فصلنامه پژوهش های جغرافیای طبیعی
پیاپی 86 (زمستان 1392)

Temperature and its changes are considered as an important factor in the physical weathering of rocks. The maximum influence of temperature is frost action and thermal expansion. The effect of temperature on the degradation of rocks، moreover temperature range، depends on the strength of rocks. During freezing، water in cracks and fissures of rocks is increased 8 to 11 percent in volume and this has a force of about 2000 pounds per square inch. The continued practice of freeze and thaw can cause small fissures، cracks and separation. The result of this process is formation of the Talus and debris cones (Blyth and Freitas 2005). Evidence of glacial geomorphology is one of the most visible legacies of the Quaternary period Climate change (Mahmoudi 1988). One of the most important legacies of Pleistocene climate in the highlands of the Iran، especially in the Alborz Mountains، West and North West of Iran is the dominance of the glaciers and related landforms (Yamani 2002). West region of Kurdistan province with collection wide variety of heights and glacial heritages in recent centuries has been studied by Iranian and foreign researchers including Van Zeist and Wright (1962)، Wright (1980،1967،1962)، Hutchinson and Cowgill (1963)، Van Zeist (1966)، Megard (1967)، Pedrami (1982)، El-Moslimany (1986)، Brooks (1989)، Bottma (1995)، Snyder et al. (2001)، Stevens et al. (2001)، Wasylikowa (1966،2005)، Ehlers and Gibbard (2004)، and Wasylikowa et al. (2006). Given the rare geomorphologic studies in our country about weathering processes and zonation of morphoclimatic areas، this article aims to examine weathering and morphoclimatic processes in west and northwest of Kurdistan and classify weathered and morphoclimatic areas according to climate variables and glacial traces. Based on the purpose of the research، this research has used some materials including topographic maps at scale of 1:50000، satellite images of Landsat-TM and ETM، Aster elevation model 1. 5arc، Google Earth (6. 2. 2. 6613) images، and 12-year period climatic data about average temperature and annual precipitation of eight synoptic stations. Toe-to-headwall altitude method used for calculating Holocene snowline and Peltier weathering regimes model is used for the weathering classification. For production and analysis of maps we have used software including Ilwis 3. 3، ArcGIS 9. 3، Globalmapper 12. 1 and Excel 2007. Then، more analysis was conducted by ArcMAP software and various maps were produced. To calculate Holocene snowline in the study area based on theoretical and local knowledge using Landsat images، four mountainous series sites including Arbaba، Chelchama، Qalabard and Zarvah were selected to reconstruct Holocene snow-line. Based on the linear regression between temperature and precipitation and paleosnowline، wurm temperature and precipitation maps were prepared. Weathering map regimes، in considering the location of the stations in the Peltier weathering regimes model، was prepared using weighted method. Based on the results of weathering zones، wurm temperature and precipitation and the extent of glacial and periglacial landforms، wurm morphoclimatic map for the selected mountains series، was prepared. The results showed that among seven weathering models in Peltier model، three conditions occur in the study area. In most mountainous areas mechanical weathering occurs in weak to moderate، this is because of high rainfall، more moderate chemical weathering occur in western Kurdistan and in other stations chemical weathering with frost action is dominated due to low temperature. Among morphoclimatic systems in the study area، glacial، periglacial and fluvial systems have occurred in wurm. Glacial erosion system at the altitude above 2000 meters and periglacial erosion system have occurred at the height of 1600 m to 2000 m in the mountains of West Kurdistan. Remaining landforms in mountains، including cirques، glacial valleys، terminal and ground moraines، Talus and debris cones، nivation and others indicate the dominance of glacial agents in the wurm. Wurm most zones in the study area have been under the influence of moderate mechanical weathering. Poor chemical weathering has been dominant in the west strip area of Kurdistan. Remaining landforms in the Arbaba، Qalabard and Zarvah mountains including cones of debris flows، debris flow slopes and Talus، in Mountain crest to heights of about 1700 meters، are evidence of glacial erosion. Most of landslides are generated because of the prepared debris and materials from periglacial erosion. The results obtained from wurm rainfall in Zarvah and Qalabard mountains are largely matched with the results of Zeribar sedimentological and palaeobotanical study. Rainfall reduction and temperature drop during wurm period in the region has been accompanied with the steppe vegetation and lack of tree pollen.

Scientific concepts، language and terminology go through changes over time. One of the most basic and important concepts in environmental and geologic science، which has gone through this change، is the term subsidence. The depth and breadth of change in the concepts related to this term is noticeable، although it has applications in other fields، even dentistry. Known as a geomorphological phenomenon، subsidence has turned into a theory on its own in geology and with its emergence it also outlined some other concepts and schools of thought in the field of geology. It also caused evolutions in common beliefs in this field. The term was first used in 1839 by Charles Darwin and since then it went through certain semantic and conceptual changes and brought around various registered and practical achievements. Taken from an experimental research carried out in the University of Isfahan، this study’s focus was on exploration of historical، conceptual alterations incurred to the term subsidence in geology. This study strives to determine the pattern of change in the beliefs of the scientists about a geomorphologic phenomenon، by tracking the conceptual changes inflicted on this term through time. Materials & This is a study taken from an experimental research but falls، however، under the category of library research. We took out the reports written by fifteen prominent scientists in geology and geomorphology and grouped them into topics of geology، geomorphology، tectonics and hydrology، and then analyzed the historical evolution of the term in an analytical and comparative framework. The fifteen prominent scientists whose reports were used in this analysis and dissection are as follows; Darwin (1839)، Hall (1859)، Dana (1873)، Eshtile (1940)، Key (1951)، Adleman (1954)، Lofgren (1963)، Abovin (1965)، Jennings (1966)، Asemli (1967)، Allen (1969)، Gabridge (1984)، Poland (1988)، Cook & Dorencomb (1990). In content analysis based on the organized observational and qualitative content description of the concepts، texts، and phenomenon، we first scrutinized and categorized the theoretical beliefs about the event of subsidence، using a comparative method and determined interpretative paradigm. Our analysis on these beliefs covered a 151 year timescale which was from the year 1839 to 1990. The concept of subsidence carries a semantic load peculiar to some common concepts.. In addition to explicating a great number of concepts related to the earth crust movement، it also makes its association clear with the animal life and tectonic phenomena. The term of subsidence was first used in geology literature and the realm of geological theories and made dramatic changes in the beliefs of geologists and geomorphologies. The rise of concept of subsidence from the mysteries of nature helped scientists to answer difficult questions that were ever hardly possible to answer. The concept of subsidence has always been considered by many scientists (Darwin 1839، Hall 1859، Dana 1873، Eshtile 1940، Key 1951). Lofgren (1873) attributes subsidence to extracting the underground water resources and mines such as oil and coil. Abovin (1965) also analyzed the occurrence of subsidence in geo-signals. Jennings (1966) introduced the dissolution in dolomite formations which is caused by human activities as the natural agent that triggers the event of subsidence. Edelman (1954) and Asmly (1967) believed the earthquake of Mars، 1964، and the movement of the crust in large scale to be the main cause of the occurrence of subsidence in Alaska and the North Sea area، all as a result of human activities. Gabrysch (1984) introduced the pressure level decrease in Artesian wells and the receding of water in aquifers as the main cause of the occurrence of subsidence. Poland (1988) believed that a reduction in water level in Artesian wells and a time dependent increase of stress and pressure in the water sediments causes the subsidence to happen. Cook & Dorencomp (1990)، considered natural and human related factors as the cause of subsidence. We can conclude from this study، that The concept of subsidence was first used by Darwin in 1839 in the domain of sedimentology and geomorphology and theoretically supported by the gradual convergence and uniformitarianism schools of thought. The concept of subsidence has some theoretical load and should not be considered as just a pure geomorphologic event. The concept of subsidence can be applied within the three domains of geology، geomorphology، tectonic and hydrology. Discussion & The results obtained from the study about the evolution of the subsidence concept shows that it is used in academic setting as to be a phenomenon and that it also drags has the conceptual load of a theory. It’s The semantic load of this concept consists of mostly some common concepts that are used along with. Hence we can say that; The conceptual and semantic load of the term subsidence has not been fixed over time and is differently used by different scientists in different times. The concepts that Darwin knows as ‘subsidence’ has important theoretical implications in a way that it changed the view of geologists about the earth life span and turned into a documented proof to support the theory of gradual convergence in geology. The concept of subsidence in geomorphology mostly refers to exploiting underground aquifer water resources. Translating the word ‘subsidence’ as sediment cannot reflect its real conceptual load and theoretical aspect and hence it is advised to use the original word subsidence in written text.

The word «Loess» has been derived from the German word «Lӧs»، meaning loess، which was used for the first time by Leonard in 1824. Regarding the definition of loess presented by many authors، aeolian origin and silt fraction dominance have been accepted as the two main attributes of loess deposits. Wind- blown deposits of loess are characterized by a lack of stratification and uniform sorting and occur as blanket deposits (Bell، 2000). The common mineralogical composition of loess deposits is as follows: quartz، feldspars، carbonates، mica and heavy minerals in the silt fraction. According to Pye (1995)، four fundamental requirements are necessary for its formation; a dust source، adequate wind energy to transport the dust، a suitable accumulation area، and a sufficient amount of time. The study area is situated in southeastern coast of the Caspian Sea. Most of this area is covered by Quaternary deposits including loess. The loess deposits، in this area have questionable distributions، and are as the bed of specific landforms. Moreover، they often have sufficient void space in their natural state، high porosity، high permeability، and low compaction. This may be representative of collapse، subsidence، landslide، and liquefaction. The aim of this research is answer the questions: what is Loess? How are their distributions in Iran? How are distributions of loess deposits in the study area? What is the role of loess deposits on morphogenesis systems? And what is their role in environmental management? In this research، field works and document data such as satellite images (LANDSAT of Mars 19، 2011، July 18، 2011، and July 27، 2011)، and NIOC geologic maps at 1:100،000 and 1:250000 scales have been used. Therewith، the Digital Elevation Model (DEM)، acquired from Digital Topography Maps of National Cartographic Center of Iran (NCCI)، at scale 1:25،000، and its derivatives and also land use maps were used for spatial analysis. Field observations were carried out in May، 2012، afterwards the spatial distribution of loess was mapped and the spatial analysis based on GIS functions were performed to show the role of loess deposits on morphogenesis systems. Most of this area is covered by Quaternary deposits including Quaternary marine deposits، alluvial deposits، debris and landslides، and wind deposits. Loess as wind deposit covered a considerable part of the research area. The loess distribution analysis indicates that loess is found in two regions. One of them is situated between Gorgan and Atrak Rivers in Golestan province and the other one in foothills of northern slope of Alborz mount، which totally covers an area of about 1011 square kilometers. Neka، Gorgan and Atrak River basins all have different amount of loess deposits. Loess elevation distribution analysis shows that about 77% are located in elevations of 100 to 400 meters. Loess slope distribution analysis expresses that 88. 29% are located in 1 to 15 degrees of slope. So it can be concluded that Loess deposits in north of Iran cover evenly the area، but over time and due to highly erosion they remained just on the eroded slops، behind anticlines، hills and low- slope mount sides. The analysis of loess distributions according to landuse map indicates that 13% percent of loess sediments are used for agriculture and in Garden they are covered about 15% by forest. While more than 63% of loess areas is covered by pastures. It is recommended to use these sediments for pasture and forests for management of erosion. The analysis of spatial loess distributions and villages show that within 13 to 28 percent of villages including Tamran، Roshan Abad، Atrak، Anjirab، Yanghagh، and Agh Abad are located inloess depositions. Therefore، to prevent environment hazards any environment development plan must be associated with exact assessment and usage of different ways of loess compacting. Presence of high percent of loess deposits in low slope and low elevation areas is the consequence of high erodibility of the deposits. Regarding the high erodibility of loess deposits، it seems that the existence of loess deposits in low slope and low elevations is the consequence of fluvial processes over time. The presence of cutting hills and different erosion types such as rill erosion، gully erosion، piping، and badland erosion in the research area confirm this fact. The loess distribution analysis considering landuse map indicates that a remarkable parts of loess areas is pasturage. It seems very important to prevent intensifying erosion in this area، prevention of pasturage destruction and their improvement. Existence of considerable thickness of loess، that contains silt and clay which can absorb and retain high moisture، and their highly coincidence with low-slope area have provided suitable conditions for agricultural activities. Consequently، gully erosion has been intensified. Different erosion types، such as rill، gully، piping، and badland are found in the study area because of loess deposits. The loess distributions in upstream of basins result in an increase in sediment load of rivers especially in Gorganroud. Therefore، the viscosity of floods and their destructive effects are increased. The results of this study indicate that morphogenesis systems in this region are strongly affected by loess deposits distribution and their land use type. Ultimately، this can be said that southern and eastern Caspian Sea loess deposits have effective role in landform and landscape genesis and also their specific attributes are reason of various environment hazards. Hence، their spatial analysis can be useful in environmental management and hazard prevention.

Energy is one of the necessary factors for industrial activities and a requirement for today life. Hence، demand and supply of energy in human society is increasing continuously. Population growth and its distribution، along with the increasing need of human being to newer and more efficient energy resources have changed the human approaches to natural renewable energy forms. Since the fossil fuels as the primary fuels of are going to exhaust rapidly and cannot be a reliable energy source as well as due to the global warming issue، the use of fossil fuels should be limited as soon as possible. Henceforth، renewable energy resources were proposed to solve these challenges. Solar energy is one of the best and most economical renewable energy in Iran. This energy not only can resolve many human concerns such as environmental pollutions، newborn diseases، energy finitude، and energy transformation، but can also be well developed in climate of Iran. As the photovoltaic systems are one of the most efficient systems in producing solar electricity and can be employed in a vast area of Iran، a significant proportion of energy consumption of Iran can be supplied by developing these systems. Photovoltaic cells transform solar energy into electricity directly. In this process، semiconductor materials such as Silicon، Gallium Arsenide، or Cadmium Telluride are used. Today، about 95 percent of the world solar cells are made of Silicon. Since the prime cost for establishing photovoltaic field is relatively high، optimizing the establishment sites of these systems can play a key role in increasing the efficiency of the system. The aim of this study is to introduce a new method for spatial optimization of the sites of photovoltaic fields in Iran. In this research the DELPHI technique was employed to identify the effective factors. The DELPHI is a systematic process for collecting and classifying the knowledge of experts through distributing questionnaire between the experts and studying the feedbacks. After the DELPHI technique carried out، 14 criteria were extracted and then classified into three main groups. In order to weight the criteria، the Analytical Network Process was employed. To do so، the pairwise comparison questionnaire was produced and distributed to the experts. According to the results derived from the questionnaire، the pairwise comparisons were done in Super Decision software and the weight of each criterion was calculated. An initiated model is introduced to combine Simple Additive Weighting method and Fuzzy Inference System. In the mentioned technique، the main entrance of the final layer is a result of Simple Additive Weighting. Primarily، the concluded layer from the Simple Additive Weighting was classified into six classes of very poor، poor، moderate، good، very good، and excellent using the trapezoidal membership functions and then the fuzzy laws were defined based on the requirement of the research. After the output distribution map was concluded for each law، all outputs were added together and the whole study area was divided into seven areas of inappropriate، very poor، poor، moderate، good، very good، and excellent. Finally، the experts'' viewpoints were used to estimate the accuracy of the results and according to the average of the results، the accuracy of the estimated sites is approximately 84 percent. The results indicated that the most effective factors on feasibility of lands in Iran to establish photovoltaic fields are 14 criteria in which the criteria of direct radiation، distance from the power lines، and temperature are of the most importance. However، except for the inappropriate class (mainly because of high slope and improper land use)، most of the regions (more than 31 percent of lands of Iran) are in classes of excellent، very good and good. Furthermore، only one percent of the lands are in class 1 (the class poor). According to the results، Provinces of Yazd، Kerman، South Khorasan، Sistan and Balouchestan، Isfahan، Fars، and Khorasan e Razavi، in order، have the most area in the class excellent، and Provinces of Guilan، and Mazandaran have the most area in the class very poor. Proper use of solar energy requires the identification of highly potential regions. Besides the benefits of using the photovoltaic technology، one of the difficulties of these technologies is the high cost of establishing such power plants. Therefore، recognizing the best regions for installing the photovoltaic equipments could be the main step in the establishment of photovoltaic power plants. In this article، authors have tried to introduce an applied method for optimizing the sites of photovoltaic equipment installation to have the most efficiency and lifetime. The results showed that Iran has very high potential to utilize the photovoltaic technology.

Wind is considered as one the most important causes for erosion and land degradation in arid and semi arid regions. Thus، it is necessary to study temporal pattern of wind properties to prevent the huge damages. (Refahi، 1999:22). There are a variety of different methods، parameters، indicators and diagrams for analysis of windy status and wind dynamic conditions. These are wind rose، storm rose and sand rose diagrams، drift potential، dustiness indices and wind threshold velocity maps. The main objective of this research is the investigation about the effects of wind direction on the orientation of coastal sand dunes in the southern coast of Iran. The results of this research can play a significant role in designing wind breaks and sand dune stabilizing projects. This study is done on coastal sand dunes، in south of Iran، in Khuzestan، Bushehr، Hormozgan، Sistan and Baluchestan Provinces. Commonly، western and south western winds influence the sand dunes located in southern Iran (Zareian Jahromi، 2008). These winds with high sand drifting potential cause strong sand storms in this area، from end of winter to begining of fall. In addition، Monsoon hurricanes blow in eastern and south eastern coasts of Iran، during summer. The application of WR PLOT View 5. 2. 1. is employed for anemometer data analysis and drawing storm rose and wind rose. Data from five synoptic stations in the southern coast of Iran including Ahvaz، Kangan Jam، Bandar Lenge، Bandar Jask، and Chabahar with 25 years period (1982 - 2006) were selected. WD Convert 2. 0. is used for converting data format (IRIMO to SCARM format) for wind data analysis and preparing data for drawing Wind Rose. Sand Rose software designed by Ekhtesasi and Saremi Naeeni (2003) based on Fryberger & Lettau (1975) equation is used for drawing Sand rose. Sand Rose was able to show different factors of wind data characteristics. Result of wind rose showed that dominant wind direction in surveyed stations is from west. Analysis of dust storm rose based on wind erosion threshold، at minimum speed (6. 5 m/s)، showed that hurricane and erosive winds in the study area is blowing from the west and southwest direction. Sand Rose Graph 3. 0. software was used for sand rose drawing، sand drifting potential and sand dunes morphology analysis. The results showed that the direction of sand transition in study area is dominantly from south and west south to north and north east. Thus، high conformity can be observed between wind direction and sand dunes orientations (RDD index: Resultant Drift Direction)، with 90. 5 percent conformity by Boolean logic approaches. It is reported that Ahwaz station in the northeast sector of Iran has highest accuracy. The most of the sand transport report (Total Drift Potential: DPt equal to 336. 8) is belonging to Bandar e Jask station، that lead to the formation of sand dunes in Surgalm، Sedij and Bayahi Region. UDI index (Uni- Directional Index) value derived from sand rose is less than 0. 59 for all stations. Therefore، this represents a bi- directional wind in study region. Different landforms such as sand dunes، longitudinal dunes، zigzag silk and Sif are observed in study area by interpretation of aerial photos and satellite imagery on Google Earth. These formations are evidence for existing bi - directional winds that blows from the southwest (erosive winds) and southeast (formed winds). Analyzing the results by sand rose and also sand dunes in a vast area of southern Iranian coasts revealed that southern (southwest to southeast) winds with local origin، reinforced by crossing the sea and warm coast (anabatic conditions)، cause wind erosion and sand drifting from beach into plains and Pedi- plains. Southeast and southwest winds and different sand drift potentials is resulted in reduction of unidirectional index (UDI) in all over the southern coasts of study area. Qua، the UDI varies from 0. 2 to 0. 5 in most cases، indicates the potential formation of longitudinal dunes in the region. Bidirectional winds influence most of the southern Iranian coast dunes as longitudinal dunes such as sif، Linear Silk and zigzag Silk. The role sea shore wind play in abrasion، transition and formation of sand dunes in southern Iran is determined by matching results obtained from analysis of erosive wind the morphology of hill sand.

Dust storms are atmospheric phenomena in arid and semi-arid areas such as Middle East. Iran in west of Asia regularly experiences dust storms (Modarres and Silva، 2007) due to its location in arid and semi-arid belts of the world (Jalali et al.، 2008). For example، intense dust storm occurred over Middle East in 18 Mars 2012. This dust storm affected many countries such as Iran، Iraq، Kuwait، Bahrain، Qatar، and Saudi Arabia. Aerosols perturb the Earth’s energy budget by scattering and absorbing radiation and by altering cloud properties and lifetimes. They also exert large influences on weather، air quality، hydrological cycles، and ecosystems (IPCC، 2007). Industrialization and human activities in the past several decades have caused changes to the air quality and Earth’s climate by releasing excessive amounts of trace gases and aerosol particles. It is important to regularly monitor the global aerosol distributions and study how they are changing، especially for those aerosols with large spatial and temporal variability، such as dust storms. Detection of these highly variable aerosol events is challenging because of: episodic features، short lifetimes، multiple-scales، and strong impact on local surface and meteorological conditions (Zhao et al.، 2010) Based on the identification techniques، more recent studies have been carried out to quantitatively determine the physical parameters of dust storms، such as aerosol loading. The aerosol loading is a key parameter for dust storm assessment، modeling، and forecasting. The VIR technique can be used to retrieve this parameter over ocean (Tanré et al.، 1997); but to do so over land there is a major challenge. Because dust storms mostly occur over desert or arid regions with bright surfaces، such as the Sahara Desert and the Gobi Desert، the surface contribution to the satellite signal is quite large and often unknown. As a result، estimates of the properties of dust aerosol are highly uncertain (Zhang et al.، 2006). Although many studies were conducted on dust detection، but there are still problems for the enhancement of dust. So far، considerable researches and appropriate methods have not been done for detection of dust using the satellite images over Middle East. Hence، in this paper، two methods used for detection of dust storm over Middle East and the results of each method are compared.

The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra and Aqua satellites is making near-global daily observations of the earth in a wide spectral range (0. 41–15 µm) (Remer et al، 2005). MODIS has been acquiring daily global data in 36 spectral bands from visible to thermal infrared (29 spectral bands with 1km resolution، five spectral bands with 500m resolution، and two with 250-m resolution، nadir pixel dimensions) (Levy et al.، 2007). Daily MODIS Level 1B (L1B) 1km data (MOD021KM=Terra) were used in this paper. Data were obtained from the Level 1 and Atmosphere Archive and Distribution System (LAADS; http: //ladsweb. nascom. nasa. gov/) Dust Detection Algorithm 1: (Zhao et al.، 2010) The following methods used for dust detection over Middle East: Let’s first define some variables and their symbols that will be used throughout the paper BT—brightness temperature (wavelength is given in subscript، e. g.، BT11µm) R—reflectance (wavelength is given in subscript، e. g.، R0. 64µm) BTD—brightness temperature difference MeanR—mean of reflectance for 3 x 3 pixels (wavelength is given in subscript، e. g.، MeanR0. 86µm) StdR—standard deviation of reflectance for 3 x 3 pixels (wavelength is given in subscript، e. g.، StdR0. 86µm) Rat1 = (R0. 64µm − R0. 47µm) / (R0. 64µm + R0. 47µm) Rat2 = (Rat1 × Rat1) / (R0. 47µm × R0. 47µm) R1 = R0. 47µm/R0. 64µm R2 = R0. 86µm/R0. 64µm NDVI = (R0. 86µm − R0. 64µm) / (R0. 86µm + R0. 64µm) MNDVI = NDVI2/ (R0. 64µm × R0. 64µm) The specific visible reflectance and IR brightness temperature tests currently implemented are: 1. Good data test for BT and R: • R0. 47µm، R0. 64µm، R0. 86µm، R1. 38µm > 0 • BT3. 9µm، BT11µm، BT12µm > 0K 2. BTD and R tests: • BT11µm − BT12µm ≤ −0. 5K & BT3. 9µm − BT11µm ≥ 20K & R1. 38µm < 0. 055 (Screen for pixels that are water cloud free. If these conditions are not met، then the pixels are cloudy and terminate testing) 3. Dust test: • If BT3. 9µm − BT11µm ≥ 25K then dust • If MNDVI < 0. 08 & Rat2 > 0. 005 then dust 4. Thick dust test: • BT11µm − BT12µm ≤ −0. 5K & BT3. 9µm − BT11µm ≥ 25K & R1. 38µm < 0. 035 • MNDVI < 0. 2 Dust Detection Algorithm 2 The flowchart of dust detection algorithm is shown in the following figure. Discussion of

The natural color image (RGB143) of MODIS sensor and atmospheric level 2 products، including Aerosol Optical Depth (AOD) and Fine Aerosol Mode Fraction (FMF) were used to compare and evaluate different methods of dust detection. The results showed that، although the algorithm 2 is able to detect dust، it couldn’t detect the exact boundaries of dust plumes very well. Instead، dust detection algorithm 1 extracted the dust plumes in a good level. In addition، by using the dust detection algorithm 1، it is possible to detect thick dust، as well.

The results showed that، although the algorithm 2 is able to detect dust، it couldn’t detect the exact boundaries of dust plumes very well. Instead، dust detection algorithm 1 extracted the dust plumes in a good level. Therefore، it is suggested that dust detection algorithm1 will be used for detecting dust plumes over Middle East countries.

Due to capabilities of imaging radar, there has been an enormous surge of interest in microwave imaging technology. Unlike optical imaging, understanding the theoretical underpinnings of imaging radar can be challenging, particularly when new to the field. The technology is relatively complicated, and understanding the interaction of the incident microwave energy with the landscape to form an image has a degree of complexity well beyond that normally encountered in optical imaging. The aim of this paper is to assess the use of RADARSAT data for estimation of rice vegetation indices. The radar backscatter coefficient of rice fields appears to have a significant temporal variation. Due to weather conditions in the north of Iran, microwave sensors can be more effective in monitoring rice growth than optical sensors, since a longer wavelength electromagnetic wave is less affected by clouds and precipitation events. The backscattering measurements of rice-growing areas have already been acquired using satellite synthetic aperture radars. Time series RADARSAT fine beam mode data was acquired from May till August 1998 for seashore of Behshahr, Behshahr seashore of Mazandaran province to assess and monitor rice crop from the space. Vegetation indices (VIs) are among the oldest tools in remote sensing studies. Although many variations exist, most of them are coefficients of the reflection of light in the red and NIR ranges of the electromagnetic spectrum to separate the landscape into water, soil, and vegetation. To determine the density of green on a patch of land, researchers must observe the distinct colors (wavelengths) of visible and near-infrared sunlight reflected by the plants. As can be seen through a prism, many different wavelengths make up the spectrum of sunlight. When sunlight strikes objects, certain wavelengths of this spectrum are absorbed and other wavelengths are reflected. The pigment in plant leaves, chlorophyll, strongly absorbs visible light (from 0.4 to 0.7 µm) for use in photosynthesis. The cell structure of the leaves, on the other hand, strongly reflects near-infrared light (from 0.7 to 1.1 µm). The more leaves a plant has, the more these wavelengths of light are affected. Theoretical analyses and field studies have shown that VIs are near-linearly related to photo synthetically active radiation absorbed by a plant canopy, and therefore to light-dependent physiological processes, such as photosynthesis, occurring in the upper canopy. Practical studies have used time-series VIs to measure primary production and evapotranspiration. In this paper 5 VIs was investigated and compared with radar backscatter coefficient of rice and made a mathematical linear regression model with the correlation coefficients for estimation VIs from RADAR images. This research is a descriptive-analytical study based on acquired data and statistical methods. The following stages and procedures are to be considered: Pre-processing stage; included: 1. Co registration 2. Calibration (speckle reduction) 3. and extraction from time series of RADAR images. Atmospheric correction of optical Landsat images with FLAASH (MODTRAN4) module. processing stage; included: 1. Converting DN into radiance and reflectance coefficients in optical bands of Landsat images 2. Generating NDVI, DVI, IPVI, SR, RDVI, vegetation indices from three Landsat images (red and near infrared bands). 3. Extraction of statistical parameters in 10 test site same as RADAR images. Calculation of obtained statistical data with MATLAB software and creation of linear regression equations and correlation coefficients. To further explore the relationship between paddy growth stage and radar backscatter, mean backscatter values were calculated for all the test fields for three different dates. The plants showed very low backscattering in early stage of plantation –12dB to –10dB. It started increasing up to –6 dB during vegetative phase of the plants, which is due to increase in height as well canopy cover. There was an increase up to –5 dB further in reproductive stage of the plants. During ripening phase, backscatter remained almost same until the field was being harvested. This is due to not much change in plant growth during the ripening period. All considered VIs in this research shows increasing in reflectance proportional to paddy growth stage. Because of high correlation between red and near infrared bands in optical images with chlorophylls and fresh biomass of plant (VIs) and again, high correlation between radar backscatter coefficients and biophysical parameters (content of water, canopy, height plant, plant structure), we can make a connection between those statistical parameters and create a mathematical model (simple linear regression equations) with different correlation coefficients. The results showed that the NDVI with R=0.92 has the best performance among the other four VIs. NDVI is calculated from the visible and near-infrared light reflected by vegetation. Healthy vegetation (left) absorbs most of the visible light that hits it, and reflects a large portion of the near-infrared light. Unhealthy or sparse vegetation (right) reflects more visible light and less near-infrared light. The numbers on the figure above are representative of actual values, but real vegetation is much more varied.

Cities with their physical development are the major causes of land use and land cover changes which lead to many problems such as loss of agricultural land، loss of green space، water pollution، soil erosion and declining of environment quality. The main reason for physical development of cities is population growth in urban areas which enables the physical expansion of the cities in geographical space. Tabriz، as the center of East Azerbaijan Province، has experienced considerable changes in recent decades due to increasing population in the surrounding lands and rural communities located in regions of influence sphere. The present study was conducted for modeling of land use changes in Tabriz City for the years 2016 and 2021 by using the Land Change Modeler (LCM) in GIS environment. The study area in this research is the Tabriz، as the center of East Azerbaijan Province in the north west of Iran. Extent of the area is approximately 2179 square kilometers and is situated in the geographical position of 45˚ 52'' to 46˚ 34'' of eastern longitude and 37˚ 46'' to 38˚ 28'' of northern latitude and the average altitude is about 1340 m above sea level. In order to produce land cover maps of the study area، Landsat satellite images of TM sensor for years 1989 and 2011 and ETM+ sensor for 2000 were used. In the following steps of production of land cover maps، the maximum likelihood supervised classification method was used as one of the most accurate methods of cell based classification. The first step in performing the supervised classification is introduction of training samples for each land cover class. By using the 1:50. 000 topographic maps and visual interpretation of false-color images، the training samples for each land cover class were introduced. At the end of this phase، 6 classes of land cover were specified. These land cover classes were: 1. Irrigated agriculture and gardening، 2. Grassland (grade 1) and dry farming، 3. Grassland (grade 2)، 4. Grassland (grade 3)، 5. Salt marsh، and 6. Urban and residential areas. In order to assess the accuracy of produced land cover maps، 389 accuracy assessment points systematically in the networks in 2. 5×2. 5 km by using GPS were marked on the images. Finally، modeling of land cover changes by using LCM was done in four major steps: Change Analysis Modeling of Transition Potentials Change Prediction and Modeling Accuracy Assessment Analysis and detection of land cover changes during the study period between the years 1989 to 2011 showed that during this period، 5195 hectares of the area have been added to the urban and residential areas. The rangeland especially grassland (grade 1)، agricultural lands and finally salt marsh lands have by 3488، 1007 and 484 hectares of land conversion، respectively. The land uses have the highest roles in the increasing the extent of urban and residential areas. It is also important to note that the rate of changes in the urban and residential areas during the period under study is not identical and the growth rate for urban and residential areas has increased in recent years. For example، from 1989 to 2000، 2271 hectares and between the years 2000 to 2011، 3062 hectares have been added to the extent of urban and residential areas. During this period، grasslands (grade 1) with 36958 hectares decrease in area and agricultural and gardening lands with 26617 hectares increase in area have the most of changes in the study area، respectively. Throughout the period studied، grasslands (grade 1) have been formed in most brigades within the city of Tabriz that from 1989 to 2000، 22944 hectares and from 2000 to 2011، 26803 hectares have shown reduction in area. The highest annual rate of land cover changes between the years from 1989 to 2011 were for urban and residential areas، so that this rate for urban and residential lands، agricultural and gardening lands، grasslands (grade 2) and salt marsh and bayer lands were calculated 3. 16%، 2. 33%، 1. 46% and 1. 18%، respectively. The grasslands (grade 1) and (grade 3) had a reduction with annual rate of -1. 01% and -0. 34%، respectively. The results obtained in this study showed that over the past 23 years، 5195 hectares have been added to urban and residential areas that the shares of desirable agricultural and pasture lands have been very higher in comparison with salt marshes and bayer lands. In particular، growth and change rates of urban and residential areas in recent years have been faster. The results of this study indicate that the explosion and unbridled expansion of Tabriz based on the demands and needs of the urban population will cause widespread changes and developments in diverse areas. The most important of the changes can be observed in Tabriz integration with some of the surrounding villages. This ultimately will lead to a vast expanse of space with unit performance. Certainly، this vast expanse of space will lead to in addition of absence the certain physical boundary between urban and rural areas that the economic، cultural and other functions in each of them are not realized. Therefore، we can largely avoid future problems by compliance and enforcement of laws related to land use and participation in organizations، public institutions، trading firms and land speculators. The results of this study based on the nature of land cover changes in the city of Tabriz in the past، now and future can provide useful insights and perspectives for managers and urban planners to manage properly the land uses in Tabriz city. The results of this research can also be an introduction and complementary for environmental impact assessment projects، feasibility and site selection projects and other studies that seek to make identification of sensitive areas and vulnerable zones.