined 67.42% of total variance of the variables. KMO value in the sense of power and confidence variables was 0.72 and 65.27% of this segment can be explained by four factors the variability of the variables. In fatalism variable the KMO value was 0.599 and 59.56% of the four factors could explain the variability of variables. Finally, the KMO of socio-cultural norms was 0.71 and 70.52% of the variability of the variables was explained by five factors in this sector. Women cooperation alongside men play a major role in the use and implementation of policies and programs related to accidents. Thus, participation as one of the arguments in crisis management requires people involved in all processes related to the crisis management cycle. Since public participation opportunities and fields are different in societies and in different groups, so, to attract the participation in each group, identifying effective components is essential. Finally, after using factor analysis and extracting four factors, including knowledge of effective crisis management, cultural factors and gender, fatalism, a sense of power and self-confidence were classified. In general, most people do not do any activities in disaster management and their awareness and knowledge does not lead to disaster management needs. Thus, organizational barriers, structural, administrative and educational activities to promote social and cultural constraints are considering strategies promoting women's participation in disaster management cycle.
Amir Saffari,
Volume 1, Issue 3 (10-2014)
Volume 1, Issue 3 (10-2014)
Abstract
Today, urban and regional issues related to sustainable development is a key challenge for policy-makers, planners and specialists in various disciplines. Geomorphologic studies can be useful and effective in analyzing and deriving acceptable means to assess the growth and development of the city, and to set criteria to determine the directions of urban development. Landslides range of motions not only affect the human structures such as roads, rail lines and residential areas, but also lead to casualties. Tehran metropolis mountainous basins, including Kan, Vesk, Farahzad, Darake, Velenjak, Darband, Golabdare, Darabad, Sorkheh-Hesar, and Sohanak due to the lithology, geologic structure, weathered sediments, steep slope, rainfall and poor urban development are considered as one of the places where landslides are a range of geomorphologic processes can be studied. At this research, using Fuzzy and AHP methods and by the use 8 factor variables such as lithology, elevation, slope, aspect, annual rainfall, maximum daily rainfall, distance from fault and drainage system. the map of landslide zonation hazard in mountainous areas of the city is prepared to determine risky strips. After the standardization of the criteria for the occurrence of landslides and using frequency ratio method and fuzzy model and functions, Landslide hazard zonation maps was prepared for evaluating from the fuzzy sum, fuzzy product and fuzzy gamma operator 0.8 and 0.9. Then the final map of landslide zonation, obtained from the above-mentioned method matched with the map of urban regions in mountainous areas. In this way the constructed region have been distinguished from very high and very low hazard zonation. Lithological studies showed that most of the basin areas covered by Karaj Formation. About 45/7 percent of units with sliding movement in areas with "rock crystal tuff and tuff lytic green, with the layers of limestone" (unit Et2) of the intermediate tuff formation occurred. Cross of faults distance map with landslide density map showed that about 33/1 percent of landslides occurred within 200 m of the fault lines and 78/4 percent of landslides occurred within 500 m of drainage network. Most sliding movements (60/2 percent) in the range of 1900 to 2500 meters altitude and about 35/3 percent of this type of range of motion in height of 1500 to 1900 meters occurred. This area is about 81/6 percent of sliding movements in slopes between 15 and 40 degrees (26/8 to 83/9 percent) and about 17/6 percent on slopes less than 15 degrees (26.8 percent) occurred. In the aspect, sliding movements of the basin, mainly in the south-western slopes (about 23/2 percent), the South (about 17/5 percent), West (about 16/6 percent) and Southeast (about 77/1 percent), northwest (about 33/1 percent) occurred. About 88/9 percent of sliding movements in areas with average annual rainfall of 244 to 280 mm occurred. According to the zoning map, 12 percent of mountainous basins area (approximately 10,057 acres) is in the zone of very high risk, 33 percent (approximately 27,723 acres) is in high risk areas, 20.5 percent (approximately 17,143 acres) in the moderate risk zone, 30/ 7 percent (approximately 25,672 acres) in area and 3.8 percent of the total area of the basin, low risk (approximately 3172 acres) located in low risk areas. The results showed that approximately 5.2 hectares (about 0/05 percent) of the urban in zones with a huge landslide, about 51/5 acre (approximately 1 percent) in zones with high landslide risk and about 821 acres (equivalent to 25/16 percent) in the medium risk landslide zones are located and developed. The final results indicate that some mountainous regions of Tehran Metropolis are apt to landslide with middle to high risk. (Apart from strengthening the vulnerable area) avoiding these areas is an important solution to decrease damages caused by landslide.
Amir Saffari, Amir Saffari, Ezatollah Ghanavati, Amir Karam,
Volume 1, Issue 4 (1-2015)
Volume 1, Issue 4 (1-2015)
Abstract
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.
Farimah Bakhshizadeh , Hani Rezayan, Mehry Akbary,
Volume 2, Issue 1 (4-2015)
Volume 2, Issue 1 (4-2015)
Abstract
Air pollution has become one of the main problems of cities. Among the sources of air pollution, vehicular traffic plays an important role. Planning for efficient management and control of the air pollution caused by vehicular traffic requires accurate information on spatio-temporal dispersion of the pollutions. This research studies 3D spatio-temporal dispersion of NOx pollution caused by vehicular traffic at Valieasr-Fatemi intersection resides in Tehran, Iran. It is selected for being crowded and having the required meteorological and pollution data sensed by the Air Quality Control Corp. of Tehran Municipality.
This study uses GRAL that is a local micro-scale air dispersion model defined based on Euleran-Lagrangian dispersion models. It investigates the level of spatio-temporal autocorrelation generated by GRAL simulations at both 2D and 3D modes and discusses how it adapts with the reality.
Adopting the GRAL air pollution dispersion model, streets are defined as the linear source of pollution of NOx caused by vehicular traffic. The traffic rate is estimated based on street areas and directions, the designed average traffic velocity, traffic volume and car passage counting at the intersection. The 3D geometry of the buildings is also added to the model. All the required data that were available for winter of 2007 are gathered and introduced into the model.
The model is executed at 9 heights vary from 1.7 m to 52.5 m. These heights are defined covering a range from an average human level height to average building height and above. These levels are considered both separately in 2D mode and integrated into a 3D mode. The formation of NOx clusters is investigated analyzing their autocorrelation using Moran Index at global and local scale.
The calculated Moran-I at global scale at each 9 levels of heights, varies from 0.7 to 0.9 that depicts the validity of the GRAL model adopted to simulate the expected autocorrelation of pollution density affected by spatial issues. The Moran-I increases at higher levels as less air turbulence happens. However the result show that the turbulence increases temporarily at about 10m to 15m which are the average building heights. At local scale, the Moran-I/Anselin shows that HH clusters dominate at lower levels, around streets central areas that are farther from the buildings, and around the intersections. At higher levels, esp. higher than buildings average height, the LL clusters dominate. However the HH clusters formed around intersections, while are shrank, are still visible at high levels. The turbulence caused by building fronts and their down wash effect is also shown in the result as no definite cluster is formed near the buildings front and back.
The autocorrelation analysis is also carried for an integrated 3D model consists of all the 9 levels of heights. Considering the weight matrix for a 20m 2D neighborhood and 1m/s dispersion of the pollution vertically, the global calculated Moran-I equals 0.229 which shows existence of a spatio-temporal autocorrelation of the results generated by GRAL. At local scale the results show that the HH clusters have higher temporal dispersion rate than LL clusters.
Manijeh Ghahroudi Tali, Khabat Derafshi,
Volume 2, Issue 2 (7-2015)
Volume 2, Issue 2 (7-2015)
Abstract
Flood as a natural disaster follows certain erratic patterns which was made confounding factor. Flood risk is variable and complex that depends on very phenomena such as rainfall, runoff concentration and high exposure of the flooding downstream areas.
This are changes over time and from regions due to natural conditions, human activities, and damage culture of the community at risk. Occurrence of chaos at flood risk changes the trend of predictable processes. In the other words, although flood is a disaster, the occurred irregularities in its patterns can reveal its complicated nature. Flood pattern irregularities are the incident evidence of chaos in the system which can be studied by fractal geometry. The occurred events in spatial variability of floods in the last 50 years show they can be occur as unusual urban flood in Tehran.
Tehran city may experiences the difference life and property damages because the high varieties in the socio-economic and the life quality level in regions, also structural varieties in the city fabric??. Ignoring the natural factors in spatial planning, overrun and destruction of natural morphology as a result of urban activities and subsequently disturbing urban drainage system lead to unpredictable and destructive floods in Tehran.
The Tehran precipitation layer was prepared based on 27 weather stations data in the period of 10 years (1998-2009) and Kriging model with a Gaussian function. The runoff is calculated by Soil Conservation Service Curve Number (SCS-CN) and precipitation layer. The flood hazard potential map has been created by 8 variables and Analytic Hierarchy Process (AHP). This map as an index to define the said complexity was prepared in 5 categories of risk by combination of Tehran metropolis flood hazard and vulnerability maps. Then it was divided into hydrological basins and 12 basins were selected randomly. The Perimeter-Area Fractal and Number-Area Model were used to study the chaos and turbulence in the Tehran’s flood pattern.
Explanation of locational changes of risk between the basins needs to calculate the weighted average risk and the independent variables in 12 basins that obtained by zonal statistics. Based on these average values the factor analysis used to determine the Varifactors or main components of the variability in flood risk between the basins. Finally, fractal geometry models (perimeter-area and cumulative number-area) were used to demonstrate the chaos of the flood risk value in 5 categories of risk.
In this research the Tehran flood zoning map was calculated at 5 hazard categories. The fractal of sample basins had increased by increasing in the level of hazard map. Generally, the higher DAP values from 1 represented increasing in the chaos or irregularities of Tehran floodhazard. The obtained DAP from very low to very high risk levels are 1.206, 1.216, 1.23, 1.263 and 1.293 respectively. The increasing of DA indicated that turbulence hazard increases based on Perimeter-Area fractal model, thus, with the increase in hazard the DAP and DP values were greater. Also, the results of Number-Area Model showed turbulence floods in the five classes of hazard. The area cumulative number of risk levels are 0.74, 0.79, 0.85, 0.86 and 0.88 respectively; this trend showed the less size of flood risk polygons from very low to very high risk levels. In the other words, by increasing the risk level the polygons gets smaller and indicates the increase the flood risk chaos.
The occurrence pattern of natural phenomena and even natural hazards have a regularity type in normally condition; if this regularity disrupts for any reason, irregularities or chaos happens. In present study, the results of fractal analysis in sample basins presented the chaos pattern in Tehran floods. Also the heavy rainfall can be predicted in Tehran but the prediction of the flooding distribution was not provided. According to the recorded floods in Tehran the flooding begins always in the northern valleys of Tehran, like Darband, Kan or Golabdareh basins, are not similar to damage pattern. As a result, despite several studies and projects which have been implemented about flood phenomenon in Tehran, this is unpredictable and uncontrollable in the city.
Mohamad Saligheh,
Volume 2, Issue 3 (10-2015)
Volume 2, Issue 3 (10-2015)
Abstract
Tehran, in the south of Alborz Mountains, is faced with three types of weather risk, weather risk caused by geography, climatic risks caused by air resistance and weather risk due to global warming. The aim of this study is to examine the three types of risk in Tehran. The method of this study was to evaluate the changes of synoptic factors that affect global warming and urban development. In order to detect the height changes of 500 hPa two 5-year periods including 1948 to 1952 and 2010 to 2014, were studied.
The results showed that changes in heights of 500 geopotential, there was an increased risk in the city of Tehran. The effect of climate change in recent decades, increased the stability of air in Tehran. Human factors in the formation of heat islands, increase LCL height and density of the air balance is transferred to a higher altitude. Changing urban wind field, atmospheric turbulence intensified, exacerbated thermodynamic gradient, fat and refugee cyclones, heat island effect of the city.
Thermal stability in the warm period will appear. The thermal stability of all levels of lower, middle and upper troposphere was intensified. Thermal stability couraged the development of subtropical high pressure in the area. With the arrival of the atmospheric pressure during calm and humid days the stability and pollution were increased. Negative vorticity from early June developed the intensive high pressure over the region. Compare the conditions of the two study periods showed that : the height of the high pressure was 100 meters higher than the second period. The number of days of intensified subtropical high increased during the second period. The high pressure has moved to the northern areas during the second period. This change in the subtropical high pressure increased the dry periods motivating the loss of vegetation. Heat island effect was increased as well. More than 90% of the temperature inversions occurred at an altitude of less than 500 meters in both warm and cold periods of year. Wind direction at both stations has shown that the establishment of any pollutant source in the West of Tehran will increase the pollution.
Hassan Afrakhteh,
Volume 2, Issue 4 (1-2016)
Volume 2, Issue 4 (1-2016)
Abstract
The City-region of Tehran is encountered with various environmental problems, including traffic, air pollution, lack of drinking water and green space, physical texture conflict, flood and earthquake. Capital accumulation has considerable role in shaping spaces which can create and intensify environmental disaster in special socio-economic situation. The second cycle is the conversion of capital to fixed and long-term assets with the aim of further benefits, which in fact produces two types of artificially environment during this process namely the built environment for production, and the built environment for consumption.
The third cycle is aiming to connect science to production and increase production capacity by investment in science and technology. When production of surplus value reduced in the first cycle, surplus value of second cycle increases through speculation and real estate transaction (real estate capital). Therefore, the owners of the lands and buildings are encouraged in production, trade and supply of these type assets.
In the courtiers that are legally and administratively encounter with tax receipt problems, urban lands ownership is deposited to market system without any control, hosing transaction continues without any limitation, situation is moving forward to personal vested interests, asset value rises rather than production value, the price of land and construction increase severely. In the above mentioned condition, beneficiaries attempt convert the natural resources including park, mountain, river privacy and road privacy to marketable commodity and legally or quasi legally seize them. Therefore, unreasonable construction and population density increases and city-region will encounter with environmental disasters.
The main objective of this research is to understand the underlying factors of capital accumulation through construction and its impacts on createion and intensification of environmental disasters in the Tehran city-region.
Five different regions of Tehran were selected for data collection. "Q-methodology" was used for gathering and analyzing data. The society of communication or people whom the study sought to identify their mentality towards the research topic, were 25 experts selected through purposive sampling. To set the concourse of communication, a combination of primary (experts commented in an interview) and secondary (sources of credit) sources have been used and 34 statements have been developed. After sorting the data for analysis, SPSS software data matrix is formed. Factor analysis, as main method of analyzing Q data matrix has been used based on Q logical methodology.
The results of Q analysis depicted four viewpoints with variance of 95.911 percent on the underlying cause of capital accumulation through construction and its contribution on increasing risk of natural hazards in Tehran city-region.
The first viewpoint has devoted 52.800 percent of total variances and can be titled as" Function of real estate transaction and Non-productive economic domination".
The second viewpoint which has received 18.914 percent of total variances is accordance with "commodification of land and housing". The third viewpoint is" management and monitoring of the city-region space" with 15.163 percent of total variances. The fourth viewpoints under the title of" monitoring and control of natural resources" has assigned 9.034 percent of total variances.
As result of these processes, land and housing business have weakened society's productive capacity by extensive land use change in the urban peripheral area's due to its huge and quick profit. The above process accompany with selling excess density policy created a powerful political and economic stratum which harmed city sustainable development. The mountainous area of north, north east and west of Tehran, have annexed to metropolis as a result of above mentioned regulation and may gardens have converted to construction by different gropes and institutions.
Q method analysis depicted that the Tehran City-Region has converted from use value to exchange value. It means that values of the city including work, security, education, leisure and welfare have been lost in favor of exchange value. In other words, the city has been converted to a commodity for exchange and selling in pursuit of profit, rising cost of urban land, building and housing. Consequently, the city-region construction site is extended to the river beds, steep slops and surrounding natural environment. This in turn is leading to rapid land use change and violation of environmental and spatial rules and regulations and intensification of environmental hazards.
Jalal Karami , Aminah Mohamadi, Mohammad Sharifikia,
Volume 3, Issue 2 (5-2016)
Volume 3, Issue 2 (5-2016)
Abstract
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.
Mojtaba Rafiean, Hadi Rezai Rad,
Volume 4, Issue 3 (9-2017)
Volume 4, Issue 3 (9-2017)
Abstract
The simplest definition of urbanization is that urbanization is the process of becoming urban. Urban climate is defined by specific climate conditions which differ from surrounding rural areas. Urban areas, for example, have higher temperatures than surrounding rural areas and weaker winds. Land Surface Temperature is an important phenomenon in global climate change. As the green house gases in the atmosphere increases, the LST will also increase. Energy and water exchanges at the biosphere–atmosphere interface have major influences on the Earth's weather and climate. Numerical models ranging from local to global scales must represent and predict effects of surface fluxes. The urban thermal environment is influenced by the physical characteristics of the land surface and by human socioeconomic activities. The thermal environment can be considered to be the most important indicator for representing the urban environment. Vegetation is another important component of the urban ecosystem that has been the subject of much basic and applied research. Urban vegetation influences the physical environment of cities through selective absorption and reflection of incident radiation and regulation of latent and sensible heat exchange Satellite-borne instruments can provide quantitative physical data at high spatial or temporal resolutions. Visible and near-infrared remote sensing systems have been used extensively to classify phenomena such as city growth, land use /cover changes, vegetation index and population statistics. Finally, we propose a model applying non-parametric regression to estimate future urban climate patterns using predicted Normalized Difference Vegetation Index and Heat Island Intensity.
I conducted all spatial analysis in the UTM Zone 39 Northern Hemisphere projection. The fundamental procedure I used for evaluating change in land surface temperature was to relative temperature for both images, so that the values are temperature difference between the coldest and hottest areas in Tehran metropolitan. subtracting these images from each other results in relative temperature change from 2003 to 2015. Landsat satellite data were used to extract land use/land cover information and their changes for the abovementioned cities. Land surface temperature was retrieved from Landsat thermal images. The relationship between land surface temperature and landuse /land-cover classes, as well as the normalized vegetation index (NDVI) was analyzed.
In this study, LST for Tehran metropolitan was derived using SW algorithm with the use of Landsat 8 Optical Land Imager (OLI) of 30 m resolution and Thermal Infrared Sensor (TIR) data of 100 m resolution. SW algorithm needs spectral radiance and emissivity of two TIR bands as input for deriving LST. The spectral radiance was estimated using TIR bands 10 and 11. Emissivity was derived with the help of land cover threshold technique for which OLI bands 2, 3, 4 and 5 were used. The output revealed that LST was high in the barren regions whereas it was low in the hilly regions because of vegetative cover. As the SW algorithm uses both the TIR bands (10 and 11) and OLI bands 2, 3, 4 and 5, the LST generated using them were more reliable and accurate. NDVI negatively affected LST and Urban Heat Island in vegetation areas in 2003 and 2015 in Tehran metropolitan. This analysis provides an effective tool in evaluating the environmental influences of zoning in urban ecosystems with remote sensing and geographical information systems. This method exhibits a promising performance in UHI forecast. The predicted LST confirms that urban growth has severely influenced UHI pattern through expanding the hot area. Our study confirmed that LST prediction performance is strongly depended on the resolution.
The results reveal that the urban LST is affected mainly by the land surface characteristics and has a close relation to the abundance of vegetation greenness. The spatial distance from the UHI centre is another important factor influencing the LST in some areas. The methodology presented in this paper can be broadly applied in other metropolitans which exhibit a similar dynamic growth. Our findings can represent a useful tool for policy makers and the community awareness of environmental assessment by providing a scientific basis for sustainable urban planning and management. This provides an effective tool in evaluating the vegetation greenness of different zoning in urban ecosystems with remote sensing and geographical information systems. From the perspective of land use planning and urban management, it is recommend that planners and policy makers should pay serious attention to future land use policies that maintain a relevant proportion of public space, green areas, and land surface physical characteristics.
I conducted all spatial analysis in the UTM Zone 39 Northern Hemisphere projection. The fundamental procedure I used for evaluating change in land surface temperature was to relative temperature for both images, so that the values are temperature difference between the coldest and hottest areas in Tehran metropolitan. subtracting these images from each other results in relative temperature change from 2003 to 2015. Landsat satellite data were used to extract land use/land cover information and their changes for the abovementioned cities. Land surface temperature was retrieved from Landsat thermal images. The relationship between land surface temperature and landuse /land-cover classes, as well as the normalized vegetation index (NDVI) was analyzed.
In this study, LST for Tehran metropolitan was derived using SW algorithm with the use of Landsat 8 Optical Land Imager (OLI) of 30 m resolution and Thermal Infrared Sensor (TIR) data of 100 m resolution. SW algorithm needs spectral radiance and emissivity of two TIR bands as input for deriving LST. The spectral radiance was estimated using TIR bands 10 and 11. Emissivity was derived with the help of land cover threshold technique for which OLI bands 2, 3, 4 and 5 were used. The output revealed that LST was high in the barren regions whereas it was low in the hilly regions because of vegetative cover. As the SW algorithm uses both the TIR bands (10 and 11) and OLI bands 2, 3, 4 and 5, the LST generated using them were more reliable and accurate. NDVI negatively affected LST and Urban Heat Island in vegetation areas in 2003 and 2015 in Tehran metropolitan. This analysis provides an effective tool in evaluating the environmental influences of zoning in urban ecosystems with remote sensing and geographical information systems. This method exhibits a promising performance in UHI forecast. The predicted LST confirms that urban growth has severely influenced UHI pattern through expanding the hot area. Our study confirmed that LST prediction performance is strongly depended on the resolution.
The results reveal that the urban LST is affected mainly by the land surface characteristics and has a close relation to the abundance of vegetation greenness. The spatial distance from the UHI centre is another important factor influencing the LST in some areas. The methodology presented in this paper can be broadly applied in other metropolitans which exhibit a similar dynamic growth. Our findings can represent a useful tool for policy makers and the community awareness of environmental assessment by providing a scientific basis for sustainable urban planning and management. This provides an effective tool in evaluating the vegetation greenness of different zoning in urban ecosystems with remote sensing and geographical information systems. From the perspective of land use planning and urban management, it is recommend that planners and policy makers should pay serious attention to future land use policies that maintain a relevant proportion of public space, green areas, and land surface physical characteristics.
Farzaneh Sasanpour, Navid Ahangari, Sadegh Hajinejad,
Volume 4, Issue 3 (9-2017)
Volume 4, Issue 3 (9-2017)
Abstract
International studies show that the damages caused by natural hazards is essential that special attention to natural hazards in urban societies of the world, especially in urban areas of developing countries. In many of these communities needed new ways to deal with these challenges. This method should provide sufficient knowledge to identify the nature of problems and the identification of individual characteristics, socio-economic, physical, environmental and management, would in effect do the "Back to Balance" against natural hazards. This feature Back to Balance the same resiliency. The term resilience has a very long history and its use goes back at least a century BC. According to the different interpretations of the concept of resilience, this term is rooted in the traditions of various disciplines such as law, engineering, ecological and social sciences. Today, the concept of resilience has entered the field of planning with different orientations (social, economic, physical, and administrative, etc.).Although it still focuses more attention on environmental issues and a large part of its exploration dedicated to managing the environmental hazards such as earthquakes, floods, hurricanes and global warming. Tehran, as a result of political and economic influence, special conditions to deal with the crisis in terms of the influence of natural disasters and crisis management in terms of organizational structure and legal. In this respect, residential and urban areas of 12 with characteristic their history can be acute against the imbalances caused by natural hazards and create a crisis in urban life. Therefore, the present study has been prepared for the purpose of stability analysis flexibility in District 12 of Tehran metropolitan city.
This is of cognitive research that has been done for analytical and descriptive. All data is obtained in the manner of library and field. The library of available resources and work conducted the form of a questionnaire survey. Questionnaires have been used of type Likert spectrum (numerous, high, high, somewhat, relatively low, low and very low), and its completion is done by fieldwork. Statistical population has problems of urban planning experts, among them 80 people were interviewed for targeted samples. Resiliency that includes four dimensions (economic, social, ecological, environmental and institutional). Was approved the validity of the index by 7 experts manage urban planning problems. For measuring reliability coefficient is calculated Cronbach's alpha equal to 0/79. For data analysis, the use of statistical analysis such as frequency, maximum and minimum, average and standard deviations, T-Test one sample test and Friedman nonparametric test
The results of the indicators of urban resiliency against natural hazards suggests that economic indicators 73/24 Average been determined and relatively low level, ie below the average level. Results of the test showed one sample T-Test is an indicator of economic status of urban resilience against natural hazards of poor utility. As well as the social, ecological, environmental and institutional (organizational) urban resilience against natural hazards associated with poor utility. Finally the 12 metropolitan Tehran metropolitan areautility resilience against natural hazards with respect to all dimensions were too weak. Friedman test results on the scoreboard indicators showed that the index of environmental sustainability (20/33) related to the ecology and environment in the first rank the importance of urban resilience and adaptability Index System (10/11) related to next institutional (organizational) is set as the least significant indicator. Also, significant chi-square statistic is calculated at a rate of 09/67 in three degrees of freedom at the level of 0.000. So, with a probability of 99% can be said that there is a significant difference between the performance rating of 80 specialist urban resilience dimensions (economic, social, ecological, environmental and organizational) against natural hazards, and not the distribution of the same rank.
This research been prepared with the aim of assessing the scale of urban resilience against natural hazards in District 12 of Tehran Metropolis. Results showed that social, environmental and institutional ecology and urban resilience against natural hazards associated with poor desirability. According to this result, it is concluded that the region as a whole is resilient against natural hazards. In this direction, the resilience approach guidance to managers and practitioners use of flexible decisions and concerted policy for urban management. Build resilience in this area to support programmes should invest in organizing access to both external and existing resources in a fair manner, with a coordinated governance structure, and to facilitate social solidarity and support as part of disaster response. The findings also stress the importance of taking an ecological approach to studying resilience to disasters. Many factors from individual, community, and societal levels seem to be important in shaping resilience perceptions of natural hazards survivors. Understanding this evidence will help to validate and further develop indicators of resilience. Our findings point out that, despite existing pre-disaster vulnerabilities, resilience can be fostered following disasters if community members perceive availability of aid and support and mobilize resources Hence, psychosocial support programmes should invest in organizing access to both external and existing resources in a fair manner, with a coordinated governance structure, and to facilitate social solidarity and support as part of disaster response. The findings also stress the importance of taking an ecological approach to studying resilience to disasters. Many factors from individual, community, and societal levels seem to be important in shaping resilience perceptions of natural hazards survivors. Future research should conduct multiple levels of analysis with an all-hazards perspective to reveal how they can be integrated to increase adaptive capacities. Future research should focus on the process of capacity building through informing action to better prepare for disasters. Finally, this research tells us that due to the resiliency of the city will be able to have knowledge of all relevant indicators in the resiliency and reduce the adverse effects of these risks in urban communities
This is of cognitive research that has been done for analytical and descriptive. All data is obtained in the manner of library and field. The library of available resources and work conducted the form of a questionnaire survey. Questionnaires have been used of type Likert spectrum (numerous, high, high, somewhat, relatively low, low and very low), and its completion is done by fieldwork. Statistical population has problems of urban planning experts, among them 80 people were interviewed for targeted samples. Resiliency that includes four dimensions (economic, social, ecological, environmental and institutional). Was approved the validity of the index by 7 experts manage urban planning problems. For measuring reliability coefficient is calculated Cronbach's alpha equal to 0/79. For data analysis, the use of statistical analysis such as frequency, maximum and minimum, average and standard deviations, T-Test one sample test and Friedman nonparametric test
The results of the indicators of urban resiliency against natural hazards suggests that economic indicators 73/24 Average been determined and relatively low level, ie below the average level. Results of the test showed one sample T-Test is an indicator of economic status of urban resilience against natural hazards of poor utility. As well as the social, ecological, environmental and institutional (organizational) urban resilience against natural hazards associated with poor utility. Finally the 12 metropolitan Tehran metropolitan areautility resilience against natural hazards with respect to all dimensions were too weak. Friedman test results on the scoreboard indicators showed that the index of environmental sustainability (20/33) related to the ecology and environment in the first rank the importance of urban resilience and adaptability Index System (10/11) related to next institutional (organizational) is set as the least significant indicator. Also, significant chi-square statistic is calculated at a rate of 09/67 in three degrees of freedom at the level of 0.000. So, with a probability of 99% can be said that there is a significant difference between the performance rating of 80 specialist urban resilience dimensions (economic, social, ecological, environmental and organizational) against natural hazards, and not the distribution of the same rank.
This research been prepared with the aim of assessing the scale of urban resilience against natural hazards in District 12 of Tehran Metropolis. Results showed that social, environmental and institutional ecology and urban resilience against natural hazards associated with poor desirability. According to this result, it is concluded that the region as a whole is resilient against natural hazards. In this direction, the resilience approach guidance to managers and practitioners use of flexible decisions and concerted policy for urban management. Build resilience in this area to support programmes should invest in organizing access to both external and existing resources in a fair manner, with a coordinated governance structure, and to facilitate social solidarity and support as part of disaster response. The findings also stress the importance of taking an ecological approach to studying resilience to disasters. Many factors from individual, community, and societal levels seem to be important in shaping resilience perceptions of natural hazards survivors. Understanding this evidence will help to validate and further develop indicators of resilience. Our findings point out that, despite existing pre-disaster vulnerabilities, resilience can be fostered following disasters if community members perceive availability of aid and support and mobilize resources Hence, psychosocial support programmes should invest in organizing access to both external and existing resources in a fair manner, with a coordinated governance structure, and to facilitate social solidarity and support as part of disaster response. The findings also stress the importance of taking an ecological approach to studying resilience to disasters. Many factors from individual, community, and societal levels seem to be important in shaping resilience perceptions of natural hazards survivors. Future research should conduct multiple levels of analysis with an all-hazards perspective to reveal how they can be integrated to increase adaptive capacities. Future research should focus on the process of capacity building through informing action to better prepare for disasters. Finally, this research tells us that due to the resiliency of the city will be able to have knowledge of all relevant indicators in the resiliency and reduce the adverse effects of these risks in urban communities
Jamileh Tavakolinia, Alireza Mehrabi, Ehsan Allahyari,
Volume 6, Issue 2 (9-2019)
Volume 6, Issue 2 (9-2019)
Abstract
Today, air strike on installations and urban areas, is normal. As such, vulnerability assessment cities and provide the right solution for harm reduction is essential. The purpose of this investigation was to identify factors causing damage in the district of twenty in Tehran. The research method is descriptive-analytic and Data collection is library and field. Data analysis is based on using Ahp and GIS. Results show, In the district twenty , There are three zones vulnerable. Including, The old Central, The high-density Dolatabad and sizdah aban neighborhood. These zones are 34 percent of the land. The reason of it is Poor physical structure. Statistical Society is Twenty district in Tehran. Sample size is 384 people of residents of the district. Because, in this area there are strategic factors, is An important part of the tehran city. in the end, are provided The right solution of Reducing vulnerability.
Dr Abolfazl Meshkini, Mr Ali Mohammad Mansourzadeh, Mr Zeynab Shahrokhy Far, ,
Volume 6, Issue 3 (9-2019)
Volume 6, Issue 3 (9-2019)
Abstract
Identifying spatial patterns in vulnerability involves a comprehensive look at vulnerable points. And provides analytical power to the authorities. Therefore, it is necessary to recognize patterns of vulnerability so as to minimize the amount of damage to them in the event of a crisis. The city of Tehran, as the political and administrative center of the country, is faced with a variety of risks due to demographic burden and physical development. In this research, we tried to analyze the spatial distribution pattern of urban vulnerability to natural hazards in social and physical dimensions in Tehran's 7th region. The method of this descriptive-analytic study and the model used for trigonometric fuzzy logic. The results indicate that: According to the z score, the positive values are 1.96 up, which form the clusters of hot spots in the southeastern region of the arena; It is a sign of more vulnerability in these areas. Also, negative values of 1.96 and less, which are statistically significant and blue, have formed cold spots, And it is interpreted that low vulnerability zones are clustered in space and are mainly located in the northwest. Therefore, the lower the color range in the red and blue areas was less statistically significant to the point where this positive net worth is 1.65 that in this situation, the spatial behavior of the vulnerability is considered to be non-significant in terms of hot or cold clusters with high and low values and spatial autocorrelation that the map is also displayed in yellow.
Aydin Moradi, Somaye Emadodin, Saleh Arekhi, Khalil Rezaei,
Volume 7, Issue 1 (5-2020)
Volume 7, Issue 1 (5-2020)
Abstract
Khabat Derafshi,
Volume 7, Issue 3 (11-2020)
Volume 7, Issue 3 (11-2020)
Abstract
In this study, the risk map as an index to define the said complexity was prepared in 5 categories of risk by combination of Tehran metropolis flood hazard and vulnerability maps. To analyze the risk varieties, the hydrological catchments of Tehran were extracted by Arc Hydro model and 12 catchments were selected. Using land use, roads network, and the percentage of residential floor area, bridges, altitude, slope and drainage density variables, the flood hazard map was calculated. Dilapidated urban blocks, population density, land use, bridges, slope and drainage density layers were used as variables which affecting the flood vulnerability. Covariance index was applied for matched variables and considering the locational coherence between the values of them. Based on the new raster layers, flood risk variability in Tehran metropolis as well as in each of the catchments were analyzed using stepwise regression model. Explanation of locational changes of risk between the catchments needs to calculate the weighted average risk and the independent variables in 12 catchments that obtained by zonal statistics. Based on these average values the factor analysis used to determine the varifactors or main components of the variability in flood risk between the catchments. Finally, fractal geometry models (perimeter-area and cumulative number-area) were used to demonstrate the chaos of the flood risk value in 5 categories of risk. According to the flood hazard zoning map of Tehran metropolitan area, the extent of high hazard zone is 129.6 square kilometers. High risk zone covers 28.6% of Tehranchr('39')s area, indicating that most of the citychr('39')s extents (174.4 square kilometers) are located in the high flood risk zone. After that, the moderate hazard zone is 28.5% of the city area. Very low zones with 3.53% of the total area are the smallest zones in the city, which are only 21.5 square kilometers. Overall, 78.3 percent of the total area of the city is located in the moderate to very high zones of flood hazard, reflecting Tehranchr('39')s challenge to flooding. The vulnerability map defines that 138 km2 of the Tehran city area is located in high and very high zones of the flood vulnerability. According to Tehran metropolitan flood risk zoning map, 163.1 km2 of Tehran city area is located in high risk zone which has the highest rate among flood risk categories in Tehran metropolis (26.9%).
Alireza Kazemi, Behnod Barmayehvar,
Volume 7, Issue 4 (2-2021)
Volume 7, Issue 4 (2-2021)
Abstract
Due to the insecurity of the construction industry, the purpose of this study is to evaluate safety management and investigate its impact on reducing accidents of sites in urban construction projects in the south of Tehran. Due to the nature and type of research, the present study is descriptive-correlational and practical research. The statistical population in this study is supervising engineers working in the field of urban construction in the south of Tehran (15, 16, 17, 18, 19, and 20 areas). Therefore, according to the latest statistical report published by the Tehran Engineering System Organization (5000 people) and based on the Morgan table, 351 acceptable answer sheets were collected.
In this research, data collection and information were performed using the library-documentary method and field method (with the help of observation tools, interviews, and especially questionnaires) and through a combined method (quantitative-qualitative) with quantitative nature and focus as well as survey strategy. Also in this research, in addition to utilizing the capacities of qualitative content analysis, the methods of quantitative analysis include descriptive statistics including frequency, average, and standard deviation, as well as inferential statistics including Kolmogorov-Smirnov, Friedman, Pearson, T-tests and regression analysis by SPSS 24 software, was used. Questionnaire questions were validated by reviewing previous research, consulting with experts, and validating with factor analysis and reliability using Cronbach's alpha method.
The results show that among the three effective factors in improving safety management and reducing site accidents in urban construction projects in the south of Tehran, the factors of “use of protective equipment”, “compilation of responsibilities” and “risk management” with averages of 4.0864, 4.0741, and 3.9812 are ranked the first, second, and the third rank, respectively. Besides, the average part of various site accidents is 4.0000.
According to the results of the research, from the total types of site accidents of “injuries to people due to non-use of personal protective equipment”, “damage to urban underground facilities during nailing operation”, “life and financial losses due to standard and unsafe construction site equipment”, “occurrence of silent death in workers' rooms due to unsafe gas appliances and lack of proper ventilation, “collapse of structural parts during welding”, “fall of workers, materials, and equipment from a height”, and “collapse of the walls of the pit and adjacent plaques due to lack of standard and standard excavation” are ranked first to seventh with an average of 5.7692, 4.8148, 3.8490, 3.7322, 3.7236, 3.1282, and 2.9829, respectively.
According to previous research, the “policy (compilation of responsibilities)” factor has the first impact on the safety of the construction industry, but in a case where the field of research is limited to construction projects and urban constructions (personalization) in which in such projects safety management is not generally systematic in the site, the prioritization between the factors affecting the safety management of the site has changed and the “policy (compilation of responsibilities)” factor is transferred to the second rank and the “use of protective equipment” factor is placed in the first rank. Therefore, builders and employers, and that project supervisors must be required to closely monitor this carefully formulate safety responsibilities in construction workshops.
Considering that, the factor of “non-use of personal protective equipment” is in the first place as the cause of site accidents and has already been ranked in the fifth place of safety hazards, so it can be concluded that since the last decade, the factor of “non-use of personal protective equipment” has risen from the fifth to the first rank. Therefore, it is necessary to pay more attention to the use of protective equipment in construction sites in Tehran, project supervisors should be stricter in this regard, and engineering organizations and municipalities should enact stricter rules and regulations.
According to the supervising engineers active in the field of research, “damage to urban underground facilities during nailing method” is in the second place in the classification of common types of site accidents in the field of urban construction of Tehran and nailing method for stabilization of deep urban ditches causes legal problems to enter the privacy of adjacent license plaques and obtain notarized consent from the owners of adjacent license plaques, in addition to the risk of damaging underground urban facilities and causing heavy damage to the project and it is necessary to use other modern methods of deep pit stabilization, including the “Top-Down” method.
In this study, “human and financial losses due to non-standard construction site equipment” is classified in the third rank of site accidents. Therefore, the municipalities and organizations of the engineering system must make the issuance of technical inspection certificates for site equipment mandatory and if the employer and the constructor do not provide the necessary documents in this regard or to prevent the continuation of executive operations.
Because accidents due to non-observance of safety issues in construction sites continue to occur for various reasons, it is necessary to establish stricter rules and regulations regarding non-compliance with safety issues in construction sites in the field of urban construction and the use of a safety officer in the site with relevant educational and professional backgrounds and qualifications is mandatory for all construction sites.
The results of this study show that increasing attention and accuracy in the areas of responsibility compilation, risk management, and use of protective equipment improves safety management and reduces accidents in construction sites in the field of urban construction of south of Tehran.
In this research, data collection and information were performed using the library-documentary method and field method (with the help of observation tools, interviews, and especially questionnaires) and through a combined method (quantitative-qualitative) with quantitative nature and focus as well as survey strategy. Also in this research, in addition to utilizing the capacities of qualitative content analysis, the methods of quantitative analysis include descriptive statistics including frequency, average, and standard deviation, as well as inferential statistics including Kolmogorov-Smirnov, Friedman, Pearson, T-tests and regression analysis by SPSS 24 software, was used. Questionnaire questions were validated by reviewing previous research, consulting with experts, and validating with factor analysis and reliability using Cronbach's alpha method.
The results show that among the three effective factors in improving safety management and reducing site accidents in urban construction projects in the south of Tehran, the factors of “use of protective equipment”, “compilation of responsibilities” and “risk management” with averages of 4.0864, 4.0741, and 3.9812 are ranked the first, second, and the third rank, respectively. Besides, the average part of various site accidents is 4.0000.
According to the results of the research, from the total types of site accidents of “injuries to people due to non-use of personal protective equipment”, “damage to urban underground facilities during nailing operation”, “life and financial losses due to standard and unsafe construction site equipment”, “occurrence of silent death in workers' rooms due to unsafe gas appliances and lack of proper ventilation, “collapse of structural parts during welding”, “fall of workers, materials, and equipment from a height”, and “collapse of the walls of the pit and adjacent plaques due to lack of standard and standard excavation” are ranked first to seventh with an average of 5.7692, 4.8148, 3.8490, 3.7322, 3.7236, 3.1282, and 2.9829, respectively.
According to previous research, the “policy (compilation of responsibilities)” factor has the first impact on the safety of the construction industry, but in a case where the field of research is limited to construction projects and urban constructions (personalization) in which in such projects safety management is not generally systematic in the site, the prioritization between the factors affecting the safety management of the site has changed and the “policy (compilation of responsibilities)” factor is transferred to the second rank and the “use of protective equipment” factor is placed in the first rank. Therefore, builders and employers, and that project supervisors must be required to closely monitor this carefully formulate safety responsibilities in construction workshops.
Considering that, the factor of “non-use of personal protective equipment” is in the first place as the cause of site accidents and has already been ranked in the fifth place of safety hazards, so it can be concluded that since the last decade, the factor of “non-use of personal protective equipment” has risen from the fifth to the first rank. Therefore, it is necessary to pay more attention to the use of protective equipment in construction sites in Tehran, project supervisors should be stricter in this regard, and engineering organizations and municipalities should enact stricter rules and regulations.
According to the supervising engineers active in the field of research, “damage to urban underground facilities during nailing method” is in the second place in the classification of common types of site accidents in the field of urban construction of Tehran and nailing method for stabilization of deep urban ditches causes legal problems to enter the privacy of adjacent license plaques and obtain notarized consent from the owners of adjacent license plaques, in addition to the risk of damaging underground urban facilities and causing heavy damage to the project and it is necessary to use other modern methods of deep pit stabilization, including the “Top-Down” method.
In this study, “human and financial losses due to non-standard construction site equipment” is classified in the third rank of site accidents. Therefore, the municipalities and organizations of the engineering system must make the issuance of technical inspection certificates for site equipment mandatory and if the employer and the constructor do not provide the necessary documents in this regard or to prevent the continuation of executive operations.
Because accidents due to non-observance of safety issues in construction sites continue to occur for various reasons, it is necessary to establish stricter rules and regulations regarding non-compliance with safety issues in construction sites in the field of urban construction and the use of a safety officer in the site with relevant educational and professional backgrounds and qualifications is mandatory for all construction sites.
The results of this study show that increasing attention and accuracy in the areas of responsibility compilation, risk management, and use of protective equipment improves safety management and reduces accidents in construction sites in the field of urban construction of south of Tehran.
Mohhamad Soleimani Mehranjani, Ali Movahhed, Ahmad Zanganeh, Zeinab Ahmadi,
Volume 8, Issue 1 (5-2021)
Volume 8, Issue 1 (5-2021)
Abstract
Explain the Processes of Modernization on the Spatial Mismatch in Urban Neighborhoods
(The case of, Region 4 of Tehran Municipality)
Modernization processes and modern urban planning policies have had significant effects and consequences on the spatial transforms of cities in the world and Iran. Among that processes, we can mention the growing gap between social groups and urban spaces based on a number of contexts and mechanisms that, from the late 1960s onwards, have been conceptualized and measured experimentally under what is called the “spatial mismatch hypothesis”. The basic methodology for estimating the state of spatial mismatch in cities or urban regions is based on the logic of “spatial segregation” between social groups and land uses simultaneously; Because based on the spatial mismatch hypothesis, it is not possible to explain the segregation mechanisms between social groups in the city without considering its relation with segregation mechanisms in urban spaces or land uses, and vice versa. Based on such methodological logic, the present paper has assessed the state of spatial (mis)match in Region 4 of Tehran Municipality. The method of data collection was in the form of libraries and data available in the Statistics Center (General Census of Population and Housing in 2016 and at the level of demographic blocks of the region), Road and Urban Development Organization, Municipality of Region 4. Variables used to analyze the spatial mismatch in the region
The level of education, employment in study abroad and inside the country, employment and unemployment status, level of housing infrastructure, type of housing ownership, changes in land use pattern and the amount of daily commutes in the study area.
Findings obtained based on the defined variables and techniques used in Segragation Analyzer and ArcGIS software show that the state of spatial mismatch in this urban region (like many other cases in cities around the world) is high, but its intensity is higher in terms of job and literacy of social groups in relation to the state of activity and residential land uses. Relying on such findings, some strategies and policies have been proposed to reduce the state of spatial mismatch in Region 4, and to contribute to a more even and equitable distribution of development in this region and hence reduce poverty among the lower classes.
Keyword:
Urban modernization, spatial mismatch hypothesis, socio-spatial segregation, Region 4 of Tehran Municipality
Mahmoud Ahmadi, Zahra Alibakhshi,
Volume 8, Issue 2 (9-2021)
Volume 8, Issue 2 (9-2021)
Abstract
Evaluation of hot spots changes in Tehran city and satellite based on land use and its role in urban heat hazards
Expanded abstract
Problem statement:
Urbanization and human activities affect the urban climate and clearly affect the air temperature close to the surface. In Tehran and its satellite, factors such as climatic region, season, time of day and wind regimes, topography, urban environments, population density, residents' activity, vegetation structure and urban physical form play an important role in the formation of urban heat islands. The purpose of this research is to determine the type of spatial distribution of heat islands of Tehran metropolis and satellite cities using land use and land cover. Replacing natural land cover with impervious surfaces due to urban development has negative environmental, social and economic impacts, in addition to beneficial aspects. Most of the albedo belong to the built areas and the bare land and the smallest of the Albedo belong to the aquatic areas and vegetation. In this research, the hypothesis is whether the suburbs may have higher temperatures than urban areas depending on the type of land use? In fact, it is examined the spatial distribution of the heat island of Tehran and its satellites, in which the use of land and land cover are analyzed as a factor contributing to the creation, intensification or reduction of the thermal island.
Methodology:
Extraction and preparation of imagery data through the Landsat 7 Satellite ETM + sensor over the years 2001-2015 and selection of June as the hottest month of the study area. These images were extracted from Route 164 and Row 35 of the USGS. An assessment was carried out through the accuracy of ground surface temperature data by Landsat satellite images and obtained temperatures from the weather stations in the area based on the Taylor diagram. In order to investigate the spatial structure of the cells obtained in each map, each containing surface temperature and heat island extraction, it used the methods of world spatial autocorrelation (high and low clustering, spatial correlation) and local (Cluster and Outlier analysis, hot spot analysis). The high and low clustering statistics show how the concentration of high or low values in the region. In the next step, the results of analysis of Anselin Local Moran and hot spots were compared in map format. Hot spots were analyzed in all studied regions and in all 7 cities. The area of hot spots was investigated over the course of 15 years and the results were presented in table and diagram form.
Land use was surveyed for every 7 county. In the last section were studied, the relationship between hot spots in each city and type and land use changes over 15 years.
Surface spatial analysis of the surface temperature of the area showed that the cells follow a cluster pattern and their trend towards clustering. Any kind of land cover and land use will create special features in a place that can be increased or decreased with a specific microclimate.
Explaining and results:
After selecting the years 2001, 2005, 2010, and 2015 as the sample and survey of the temperature of each land use in that year, it was determined that artifact, pasture, bare lands, forest, aquatic areas, agriculture and green spaces were respectively have the highest to the lowest temperature in the area. On the other hand, in the area of heat island in a region are Rabat Karim, Ray, Islamshahr, Tehran, Shahriar, Karaj and Shemiranat, respectively.
In spite of the reduction of aquatic areas and even bare lands, because of the large impact of green space or agricultural land was reduced the extent of heat islands during the statistical period, and on the contrary, the reduction of green space and agricultural land in places where even their forest areas have grown, has increased the levels of heat islands. This suggests that the dispersion and extent of green spaces has a more effective role in reducing the heat island compared with the creation of limited forest and planted surfaces in one place. Hence, in Tehran despite the significant growth of artifacts, due to the increasing growth of green space, the heat islands has been reduced compare with the Ray, Robatkarim and Islamshahr cities, which are exactly on its suburbs.
Keywords: Heat Island, hot spots, land use, Tehran, satellite cities.
© 2024 CC BY-NC 4.0 | Journal of Spatial Analysis Environmental hazarts
Designed & Developed by : Yektaweb