Gholam hassan jafari; Mina Avaji
Abstract
1-IntroductionEarth's climate is one of the most important structural factors. More natural and human trappings are affected by the weather. The coefficient of variation of less precipitation is reagent stability and steady time distribution (Fatahi, & Rezaei, 2009). The quaternary climatic changes ...
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1-IntroductionEarth's climate is one of the most important structural factors. More natural and human trappings are affected by the weather. The coefficient of variation of less precipitation is reagent stability and steady time distribution (Fatahi, & Rezaei, 2009). The quaternary climatic changes have created different landscapes, such as glacial circus, glaciers, and especially erratic rocks, according to the first topography of Iran that found in high regions of Iran. Geomorphologists' permanent snowline altitude is determined to help the circus of mountain effects. The continuous snow line, altitude above which or latitude beyond which snow does not melt in summer (Ramesht, & Shah Zidi, 2011). The temperature conditions quaternary reconstruct based on a permanent snowline altitude temperature difference compared to today. They also estimate the maximum expansion of tabs by ice moraines, the erratic rocks, valleys of glacial sediments and granulometry, and its height to consider as ice and water equilibrium line altitude. The water and ice equilibrium line is where ice flows entirely replace the water ice flows wholly replacing the water. The quaternary climatic changes, according to particular topography of Iran, have inherited different figures and landforms such as glacial circus, glaciers, and especially wanderer rocks. We cannot analyze by changing one element changes made; a complex mix of elements change been led to changes in the process and enduring numerous landforms. Any anomalies in each component s will cause defects and commotion in the whole system. 2-MethodologyAccording to the geomorphological landform, the remaining lake last is one of the methods of forecasting and estimating their condition. The Climatic factors role has particularly essential in the current situation of the Iranian domestic water hole. We used to examine the relationship between climatic factors and its effect on local lakes, dewatering of the temperature and precipitation data of the 50-year-old Asfazari database in cells 15 x 15 km (Masoudian, 2012). In addition to measurements of temperature and precipitation of central tendency, indexes used of dispersion indexes in statistical processes (Standard deviation and Coefficient of variation). Since the standard deviation is not used to compare the distribution of both characteristic varies with different units, the coefficient of variation (CV) used. Since most time, the Earth's surface has a temperature higher than the surrounding air, in this study were rainfall receiving below two degrees Celsius on the Basin. The coefficient of snow by reducing the temperature was estimated. With put, the factors in its relations appropriate amount of heat and precipitation determined in the Quaternary cold periods. We expect the coefficient of snow and temperature changes and precipitation decrease of 3, 6, and 9°C temperature for sub-study briefly. We cannot continuously study the effect of all elements and factors related to Quaternary climate changes. Still, we are trying to interpret the lake volume fluctuation due to climate change as a system through changes in temperature, precipitation, the coefficient of rain below 2°C, the ratio of variation coefficient of variation of temperature and precipitation.3-Results and DiscussionThresholds obtained show that the basin con ensures the exit of the lake that to be the average temperature of less than 15.78, average annual rainfall more than 215 millimeters, snowy coefficient more than 13 percent, the coefficient of variation of precipitation less than 40 percent and the ratio of difference of temperature more than 7.43. All basins inside Iran changed to a temperature not fit in the Quaternary. Status and evidence there are of lakes dewatering in the Quaternary do not match whit precipitation double and decline of temperature 6-12 degrees compared to the current conditions. So that line equilibrium of water and land could be the effects of the Quaternary terrace lacks by reducing three, nine, and 12-degree temperatures and increased precipitation. Change the line equilibrium of water and land cannot interpret with a temperature and precipitation changes alone, and causality of these changes in the line equilibrium of lakes water and soil must search in changes of precipitation regime and geomorphology of the region4- ConclusionsTo investigate the impact of climate parameters on the dewatering amount of water, we used primarily average of them. Accordingly, they are receiving basins Maharloo (375), Urmia (372), and Meighan (314 mm) maximum and basins Yazd (92), Bafgh (95), and Ardestān (114 mm) minimum of basin precipitation average. The basin has a higher temperature water demand more. If they receive Precipitation equal, drought intensity increases, the average temperature of pond, and their condition are such that allocated the lowest temperature to the basins of Urmia, Meighan, Gavkhoni, and the highest temperature to the lakes Qom and basins Jazmurian, Lute, the Bafgh and Qatruyeh. Basins of Urmia and Meighan have the best conditions. The basins Bafgh and Yazd have the worst conditions dewatering in terms of combining two elements of climate, temperature, and precipitation. These parameters alone will not be able to estimate the dewatering basins' performance reliable be due to the difference in average temperature and precipitation in the basin. Therefore, we used other vectors such as the coefficient of variation of climate (temperature and precipitation) and the coefficient of rain below 2°C. Investigation and compared the ratio of precipitation below 2°C on precipitation full in fourteen basin studies represents that the basins Meighan 21%, Urmia 20.8% and Qom 20.4% allocated to the most extensive and basins Jazmurian 1% and Qatruyeh 0.6% accounted to the lowest percentage of precipitation in below 2°C. To estimate sufficient rainfall in dewatering lakes, we can put number 40 in equation (2) instead of CVp, and we expect threshold precipitation of the basins. Number 40 is a threshold effect coefficient of variation Precipitation in dewatering lakes.Keywords: Quaternary, Climate, line equilibrium of water and land, Interior Lakes of Iran. 5-ReferencesFatahi, E., & Rezaei, T. (2009). Pattern of Daily Climate Circulation on Iran, Journal of Geographical Research, Isfahan University, No. 93: 45-74Masoudian, A. (2012). Iranian Climate, Sharia Toos Publications, Isfahan.Ramesht, M., Shah Zidi, S. (2011). Geomorphology Application in National, Regional, Economic, Tourism Planning, Second Edition, Isfahan University Press.
Gholam hassan jafari; Nasrin Hazrati
Volume 6, Issue 18 , June 2019, , Pages 79-96
Abstract
Introduction The climate change that has started since the Quaternary period continues to shape the current morphology of the Earth. During the Quaternary period, glacial and interglacial periods have been continuously occurring and have undeniable geomorphologic evidence. Using this evidence, it is ...
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Introduction The climate change that has started since the Quaternary period continues to shape the current morphology of the Earth. During the Quaternary period, glacial and interglacial periods have been continuously occurring and have undeniable geomorphologic evidence. Using this evidence, it is possible to determine the ELA and the extent of glacial expansion and the study of climate change. This is because of the fact that exogenous Earth-changing processes have not been able to completely eliminate the remaining effects of quaternary glacial erosion (Yamani & Zamani, 2007: 100). The Northwestern unit, which is the intersection of the northern and southwestern mountain ranges of Iran, is a mountainous region. There is an extensive evidence of Quaternary glacial activity remained in this unit. In this regard, this article seeks to estimate the Quaternary ELA considering the glacial effects of the region. Talrghani (2012) has introduced the Northwestern unit as a mountainous region of Iran, as the north and southwest mountain ranges of Iran meet with different structures in the area; in addition, since the northwest is the intersection and the density of the three plateaus, it has led to its complexity and disorder of its terrains. Methodology Among the basic issues in glacial studies are the ELA and the water and ice equilibrium line .Using topographic maps with the scale of 1: 50000 and the reflection of the glacial evidence on maps, more than 4000 cirques, dispersed among the basins of Aras, Sefidrud and Lake Urmia, were identified. The overall direction of the identified cirques was determined according to the continuity of the terrains in a way that the main ridge of each basin determined the direction of the formation of the cirque. Using the geological map with the scale of 1: 100000, the lithological conditions of the cirques location were investigated. The data of those cirques located in sediments that had not undergone diagenesis such as conglomerate and were loose (such as marl, clay, and evaporite sediments) were extracted. Considering the mountainous nature of this region, glacial cirques were identified in the western, eastern and central parts of the unit. The ELA was estimated by Wright, Cirque-floor altitude, Terminus-to-Head Altitude Ratio (of Wright and Porter), and Altitude Ratios' methods.ResultsIn this geomorphic unit, glacial cirques can be formed from a height of 1800 m above the surface. The analysis of the ELA estimated by cirque-floor altitude method indicated that it was more consistent than the other methods due to the reflection of the direct effects on ELA. The ELA between 2453 m (Aras basin) to 2685 m (Sefidrud basin) was estimated (with 232 m height difference). This difference indicated a decrease in the ELA from the south to the north. The average elevation of the ELA was 2586 m. The average elevation of the ELA in the Aras basin, Lake Urmia, and Sefidroud were respectively 2453, 2621, and 2685 m. The analysis of the findings showed that this unit was controlled by the glacial system during the cold periods.Discussion and conclusionSince the quaternary survey was about 12000 years ago, it was obviously impossible to accurately estimate the ELA, and there were inevitable differences in the estimated ELA by different methods. The highlands of the Northwestern geomorphic unit were located in the western, eastern and centeral parts. The Aras River, Lake Urmia and Sefidrud basins were located in this unit. The terrains’ direction of this unit was in six directions of north-south, east-west, and northeast-southwest. There was a possibility of the formation of a cirque glacial. 4059 cirques identified in this unit with the dispersion of 1,215 cirques in the Aras Basin, 1442 cirques in the Sefidrud Basin, and 1643 cirques in the Lake Urmia Basin. After the removal of pseudo-cirques (2720), remained the landform Cirques. The percentage of cirques was then estimated in different directions. The findings showed that while 71.25% of the identified cirques were in the Nesar slopes, 28.69% of them were in the Negar slopes. After identifying the cirque, the Wright method was used to estimate the ELA. By applying this method, in the first stage, the lowest ELA was estimated in the Aras Basin (1826 m). In the second stage, with the elimination of cirques pseudo-data, it was allocated to the Lake Urmia Basin (2360 m). Estimated ELA in different methods indicated that the ELA was less 232 m from the southern basin (Sefidrud) to the northern basin (Aras).
Gholam Hassn Jafari Jafari; Mehdi Abasi
Volume 5, Issue 14 , June 2018, , Pages 1-22
Abstract
Introduction Investigation of river terraces is one of the main issues in the field of river geomorphology. River terraces, as a medium of alluvial landforms and heritage of stratigraphy, are widely investigated by geomorphologists to understand the tectonic and climatic time. The formation of alluvial ...
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Introduction Investigation of river terraces is one of the main issues in the field of river geomorphology. River terraces, as a medium of alluvial landforms and heritage of stratigraphy, are widely investigated by geomorphologists to understand the tectonic and climatic time. The formation of alluvial terraces is primarily the result of tectonic rise alongside the cycling cycles. The edges of a river that is hard and resistant to geology are wall-bound or steep sloping, similar to water-breakers, and limit the number of the steppes to the alluvial terraces; but on the sides with a looser lithology, alluvial terraces are formed with a slight slope. Go up or down to the basin or the sea level changes are accompanied by a change in the slope along the river, creating tectonics alluvial terraces. Ghezel Owzan River, as one of Iran''s longest river systems, has well responded to lithological and tectonic factors. The Ghezel Ozan Basin is located in the northwest of Iran, and in latitude of 34° 53'' 21" to 37 ° to 56'' 2" north and longitude is 46 ° 27'' 43" to 49 ° 19'' 43 "east. The origin of the Ghezel Ozan River is from the heights of Chehel Cheshmeh Kordestan and with a length of more than 550 km, after crossing Zanjan, East Azarbaijan and Ardebil provinces, along with several streams along its path, intersects in the Guilan province with the river Shahroud and enters the reservoir of the Sefidrood Dam. Methodology Accordingly, river terraces are lithologically divided into marl, crystallized and conglomerate periods with the help of geological (1/100000) and topographic (1/50000) maps and using computer software such as Arc, GIS, Global Mapper, and Excel. River path is also lithologically and tectonically divided into eight periods and profiles of each period are drawn. In order for the collection of information, we have translated several English articles and examined various internal sources related to the subject matter of the research. With the help of geological maps and field observations of the region, we investigated the effect of tectonics and lithology on topography (symmetric-asymmetric) on alluvial terraces. Using the Global Mapper, the cross-sectional profile was mapped along the river''s perpendiculars and analyzed. Result Results show that from among the major lithologies of Ghezel Owzan terraces (marl, crystallized, and conglomerate), marl terraces are more asymmetric and crystallized terraces are more symmetric in areas without tectonic movements. Symmetrical terraces are formed in areas without tectonic movements or in areas with the same tectonic movements on both sides with resistant lithology. Asymmetrical terraces are also formed in areas where tectonic movements are not the same on both sides or in areas where there are marls in-between geological layers. Marl lithology, which is the dominant lithology of the basin, has the greatest impact on the asymmetry of terraces on this river. Tectonic has been active in A, C, E, F & H periods and inactive during B, D & G periods. Discussion and Conclusion On the bed of the Ghezel Ozan River and major parts of Dyvandra to the Miyaneh, Qareaghaj and the greater part of the province of Tarom, it is overcome with Marl Lithology (Hashtchin to Khalkhal, upper and lower part of Hashtrood and Turkmen Chay, southern provinces of Miyaneh and Zanjan, middle section of Sojas). The conglomerate sediments are the dominant lithology of Qazlazan from Soltaniyeh to Nikpay and the upper of most major branches. The irregular dispersion of lithology and faults in different parts of the Ghezel Ozan River makes it impossible to sequentially divide the alluvial terraces. In resistant lithology, alluvial terraces of symmetrical are formed and in the marl lithology, the slope of the arches of the arches provided the possibility of a deep cut and, with deep erosion and common landslides in the transverse surfaces, low-calorie alluvial terraces is created with low altitude difference. Another factor in the asymmetric of the alluvial terrace is the lithology of the basalt and limestone of the Ghezel Ozan River terrace that act as a barrier and by reducing the river slope and reducing the erosion of the water, the river is forced to move horizontally before the strait, the degradation of the compressive levels has led to asymmetry of the terraces and denser plains.
