جستجوی مقالات مرتبط با کلیدواژه "سبلان" در نشریات گروه "جغرافیا"

The start of the Quaternary period, along with all geologists and geomorphologists and other geoscientists, has been accompanied by climatic changes, in other words, the spread of glaciers in high latitudes and high ground elevations. The glaciers and glaciers of the Quaternary Mountains have eroded the lake of these areas and created numerous geophysics at different altitude levels. In the first half of the nineteenth century, Swiss geologist Luigi Agassis studied the role of natural glaciers in the evolution of the landscape. After that, glaciers were considered as one of the processes in the formation of geophysics in geomorphology. Continuous assessment of glaciers is important in terms of global warming as well as water supply downstream. The evolution and variety of geomorphic forms of the Earth's surface is affected by various morphogenesis processes that have been active over time and have created distinct landscapes.

In this study, in order to reconstruct and estimate the snowboard of the last Quaternary glacier period in the northern slope of Sabalan Mountain, Wright and Porter Methods (altitude of circus floor and altitude proportions) were used and past morphoclimatic condition based on geomorphologic evidence and temperature and rainfall of the Glacier Vorm period (using climatic evidence and climatic condition) was estimated. To better identify and reconstruct the glacier forms in the last Quaternary glacier period at the studied area, a combination of topography maps, field observations, satellite imagery, Digital Elevational Model (DEM), images received from Google Earth and climatic data was used. By identifying 25 circuses at different altitudes and based on the mentioned methods, the permanent snow line of the studied area was determined in the last the Quaternary glacier period. The basis of the Wright method is to determine the altitude that 60% of the circuses are above it. In order to estimate the temperature conditions and to prepare the companion map of the studied area, the regression equation between temperature and elevation was calculated in Excel software. Using this relationship and the raster computation function, a homogeneity map was prepared. The regression equation between precipitation and elevation was calculated in Excel software and then, using the raster computational function, a map of the plot was prepared.

The permanent flood line of the last Quaternary glacier (Vorm) in Northern slopes of Sabalan was 3242 meters in Wright method, the altitude ratio method was 3500 meters and the circus floor height was 3473 meters. According to Wright’s method, height of the permanent snow line in the last glacial period was 3869 meters and according to Porter’s methods (altitude of circus floor and altitude proportions) 3749.32 and 4017.5 meters, respectively. After calculating the height of the Quaternary permanent snow line in Sabalan Mountain by Wright’s method (3769 m) using Digital Elevational Model, the study area was divided into two parts: areas covered by permanent snow and adjacent areas of glacier or preglacial. After calculating the height of the Quaternary permanent snow line in Sabalan Mountain by Porter’s methods (altitude of circus floor 3749.32 m and altitude proportions 4017.5 m) using DEM, the study area was divided into two parts: areas under permanent snow control and areas outside permanent snow control. To prepare the coherent map, regression equation was calculated between temperature and altitude. The height of 4066 m was estimated as the snow line of the current permanent boundary of Mountain. Reconstruction of the temperature conditions of the study area in the last Quaternary glacier period, the average temperature was estimated to be 3.68 ° C cooler than the present. Also, the regression equation was calculated between precipitation and height in order to study the rainfall and moisture conditions of the study area. With regard to the current snow depth of the studied area, rainfall is reduced by 26 mm compared to Vorm.

The Wright and Porter methods estimate the snowfall of the Northern slopes of Sabalan in the Quaternary, 3242, 3473, and 3500 meters, respectively. Comparison of the results obtained for the height of the current snowboard line shows that the current snowboard at study area is 197, 48.5 and 317 m higher than the last Quaternary glacier period calculated by Wright and Porter methods (altitude of circus floor and altitude proportions), respectively. The necessary condition for the formation of glaciers is 0° C and an increase in precipitation compared to the current. According to the estimated snowfall height of the current in study area (4066 m), the current precipitation decreases by 26 mm compared to Vorm and also, the past temperature was estimated to be 3.68° C colder than the current. Therefore, increasing rainfall in the studt area (26 mm) in the past along with decreasing its temperature (3.68° C) compared to the present can prove the existence of Sabalan Mountain glaciers in the quaternary era.

The knowledge about spatial relationships of vegetation with sediment yield (S.Y) in watersheds is essential for optimal controlling and managing of water and soil resources. The purpose of this study was to recognize and determine the relationship between vegetation cover and annual S.Y of Sabalan catchments, N.W Iran. In this regard, the possibility of presentation of regional S.Y estimation models based on correlation and regression analysis were considered. Independent variables include average, minimum and maximum NDVI (Normalized Differential Vegetation Index), extracted through the processing of Landsa.t 8 satellite imagery in the ENVI environment. The dependent variable, which was the annual S.Y, was obtained through calculations on sediment load data of 10 sample hydrometric stations. Results of correlation test showed that there was a strong and significant relationship between the average NDVI and the annual S.Y in the catchments (r = -0/758). This inverse relationship emphasizes the importance and apparent role of vegetation in reducing sediment production and transporting in the region. Moreover, the results of regression tests showed that is possible to present the regional estimation models regards to annual S.Y by fitting linear, quadratic and power functions. In this regard, the quadratic model has the highest performance and explain 75% of the annual S.Y variance. The linear relationship was also able to explain 57% of the annual sedimentary variance.

It is very matter to study and measure snow covers as one of the important sources of water supply. Due to the hard physical conditions of mountainous environments, there is no possibility of snow measurement. the use of  remote sensing with regard to low costs, up-to-date and extensive coverage in this field can be proven to be a good way to identify in snowflake areas. the main objective of this research is to estimate the surface coverage of Sabalan mountains using satellite images of OLI and TIRS sensors and using the object-oriented classification method. The classification of satellite digital images is one of the most important methods for extracting information, which is currently done with two pixel-based and object-oriented processing methods. The base pixel method is based on the classification of numerical values of images, and the new object-oriented method, which, in addition to numerical values, uses content, Texture, and Background information also in the image classification process. Therefore, in the present study based on the precision of the object-oriented classification, the object-oriented techniques were used to extract the surface of snow cover. In this study, due to the use of high resolution spatial resolution (Landsat 8) and the new method of classification of images, the snow surface was characterized by Normalized Difference Snow Index (NDSI), Normalized Difference Vegetation Index (NDVI), Land Surface Temperature (LST), Brightness with a total accuracy of 91 percent, to 2142.62 square kilometers for the range Sabalan mountains have been extracted and the results can be used as alternatives to snowflake stations.

Snow reserves of mountain areas considered as one of the most important water resources of country which accurately recognition of quantity of these resources are essential due to the increasing value of freshwater and optimal utilization of resources. Sabalan mountain are one of the important basins of country that the water from melting snow which has fallen in winter, provide water for agriculture and surrounding areas drinking in spring and summer.  In this study for simulations runoff from snowmelt in the Sahzab catchment, (of sub-basin in the southern part of Sabalan) from mod 10a2 product and changes in snow cover of 2010-2011, using SRM model(based on degree-day method), has conducted. Results suggest during the statistical period, the greatest and lowest amounts of snow coverage are for February and may, respectively.

 The Snowmelt Runoff Model (SRM) as the most frequently used model in model in prognosticating and simulating runoff in mountainous basins using snow covered areas as an input, was employed in current study to simulate the runoff produced from snowmelt. The S factor (snow cover area) was extracted using 8 day images of MODIS sensor (combining bands number 6 and 4), NDSI index (with the necessary thresholds) ENVI and GIS software. In order to achieve the desired objectives, ground data such as temperature , rainfall and debit were also used.

Evaluation of SRM model using correlation coefficient and volume subtracting indicator are 81 and 2/3 percent, respectively. R-value indicator acceptability depends on the quality of data and may not be acceptable even by having enough data of 85% value but in a catchment with inappropriate and low data, lower value also is acceptable. With respect to shortage of meteorological and terrestrial data in Sahzab catchment, the SRM results of this study showed acceptable simulations for runoff simulation that was caused by snow melting in sahzab catchment.

Using of hydrological models and satellite images combined with powerful ground-based data can be used as a tool for planning and management of water resources, particularly in the area where snow melting is one of the factors leading to runoff. If studies on snowcovered area, snowmelt and its effects are considered on small scale such as riverside tributaries extraction of snow cover maps for each of the catchment basins, careful planning can be done for each region which will be in line with sustainable development.

Geomorphometry is the science of quantitative land-surface analysis (Pike, 1995, 2000a; Raseman et al., 2004). It is an interdisciplinary field that has evolved from mathematics, the Earth sciences, and most recently computer sciences (Pike et al, 2008, 3). It is well to keep in mind the two overarching modes of geomorphometric analysis first distinguished by Evans (1972) as specific, addressing discrete surface features (i.e. Landforms), and general, treating the continuous land surface. The morphometry of landforms per se, with or without the use of digital data, is more correctly considered part of the quantitative geomorphology (Thorn, 1988; Scheidegger, 1991; Leopold et al., 1995; Rhoads &Thorn, 1996). The shape of terrain, i.e. landforms, influences flow of surface water, transport of sediments, and soil production, and determines climate on local and regional scales. Furthermore, natural phenomena like vegetation are directly influenced by landform patterns and their relative position across the landscape (Blaszczynski 1997; Blaschke & Strobl, 2003).
The Earth’s surface is structured into landforms as a result of the cumulative influence of geomorphic, geological, hydrological, ecological, and soil forming processes that have acted on over time. Landforms define boundary conditions for processes operative in the fields of geomorphology, hydrology, ecology, pedology and others (Dikau, 1989; Dikau et al., 1995; Pike, 1995, 2000a; Dehn et al., 2001). In this study, using MRS algorithms and Ecognition software, landforms in the northern slopes of Mount Sabalan have been extracted and the effects of Landform morphometry on its hydrology have been investigated The semi-automated methods refer to the automatic procedures of extracting a landform based-process. This is mainly relying on unsupervised isodata classification, pixel-based classification (supervised /subpixel classifier based on training material), the analysis of digital elevation models (DEM), algorithms, hydrological modelling, and object oriented analysis (Nabil and Moawad, 2014:42).
In this study object-oriented methods and Ecognition software were used for the classification and the extraction of landforms. The object-oriented classification was used as an alternative to traditional pixel-based classifications, to cluster grid cells into homogeneous objects, which can be classified as geomorphological features (Seijmonsbergen, 2012). In addition, the DEM and its derivation (Slope, Profile and plan curvatures, maximum and minimum curvatures), were used in order to extract landforms. Then, using fuzzy logic method, the landform, land use, NDVI index , precipitation, density of river, and lithology layers were Overlaid and the potential flooding area was obtained. In the object-oriented method, determining the scale parameter is a very important factor in the separation of different objects in an image. Scale parameter is a crucial threshold that determines the maximum allowed heterogeneity for segmentation and has a direct influence on the size of the objects to be obtained. The scale parameter, after a trial and error process, is recognized to be within a particular range (Gerçek, 2010:115). A novel method that was introduced by Dragut et al. (2010) and the ‘Estimation of Scale Parameter (ESP) that built on the idea of ‘Local Variance’ (LV) were employed to obtain the optimum scale out of a range of scales. By interpreting thresholds and prominent peaks in the ROC-LV graph, characteristic scales relative to data properties at the scene level could be found. This curve in 100 scale level was produced for the study area by using the ESP software and with respect to curve, the scale of 25 was selected for the segmentation. After segmentation, using the morphometric differences between the landforms, the landforms were extracted. After this stage, the landforms along with three layers of NDVI index, land use, and lithology was fuzzy. Finally, using gamma 0.8, they were combined and the zoning map of the potential flooding was estimated. Flood zoning map was classified into 5 classes and the percentage of each zone risk was calculated in each landform. In this research, using an object-oriented model, landforms were extracted as plain, peak, pit, ridge, channel, nose, shoulder slope, hollow shoulder, spur, planar slope, hollow, spur foot slope, and hollow foot. An assessment of the effect of landforms on the hydrology of the area revealed that three landforms of hollow, shoulder and planar slope which were respectively 67.3%, 62.9%, and 53.2% had the greatest impact on flooding and their area were zoned as high and very high flooding. On the other hand, plain and pit landforms were zoned in the form of low and very low flooding areas.

Introduction Semi-automated extraction of selected landform types from land-surface models such as digital elevation models (DEMs), curvatures, and slope gradients is of particular interest in geomorphology, hydrology and related fields(Eisank et al,2010:1). Geomorphometry is the science of quantitative land-surface analysis (Pike, 1995, 2000a; Rasemann et al., 2004). The morphometry of landforms perse, by or without the use of digital data, is more correctly considered part of quantitative geomorphology (Thorn, 1988; Scheidegger, 1991 Leopold et al., 1995; Rhoads and Thorn, 1996).
Evans (1972) was the first person that divided Geomorphometry in two branches the general and special Geomorphometry, in special Geomorphometry More is be discussed landforms and geomorphic processes such as glaciers and runoff in geomorphometry terrain segmentation is an approach for structuring terrain data such as digital elevation model(DEM) via derived land-surface into spatially discrete plan-view areas known as terrain units(strobl,2008).The shape of terrain, i.e. landforms, influence the flow of surface water, transport of sediments, soil production, and determines climate on local and regional scales, furthermore, natural phenomena like vegetation are directly influenced by landform patterns and their relative position across the landscape Landforms although have different meaning to different disciplines, they reveal common physiological and morphological characteristics of terrain which may guide through understanding past and present processes acting on terrain and provide necessary information to related disciplines about land characteristics and potentials(Gerçek, 2010:9). In this study, using MRS algorithms and Ecognition software have been studied glacial landforms the northern slopes of Sabalan.
Methodology In this study, the DEM and derivative of its, have been used in order to extract glacial landforms. To prepare the digital elevation model layer have been used of topographic maps with 1: 25000 scale. Profile curvature, plan curvature and mean curvature are three important layers used in this study.The semi-automated methods refer to the automatic procedures of extracting landform based-process. This is mainly relying on unsupervised isodata classification, pixel-based clasification (supervised /subpixel classifier based on training material), analysis of digital elevation models (DEM), algorithms, hydrological modelling and object oriented analysis (Nabil and Moawad, 2014:42). In this study object-oriented methods and Ecognition software is used for classification and extraction of landforms.
Results and discussion In this study, we are looking for are extracted cirques the northern slopes of Sabalan. This area because of the high altitude receives high humidity this precipitation is mainly in the form of snow and is appropriate for the formation of glacier and for cirques. A cirque is one of the most prominent forms of glacial erosion (Embleton and Hamann, 1988). According to Evans (2004: 154) cirques are “hollows formed at glacial sources in mountains and partly enclosed by steep, arcuate slopes (headwalls)”. In general cirques exhibit concave shape in both plan and profile direction, with a size ranging from hundreds of metres to a few kilometers (Glasser and Bennett, 2004). They are typically composed of a cirque crest, a steep headwall, and a gentler cirque floor often filled by a cirque lake. For extraction of circus having profile curvature, plan curvature and mean curvature layers is necessary. With respect to this aforementioned layers were obtained in the SAGA software.
Scale parameter is a crucial threshold that determines the maximum allowed heterogeneity for segmentation, which has a direct influence on the size of the objects to be obtained. Scale parameter is recognized after a trial and error process (Gerçek, 2010:115). In this study ultimately scale of 36 was selected for the segmentation.
Extracting ridge line position is very important in determining and identifying the the cirque. According to the morphometry of this landforms for classification the ridge were used convex shapes in layers.
In general, the convex shape of the ridge is determined by the positive values in mean and plan curvature. The Ecognition software and MRS algorithm was used for the execution of the model and Segmentation of the layers. Ridge layer was obtained by defining morphometriy characteristics of the ridge and comparing the results with field data. Finally, according to the semantic model of research, the relevant rules defined in Ecognition software and was extracted circus position.
Conclusion In this study glacial landforms (circus) were extracted with semi-automatic approach and by using object-oriented approach in northern slopes of Sabalan. The Result of research were presented in the form of a map which shows the location circuses.

Assessment of watershed tectonic activities is interesting for earth science researchers, especially tectonic geomorphology. In this regard, different methods have been used by researchers. These methods have been constantly developing and they consist a range of Geomorphometric methods, remote sensing, Digital Elevation Models (DEM) and other advanced techniques. In this study the remote sensing methods, Digital Elevation Model and geomorphic indicators (in the form of TecDem) were used to evaluate tectonic activity in southwest side of Sabalan Mountain. To determine the boundary of drainage basins Arc Hydro Model was used. The indices of concavity (Ѳ), slope (S), Iso Base Map and the profile of distribution slope with regression of log Networks were extracted from Digital Elevation Model and then the tectonics uplift rate of basins was calculated by using Stream Power Model. By using morphometric parameters and geomorphic indicators such as Transverse topographic symmetry factor (T), Stream Length-gradient index (SL) and Hypsometric integral (HI) in TecDem Model; Tectonic activities were evaluated in the studied basins. The results of the extracted components (i. e. distribution logarithmic regression of networks and slope, skewness values, Hypsometric integral, Iso Base Map, knick points and steepness and uplift rates proved dominance of active tectonic in the studied basins. So that the uplift tectonic rate is 0.33 to 0.51 mm/yr. Also, low indices of concavity (0.24 to 0.45) and high values of maximum gradient (80.6 to 132.2 percent) confirm the existence of high tectonic activity in study area. Accordingly, the results of surveys and morphotectonic evidences such as linear valleys, reverse fault scarps in Tajyar and Aghmiyun basins, the Shutter and liner rides along the Aghmiyun and Tajyar networks, replacement of Fan apex and diversion of networks caused by fault activity in southwest of Sabalan; prove the presence of active tectonics and good efficacy of TecDEM Model in evaluation of Tectonic Activities in study area.

Condition of contour lines in topographic maps, explains more geomorphologic issues such as effective processes in the land forms found in nature. Change in the curvature of the transverse profile of a valley in mountainous areas, the peak of the mountain range, also reflect the geomorphologic features and expresses the tectonic events and climate changes occurring in the region. These changes are traceable along the valleys, according to the width of the valley floor to the height of its sides or curvature coefficient of rate curve. through examining this curvature at different heights, we can determine changes in the valleys and express on how to operate the various processes of exploration and cumulative throughout the valley.In this article Tried that, through classical methods and mathematical analysis, all major subbasins and valleys around Sabalan be examined. Using main rate curved lines flection coefficient, with the height distance of 200 meters, and if necessary with shorter distance (50 meters), addressed to identify the part of mountain, that had been Indicate the location's focus of geomorphological processes over time. To this end, For the 21 major basins of Sabalan, prepared some table and relationship, which represent the way of arrangement of the transverse valley profiles at different altitudes is associated with processes. Studies in sabalan, suggest that in the height of 2800 meters has been the place of changes in geomorphological processes, over time.

Rural area's Residents Are Dependent On Environment Directly or Indirectly toLive. Grown in The Field or Garden, Products Obtained From Domesticated Animals,Animal Increasing Population, the Requirement to Provide Stable Employment forExtra Population Taking into Account the Maintenance and Stability of Environment,Maintenance and Revival of Environmental PatternsTribal, Rural, Urban, and FoodSecurity are Now very Important. Therefore, it Requires Programming in allDimensions Especially Environmental, Economic, Social, Cultural, And Physical-Bodily Aspects so that it Leads to Comprehensive and Stable Development.Meshkinshahr Being Mountainous Area, Having Three Environmental Patterns Tribal,Rural, Urban with Anthropolgical Point of View, Moderate Andcold winter andsummer Humid Climate With High Comfort Level Especially in Eight Monthes ofYear, Geomorfologic and Natural Condition of Saban Mountain from Mountainingand Geoparking Point of View, Green Countries and Meadows and Forest Parks,Rivers Filled with Water Such as Khiavchay, Meshkinchay, Ghareh Soo, AgriculturalFields and Gardens to Develop Ecotourism Require Condition to ProgramEspeciallyNatural Tourism Which Is Suggested For Post-modernismEra.

Slope rupture in the area of study that is caused in different forms and appeared on various slopes mainly due to different factors, in addition to resulting in direct death tolls and financial losses, increases the amount of sediments entering rivers. Taking this concept that such ruptures directly or indirectly are coincided with geomorphic characteristics of the basins, in this article, we have analysed the amounts of sediments resulting from slope ruptures in relation to these specifications, using experimental approaches and taking into consideration various parameters such as the area of basins, the curvature of slopes, have been calculated. Applying the results, we have specified those sections that are more susceptible to the slope failures and providing more slope materials to the rivers. The results of the analyses being carried out indicate that different sections of the area have different potentials of failure, and the southern and south eastern areas are completely different from each other. The different sections and the slopes composed of old unconsolidated alluviums and show higher rates of susceptibility to water erosion, and they provide each year considerable amounts of sediments into the rivers.