Basin Erosion Study of Fadami Salt River (Fars Province) by Using Entropy Model
E
Moghimi
استاد گروه جغرافیای طبیعی، دانشکدهی جغرافیا، دانشگاه تهران
author
S
Negahban
دانشجوی دکترای ژئومورفولوژی، دانشکدهی جغرافیا، دانشگاه تهران
author
text
article
2012
per
Extended Abstract
Introduction
Erosion is the process by which soil and rocks are removed from the Earth's surface by natural processes such as wind or water flow, and then transported and deposited in other locations.
Human activities have dramatically increased (by 10-40 times) and accelerated the rate of erosion globally. Excessive erosion causes problems such as desertification, decreases in agricultural productivity due to land degradation, sedimentation of waterways, and ecological collapse due to loss of the nutrient rich upper soil layers. Water and wind erosion are now two primary causes of land degradation; combined, they are responsible for 84% of degraded acreage, making excessive erosion as one of the most significant global environmental problems.
Water is the most important erosion agent and erodes most commonly as running water in streams. Raindrops (especially in dry environments) create splash erosion that moves away tiny particles of soil. Water affecting the surface of the soil as it moves towards tiny rivulets and streams and creates sheet erosion.
In streams, water is a very powerful erosion agent. The faster water moves in streams, the larger objects it can pick up and transport. This is known as critical erosion velocity. Fine sand can be moved by streams flowing as slowly as three-quarters of a mile per hour.
Entropy was born as a state variable in classical thermodynamics. But the advent of statistical mechanics in the late 1800’s created a new looks for entropy. It did not take long for Claude Shannon to borrow the Boltzmann-Gibbs formulation of entropy, for use in his own work, inventing the “information theory”. Our goal is to show how entropy works, in all of these cases, not as some fuzzy and ill-defined concept, but rather as a clearly defined mathematical and physical quantity with well understood applications.
Soil erosion is one of the most important factors that threatens large areas of Iran annually and decreases or eliminates the quality of agricultural lands and rangelands. Due to highlands of Iran in comparison with the grounds and surrounding plains (mean elevation of 1250 m), it has been affected by water erosion. So it is very important to study erosion and present management strategies to reduce the impacts of erosion in basins of Iran. This study aims to identify erosion level and effective parameters in Basin of Fadami Salt River in Fars province.
Methodology
This research is a descriptive-analytical study based on library, statistical and filed methods. First of all the most important erosion factors were recognized in the basin including (slope, land type, soil type end etc) and then the factors were weighted by using AHP method in order to be classified. Then the level of imbalanced distribution rate of effective parameters classes in basin erosion were determined using Entropy model.
Results and Discussion
The results indicate that among the slope classes, the one with slope of more than 15 percent which causes a higher level of erosion has a balanced distribution with entropy coefficient of 0.85, so it causesa high level of erosion.
And also among the geological formations in the basin, Quaternary formations with a high level of erosion have almost a balanced distribution in the basin with entropy coefficient of 0.7.
Among the soil levels , light soils ( coefficient of 0.89 ) had a balanced distribution and among the land uses , rangelands (coefficient of 0.97 ) also had a balanced distribution. Both of them have the high levels of erosions.
Conclusion
The Conclusion of this study stresses thatentropy models have high - performance for studying erosion in basins . GIS Software and AHP model has helped us to improve performance model . In addition indicators slope , geology , land use and soil are the best indicators to determine water erosion in the basins.
Management of soil for water erosion control is based on sensible soil conservation practices. The majority of these practices are recognized components of good soil , crop , and water management . For effective erosion control : maintain good soil structure , protect the soil surface by adequate crop and residue cover , and use special structural erosion control practices where necessary are the recommended procedures.
Keywords: Entropy, Erosion management, Salt River, Fadami.
Physical Geography Research
University of Tehran
2008-630X
44
v.
3
no.
2012
1
16
https://jphgr.ut.ac.ir/article_29211_1c45f0372077184921e0009e5531be1a.pdf
dx.doi.org/10.22059/jphgr.2012.29211
Active Tectonics, Humans, and Civilization
ghasem
khosravi
دانشجوی دکترای ژئومورفولوژی، دانشکدهی جغرافیا و برنامهریزی، دانشگاه اصفهان
author
M.H
Ramesht
دانشکدهی جغرافیا و برنامهریزی، دانشگاه اصفهان
author
Mohammad Reza
Sarvati
گروه جغرافیا، دانشکدهی علوم زمین، دانشگاه شهید بهشتی، تهران
author
E.R
Force
دانشکدهی علوم زمین، دانشگاه آریزونا، توسان، ایالات متّحده
author
text
article
2012
per
Introduction
Growth in our understanding of active tectonics and tectonic geomorphology during the past 25 years has made it clear that tectonic processes happen at a variety of scales relevant to human history. This fact has presented researchers with an important question that what is the impact of active dynamics of earth's crust in continental region on human societies in both our past and future. A review of published studies shows that there are two viewpoints about the relation between active tectonics and humans. Some of the researchers emphasize the dangers of active tectonics for human beings. The other group of researchers believe that tectonic is an important factor in the evolution of humans, civilization, and the formation of ancient complex cultures.
Methodology
The aim of this study is to review the important published articles, and to analyze the corresponding viewpoints. The methodology in this study is analytic.
Results and Discussion
Functional variables
Some of the researchers believe that tectonic activity is a creative agent in human evolution and cultural development. Based on this theory, the functional variables of creative tectonics include: landforms (Bailey et al. 1993, King et al. 2010, Bailey et al. 2010 a,b) – landuse (Baileyet al. 1993, Kinget al. 2010, Baileyet al. 2010 a,b) - topographic barriers (Baileyet al. 2010, Kinget al. 2006) – active tectonic coast line (Inman 1983, Baileyet al. 2010 a,b) – roughness of earth surface (Baileyet al. 2011) – hydrology (Shrifikia 1992, Force 2008, Jackson 2006) – underground dams (Nojavan 2001) – Impact of temporal factors on geomorphic spatial characters (Babajamali 2008) – road and accessibility (Ben avraham 2005, Force and Mcfadgen 2010, Hasanalian 1991) –of chemical anomales in water, soil, rock, and biomass (Trifonovet al. 2005) – culture (Force 2010).
Ecologic influences of tectonism
Active tectonic movements can be divided into two categories: seismic movements and non-seismic movements. Non-seismic movements mainly lead to formation of various landforms, which eventually affects human ecology. Seismic movements affect cultural ecology by rupture in the surface and creation of sedimentary traps.
Hierarchy structures
Hierarchy structure is one of the fundamental characteristics of natural systems. For the first time, Hortton (1945) used hierarchy structure for ordering in the basin. Schumme (1997), Frissell (1986), Klijen (1997), Naiman (1992), and Townsend (1996) used hierarchy structure to describe natural systems. Forces shows that Alp-Himalaya belt matches 13 ancient cultures. Based on this theory, two hierarchy structures can be suggested. One hierarchy system for fault thrust belts, and the other one for human societies. This hierarchy structure that contains four levels shows matching elements in system.
Temporal and spatial scales
Active tectonic emphases on time scale of active tectonic movements. Holocen tectonic movements include the movements between 10000 B.P. and the modern era. So temporal and spatial scale should be denoted before any study, because tectonic has different effects in different temporal scales. Therefore, there is a relationship between temporal and spatial scales of active tectonics and human civilization.
Conclusion
In comparing two different viewpoints, we suggest that each has its own epistemology. In the first viewpoint (tectonic as a destroying agent), the researcher studies the subject in a static state, while in the second viewpoint (tectonic as a creative agent) the subject is studied in a dynamic state considering the time element, i.e. replacing Boolean logic by fuzzy logic. It should also be noted that some of the natural phenomena are best described with Boolean logic and some of them with fuzzy logic. We also see that some of the phenomena are in both states. The Yin-Yang symbol is the best example for this subject. So it can concluded that while tectonic activity is destructive in the static state, it is creative in the dynamic state. In other word, as far as time parameter is concerned, we can have better understanding from constructive tectonic characteristic versus civilization and human societies.
In this case zone with active tectonics, direct or indirect lead to biological optimum conditions. These areas can be the location of the collection of plants, animals and human societies and finally, civilization and cultural have been resulted.
Although we cannot ignore the dangers of earthquake, it is really important to consider the constrictive tectonic aspect for human societies which are superior to its destructive aspect.
Physical Geography Research
University of Tehran
2008-630X
44
v.
3
no.
2012
17
38
https://jphgr.ut.ac.ir/article_29212_715cc05de056d1fd16ddc8be8c296f07.pdf
dx.doi.org/10.22059/jphgr.2012.29212
Identification of Synoptic Climate Types in Sistan Area (Zabol Station)
M.
Khosravi
دانشیار اقلیم شناسی، دانشکدهی جغرافیا و برنامهریزی محیطی، دانشگاه سیستان و بلوچستان
author
hamid
Nazaripour
استادیار اقلیمشناسی، دانشگاه تحصیلات تکمیلی صنعتی و فناوری پیشرفته، کرمان
author
text
article
2012
per
Introduction
Within a synoptic weather, the classification of ambient weather conditions into categories is a useful tool for numerous climate impact applications.
Air mass is a large and homogeneous volume of air which is adequately located over a certain area and captured properties of its below area. In order to form air masses, it is necessary that air remains stable in an area for a long period of time. Ultimately, general flows of air make them move. While moving and passing different regions, characteristics of air masses are changed, modified and also transformed into another air. A location’s climate follows air masses entering to that region and, reflects geographical conditions of that location. One of the objectives of synoptic climatology is to carry out synoptic categorization or to determine dominant air types (climate) in a location in a year. Air masses are generally categorized based on potential temperature and humidity. However, other criteria are considered as bases for their categorization.
The Sistan basin is located in a arid zone with less than 60mm precipitation. This region in the east of Iran and northern regions of Sistan and Baluchistan Province has special climate that is affected by severe winds and dusty air.This climate distinguishes this region from others in Iran. The region depends onHirmand river and its embranchments inflows that import more than billions cubic meter waters and can support the survival of Hamoon international wetland and the populations of region.
The occurrence of periodic fluctuations in water inflows and potential climatic, geomorphologic and hydrologic conditions cause the surface to be exposed in winds flows. In Sistan region winds are blown throughout the year, but during the June to September the direction, frequency and intensity of wind blows are more pronounced. This wind is distinguished as 120 days winds and is one of the most famous moderate scale wind systems in the northern hemisphere.
Identifying effective air masses on this region is of considerable importance in order to better plan and make use of available resources in this region. It is because of the fact that by the analysis of its effects on the surface phenomena (e.g. dust), environmental planners would be able to find better ways for decreasing environmental problems. Finally recognizing these relationships allows us to predict many environmental accidents in order to, at least, decrease their harmful effects by these predictions.
Methodology
In this paper, to identify the prevailing air masses in the North of Sistan and Baluchestan province (East of Iran),daily data of 14 climatic variables of Zabol weather station were used.
The data were considered against atmospheric variables and utilized as a P matrix from 21/03/1975 till 20/03/2005. At first, to explore the major source of variance in climatic variables in the region, a Principle Component Analysis (PCA) was applied to the Z scores of primary data in a 10825*14 cells matrix. Findings showed that three principle components (Thermal-humidity, Wind and precipitation) could account for 87 percent of data variances and were selected as the most effective factors. Then, the principle components matrix was used as input variables in a cluster analysis for identifying prevailing climatic conditions of the region. Principal Component Analysis (PCA) involves a mathematical procedure that transforms a number of (possibly) correlated variables into a (smaller) number of uncorrelated variables called principal components. The first principal component accounts for as much of the variability in the data as possible, and each succeeding component accounts for as much of the remaining variability as possible. To obtain classes from a PCA, the component scores can be grouped via cluster analysis. A common procedure involves hierarchical clustering. HCA is a technique of choice for exploring and visualizing large data sets. HCA consists in calculating the dissimilarity, usually called the distance, between the individuals with one individual corresponding generally to one column of the data matrix.
Results and Discussion
The Hierarchical Clustering Analysis (HCA) with sequential combination methods havebeen applied to components scores and findings showed six various air masses in climatic regimes of region. These air masses are:
a) warm, without precipitation and relatively quiet;
b) dry, warm, no precipitation and windy;
c) cold, dry and windy air mass;
d) high precipitation, temperate and relatively windy;
e) very warm, dry, no precipitation and severe windy air mass;
f) very cold, quiet and less precipitation air mass.
Characteristics of air masses and their comparison with each other showed that precipitation and cooling in the region were heavily concentrated and the period of their activities were very limited. On the other hand, warm and dry air masses controlled a large part of times in a year.
Conclusion
The study of characteristics of Zabol weather showed that precipitation and cooling in regional climatic condition of Sistan area are highly concentrated and the period of their activities is very limited. On the other hand, the warm and dry weather types prevail during the large part of the year. The analysis of annual trends of air masses occurrence indicated that the frequency of very cold events was reduced while the recurrence of cold air masses increased. In addition, the warm and dry air masses frequency was limited by dominating the very warm and dry air masses. Consequently, the climatic seasons in the North of Sistan and Baluchistan Province was changing and shifting and the duration of very warm and dry period was increasing.
The four major patterns of sea level pressure are controlled by the interactions and characteristics of Sistan region weather types.
Physical Geography Research
University of Tehran
2008-630X
44
v.
3
no.
2012
39
62
https://jphgr.ut.ac.ir/article_29213_3745e65db1b0b9741b6067e3de3cf1bc.pdf
dx.doi.org/10.22059/jphgr.2012.29213
Duality in Geomorphology
mohsen
poorkhosravani
دانشجوی دکترای ژئومورفولوژی، دانشکدهی علوم جغرافیایی و برنامهریزی، دانشگاه اصفهان
author
M.H
Ramesht
استاد دانشکدهی علوم جغرافیایی و برنامهریزی، دانشگاه اصفهان
author
S.A.
Almodaresi
استادیار گروه مهندسی عمران، دانشگاه آزاد اسلامی، یزد
author
text
article
2012
per
Duality in Geomorphology
Pourkhosravani M.
Ph.D. Candidate in Geomorphology, College of Geographical Science and Planning, University of Isfahan
Ramesht M.H.
Prof. in Geomorphology, Dep. of Geography and Planning, The University of Isfahan
Almodaresi S.A.
Assistant Prof., Dep. of Civil Engineering, Islamic Azad University of Yazd
Extended Abstract
Introduction
Some of phenomena have certain relationships which cannot be raised as correlation , but they considered as duality . Concept of duality is regarded when a phenomenon with another phenomenon is dual . Although each of these phenomena are independent in nature , there is a relationship between them . So , we will analyze the behavior of phenomena in relation to other phenomena .
Earth subsidence has been one of the important issues jeopardizing environment and there are many studies , which blame shortage of underground water resources for having uplift and subsidence . However , many argue such conclusion and believe that earth subsidence has been studied in the past without considering the changes in the hill over a long period . In this study , we use SAR interferometry study to investigate earth subsidence in many plains of Iran and explain duality theory in the geomorphology . Concept of duality in geomorphology is mostlyrely on the land subsidence and the uplift in the adjacent hills .
Mahyar plain is located 25 kilometers south of city of Isfahan, Iran . The region is covered with calcareous rocks of cretaceous and there are many rocky mountains . Many sediment erosions cover the areas of desert and there are various faults .Yazd - Ardakanregion is located in central part of Yazd and it contains many well - known faults . Ardabil plain is located in west northern part of Iran .
Methodology
In order to achieve the aims of research in this paper, the following stages and procedures are to be considered :
? Studying and examining of the documents relevant to the plains in Iran and the amount of their subsidence ,
? Selecting , three plain ( Mahyar with Yazd – Ardakan and Ardabil ) in different formation system for research ,
? Analysis of acquired data using SAR Scape software ,
? Providing and processing the radar data from the study area and applying the method of radar wave's interference measuring in two certain time frames .
Radar interference measuring can help us explain this issue . This method enables us to assess height changes of the earth in centimeter scale per year . The processing of SAR interferometric data is a complex procedure . Based on the quality of the datasets, the performance of each processing step is crucial . To summarise , the interferometric processingconsists of the following steps :
( 1 ) image registration ,
( 2 ) calculation of modulate phase difference ,
( 3 ) phaseunwrapping and geocoding .
Results and Discussion
Data analysis of Envisat Satellite ( Alospalsar ) in Mahyar plain shows the land subsidence of plain has been synchronized with uplift occurred in the mountains of adjacent plains . The results show that most uplift is in the Kolah Ghazi Mountain and the rate of subsidence is increasing towards the center of plain . The results indicate that the maximum subsidence in Yazd - Ardakan belongs to a Tile producer located 14 kilometers from the road of Yazd-Meibod . In addition , the maximum uplift is North - East to east part of desert of Yazd-Ardakan .
The analysis of radar data into the Ardebil plain on 3 September 2009 and 11 September 2010 shows the highest rate of subsidence in Ardabil airport and the highest uplift in the adjacent hills .
Conclusion
Although the effect of irregular exploitation of water resource can be linked to an increase in land subsidence , the main cause of land subsidence in the plains of Iran is the simultaneousness raising the subsidence in the floor of plains and adjacent mountains . These processes , as a series , act together and coordinate in reverse order . This is called duality in geomorphology . Although each of these phenomena is independent in nature , there is a relationship between them .
Keywords : Duality , Geomorphology , Plain , Subsidence , Uplift , Iran.
Physical Geography Research
University of Tehran
2008-630X
44
v.
3
no.
2012
63
72
https://jphgr.ut.ac.ir/article_29214_a9f5a0c468588ad5c32cb60498dd4236.pdf
dx.doi.org/10.22059/jphgr.2012.29214
Studying of Meteorological Patterns, Identifying of Dust Sources and Motion Track of Particles for Dust Storm, July 2009
Abbas
RanjbarSaadatabadi
استادیار سازمان هواشناسی کشور، تهران
author
Ghasem
Azizi
دانشیار دانشکدهی جغرافیا، دانشگاه تهران
author
text
article
2012
per
Extended Abstract
Introduction
In arid and semiarid areas, dust storms occur frequently. When surface winds are strong, large amounts of sand and dust can be lifted from bare, dry soils into the atmosphere and transported downwind affecting regions hundreds to thousands of kilometers away. Dust storms are most commonly caused by strong pressure gradients which cause an increase in wind velocity over a wide area. For countries in and downwind of arid regions, airborne sand and dust presents serious risks to the environment, property and human health. In recent years, systematic research on dust storms has been carried out. Dust storm in the east of Asia, is quite well documented through the analyses of synoptic records over the past 50 years (Sun et al., 2001; Zhou, 2001; Chun et al., 2001; Qian et al., 2002; Natsagdorj et al., 2003; Kurosaki and Mikami, 2003; Shao and Wang, 2003). Sun et al. (2001, 10331) analyzed the synoptic reports over the 40years period between 1960 and 1999 and found that Gobi in Mongolia and north of China are major dust sources. In this paper, we identify the main sources of dust production, test forward trajectory technique and investigate characteristics of pressure patterns of dust events in July 2009 in Western Iran.
Methodology
Throughout this study, it is attempted to determine characteristics of effective pressure patterns and main dust emission's sources and forward trajectory based on meteorological information including: meteorological maps at the standard levels (1000mb, 850mb, 700mb and 500mb), satellite images and some products of the numerical weather prediction models. Meteorological maps data analyzed at 00UTC and satellite images (interval time is 30min.) of dust events from 2th to 7th of July, 2009. Satellite images were used to compare the spatial pattern of a large scale dust event with the pattern predicted by the model.
Results and Discussion
Surveys show that in recent years the event frequency, intensity and the extent of the region affected by sand and dust have been increasing. Water irregular consumption and inhibition, particularly widespread constructing dams in the south of Turkey and the North of Syria and Iraq, cause the creation or development and spread of producing sources of dust in the eastern north of Syria and the north of Iraq especially Mesopotamia that provide suitable conditions for dust formation in these areas and delivering it to vast areas of Iran. On the other hand, it can be claimed that in past, the sources of dust were mostly in the south of Iraq, some parts of Jordan, Kuwait, and the north of Saudi Arabia. These sources has influenced already on the south west of Iran through the south westerly or the north westerly winds, now by spreading and creating sources in the north of Iraq and eastern north of Syria, the west of Iran is affected with more intensity, frequency and permanency by this event. The two following reasons are of most importance to produce dust storm:
1. 1-There are soft soil particles and clay in the Region,
2. 2-As these Regions are located nearer to the north comparing to the previous mentioned areas, meteorological condition is suitable for dust formation.
Maximum number of dusty days and severe dust events usually occur in summer. Because of strengthening the subtropical high pressure, the waves of Mediterranean have been delivered to northern latitudes, and there will be no possibility of moisture feeding and no precipitation. Thus, its deployment on dry areas provides suitable conditions for ascending air and dust particles. While low pressure system moves to the east, the conditions for high pressure system's deployment located in the west of upper trough, by convergence of upper flows, leads to its creation and strengthen of high pressure. So, intensive pressure gradient is created between low and high pressure systems which leads to creation of strong winds and causes dust storm. However, geographic condition might have an effective role in creating strong winds.
In this case study at 700hPa level, in addition to the lack of deep and noticeable trough, contour gradient is low and probably provides suitable situation for the persistency and accumulation of dust particles in this level and near levels. Then, regarding Zagros' height (in average 3 km above sea surface), the particles pass above the mountain and impacts expand areas of the east of Zagros such as Tehran.
Due to decreasing the wind speeds (on surface and low level troposphere) from Iraq to Iran and also confluence of west and east winds the convergence zones have been created over the west of Iran. This Convergence of winds has an important role in accumulation and suspended of particles over the region. For determining the convergence due to the winds with opposite
directions, an imaginary line can be considered which continues from Iran's low pressure center to eastern south of Turkey.
Conclusion
Output results indicate that the sources of dust production were in the East of Syria and the North West of Iraq that through storm movement to the east, the density of suspended particles were increased and had impacts on western of Iran. The main meteorological factors in creating storms and delivering the suspended dust particles over the western of Iran are as following order:
Extending of thermal low pressure system from the center of Iran to the north of Iraq and south of Turkey, spreading of high pressure system from the Black sea to Caspian sea, the north band of Iran and the south east of Turkey, the strong pressure gradient created between the two pressure systems and passing waves out of Mediterranean in the mid troposphere level have an essential role in creating storm and carrying the suspended particles.
During the years that precipitation decreases, the occurrence of the event increases; thus, there is a meaningful relation between drought and the increasing of the frequency and intensity of sand and dust.
Physical Geography Research
University of Tehran
2008-630X
44
v.
3
no.
2012
73
92
https://jphgr.ut.ac.ir/article_29215_4ee1fc47c70b2e50c8f2a1b1e20bb1d6.pdf
dx.doi.org/10.22059/jphgr.2012.29215
Mapping Air Pollution Using Magnetometery on Tree Leaves in Tehran Metropolitan, Iran
M
Mollashahi
دانشجوی دکترای رشتهی جنگلداری، دانشکدهی منابع طبیعی و علوم دریایی، دانشگاه تربیت مدرّس
author
Habib
Alimohammadian
استادیار آزمایشگاه محیط مغناطیس، سازمان زمینشناسی و اکتشافات معدنی کشور
author
S.M
Hosseini
دانشیار گروه جنگلداری، دانشکدهی منابع طبیعی و علوم دریایی، دانشگاه تربیت مدرّس
author
A.R
Riahi
استادیار گرو محیط زیست، دانشکدهی منابع طبیعی و علوم دریایی، دانشگاه تربیت مدرّس
author
V
Feizi
دانشجوی دکترای رشتهی اقلیمشناسی در برنامهریزی محیطی، دانشکدهی جغرافیا، دانشگاه تهران
author
A.
Satareiyan
استادیار گروه جنگلداری، دانشگاه منابع طبیعی، گنبد کاووس
author
text
article
2012
per
Extended Abstract
Introduction
Air pollution is one of the major anthropogenic related productions which has had direct or indirect impact on environment during past recent century. Tehran metropolitan is one of the polluted cities in the world, in such way that in 2010, 120 days out of 365 days, were much polluted with one or several polluted elements. The major aim of this work is to map air pollution of Tehran metropolitan using new technique and method of magnetometry of tree leaves. Application of magnetic measurement is known as a new advanced method in investigation of the magnetic mineral emitted in to the air in industrial area.In recent years magnetic measurements have been increasingly used as a proxy for the heavy metal content in soils and sediments influenced by industrial emissions. Also, Magnetic particles are found almost invariably amongst atmospheric particulate pollutants. But sometimes it is difficult to judge if the measured distribution really reflects the present situation or if it is a product of past industrial activities. Therefore, we tested,to what extent, magnetic measurements of tree leaf samples can give information on the current spread of magnetic dusts. In fact, this project examines the capability of Tehran air pollution to produce some pollutant elements applying magnetic parameters leaves in urban green space. These elements deposited by vehicles and plants. Tree leaves with large surface areas can accumulate efficiently urban dust on their surfaces. This dust is partially washed out during rain precipitation, and therefore, monitoring pollution through the magnetic properties of tree leaves provides time-averaged results, which are more useful when studying regular patterns of urban pollution, than the direct measurement of air pollutants in a short period. Due to their widespread distribution, tree leaves allow for the construction of sampling grids of different scales (e.g., from streets to entire urban areas), with a high density of sampling points and with a spatial resolution which is hard to achieve with monitoring stations.
Methodology
Sampling was carried out during a fifteen-day period in September. As far as possible the sampling points were evenly distributed over the area in and around of the Tehran city.Sampling points were chosen with the help of the urban administration of Tehran city. We collected more than 1000 leave samples from 3 species namely Morusalba, Fraxinus excelsior and Pinuseldarica from 22 sectors at Tehran metropolitan.Whenever possible, sampling was confined to branches, facing road, at a height of 1-1.5 m above ground. Samples were put in pocket-sized sealable plastic bags, and then were refrigerated at 5°C before being returned to the, environmental and paleomagnetic laboratory, based at Geological Survey of Iran for magnetic analysis. Specimen preparation includes drying at open air, powdering before measuring them in the laboratory. Then the samples were place in 6 cm3 plastic boxes, specifically designed for sampling of paleomagnetic specimens.Each sample was weighted before the measurements in order to normalize the magnetic susceptibility values relative to the leaf mass (?, m3 Kg-1). Magnetic susceptibility was measured using an AGICO Kappabridge MFK-1 instrument. Then susceptibility data used to map air pollution with the help of GIS software. The one way ANVOA was performance for the variability of magnetic susceptibility in three different species at 22 sectors of Tehran city.
Results and Discussion
The Magnetometery measurement results of the polluted air showed that sectors 9, 11, 12, 14 and15 in Tehran city have highest pollution. Then these results compared with the result of Co content and major wind direction of Tehran metropolitan. All of these researches had same results and confirmed that sectors located in south and south-west of Tehran city have the highest pollution. These sectors have higher population per area so there is high traffic of vehicles in these regions. The magnetometry results show the maximum absorption of pollution by Morusalba.
Conclusion
The results indicate that a magnetic survey of tree leaves, which is relatively rapid and inexpensive, may be used in addition to the classical air quality monitoring systems to identify and delineate high-polluted areas in urban environments. Compared with other analytical methods, magnetic minerals provide a compositional tool, which is reliable, rapid, non-destructive, inexpensive and sensitive to low detection levels.
Keywords: Susceptibility , Tree Leaves , Air Pollution , Tehran .
Physical Geography Research
University of Tehran
2008-630X
44
v.
3
no.
2012
93
108
https://jphgr.ut.ac.ir/article_29216_bedfacaf7071e33a5eee06274b4c88dc.pdf
dx.doi.org/10.22059/jphgr.2012.29216
Investigation of Blocking Pattern Role on Precipitation in North East of Iran Using Data Mining Analysis
Ghasem
Azizi
دانشیار دانشکدهی جغرافیا، دانشگاه تهران
author
S.O
Nabavy
کارشناس ارشد اقلیمشناسی، دانشکدهی جغرافیا، دانشگاه تهران
author
M
Miri
دانشجوی کارشناسی ارشد اقلیمشناسی، دانشکدهی جغرافیا، دانشگاه تهران
author
text
article
2012
per
Extended Abstract
Introduction
The importance of atmospheric precipitation in human life turns it into one of the most common subject of various studies. Minimal changes in the amount and intensity of precipitation would face the communities’ social and economic infrastructures to serious problems. Even though these studies have yielded very precious results but in most cases atmospheric precipitation patterns were analyzed not only at a limited regional scales but also only for heavy precipitation (high intensity precipitation). However, synoptic weather patterns, creating precipitation or other atmospheric phenomena, are formed within hemisphere-scale pattern. Among them, blocking pattern is one of the most important large scale circulations. As sometimes blockings embrace a wide range of western Atlantic coast to the Far East. Undoubtedly the identification of these patterns naturally requires a study area much wider than synoptic scope. In addition, understanding of the extreme natural phenomenon like heavy precipitation requires the knowledge of their normal modes. Therefore, this study aims at examination of hemispheric and synoptic circulations along with both heavy (high) and normal (moderate) precipitation (intensities) in Khorasan Razavi and Khorasan Shomali provinces. Investigation of relationship between precipitation amount in Khorasan Razavi and Khorasan Shomali provinces and blocking pattern is the main purpose of this study.
Methodology
To achieve considered goals, statistical data of daily precipitation were obtained from 20 stations located in the mentioned regions. Given the amount of precipitation is different in each area, the intensity of the precipitation cannot be determined based on a fixed number and it should be calculated according to its average quantity in given place. Hence, precipitation rate between ±0.2 and above 7 were considered respectively as normal and heavy precipitation in a normalized scores scale. Besides taking into account aforementioned intensities in at least one station, precipitation rates greater than 1 and 0.1 mm in at least 50% of the stations are also required for choosing heavy and normal cases. As a result of precipitation data processes, 46 and 92 days were identified with normal intensity respectively.
Results and Discussion
Having determined precipitation cases, atmospheric circulations were analyzed for two synoptic and hemispheric scales. Geopotential height at 500 level extracted from US atmospheric database called National Centers for Environmental prediction ( NCEP ) was used to identify synoptic and hemispheric patterns . Similarly the study has two kinds of methodologies . Synoptic patterns were analyzed by manual ( subjective ) method whereas hemispheric circulations were investigated through quantitative blocking index to determine whether block has happened within large scale circulations. Manual analysis indicates that the only synoptic circulation, creating precipitationwhether heavy and normal quantities, is trough pattern. This result is completely expectable for places like north east of Iran. Because in such regions far from massive water bodies, synoptic-scale dynamic processes play a big role in formation of rainfall. Through this pattern, the study area is located under trough front or upper convergence and surface divergence section. After determination of predominant precipitation synoptic pattern, the main part of study is put forward. In this step, the role of hemispheric blocking pattern on creation and location of trough pattern was investigated based on blocking index.
Conclusion
According to results, 67% of high intensities and 64% of normal cases are formed (affected) by blocking patterns. This condition not only shows very important role of these circulation in formation of precipitation in north east of Iran but also it would explicate that most precipitation cases in the mentioned areas are prepared by an unusual atmospheric pattern called blocking. The characteristics of block pattern, being unusual and infrequent, justify high annual fluctuations in Khorasan Razavi and KhorasanShomali’s precipitation. Spatial distribution blocking patterns indicates that Atlantic and Western is the main host for most blocking cases during both heavy and normal intensities. In addition to spatial distribution of the blocking pattern, its model is also significant; Omega block has the relative frequency of 74/2 and 72.9 simultaneous with high and normal intensities respectively. Based on block pattern temporal regime, late cold period of year and spring has the highest frequency of
blocking pattern along with heavy precipitation, whereas blocking pattern creating normal precipitation takes place mostly during wintertime.
Keywords: Heavy And Normal Precipitation, Synoptic Analysis, Trough Pattern, Blocking Index.
Physical Geography Research
University of Tehran
2008-630X
44
v.
3
no.
2012
109
126
https://jphgr.ut.ac.ir/article_29217_e58f551a580057780395d9ae02e795a9.pdf
dx.doi.org/10.22059/jphgr.2012.29217
Analysis of the Urban Heat Island Spatial Variability over Tehran
Ali
Shamsipour
استادیار اقلیمشناسی، دانشکدهی جغرافیا، دانشگاه تهران
author
M.
Mahdian Mahforouzi
دانشجوی کارشناسی ارشد اقلیمشناسی، دانشکدهی جغرافیا، دانشگاه تهران
author
Z
Hosseinpour
دانشجوی کارشناسی ارشد اقلیمشناسی، دانشکدهی جغرافیا، دانشگاه تهران
author
text
article
2012
per
Extended Abstract
Introduction
The Urban Heat Island (UHI) effect refers to the temperature rise of any man-made area. It is a phenomenon in which cities become warmer than the surrounding suburbs. In other words, there is a temperature difference between the cities and the area surrounding them. Generally, the UHI effect could be a result of excessive and unplanned growth of urbanization. The behavior of artificial urban texture in terms of absorption of short-wave and long-wave radiation, transpiration, releasing of anthropogenic heat, and blocking prevalent wind is significantly different from that of the rudimentary nature. Surface geometry on the other hand, decreases wind speed in urban regions which plays a great role in formation of UHI. As the energy balance inside a city alters, UHI intensity varies. This means that UHI intensity is not spatially and temporally similar in different cities. Also it must be noticed that UHI formation in a city usually has diurnal or seasonal patterns which are mostly affected by synoptic weather conditions. There are three main synoptic and local climatology parameters affecting UHI formation: air pressure systems, cloudiness, and wind speed. Under stationary high-pressure system conditions temperature differences between urban and rural areas become large. UHI intensity is largest in calm air and cloudless sky conditions and tends to disappear in cloudy and windy weather.
The urban heat island can lead to urban temperatures being 2–5 ?C higher than those in rural surroundings. Studies have shown the difference in temperature between urban and rural regions (UHI Intensity: ) is revealed in minimum temperatures rather than maximums. TheMaximum UHI intensity usually occurs 3–4 hours after sunset in the urban area. Other impacts of the UHI could be intensifying pollutant concentration over urban areas, altering local wind patterns, increasing humidity, forming cloud and fog, and changing the precipitation rate over a city.
Methodology
In this study, the urban heat island over Tehran was analyzed. Tehran is the largest and the most populated city of Iran, with an approximate area of 750 Km2 and a population of 8 Million during night time. The city lies almost in the middle of the Tehran province (1882 Km2 of area) in the southern side of the Alburz Mountain and is limited to the highlands in northern and eastern parts. On the southern and western parts, it is connected to the flat plains of Varamin, Shahriar and Karaj.
To investigate the spatial and temporal patterns of the UHI over Tehran, after studying the literature reviews and earlier studies, 24 days from the year 2006 were chosen; two days of each month, one day with the highest and the other with the lowest air pressure over the urban area were chosen. Then, the climatologic data (including temperature, cloudiness, air pressure, wind direction and wind speed) for each day were gathered from different data sources: 1- Iran Meteorology Organization stations including synoptic and climatology stations, 2- Air quality measuring stations including Air Quality Control Company and Department of Environment stations.After data refinement, in order to choose the sample days for UHI illustration, primary maps were drawn using ArcGIS 9.3, then 216 maps were drawn (9 maps with 3 hours interval for each day); also, for a better perception of the temporal patterns of the UHI, the measuring times were transformed from Greenwich Mean Time (GMT) to the Local Time (LT) by adding 3:30. The difference between the average temperature of the urban district (TU) and the rural area (TR) was calculated by MS Excel 2007 for collecting the UHI intensity during different seasons and months and for all 24 days at each measurement hour. In the next step, due to primary results four typical days were chosen to represent each season. Aside from the obtained data from the surface measurement stations, the Air Pollution Model (TAPM) was employed to compensate the lack of data on the rest of the study area by modelling the wind field (i.e. wind direction and speed) over the study area. Therefore, all hours in chosen days were modeled with a 10 kilometers resolution with synoptic that shows the actual wind condition. Finally, integrated maps were drawn which the final analysis were based on.
Results and Discussion
Results show that an increase in the wind speed causes a reduction in the UHI intensity, also in high-speed winds (4 knot and up) the formation of the UHI tends to disappear. Moreover, no significant correlation was found between the air pressure and the UHI intensity and formation. Only in summer, and in the high pressure conditions, maximum intensity has occurred at 00:30, and in the low pressure condition the minimum intensity occurred at 09:30. Also, the summertime UHI intensity is much higher than the wintertime intensity. The spatial variation of the UHI does not seem to have a regular pattern, because it varies in different seasons and months. Totally, the spatial extent of the UHI is limited by the wind direction and velocity.
Conclusion
The spatial variation of the UHI seems to be significantly affected by the wind velocity. Hence, in order to determine the main thermal core of the UHI, the wind field must be considered. The results have shown that the distribution of the heat island main cores during the year, is mostly dependant on the wind velocity. However, it could be concluded that the main core of the UHI is usually located somewhere between Mehrabad, Fatemi, Bahman, and DoushanTappeh Stations. Also during different months, Bazaar, Bahman and Azadi Stations mostly show a higher temperature in comparison to their surroundings.
Physical Geography Research
University of Tehran
2008-630X
44
v.
3
no.
2012
127
146
https://jphgr.ut.ac.ir/article_29218_c5ad82f54ec4f422ec8ac51dd6de1886.pdf
dx.doi.org/10.22059/jphgr.2012.29218