University of TehranPhysical Geography Research2008-630X416920101122Numerical Tracking of Middle Eastern Cyclones
In the Cold Period of the YearNumerical Tracking of Middle Eastern Cyclones
In the Cold Period of the Year21510FAZHejazizadeMSedaghatJournal Article19700101This paper deals with the numerical tracking of Middle Eastern cyclones. Cyclogensis regions and their movement tracks can be determined by respective algoritms. In this paper, re-analyzed NCEP data with the temporal resolution of 24 hours and the spatial resolution of 2.5 2.5 degrees, were used for the cold period (December, January, February, and March), of the years 1993-94 to 2002-03. The area study is located at 10oN-45oN and the longitude 0oE-65oE. An algorithm written in C++ language was used for locating the points, and ArcGIS software was utilized for drawing the tracks. As a result, Five main tracks were characterized as most important tracks originated from western and northwestern areas; each month exhibits its own particular climatology. In January, the tracks tend to extend along the northern Mediterranean area. In March, the Atlantic low pressures increase noticeably. Most of the tracks have two-or three-day lifetimes; the effect of topography factor on formation of cyclogenesis regions is more outstanding than on leading the tracks. Cyclones which enter Iran are along three main tracks and three sub-tracks. The most important track is the one that enters from the west, originating from Cyprus region; the frequency of occurrence of cyclones exhibits an ascending trend.This paper deals with the numerical tracking of Middle Eastern cyclones. Cyclogensis regions and their movement tracks can be determined by respective algoritms. In this paper, re-analyzed NCEP data with the temporal resolution of 24 hours and the spatial resolution of 2.5 2.5 degrees, were used for the cold period (December, January, February, and March), of the years 1993-94 to 2002-03. The area study is located at 10oN-45oN and the longitude 0oE-65oE. An algorithm written in C++ language was used for locating the points, and ArcGIS software was utilized for drawing the tracks. As a result, Five main tracks were characterized as most important tracks originated from western and northwestern areas; each month exhibits its own particular climatology. In January, the tracks tend to extend along the northern Mediterranean area. In March, the Atlantic low pressures increase noticeably. Most of the tracks have two-or three-day lifetimes; the effect of topography factor on formation of cyclogenesis regions is more outstanding than on leading the tracks. Cyclones which enter Iran are along three main tracks and three sub-tracks. The most important track is the one that enters from the west, originating from Cyprus region; the frequency of occurrence of cyclones exhibits an ascending trend.https://jphgr.ut.ac.ir/article_21510_05d2a0f462dcc47bad9a32fc5c13e43c.pdfUniversity of TehranPhysical Geography Research2008-630X416920101122Sediment Sourcing of Gully Erosion and Factors Affecting it
in Small CatchmentsSediment Sourcing of Gully Erosion and Factors Affecting it
in Small Catchments21511FAA.ANazari SamaniHAHMADIMJAFARIJGhoddusiJournal Article19700101Soil erosion by water is one of the most important processes of land degradation in arid and semi-arid regions of Iran. In this regard, gully erosion is a well-known process degradation which being controlled by verity of environmental conditions. The main aim of this research consist of assessing multi-parameter fingerprinting method to discriminate the sediment contributions of gully erosion through the combination of tracer properties (organic carbon OC, Nitrogen N), Phosphorous P, C/N and 137Cs) in three catchments. Results indicate that gully erosion is responsible between 86 and 99% of the catchments sediment. Due to same conditions of soil, lithology and climate different achieved contribution of gully erosion could be addressed to geomorphic parameters (e.g. area, drainage density, hillslope length and gully distribution). Generally, at a given gully density when the catchment area increase the hillslope length, which reduce the transportation of soil eroded on the hillslopes by sheet and rill, will increase and consequently gullies would deliver more sediment than hillslope processes. Further more, radionuclide 137Cs with the amount of residual root mean square error (RRMSE) (0.12%) was the most informative tracer properties to separate top-soil and gully sediment source. Finally results indicate that a gully erosion rate becomes notable from an area about 5 ha. The large influence of gully erosion, channel and river banks on sediment yields of watersheds implies that estimation of erosion rate by models such as: USLE, MUSLE, WEEP, EUROSEM, GUEST and runoff plot, which mainly focused on sheet and rill erosion, is not reliable and should be taken account by land managers.Soil erosion by water is one of the most important processes of land degradation in arid and semi-arid regions of Iran. In this regard, gully erosion is a well-known process degradation which being controlled by verity of environmental conditions. The main aim of this research consist of assessing multi-parameter fingerprinting method to discriminate the sediment contributions of gully erosion through the combination of tracer properties (organic carbon OC, Nitrogen N), Phosphorous P, C/N and 137Cs) in three catchments. Results indicate that gully erosion is responsible between 86 and 99% of the catchments sediment. Due to same conditions of soil, lithology and climate different achieved contribution of gully erosion could be addressed to geomorphic parameters (e.g. area, drainage density, hillslope length and gully distribution). Generally, at a given gully density when the catchment area increase the hillslope length, which reduce the transportation of soil eroded on the hillslopes by sheet and rill, will increase and consequently gullies would deliver more sediment than hillslope processes. Further more, radionuclide 137Cs with the amount of residual root mean square error (RRMSE) (0.12%) was the most informative tracer properties to separate top-soil and gully sediment source. Finally results indicate that a gully erosion rate becomes notable from an area about 5 ha. The large influence of gully erosion, channel and river banks on sediment yields of watersheds implies that estimation of erosion rate by models such as: USLE, MUSLE, WEEP, EUROSEM, GUEST and runoff plot, which mainly focused on sheet and rill erosion, is not reliable and should be taken account by land managers.https://jphgr.ut.ac.ir/article_21511_975c5d233a3887c99d3a0e3baa33315a.pdfUniversity of TehranPhysical Geography Research2008-630X416920101122Comparative Study of Four Meteorological Drought Index Based on Relative Yield of Rain Fed Wheat in Hamedan ProvinceComparative Study of Four Meteorological Drought Index Based on Relative Yield of Rain Fed Wheat in Hamedan Province21512FAHZare AbianehVYazdanyKhAzhdaryJournal Article19700101Quantitative measurement of meteorological drought, Z score(z), rainfall anomaly (RAI), standard precipitation (SPI) indices and Percent of normal precipitation (PNPI) based upon seasonal and annual rainfall data of the 15 meteorological stations of meteorological in Hamedan Province were used. Also, in studying influences of drought on agriculture relative yield index of wheat was used. The results have shown that Z, RAI and SPI indices in seasonal and annual scales and PNPI in seasonal scale are good estimator of drought intensity and drought duration, irrespective of indices kind mostly was medium and lower than medium. Z, RAI and SPI indices were same with agronomic index of relative wheat yield, but SPI index based upon intensity of droughts had more similarity with agronomic index of relative wheat yield. The results show that Hamedan region have suffered from one drought which lasts from a two years lasting drought period in each decade. It has been also experienced a very severe drought during the last 30 years. Occurennce of more droughts in the region might be resulted from shortening the drought return periods, and increase of low intensity drought events in the region.Quantitative measurement of meteorological drought, Z score(z), rainfall anomaly (RAI), standard precipitation (SPI) indices and Percent of normal precipitation (PNPI) based upon seasonal and annual rainfall data of the 15 meteorological stations of meteorological in Hamedan Province were used. Also, in studying influences of drought on agriculture relative yield index of wheat was used. The results have shown that Z, RAI and SPI indices in seasonal and annual scales and PNPI in seasonal scale are good estimator of drought intensity and drought duration, irrespective of indices kind mostly was medium and lower than medium. Z, RAI and SPI indices were same with agronomic index of relative wheat yield, but SPI index based upon intensity of droughts had more similarity with agronomic index of relative wheat yield. The results show that Hamedan region have suffered from one drought which lasts from a two years lasting drought period in each decade. It has been also experienced a very severe drought during the last 30 years. Occurennce of more droughts in the region might be resulted from shortening the drought return periods, and increase of low intensity drought events in the region.https://jphgr.ut.ac.ir/article_21512_ccbf303de4e2d2ff7942af8006bef547.pdfUniversity of TehranPhysical Geography Research2008-630X416920101122Study of Karst Development Using Recession Coefficient, Spring Death Time and Chemical and Isotope Analysis in Parav-Bistoun Massif (Kermanshah Province-West of Iran)Study of Karst Development Using Recession Coefficient, Spring Death Time and Chemical and Isotope Analysis in Parav-Bistoun Massif (Kermanshah Province-West of Iran)21513FAMMaghsoudi0000-0001-2345-6789HKarimiFSafariZCharrahiJournal Article19700101توده پرآو ـ بیستون با وسعت 880 کیلومترمربع در زون زاگرس رورانده و در استان کرمانشاه واقع شده است. در این تودة کوهستانی تحت تأثیر شرایط پالئوکلیما، اشکال متنوع کارستی همچون جاما، اووآلا و دولینها شکل گرفته است و با شرایط اقلیمیِ حاضر، در ارتفاعات بالاتر از 2500 متر شرایط برای فعالیتهای کارستی فراهم آمده است. میزان توسعه کارستی، میتواند ضریب هیدرولیکی و سرعت تأثیرپذیری آبدهی چشمهها از بارش را تحت تأثیر خود قرار دهد، به همین دلیل در پژوهش حاضر، تحولات کارستی در توده پرآو ـ بیستون براساس فاکتورهای هیدروژئولوژیکی منطقه مورد ارزیابی و بررسی قرار گرفته است. بنابراین به بررسی ویژگیهای ایزوتوپی ـ شیمیایی، برآورد ضریب خشکیدگی، حجم ذخیره دینامیکی و تفسیر رژیم تخلیه چشمههای اصلی منطقه پرآو ـ بیستون (سراب برناج، سراب بیستون و سراب طاق بستان) در مقایسه با چشمههای دیگر واقع در زون زاگرس چین خورده (سراب شیان و سراب نیلوفر) پرداخته شده و برای مطالعه و ارائه تحلیلهای صورتگرفته از دادههای مربوط به سال آبی 1384 استفاده شده است. هیدروگراف چشمهها در توده پرآو ـ بیستونِ متأثر از توسعه کارستی بهوجود آمده، نوسان و پیچیدگیهای بیشتری را نشان میدهد که تغذیه بهصورت کانالیزه رخ میدهد و سطح تماس با عامل انحلال (آب) اندک است. میزان تریتیوم بالای چشمههای اطراف توده پرآو ـ بیستون به مقادیر حدی باران و آبهای جوّی نزدیک است و میزان Co2 و C14 آنها نیز از نفوذ سریع و سطح تماس کم آب با بستر ـ به علت وضعیت کانالیزة حاکم بر منطقه ـ حکایت دارد. بررسی مقادیر ایزوتوپی چشمهها همچون میزان تریتیوم، کربن 14 و فشار گازکربنیک نیز نشان دهنده کارستی بودن منطقه است. از طرف دیگر میزان ضریب خشکیدگی چشمهها، ضریب آلفا و حجم ذخیره دینامیکی آنها (چشمههای اطراف پرآو ـ بیستون)، در مقایسه با دیگر چشمهها نیز دلالت بر توسعه کارست در منطقه دارد و تغذیة مجرایی و کانالیزة چشمهها را نشان میدهد.توده پرآو ـ بیستون با وسعت 880 کیلومترمربع در زون زاگرس رورانده و در استان کرمانشاه واقع شده است. در این تودة کوهستانی تحت تأثیر شرایط پالئوکلیما، اشکال متنوع کارستی همچون جاما، اووآلا و دولینها شکل گرفته است و با شرایط اقلیمیِ حاضر، در ارتفاعات بالاتر از 2500 متر شرایط برای فعالیتهای کارستی فراهم آمده است. میزان توسعه کارستی، میتواند ضریب هیدرولیکی و سرعت تأثیرپذیری آبدهی چشمهها از بارش را تحت تأثیر خود قرار دهد، به همین دلیل در پژوهش حاضر، تحولات کارستی در توده پرآو ـ بیستون براساس فاکتورهای هیدروژئولوژیکی منطقه مورد ارزیابی و بررسی قرار گرفته است. بنابراین به بررسی ویژگیهای ایزوتوپی ـ شیمیایی، برآورد ضریب خشکیدگی، حجم ذخیره دینامیکی و تفسیر رژیم تخلیه چشمههای اصلی منطقه پرآو ـ بیستون (سراب برناج، سراب بیستون و سراب طاق بستان) در مقایسه با چشمههای دیگر واقع در زون زاگرس چین خورده (سراب شیان و سراب نیلوفر) پرداخته شده و برای مطالعه و ارائه تحلیلهای صورتگرفته از دادههای مربوط به سال آبی 1384 استفاده شده است. هیدروگراف چشمهها در توده پرآو ـ بیستونِ متأثر از توسعه کارستی بهوجود آمده، نوسان و پیچیدگیهای بیشتری را نشان میدهد که تغذیه بهصورت کانالیزه رخ میدهد و سطح تماس با عامل انحلال (آب) اندک است. میزان تریتیوم بالای چشمههای اطراف توده پرآو ـ بیستون به مقادیر حدی باران و آبهای جوّی نزدیک است و میزان Co2 و C14 آنها نیز از نفوذ سریع و سطح تماس کم آب با بستر ـ به علت وضعیت کانالیزة حاکم بر منطقه ـ حکایت دارد. بررسی مقادیر ایزوتوپی چشمهها همچون میزان تریتیوم، کربن 14 و فشار گازکربنیک نیز نشان دهنده کارستی بودن منطقه است. از طرف دیگر میزان ضریب خشکیدگی چشمهها، ضریب آلفا و حجم ذخیره دینامیکی آنها (چشمههای اطراف پرآو ـ بیستون)، در مقایسه با دیگر چشمهها نیز دلالت بر توسعه کارست در منطقه دارد و تغذیة مجرایی و کانالیزة چشمهها را نشان میدهد.https://jphgr.ut.ac.ir/article_21513_f68a37fbcdf0a7fbcabd845bdf6dc783.pdfUniversity of TehranPhysical Geography Research2008-630X416920101122Geomorphic Assessment of Active Tectonic in the Saeedabad–chai Drainage Baisn
(North Slope of Sahand Mountain)Geomorphic Assessment of Active Tectonic in the Saeedabad–chai Drainage Baisn
(North Slope of Sahand Mountain)21514FAFKaramiJournal Article19700101In this study, the quaternary deformation and tectonic activity of Saeedabad-chai drainage basin, are assessed using geomorphic approach. This drainage basin is located in northern slope of Sahand Mountain. North Tabriz Fault (NTF), is passing from the Saeedabad-chai basin. Variation in the morphology of mountain front provied the basis for geomorphic assessment of tectonic activity. Therefore, it is used from geomorphic Index as Stream Length Gradiant Index (SL), Asymmetry Factor (AF), Topographic Symmetry Factor (T), Drainage Basin ShapeRatio (Bs ), Mountain Front Sinusity (Smf), Ratio of valley – floor with to vally height (Vf), Percentage undissected mountain factors (Eu), Topographical maps, Digital Elevatiom Model (DEM), satellite images and Autocad map, Arc/view software. The results of this study that estimated by Index of relative active tectonic (Iat) , indicated that the value of tectonic activity in the Saeedabad-chai drainage basin, is high.In this study, the quaternary deformation and tectonic activity of Saeedabad-chai drainage basin, are assessed using geomorphic approach. This drainage basin is located in northern slope of Sahand Mountain. North Tabriz Fault (NTF), is passing from the Saeedabad-chai basin. Variation in the morphology of mountain front provied the basis for geomorphic assessment of tectonic activity. Therefore, it is used from geomorphic Index as Stream Length Gradiant Index (SL), Asymmetry Factor (AF), Topographic Symmetry Factor (T), Drainage Basin ShapeRatio (Bs ), Mountain Front Sinusity (Smf), Ratio of valley – floor with to vally height (Vf), Percentage undissected mountain factors (Eu), Topographical maps, Digital Elevatiom Model (DEM), satellite images and Autocad map, Arc/view software. The results of this study that estimated by Index of relative active tectonic (Iat) , indicated that the value of tectonic activity in the Saeedabad-chai drainage basin, is high.https://jphgr.ut.ac.ir/article_21514_ce2930915598849d0946447d25cc0e55.pdfUniversity of TehranPhysical Geography Research2008-630X416920101122Land Cover Mapping of Arak City Using Artificial Neural Network and Maximum Likelihood ClassifiersLand Cover Mapping of Arak City Using Artificial Neural Network and Maximum Likelihood Classifiers21515FAMAhmadi NaddoshanASoffianianS.JKhajedinJournal Article19700101Land cover map is important for many urban planning and management activities. In this study, in order to produce land cover map of Arak city, digital image of LISS-III scanner acquired on 16 June 2006 were employed. First of all, geometric correction with RMSe 0.58 pixel was applied. Considering the mountainous condition of the study area, topographic correction was applied to the image. In support of image classification, two different methods namely, supervised classification with Maximum Likelihood classifier algorithm and a three-layer perceptron neural network with and without using slope map were used. Finally, land cover map of the study region was classified into four classes: urban areas, vegetated areas, barren lands, and rocks. In order to sort out the rocks precisely from other classes, classified slope map of the study area was introduce to neural network model as an input layer. To assess the classified land cover map precision, it was controlled for ground truths with a GPS and the overall accuracies were 92.6, 92.7 and 94.6% for maximum likelihood classification, neural network classifier with and without the usage of classified slope map, respectively. The results confirm that the neural network classifier is capable to generate land cover maps with high accuracy.Land cover map is important for many urban planning and management activities. In this study, in order to produce land cover map of Arak city, digital image of LISS-III scanner acquired on 16 June 2006 were employed. First of all, geometric correction with RMSe 0.58 pixel was applied. Considering the mountainous condition of the study area, topographic correction was applied to the image. In support of image classification, two different methods namely, supervised classification with Maximum Likelihood classifier algorithm and a three-layer perceptron neural network with and without using slope map were used. Finally, land cover map of the study region was classified into four classes: urban areas, vegetated areas, barren lands, and rocks. In order to sort out the rocks precisely from other classes, classified slope map of the study area was introduce to neural network model as an input layer. To assess the classified land cover map precision, it was controlled for ground truths with a GPS and the overall accuracies were 92.6, 92.7 and 94.6% for maximum likelihood classification, neural network classifier with and without the usage of classified slope map, respectively. The results confirm that the neural network classifier is capable to generate land cover maps with high accuracy.https://jphgr.ut.ac.ir/article_21515_db5276b6d3e7971fa520e70d1a77fe16.pdfUniversity of TehranPhysical Geography Research2008-630X416920101122Study of Relationships between Plant Morphology and Nebkha Morphometry Characteristic of Reaumaria Turcestanica
in Khairabad Desert in SirjanStudy of Relationships between Plant Morphology and Nebkha Morphometry Characteristic of Reaumaria Turcestanica
in Khairabad Desert in Sirjan21516FAMPourkhosravaniA.AValiMMoayeriJournal Article19700101Modeling is important in understanding complex ecogeomorphological relationships for useful applications, include: predicting the likely success of remobilizing dormant dune systems, managing and mitigating desertification and degradation of semi-arid land, assessing the impact of climate change, investigating the effects of changes in land use and reconstructing conditions responsible for the formation and stabilization of relict systems. Nebkha dunes have been proposed as a reliable rapid indicator of Aeolian erosion and vegetation. The aim of this paper is understanding the relationships between nebkha morphometry parameters together and with morphological characteristic of Reaumeria turcestanica. For obtaining objective of study we measure canopy cover and height of plant and elevation, diameter and slop for nebkha from 10 transects and 157 samples in khairabad area in Sirjan. The technical method used for investigation of relations was simple and multivariate regression analysis. Regression analysis showed a significant relationship ( <0.01) between plant height and nebkha elevation with coefficient of determination (R2) of 0.58 for linear relationship and 0.60 for both quadratic estimation. Also a significant relationship ( <0.01) exists between canopy cover and nebkha elevation with coefficient of determination of 0.54 for linear function and 0.58 for both quadratic estimations. Analysis Regression significant relationship ( <0.01) between nebkha height and nebkha diameter with R2 of 0.49 for linear and quadratic estimation and 0.50 for cubic function.Modeling is important in understanding complex ecogeomorphological relationships for useful applications, include: predicting the likely success of remobilizing dormant dune systems, managing and mitigating desertification and degradation of semi-arid land, assessing the impact of climate change, investigating the effects of changes in land use and reconstructing conditions responsible for the formation and stabilization of relict systems. Nebkha dunes have been proposed as a reliable rapid indicator of Aeolian erosion and vegetation. The aim of this paper is understanding the relationships between nebkha morphometry parameters together and with morphological characteristic of Reaumeria turcestanica. For obtaining objective of study we measure canopy cover and height of plant and elevation, diameter and slop for nebkha from 10 transects and 157 samples in khairabad area in Sirjan. The technical method used for investigation of relations was simple and multivariate regression analysis. Regression analysis showed a significant relationship ( <0.01) between plant height and nebkha elevation with coefficient of determination (R2) of 0.58 for linear relationship and 0.60 for both quadratic estimation. Also a significant relationship ( <0.01) exists between canopy cover and nebkha elevation with coefficient of determination of 0.54 for linear function and 0.58 for both quadratic estimations. Analysis Regression significant relationship ( <0.01) between nebkha height and nebkha diameter with R2 of 0.49 for linear and quadratic estimation and 0.50 for cubic function.https://jphgr.ut.ac.ir/article_21516_99525cbcef9c40ed64620b15e0c3799e.pdfUniversity of TehranPhysical Geography Research2008-630X416920101122Spring Rainfall Prediction of Khorasan-e Razavi Province, Based upon Climatic Large Scale Signals by Using Artificial Neural NetworkSpring Rainfall Prediction of Khorasan-e Razavi Province, Based upon Climatic Large Scale Signals by Using Artificial Neural Network21517FAGh.AFallah GhalhariJKhoshhalJournal Article19700101The aim of this research is investigating the relations between climatic large scale signals and spring rainfall of Khorasan-e Razavi province.
In this research, we have analyzed 38 years of rainfall data in khorasan-e Razavi province, located in northeastern Iran. We attempted to train Artificial Neural Network based upon climatic large scale signals with 38 years of rainfall data. For performance evaluation, network predicted outputs were compared with the actual rainfall data. At the outset of this study, the relationships between synoptically pattern variations, including Sea Level Pressure (SLP), Sea Surface Temperature (SST), Sea Level Pressure Gradient (?SLP), Sea Surface Temperature Difference (?SST), Air Temperature at 700 hPa, Thickness between 500 and 1000 hPa level, Relative Humidity at 300 hPa and Precipitable water are investigated .In the second step, model was calibrated from 1970 to 1997. Finally, rainfall prediction is performed from 1998 to 2007. Simulation results reveal that Artificial Neural Network is promising and efficient. Root mean square was obtained 2.5 millimeters.The aim of this research is investigating the relations between climatic large scale signals and spring rainfall of Khorasan-e Razavi province.
In this research, we have analyzed 38 years of rainfall data in khorasan-e Razavi province, located in northeastern Iran. We attempted to train Artificial Neural Network based upon climatic large scale signals with 38 years of rainfall data. For performance evaluation, network predicted outputs were compared with the actual rainfall data. At the outset of this study, the relationships between synoptically pattern variations, including Sea Level Pressure (SLP), Sea Surface Temperature (SST), Sea Level Pressure Gradient (?SLP), Sea Surface Temperature Difference (?SST), Air Temperature at 700 hPa, Thickness between 500 and 1000 hPa level, Relative Humidity at 300 hPa and Precipitable water are investigated .In the second step, model was calibrated from 1970 to 1997. Finally, rainfall prediction is performed from 1998 to 2007. Simulation results reveal that Artificial Neural Network is promising and efficient. Root mean square was obtained 2.5 millimeters.https://jphgr.ut.ac.ir/article_21517_e524a97c6be3f70720ae23b9da7f002f.pdf