Showing 9 results for Geomorphology
Dr Mitra Saberi, Dr Amir Karam, Parviz Zeaiean, Ali Ahmadabadi,
Volume 0, Issue 0 (3-1921)
Abstract
many geomorphic landforms have fractal structures and their formation and transformation can be explained by mathematical relations. The purpose of this study is to identify and analyze the fractal behavior of landforms of macro geomorphologic regions of Iran,as well as studying and analyzing topographic and landform characteristics based on fractal relationships, and also, analyzing the characteristics of dominant geomorphologic processes based on the theory of fractals. In this study, the contour lines of different landforms of Iran (according to the territorial types) including mountains,hills, plateaus, Plain Domains, Fan Breakout, fan alluvial, for pixel sizes of 30,90,200 m, were drawn and their fractal dimension was estimated by using the box-counting method. The morphometric characteristics of the landforms and their fractal dimensions with indexes (max, mean and standard deviation) related to the five variables (height, gradient, profile curvature and planar curvature of the metric) were analyzed by Arc GIS software at each layer.After investigating their correlation with the fractal dimension, the regression analysis was performed binary and the relationship between the fractal dimension,topography, landforms and processes was analyzed. The fractal dimension has the highest correlation coefficient with the gradient and the standard deviation indices, and the lowest coefficient with the profile curvature and the mean index Moreover, for larger pixel sizes, the correlation coefficient decreases between the indices and the fractal dimension.This research can provide a ground for further research on fractal geometry in geography, geomorphology, geology, environment and other Earth sciences.
Shahram Bahrami, Nadia Baghaei,
Volume 18, Issue 48 (3-2018)
Abstract
Landforms and geomorphological processes is the most important factors that affecting dispersion and quality of building materials. Case study, consisting of both new and old alluvial fans is located in the West of the city of Sabzevar. The aim of this study was to investigate the process of freezing and thawing in the durability and quality of materials taken from the alluvial fans old and new. To achieve this goal, we dug four wells in different parts of new and old of fans. The examples of large and small stones from the depths of one meter, two meters, three meters and four, wells were removed. Then to measure resistance of material, against freezing and thawing, freezing and thawing tests were performed on all samples. According to the test on three outcomes for this study was obtained. First: weight loss of samples of the new fans of head is greater, compared with other samples are taken because of the waters. Second, samples of the new fans head because the waters have greater weight loss compared with other samples are taken. Therefore, samples of new fans is fine-grained as possible. Thirdly, if the target is high-quality materials, best materials is made of metamorphic minerals, such as andesite and pyroxene.
Dr Tayebeh Kiani, Mr. Mohamad Fatholahzadeh,
Volume 19, Issue 52 (3-2019)
Abstract
The karst areas refers to individual areas that shaped by the dissolution of bedrock and subsurface drainage grid development and are connected mainly with limestone. The karstic formations outcrop 20 percent of the land surface of the planet is covered that 11 percent of Iran are part of this 20% is included. The ZAGROS region of origin karstic formations in the country that the formation of karst forms and numerous caves in the area attest to this claim. Overall creation and development of karst geomorphology, the formation of karstic aquifers are karstic systems. In fact karstic aquifers, underground reservoirs that store water in a web of interlocking joints and cracks, caves and canals. The karst can be effective ways to develop into three categories: physical, chemical and hydrogeologic studies divided that role of lithology and its properties, weather conditions and hydrological and structural factors such as faults and fissures, and slope area are of particular importance. In this study, characteristics OSHTORANKUH region of karst processes and the formation of karstic aquifers were examined and to do so using the AHP model the effect of weight each criterion was determined in karst area. Then, using the SAW model )is a subset of multiple criteria decision-making methods( Zoning areas prone to karstic aquifers OSHTORANKUH software was Arc GIS 10.3 and defining the center of the southern slopes of the western and north-eastern slopes of the mountain that are consistent with carbonate formation, the intersection of active faults and are the focus of surface runoff ,it also has a gentle slope than other parts of the region, have Better and more suitable conditions for the formation of karst processes karstic aquifers. The adaptation of the area most prone to the aquifer karst springs evidence of the correct zoning of the area is karstic aquifers.
Doc Maryam Ilanloo, Doc Amir Karam,
Volume 20, Issue 56 (3-2020)
Abstract
The destruction of the rivers and, consequently, the need to reconstruct them, is one of the known important problems in throughout the world. However, suitable methods for assessing the morphological changes (morphology) associated with this action, as well as the cognition of the effect of the morphological factors in order to intervention in the process of river reconstruction, are still being explored. The JAJROOD and LATYAN-dam areas in the north east of Tehran due to the pleasant weather have always been and are in Eco tourists and nature interested people noteworthy. For this reason, during the recent decades and because of human manipulations, the JAJROOD River basin and its margins have been heavily affected. Hence the study of hydro morphological changes in this river is strongly needed. The object of this research is to evaluate the hydro morphological conditions of one part of JAJROOD River using the MQI method. Accordingly, Landsat 8 satellite images of 2018 and Landsat 4 in 1976 were prepared and were take placed several field observations. The results of the research show that all areas of the region are in poor and very weak conditions regarded to the MQI method. These problems are caused by the cutting of trees in order to create human structures, harvesting sand, creating numerous promenades along the river's estuaries and changing the river pattern.
Shila Hajehforosh, Amir Karam,
Volume 21, Issue 60 (3-2021)
Abstract
River management, including strategies that effectively have an effect on the behavior. Geomorphological management, is the study of shapes, nature, and origin, processes of emergence, development and use of human and material composition of the Earth. The assessment of river character and behavior in Stage 1 is based on analysis of the assemblage of geomorphic units (channel and floodplain landforms) along any reach. Arangeh River basin were identified in 1and 3 styles, including: Headwater, Gorge style in confined valley setting, planform controlled, floodplain bed, low sinuosity cobble, low sinuosity gravel, bedrock controlled sand, meandering gravel, unconfined low sinuosity cobble with Side stabilized, partly-confined low sinuosity cobble with Side stabilized, partly confined Asymmetric valley with cobble, , partly confined symmetric valley with cobble ,Artificial bed.Geomorphic conditions of each of the styles were evaluated in the two stage of river style framework. at this stage of adjustment of Each style is determined to the confusion of peak flow by using criteria such as channel characteristics (size, shape, morphology Bank and plants channels), channel plan form (sinuosity, lateral stability, geomorphic units into the channel and River flood plain and plants) and features bed . Two Style had good geomorphic conditions (floodplain bed bedrock controlled sand, unconfined low sinuosity cobble with Side stabilized) show the potential of a good adjustment, and the reach has a good of potential adjustments are more sensitive to changes . In the fourth stage of rehabilitation is carried out in reach scales, basins and river basin based on forecasts of possible changes in the future and potential of Geomorphic River Recovery. Each style is proposed management priorities in accordance with the geomorphic and recycling potential.
Khadijeh Heydarian, Siavash Shayan, Hossein Jahantigh,
Volume 21, Issue 63 (12-2021)
Abstract
Summer catchment basins surrounding the city of Tehran, due to their remoteness from atmospheric pollution and urban manifestations, is considered as a place for exploring and recreating for many people, and as a place for money making out of restaurants attracting many tourists for others. Sangan is taken into consideration as one of the most beautiful valleys in Northwest of Tehran. The summer catchment basins due to the phenomenon of counter urbanization and also escape from city pollution, easy access, and short distance, has taken too much attention, so much that the inhabitants mostly spend winter in Tehran and summer there. Since some buildings have been built along the main river, the study of the effectiveness of riparian zone and also the specification of areas susceptible to flood is of great importance. In this research, using the HEC-RAS RAS model, flood- prone areas with different return periods (2 to 100 years old) were calculated, and then for the floodplain zoning the morphological characteristics of the flood zones gathered during the fieldwork have been used. The careful study of these flood fringe zones indicates that a small percentage of the lands are included in flood hazard zone with the 25-year return period. Also, the comparison of the pictures taken from the Sangan River in the past and present shows that the use of lands in the river bank has been changed and due to unauthorized constructions and gardening along the river, the width of the bed has dramatically been decreased. This factor increases the size of the floodplain area and consequently the damages.
Dr Ebrahim Moghimi, Mr Mohamad Fathollahzadeh,
Volume 22, Issue 64 (3-2022)
Abstract
System is a set of interconnected components that are systematically interconnected, influenced by one another, interacting with one another, acting as a whole, and being purposeful. A systematic approach is a perspective that allows us to identify the forces and variables that have a significant impact on the environment outside and within a complex and to understand their function and position in the complex. In general, the interplay of form and process in landforms is based on systematic reviews and analysis by researchers and the residual effects of these changes. In this study, the study of glacial geomorphic systems with regard to systematic approach and the interaction between form and process in glaciers of Oshtorankuh is investigated. Geomorphometric analysis of the glacier cirques of the Oshtorankuh region shows that these landforms, unlike the usual glacier cirques, have been expanded more horizontally and superficially than were investigated in depth direction to justify the genesis and lithology of the area. It is often calcareous and carbonate and the carbonate nature of the environment activates the dissolution process in the environment. Therefore, in this glacier system, the dissolution factor is more effective than other active elements.
Dr Esmaiel Najafi, Dr Amir Safari, Dr Ezatoalah Ghavavati, Dr Amir Karam,
Volume 24, Issue 73 (6-2024)
Abstract
Geomorphology is related to the processes and forms of the earth's surface, and any human activity, including the construction of bridges, leads to quantitative and qualitative changes in the movement and displacement of materials and kinetic energy and affects the geomorphic system, is the concern and involvement of geomorphologists. Geomorphology, as a systematic science can also study and explain the environmental realities that have been objectified in the form of processes and forms in nature, and introduce their results and output spatially in the form of maps and models. The type of research is applied and the research method is descriptive-analytical and based on the results of the Ph.D. Thesis entitled "Geomorphological modeling of the construction of bridges in urban floodways (Case study: Tehran metropolis)". The results indicate the capability and application of geomorphology in modeling and optimal location and construction of bridges, in order to create more security and welfare of citizens, reduce costs and prevent financial and human losses due to the destruction and improper location of such structures in an urban floodway- river valleys and other natural environments. Also, this study, while enriching the literature of the field in question, has studied, explained, and conceptually modeled the role and application of geomorphology in the optimal location and construction of bridges in urban issues.
Keywords: Geomorphology, Conceptual Model, urban floodway- river valleys, Bridge Construction.
Mrs Negar Mirzaii, Dr Ali Ahmadabadi, Dr Seyed Morovat Eftekhari, Mrs Elaheh Lofti,
Volume 24, Issue 75 (12-2024)
Abstract
Rivers are always vital arteries of the earth and naturally, they have a gradual and continuous development process which has undergone fundamental changes after the expansion of human settlements and urban development and they have lost some of their natural functions. Wardvard River is no exception to this. This river flows in the west of Tehran province and has been heavily affected by urban development which has undergone continuous changes in its flow path due to human interference and considering that this river flows in the access route of western cities of Tehran province, its natural and gradual evolution has been disrupted that this transformation, it has removed the river from its natural condition. In this research, the factors affecting the geomorphological quality of Wardvard River have been identified and using MQI index, it had evaluated the quality of river morphology. In this method, Wardvard River is divided into 9 study periods and the three main components of the quality of geomorphological performance, artificial structures and channel adjustment have been evaluated in the form of 28 indicators. Results show due to the urban development of Tehran and many artificial changes in the Wardvard river channel, intervals 1, 3, 4, 6, 7 have earned a score of 0.2 due to human interference and canalization of the river and it is very poorly placed on the floor.Intervals 2 and 5 have earned 0.3 points and it is placed in the weak class and intervals 8 and 9 have scored 0.6 due to the low human interference and the natural course of the river and it is placed in the middle class in terms of morphological quality.
