@article { author = {Ghorbani, M.S. and Mahmodi, F and yamani, mojtaba and Moghimi, E}, title = {The Role of Quaternary Climate Changes on the Geomorphic Evolution of Karst Sinkholes (Case Study: Shaho Relief Western Iran)}, journal = {Physical Geography Research}, volume = {42}, number = {4}, pages = {-}, year = {2011}, publisher = {University of Tehran}, issn = {2008-630X}, eissn = {2423-7760}, doi = {}, abstract = {Introduction Karst evolution is governed by different factors. Generally karst system depends on geological and tectonic processes in one hand, and erosion and dynamic processes in the other hand. Some of the karst surveys and models concentrate on geologic and tectonic factors. While other surface processes of regional importance, have so far been largely neglected. For example, glacial erosion has been regarded as an important process in mid- to high latitude active orogenic regions, which have experienced repeated large-scale glaciations during the last two million years (Kaufmann, 2003). Markedly during the past decades, evidences for development of Pleistocene glaciations in the mountainous parts of Iran have increased. Some of the studies have reconstructed the physiographic and paleoclimate conditions of Western Iran (e.g. Wright 1961; Van Zeist and Wright 1963; Hutchinson and Cowgill 1963; Megard 1967; Mahmodi 1988; Snyder 2001, Stevens and et al 2001; Wasylikowa 2005; Wasylikowa and et al 2006). These studies mostly assume lower temperatures as well as probable increase of snowfall in western Iran during Pleistocene. Karst features have developed extensively in Shaho Ridge (Northwest Zagros) in western Iran. In this paper, different factors influencing the karst development in Shaho ridge - contain lithology, tectonic, slope, elevation and climate elements - are evaluated. The main hypothesis is that the climate elements especially glaciations during Pleistocene are of grater importance than the other factors. Materials and Methods In this research, in addition to descriptive method, determining the extension and distribution of karst landforms in respect to each influencing variable and Pleistocene glaciations features was analytical. The technique was comparison of karstic (sinkhole area) with non karstic parts. The research tools were topographic maps (1:50000), geology maps (1:100000), aerial photographs (1:50000), Google Earth and fieldwork tools such as GPS, compass and Camera. Slope and elevation map layers were derived from digitized topographic maps as well as lithology and fault and joint layers were derived from digitized geology maps. Estimation of the number of sinkholes per square kilometers was based on fieldwork. These features were counted in 9 stations and the results were generalized for the whole area. The survey of Pleistocene glaciations features like cirques, moraines and solifluction layers was based on fieldwork as well. Moreover, the authors have used the results of previous studies. Results and Discussion Karstic features are dominant features in Shaho ridge landscape. Sinkholes mostly have concentrated in two parts, respectively called Paveh karst region and Ravansar karst region. These two regions are separated by three broad valleys. Also karst sinkholes have been formed on the relatively vast interflows. Karst sinkhole regions occupy about 140 Km2 of study area (approximately 800 Km2). Geologically karst system has developed on Bistun limestone Formation that is very capable for karst development. For the assessment of influencing factors, the map of each variable (lithology, fault and joints, slope, elevation) was overplayed by sinkhole map layer. The results showed that the sinkholes mainly have been formed in Bistun formation along faults, joint systems and bedding planes as well as slopes less than 10 degree. While the most parts of Shaho ridge consists of Bistun formation and faults and joint systems and bedding planes extensively present and even slopes are less than 10 degree but there is no sign of sinkholes. The question is: why these features have been developed in specific parts? Overlaying elevation variable as a climatic index with sinkhole layer showed that these features mostly have been formed in parts with elevation more than 1900 meters. Therefore this hypothesis formed that a climatic agent such as glaciations has controlled the sinkhole formation in this region. Mahmodi (1988) believes that based on the height of bottom of glacial cirques, in western Iran during cold stages of Pleistocene, the elevation of permanent snowline had been 1800 meters above the see level, and so that, the western altitudes of Iran have been affected by glacial processes. Evidences for the occurrence of glaciers, contain cirques and glacial moraines, were found in both flanks (northern and southern) of Shaho relief. Along with the study of glacier features, the upper bound of solifluction layers as indicator for periglacial realm was studied. The ancient solifluction layers were found at the height of 1700 m. It is evident that this phenomenon has occurred under the permanent snowline (1800 m). Conclusion The results of this study indicate that the absence of karst sinkholes in the most parts of the area that geologic and even slope requirements are capable for karst development is because of the absence of appropriate climate conditions. There is a strong correlation between the occurrence of surface karst features (above 1900 m) and Pleistocene permanent snowline (1800 m). The evidences of glacial and periglacial in the area, support this hypothesis that karst features, belong to glacial cold stages. More likely, during the glacial periods the broad sinkholes (approximately 1 Km2) have had a glacial cirque role as well. Nowadays, mechanical degradation breaks down karstic features dominantly.}, keywords = {geomorphology,Karst,Pleistocene,Quaternary,Shaho}, title_fa = {نقش تغییرات اقلیمی کواترنر در تحول ژئومورفولوژیکی فروچاله های کارستی (مطالعه موردی: ناهمواری شاهو، غرب ایران)}, abstract_fa = {ناهمواری شاهو توده ای کوهستانی و آهکی است که در حدفاصل استان های کردستان و کرمانشاه واقع ش ده است و از نظر ساختاری بخشی از زاگرس مرتفع محسوب می شود. ساختار آهکی این ناهمواری دارای شرایط مناسبی برای توسعه اشکال کارستی است . در تحول و توسعه کارست های منطقه، متغیرهای اصلی سنگ شناسی، زمین ساخت، شیب و اقلیم دخالت داشته اند که نحوه توزیع فروچال ه ها با توجه به هر کدام از این متغیرها مورد بررسی قرار گرفته است . میزان تراکم سطحی فروچاله ها با استفاده از عکس های زمینی و پیمایشی میدانی در نقاط مختلفی از میدان های اصلی کارستی به صورت نمونه ای بررسی شده و 15 تا 20 فروچاله در کیلومترمربع برآورد گردیده است . با و جود اینکه در بخش های عمده ای از منطقه شرایط سنگ شناسی، زمین ساختی و شیب برای توسعه کارست فراهم است اما اثری از فروچاله های کارستی دیده نمی شود. حضور فروچاله های کارستی از ارتفاع مشخصی ( 1900 متر ) به بالا و بررسی آثار و شواهد یخچالی همچون سیرک ها، دره ها و مور ن های یخچالی و همچنین پدیده های مجاور یخ چالی شامل لایه های مختلف سولی فلکسیون در نقاط مختلف منطقه، نشان م ی دهد که در دوره های سرد پلئیستوسن از ارتفاع 1800 متر (مرز برف دائمی ) به بالا، شرایط برای توسعه انحلالی فروچاله های کارستی فراهم بوده است. در چنین شرایطی دولین های کارستی دارای نقش دوگانه سیر ک دولین بوده اند و در ابعاد وسیع شکل گرفت ه اند. در شرایط اقلیمی کنونی، کارس تهای منطقه تحت تأثیر تخریب شدید مکانیکی قرار دارند.}, keywords_fa = {geomorphology,Karst,Pleistocene,Quaternary,Shaho}, url = {https://jphgr.ut.ac.ir/article_22199.html}, eprint = {https://jphgr.ut.ac.ir/article_22199_8d4aa469751b7127f9e148a4ffb6a460.pdf} } @article { author = {Raziei, Tayeb and Azizi, Ghasem and Mohammadi, H and Khoshakhlagh, F}, title = {500 Hpa Wintertime Daily Circulation Types over Iran and the Middle East}, journal = {Physical Geography Research}, volume = {42}, number = {4}, pages = {17-34}, year = {2011}, publisher = {University of Tehran}, issn = {2008-630X}, eissn = {2423-7760}, doi = {}, abstract = {Introduction Regional weather and climate around the globe are strongly influenced by large-scale atmospheric circulation patterns (McKendry, 1994). The classification of atmospheric circulation patterns, as an attempt to reduce the dimensionality of the analysis by isolating a relatively small number of representative circulation types (hereafter CTs), has long been used in synoptic climatology to assess the influence of CTs on climatic variables, including precipitation (Yarnal, 1993; Huth, 1996). Many authors have studied the possible linkages between atmospheric circulation patterns and surface variables, such as precipitation and temperature (Romero et al., 1999; Santos et al., 2005; Kilsby et al., 1998; Wibig, 1999; Chen and Hellstr?m, 1999; Xoplaki et al., 2000; Kidson, 2000). Furthermore, several studies found relationships between CTs and natural hazards, including droughts (Duckstein et al., 1993; Bogardi et al., 1994; Pesti et al., 1996; Pongracz et al., 2003). Therefore, the present study aims at identifying daily 500 hPa CTs and their relative impacts on occurrence of precipitation events in Iran during the winter months. Materials and Methods For CT classification, daily means of the 500 hPa geopotential height, defined over a 2.5° latitude × longitude grid and covering an area from the Mediterranean basin to the Middle East (10°E–80°E, 20°N–60°N), were retrieved from the NCEP/NCAR reanalysis (Kalnay et al., 1996; Kistler et al., 2001). The latest version of APHRODITE grided daily precipitation dataset (APHRO_V0902), which is based on 337 Iranian meteorological stations, having record lengths of at least 5 years is also used for identifying the relationship between CTs and precipitation occurrences in Iran. These stations are composed of 154 World Meteorological Organization (WMO) stations and of 183 non-WMO ones, spread throughout the country and covering different temporal periods, with the longest starting in the 1960s (Yatagai et al., 2008). The S-mode PCA was applied to the correlation matrix of the daily 500 hPa geopotential height and the first six principal components were retained for Varimax rotation after applying the screen test and North’s rule-of-thumb. The spatial variation patterns of the rotated loadings, in their positive and negative phases, i.e. on a location of the dominant centers-of-action, was considered as potential groups for circulation pattern classification in a non-iterative K-means clustering (Esteban et al., 2005, 2006). The centroids are computed by averaging all days that fulfill the “extreme score criterion” for a certain pattern and phase: days with high scores for a certain component (values higher than +2 for positive phase or lower than –2 for negative phase), but with low scores in the remaining components (between +2 and –2) were selected and considered as seeds for the centroids, avoiding iterations. It is worth noting that the extreme score procedure establishes the number of groups and their centroids for K-means clustering which is applied to the RPCs of the 500 hPa geopotential. Hereafter, CT+ and CT– denote the circulation types deriving from positive and negative phases of the RPCs, respectively. The relationship between CTs and precipitation occurrences was assessed using the Performance Index (PI; Zhang et al., 1997). PI quantifies the relevance of each CT to the occurrence of precipitation, by comparing the daily mean precipitation of a given circulation type, i, with the climatological daily mean precipitation: (1) where ni is the number of days of pattern i, Ri is the total amount of precipitation falling during those days, and R is the precipitation total received in the entire period of n days (with or without the presence of type i). Thus, a PI(i) value for a particular type i is a measure of the relative contribution of that type to total precipitation; a PI(i) much higher than one indicates that type i has an important contribution to total precipitation. Results and Discussion CT1– is characterized by a weak ridge over Turkey that generates westerly winds over Iran, especially in the northern parts. In contrast, CT1+ is characterized by a cyclonic curvature over the Mediterranean and northern Iran and by an anticyclonic curvature over central-southern Iran, inducing rain-generating southwesterly flows. CT2– shows a broad ridge over the north-eastern Caspian Sea, while CT2+ reveals a widely extended trough over the north-eastern sector. Both types generate westerly flow and marginally affect Iranian weather. The spatial configuration of CT3– is very similar to CT2+ over Iran (prevalently zonal), but the centre of the upper cyclonic curvature migrates from north-eastern Russia to north-eastern Europe. CT3+ depicts a ridge over Eastern Europe and a trough over southern Russia. The flow direction over Iran is largely zonal. The circulation structure of CT4– consists of a trough over the central Mediterranean Sea and a ridge over western Iran, leading to north-westerly flows over the country. CT4+ is characterized by a deep and large trough located over the eastern Mediterranean Sea and the Red Sea, causing south-westerly flows over Iran. The geopotential gradient is strong, making CT4+ very relevant for Iranian weather. A weak as well as widely extended ridge located over Turkey and the Balkans and a weak, shallow and broad trough over eastern Iran characterize CT5–, which leads to north-westerly flows over the country. CT5+, similarly to CT4+, shows a well-established trough over the eastern Mediterranean Sea, favouring precipitation occurrences over Iran. The latter two types differ from each other in the location and direction of their trough axis. The trough location in CT6– is over Eastern Europe, whereas a ridge can be found over Russia, leading to westerly flows over Iran. Finally, CT6+ is characterized by a weak ridge and a trough located over the Balkans and the Red Sea, respectively. This circulation structure might favour precipitation occurrences over Southern Iran, as it transports maritime air masses from the Red Sea and the Persian Gulf. Spatial patterns of PI related to CT1- implied that this circulation type does not contribute to provide precipitation amounts above their climatological means over western and northern Iran. Conversely, the PI values higher than 1.5 in central-eastern Iran indicate that CT1- tends to contribute to anomalously high precipitation in this part of Iran. The PI pattern for CT1+ shows that it only contributes to precipitation occurrences over west and north-western Iran, leaving most of the country without precipitation occurrences. With respect to the PI pattern for CT2-, it is evident that this CT has no potential for precipitation occurrences throughout the country. CT2+ also tends to be mostly unfavorable to precipitation occurrences over Iran, despite some weak contributions over southern, eastern and northern parts of the country, not having impact over western Iran. The PI pattern for CT3- clearly highlights the prevailing dryness of this pattern over the whole of Iran. According to the spatial pattern of PI for CT3+, it can also be concluded that it is an essentially dry regime, though it may weakly contribute to precipitation in northern and eastern parts of Iran, where PI values higher than 1.5 are found. CT4- can be considered the driest regime, as its contributions to precipitation are negligible. Regarding CT4+, PI values are greater than 1.5 throughout the country, highlighting its key role on Iranian precipitation. The PI values of CT4+ are very high over southern Iran, emphasizing its pronounced influence in the coastal areas of the Persian Gulf.}, keywords = {Circulation types,Cluster Analysis,Iran,PI,precipitation,Principal component analysis}, title_fa = {الگوهای روزانه گردش جوی زمستانه تراز 500 هکتوپاسکال بر روی ایران و خاورمیانه}, abstract_fa = {برای شناسایی الگوهای روزانه گردش جوی تراز 500 هکتوپاسکال بر روی خاورمیانه و ایران در فصل زم ستان 1965 از مرکز - (دسامبر تا مارس )، داده های میانگین روزانه ارتفاع ژئوپتانسیل این تراز برای دوره 2000 و (PCA) تحلیل مؤلفه های اصلی S دریافت گردید و مورد استفاده قرار گرفت . به کمک آرایه NCEP/NCAR خوشه بندی چندهسته ای تمامی روزهای مورد مطالعه به 12 گروه طبق ه بندی شد و میانگین هر گروه به عنوان یک الگوی گردشی معرفی گردید . به طور کلی الگوهای گردشی به دست آمده را براساس جهت وزش بادهای غربی بر روی ایران می توان به سه دسته اصلی مداری، شمال غربی و جنوب غربی تقسیم کرد . در الگوهای مداری همیشه جهت جریان بادهای غربی بر روی ایران به صورت مداری و یا تقریباً مداری است، در حالی که در الگوهای جنوب غربی همواره یک ناوه در غرب ایران (از مدیترانه تا ایران) قرار دارد که جریا ن ها را به صورت نص ف النهاری درمی آورد و آنها را با جهت جنوب غربی تا غربی به روی ایران روانه می کند. تفاوت د ر محل، عمق و گسترش این ناوه باعث تفاوت الگوهای جنوب غربی از یکدیگر و تفاوت در میزان تأثیرگذاری آنها بر آب و هوای ایران می شوند. بررسی ارتباط میان الگوهای گردش جو?ی و بارش در سطح کشور نشان داد که برخی از الگوها با ایجاد جریان جنوب غربی و ریزش هوای مرطوب و ن اپایدار بر روی ایران سهم زیادی در تولید بارش سالانه کشور دارند . در این گونه الگوها هر چه ناوه عمیق تر و به ایران نزدیک تر باشد، اثر آن بر اقلیم کشور بیشتر است و بارش بیشتری را در پهنه گسترده تری از ایران سبب می شود. عمیق شدن این ناوه باعث نصف النهاری شدن ج هت جریان در این الگوها می شود و پتانسیل ایجاد بارش را در آنها افزایش م ی دهد. در مقابل، در جریا نهای شمال غربی این ناوه جای خود را با پشته عوض می کند و این خود موجب ریزش هوای سرد عرض های شمالی و ایجاد هوای پایدار بر روی ایران می گردد. همچنین مشخص شد که برخی از الگوها در سرتاسر کشور موجبِ بارش می شوند و برخی دیگر تنها در بخش هایی از کشور . نتایج همچنین نشان از آن داشتند که توزیع فراوانی برخی از الگوها در همه ماه های مورد مطالعه تقریباً یکسان است، در حالی که برخی دیگر در ما ههای خاصی بیشتر روی م ی دهند . بررسی روند تغییرات الگوها نیز نشان داد که بیشتر الگوها با هیچ گونه روند کاهشی و یا افزایشی معنی داری مواجه نبوده اند.}, keywords_fa = {Circulation types,Cluster Analysis,Iran,PI,precipitation,Principal component analysis}, url = {https://jphgr.ut.ac.ir/article_22200.html}, eprint = {https://jphgr.ut.ac.ir/article_22200_2954bdc8229f83ccaaacf574c2d4d741.pdf} } @article { author = {maghsoudi, mehran and Khoshakhlagh, F and Hanafi, Ali and Rusta, I}, title = {Zoning of Stone Weathering Processes, based on Peltier Models in Northwest of Iran}, journal = {Physical Geography Research}, volume = {42}, number = {4}, pages = {35-46}, year = {2011}, publisher = {University of Tehran}, issn = {2008-630X}, eissn = {2423-7760}, doi = {}, abstract = {Introduction Weathering occurs when rocks of the land surface are affected by physical, chemical or biological processes and break down to small pieces. This operate occurs by wind, water and climate (Rich, 1950). Lewis Peltier models in climatic geomorphology are as the best sources for recognition of weathering processes, those geologists and other related sciences use them to identify and interpret the forms of surface (Fowler and Petersen, 2003, 5). The average annual temperature and mean annual precipitation are two variables that have major roles in weathering. Peltier using these two variables, described the seven models can identify different types of weathering phenomena (Peltier, 1971, 214-236). Fowler and Petersen (2003) applied Peltier models using GIS software in America and classified this country to different weathered regions. Iran's Geographical location, exposed many villages and cities in the high-risk zone. (Afrakhteh, 1997, 120). Considering of rare geomorphologic studies in our country about weathering processes, this article aims to paid and analysis weathering and morphogenic processes in North western of Iran and classify weathered and morphogenesis areas according to climate variables, and ultimately offer a comprehensive plan from the mentioned process. Materials and Methods In this study for investigation the weathering and morphogenetic regions at the North Western of Iran, data of average annual temperature and precipitation were collected from website of Meteorology organization. After reconstruction of shortcomings statistics, from all stations of region, 28 synoptic stations which have appropriate data period were selected and then a database established in ArcGIS software and data were recorded in this software. Then more analysis done in ArcMAP software and various maps were produced. In order to identify weathering conditions at the study area, Peltier models were used. Among seven peltiers models, two graphs for analysis of weathering condition in study area were selected. These two models are as follows: A. Weathering processes: According to this model the most humid and the hottest areas have maximum chemical weathering, and the driest and the coldest areas have minimum chemical weathering. B. morphogenetic Regions: In this model morphogenetic regions are divided into nine different categories. Areas with low temperatures, mainly are glacial regions and high temperatures areas with low rainfall are part of arid and semi arid ones; and areas with high precipitation and temperatures are parts of moderate and Savanna regions. Results and Discussion Precipitation of study area showed that there is two maximum rainfalls in this region that one of them is located at the South western shores of the Caspian Sea and other is located at western slopes of the Zagros Mountains in Kordestan province. While the minimum rainfall appearing in North stations such as Jolfa station. Temperature condition is very different, so that there is a minimum temperature in two stations in Sarab and Khalkhal cities, while the maximum temperature is in Gilan province due to vicinity to the Caspian Sea. In terms of morphogenetic, from nine morphogenetic classes in the Peltier model, five statuses in climatic classes have happened in study area. According to the geomorphogenetic map, more parts of the area are in dry regions, the stations that located at the South western shores of the Caspian Sea and western slopes of Zagros in Kordestan province are moderate and Savanna. Major characteristics of these areas are maximum activity of fluvial system and effect of ice and wind are low to moderate level. Only Bandar Anzali station was in oceanic climate. Among the seven models of weathering classes in Peltier models, five statuses happening in North Western of Iran. In the most parts of mountainous regions, there are weak to moderate mechanical weathering. While in stations of the south western coast of the Caspian Sea in Gilan, as well as Western slopes of Zagros in Kordestan, and south parts of Western Azerbaijan province, due to heavy precipitations, chemical weathering is more moderate type, rather than severe one. And in many other stations, due to abundant of rainfall and low temperatures, chemical weathering with frosting occurs. Conclusion The results showed that among seven weathering models in Peltier model, five models happened in North Western of Iran. Most parts of the study area are located in semi-arid regions and the most important Geomorphodinamic characteristic of these areas, are the effects of wind and moderate to severe water flow activity. Weathering processes in the South western shores of the Caspian Sea and western slopes of the Zagros in Kurdistan province are moderate and near to Savanna. Main characteristic of these areas is maximum water activity and the effect of ice and wind is between low and moderate level. Also there are a weak to moderate weathering in most parts of mountainous regions. While in stations of the south western coast of the Caspian Sea in Gilan and also Western slopes of Zagros, in Kurdistan and south of the Western Azerbaijan province, due to heavy precipitations Chemical weathering is more moderate to severe type. And in many other stations due to abundant of rainfall and low temperatures, chemical weathering associated with frosting occurs}, keywords = {Models Peltier,North western of Iran,Regions morphogenetic,Weathering regimes}, title_fa = {پهنه بندی فرایندهای هوازدگی سنگ ها براساس مدل های پلتیر در شمال غرب ایران}, abstract_fa = {هوازدگی زمانی رخ می دهد که سنگ های سطحی زمین بر اثر فرایندهای فیزیکی، شیم یایی و یا بیولوژیکی شکسته می شوند و یا تغییر شکل می دهند. این عمل می تواند به وسیله باد، آب، اقلیم، عوامل گیاهی و جانوری صورت گیرد . این مطالعه براساس مدل های لویس پلتیر قرار دارد که در این مدل ها از دو متغیر متوسط دما و بارش سالانه استفاده شده است . پلتیر با استفاده از این دو متغیر هفت مدل را مشخص کرد که می توانند انواع مختلف پدیده های هوازدگی را توصیف کنند . از بین این مدل ها دو مدل مربوط به رژیم های هوازدگی و رژیم های مورفوژنتیکی در مورد شمال غرب ایران بررسی شد و رژیم های مربوط به هر ایستگاه از روی نمودارها ی مربوط تعیین گردید . به منظور مطالعه و پهنه بندی وضعیت هوازدگی و مناطق ژئومورفولوژیکی در منطقه شمال غرب کشور داده های اقلیمی شامل میانگین بارش و دمای سالانه، 28 ایستگاه سینوپتیک که دارای داده و طول دوره آماری مناسب بودند، از سایت ثبت گردید . در ادامه، بعد از بررسی GIS سازمان هواشناسی برگرفته شد و سپس در یک پایگاه داده در محیط روند دما و بارش در منطقه مورد مطالعه، رژیم های مربوط به هر ایستگاه از روی مدل های پلتیر تعیین شد و بعد از تولید شدند . Arc map دادن ارزش وزنی به آنها در پایگاه داده ثبت گردید و سپس نقش ههای مربوط در محیط نتایج حاصل نشان داد که از نه وضعیت مورفوژنتیکی موجود در مدل پلتیر، پنج وضعیت در شرایط اقلیمی منطقه اتفاق می افتد، به طوری که بیشتر بخش های شمال غرب کشور در منطقه نیمه خشک قرار می گیرند . همچنین ایستگاه های واقع در سواحل جنوب غربی دریای خزر در استان گیلان و دامنه های غربی زاگرس در استان کردستان، رژیم معتدل و ساوان دارند . از نظر وضعیت هوازدگی نیز در بیشتر مناطق کوهستانی منطقه، هوازدگ ی ها بیشتر از نوع مکانیکی ضعیف و متوسط رخ می دهد، در صورتی که در برخی از ایستگاه های واقع در سواحل جنوب غربی در یای خزر و دامنه های غربی زاگرس در استان کردستان هوازدگی شیمیایی همراه با عمل یخبندان تا هوازدگی شیمیایی متوسط و شدید اتفاق م یافتد.}, keywords_fa = {Models Peltier,North western of Iran,Regions morphogenetic,Weathering regimes}, url = {https://jphgr.ut.ac.ir/article_22201.html}, eprint = {https://jphgr.ut.ac.ir/article_22201_db1e17c0982c12f9103baed846b9d902.pdf} } @article { author = {Rezayi Banafsheh, M and Jahanbakhsh, S and Bayati Khatibi, M and Zeinali, B}, title = {Forecast of Autumn and Winter Precipitation of West Iran by Use from Summer and Autumn Mediterranean Sea Surface Temperature}, journal = {Physical Geography Research}, volume = {42}, number = {4}, pages = {47-62}, year = {2011}, publisher = {University of Tehran}, issn = {2008-630X}, eissn = {2423-7760}, doi = {}, abstract = {Introduction Our country because of locating in neighborhood great watery sources of Mediterranean sea in west, Persian gulf and Oman sea in south, Caspian sea in north, Black sea and Indian ocean has been effected from sea surface temperature of these watery surfaces mostly. Therefore studying these effects on amount of country precipitation plays the main role in understanding of oscillations of precipitation and forecast of amount of precipitation in our country. In the recent years relation among agents of climate in ocean, atmosphere and land has been noticed by meteorologists and climatologist. Results of researches have indicated that changes temperature in surfaces of water can effect on changes of precipitation in the land confidently. Anomalies of sea surface temperature effect not only on seaside but also on far regions from sea. Mediterranean Sea is in limitation of geography 32 to 46 degrees latitude of north and 3 degrees altitude of west to 35 degrees altitude of east. This sea expands about 2.5 million km2. Changes of climate in this watery great surface can effect on west climate of Iran confidently. West winds make three troughs on U.S., East Asia and Mediterranean Sea in winter. This trough (Trough of Mediterranean Sea( is replaced on limitation of Mediterranean Sea that permit entering West wind and its system to limitation of west of Iran. Therefore in this research precipitation of autumn and winter seasons of west Iran has been forecasted by using summer and autumn Mediterranean Sea surface temperature. Drought and flood enter most costs for economic different parts For this purpose forecast of precipitation has main role in management of water sources and soil, replacement of management of risk to replace management of crisis and stable development in the country. In this research, precipitation of autumn and winter seasons in western parts of Iran has been forecast by using summer and autumn Mediterranean Sea surface temperature. Materials and Methods In this research two series of data have been used; first: seasonal data of Mediterranean Sea surface temperature in statistic period (1970-2005(, and secondly seasonal data of precipitation of west Iran in statistic period (1970-2005). For this purpose the periods such as warm, cold, base ones were determined for dates of MEDSST (Mediterranean Sea Surface Temperature) in statistics period of 1970 – 2005 for each season. Then statistical Medians of precipitation in every season and every period were determined so as (Rw, RC and Rb.( Theses Medians in every season and every period are compared together to clear amount of influence of theses condition. Also the authors have used correlation method between MedSST data in summer and autumn seasons and precipitation data in autumn and winter season by using Minitab software. From Regression method used for estimation of statistic trend of confident correlation. Results and Discussion Results indicated that when MEDSST in summer season is warmer than normal, autumn precipitation of West region of Iran is increased but when MEDSST of colder than normal in autumn season is caused increase of precipitation in the winter season. There is negative and confident correlation between MEDSST anomalies in autumn season and precipitation anomalies of West of Iran in winter season and there is not confident correlation between summer MEDSST anomalies and autumn precipitation in west region but intention of certain fairly is between increase of autumn precipitation the west region of Iran and warmer than normal MedSST of summer season. Climatic Oscillations have main effect on soil, cover of vegetation, watery sources and land use. Conclusion Climate and its factors certainly precipitation and its problematic changes play important role in environment of human life in lengths of time. Climatic Oscillations have the main effect on soil, cover of vegetation, watery sources and land use. Knowledge of this changes can provides correct usage of nature and management of watery and soil sources that cause planning better consequently.}, keywords = {Mediterranean,Precipitation anomalies,SST,West of Iran}, title_fa = {پیش بینی بارش پاییزه و زمستانه نیمه غربی ایران، با استفاده از SST مدیترانه در فصول تابستان و پاییز}, abstract_fa = {کشور ما به دلیل واقع شدن در همسایگ ی منابع رطوبتی فراوان دریای مدیترانه در غرب، خلیج فارس و دریای عمان مناطق رطوبتی یاد SST در جنوب، دریای خزر در شمال، دریای سیاه و اقیانوس هند تأثیرپذیری نسبتاً زیادی از شده دارد . لذا بررسی و مطالعه این تأثیرها بر مقدار بارش های کشور، نقش اساسی در شناخت نوس ان های بارش و پیش بینی مقادیر بارش آن دارد . از آنجا که خشکسالی و سیل خسارات زیادی به جوامع و بخش های مختلف اقتصادی در ایران وارد می کند، لذا پیش بینی بارش دارای نقش اساسی در مدیریت بهینه منابع آب و خاک، و نیز جایگزینی مدیریت ریسک به جای مدیریت بحران و توسع ه پایدار کشور است . در این پژوهش میزان تأثیر فصلی بر بارش های فصلی نیمه غربی ایران بررسی شده است . (Mediterranean SST) دمای سطح آب دریای مدیترانه ابتدا دوره های گرم و سرد و پایه (شرایط معمولی دمای سطح آب مدیترانه ) تعریف شد و سپس میانه آماری بارش و Rc/Rw ،Rb/Rc ،Rb/Rw محاسبه گردید و از مقادیر نسبت های Rb ،Rc ،Rw در هر دوره ب ا عناوین به ترتیب به منظور ارزیابی میزان تأثیر این شرایط بر بارش استفاده شد . نتایج نشان داد زمانی که در فصل پاییز Rw/Rc سردتر از معمول باشد، بارش زمستانه منطقة مورد مطالعه افزایش م ی یابد ولی دمای گرم تر از معمول MedSST در فصل پاییز و بارش MedSST آن در فصل تابستان باعث افزایش بارش پاییزه می شود. همچنین بین نوسانات در فصل MedSST زمستانة ایستگاه های مورد مطالعه ، همبستگی معنی دار منفی وجود دارد، ولی بین نوسانات تابستان و بارش پاییزه ایستگاه های مورد مطالعه همبستگی معن یدار مشاهده نشد؛ اما تمایل نسبتاً مشخصی بین افزایش بارش پاییزه با دمای گرم مدیترانه ملاحظه م یشود.}, keywords_fa = {Mediterranean,Precipitation anomalies,SST,West of Iran}, url = {https://jphgr.ut.ac.ir/article_22202.html}, eprint = {https://jphgr.ut.ac.ir/article_22202_f99cccbe2bcd49d4477d95192fafb23b.pdf} } @article { author = {ehsani, amir houshang}, title = {Geomorphometry of Lut Mega-Yardangs}, journal = {Physical Geography Research}, volume = {42}, number = {4}, pages = {63-77}, year = {2011}, publisher = {University of Tehran}, issn = {2008-630X}, eissn = {2423-7760}, doi = {}, abstract = {Introduction Yardangs due to intensive wind erosion are exclusive landforms on the earth's desert and possibly occur on Mars and Venus. The recent advances in the remote sensing technique and easily available of high resolution satellite data e.g. QuickBird provide useful information of remote area. Hence the mega-yardangs with tens meter high and hundred meters long are easily identifiable on satellite images and their global distribution and properties can be mapped. The Lut desert (Dasht-e Lut) in the south east of Iran is described as the “thermal pole of the Earth” (Mildrexler et al., 2006). With an area of about 80,000 square km it is regarded to the hottest and the driest desert in the world (Alavi Panah et al., 2007; Gabriel, 1938; Mildrexler et al., 2006). Yardangs are streamlined forms up to 150 km long and 75 m in height resulting from a number of formative processes, including wind abrasion, deflation, fluvial incision, desiccation cracks, slumping, weathering and mass movement (Goudie, 2007; McCauley et al., 1977; Ward and Greeley, 1984). A limited number of morphometric investigations have been done on yardangs. Goudie (2007) identified mega-yardangs in hyper-arid environments with total rainfall less than 50 mm including central Asia, the Lut desert in Iran, northern Saudi Arabia, Bahrain, the Libyan Desert in Egypt, the central Sahara, the Namib desert, the high Andes and Peruvian desert. According to Goudie, these features develop in a wide range of rock types e.g. sandstones, ignimbrites, limestones and basement rocks by a relatively unimodal wind direction. Materials and Methods In this study 3 arc second DEM of version 3.0 SRTM data (~ 90 m) with geographic projection acquired was used. That was re-projected to UTM grid with WGS84 Datum.We used 90 m DEM produced from version 3 SRTM 3 arc second data and the SOM algorithm for identification of yardangs in the western part of Lut desert. Self Organizing Map (SOM) is an unsupervised and nonparametric artificial neural network algorithm that clusters high dimensional input vectors into low dimensional (usually two dimensional) output map which preserve topology of the input data. In geomorphic studies of landscapes, the first and second order derivatives of DEM are the basic components for morphometric analysis (Evans, 1972). The second order derivatives of DEM are affected by geomorphological processes (Evans, 1972; Wood, 1996b). To calculate the morphometric features, a local window is passed over the SRTM DEM and the change in gradient of a central point in relation to its neighbors is derived by a bivariate quadratic function. Wood (1996a) defined a set of criteria to classify DEMs into morphometric classes. Yardang identification and analysis in the study area was performed using the parameters proposed by Wood (1996a). A local window of 5×5 is passed over the DEM and slope, cross- sectional curvature, maximum and minimum curvatures are derived by fitting a bivariate quadratic approximation surface. The derived morphometric parameters were used as an input to SOM. Frequency histograms and average quantization error of the results are compared. Two dimensional plots of mean values of morphometric parameters (feature space), oblique views of map units draped over the DEM, Landsat ETM+ data and high resolution QuickBird images were used to study the mega yardangs in other places than Iran. Results and Discussion Learning of the SOM was performed with four morphometric parameters as the inputs and a two-dimensional output of 10 neurons. The map with initial radius of 3, final neighborhood radius of 0.01 and 1000 iterations shows the best performance for yardang identification. The output map units from SOM are just numbers and need to be analyzed and interpreted. Studying the spatial relationship between different map units along with their morphometric parameters using feature space analysis allowed us to interpret and label them corresponding to morphometric features e.g. yardangs. Major morphometric features (corridor, planar and yardang) are identified in two-dimensional feature space plots of mean values of maximum curvature (x-axis) and minimum one (y-axis). The analysis of the results and corresponding satellite images shows the effectiveness of the method to identify the overall pattern of the morphometric features in the Lut desert. It is clear that the pattern of yardangs and their corridors running from NNW to SSE direction is parallel to the prevailing wind known as “wind of 120 days or Bad-i-sad-o-bist rooz-e Systan. Conclusion The results show that digital terrain analysis methods applied on SRTM in the proposed way in this study could extract morphotectonic features from SRTM along Dehshir fault and they contributed to the tectonic interpretation of the study area. According to the evidences extracted from SRTM along Dehshir fault, for example: fault traces, deflected and beheaded drainages, pattern of network drainages, erosion surfaces of uplifted and back erosion of drainages because of the location (situated in quaternary landforms), they are neotectonic evidences for activity of Dehshir fault during quaternary. Our results reveal that the morphometric analysis and feature space analysis of the first and second order derivatives of DEM such as slope, cross-sectional curvature, maximum curvature and minimum curvature led to the description of SOM outputs as yardangs, corridors and planar. Slope allows distinguishing among morphometric features in sub levels. The optimal self organizing map with suitable learning parameters should be selected for feature identification. The lowest average quantization error of 0.1040 was achieved with an initial radius of 3, a final neighborhood radius of 0.01 and 1000 iterations. Result of this method revealed that from the total 6481 km2 coverage of the study area, about 2035 km2 (34%) are classified as yardang while corridors, in total cover 2732 km2 (43%).}, keywords = {geomorphometry,Mega-Yardangs,Radar,Satellite images,SOM,SRTM}, title_fa = {ژئومورفومتری مگایاردانگ های لوت}, abstract_fa = {یاردانگ‌ها لندفرم‌های منحصر به‌فردی در مناطق خشک دنیا (و احتمالاً در زهره و کره مریخ) هستند که امروزه با پیشرفت فناوری دورسنجی و دسترسی به تصاویر ماهواره‌ای با دقت بسیار بالا، امکان استخراج اطلاعات از آنها فراهم آمده است. اطلاعات ماهواره‌ای موجود نشان می‌دهند که مگایاردانگ‌ها در آسیای مرکزی (چین)، بیابان لوت در ایران، شمال عربستان سعودی، بیابان نامیبیا، بیابان لیبی در مصر، صحرای مرکزی، بیابان‌های پرو و شیلی و آرژانتین وجود دارند. در سال 2003 وزارت ملی هوا و فضای امریکا داده‌های رادار SRTM با دقت 90 متر را برای تقریباً 80 درصد کره زمین ارائه کرد. آنالیز توپوگرافی به واحدهای همگن اراضی نقش بسیار مهمی در ارائه اطلاعات پایه برای برنامه‌ریزی ایفا می‌کند. در ژئومورفومتری ـ روش اندازه‌گیری کمّی و کیفی توپوگرافی ـ پارامترهای مورفومتریک نظیر شیب، منحنی حداکثر، منحنی حداقل یا منحنی مقطع عرضی از مدل رقومی ارتفاعی استخراج می‌گردد. در این مقاله پهنه‌بندی یاردانگ‌های لوت از طریق آنالیز مورفومتریک و استخراج پارامترهای نمای اول (شیب) و نمنای دوم (مثل منحنی مقطع عرضی، منحنی حداکثر و حداقل) با کمک معادلات درجه دوم دومتغیری بر روی مدل رقومی ارتفاعی مستخرج از داده‌های رادار صورت گرفت. سپس این پارامترها به‌عنوان ورودی شبکه عصبی مصنوعی ـ الگوریتم شبکه خودسازمانده مورد استفاده قرار گرفتند و با بهره‌گیری از پتانسیل این الگوریتم یاردانگ‌های لوت به صورت نیمه‌اتوماتیک و با سرعت و دقت بالا پهنه‌بندی گردید. نتایج آنالیز مورفومتریک بیابان لوت نشان داد که لندفرم یاردانگ و راهروها 34 و 43 و اراضی مسطح با درجات شیب مختلف 23 درصد منطقه را شامل می‌شوند.}, keywords_fa = {geomorphometry,Mega-Yardangs,Radar,Satellite images,SOM,SRTM}, url = {https://jphgr.ut.ac.ir/article_22203.html}, eprint = {https://jphgr.ut.ac.ir/article_22203_ba03f77529a9a4d13016803a9882f9c5.pdf} } @article { author = {Montazeri, M. and Masoodian, S.A.}, title = {Temperature Advection Patterns Analysis of Iran in Cold Years}, journal = {Physical Geography Research}, volume = {42}, number = {4}, pages = {79-94}, year = {2011}, publisher = {University of Tehran}, issn = {2008-630X}, eissn = {2423-7760}, doi = {}, abstract = {Introduction While it seems that the temperature variations follow a general pattern, that is dependent to the variations in the sun's changes angle and how the heat energy is distributed during the months of the year, but the temperature is not fixed over time and some losses or increases are seen. For example, during the cold seasons of the year it is seen that an almost warm or mild weather enters a region; or during the warm seasons, a cool weather overcomes for some days. This kind of charging cool or warm weather is called temperature advection. Temperature advections that are in particular frequency happening during the cold seasons of the year are not under the control of local factors but are rather controlled by pressure elements and/or factors. Accordingly, the wind advection and it does determine the temperature advections and in other words, they are characteristics of the air masses they bring with. Also during the warm seasons that an almost the same and fixed pressure pattern (subtropical high pressure) covers a large part of the country, these temperature advections don't occur frequently and mostly a clear, calm, sunny and same weather appears, in such a way that most of the days are same, climatically. But in cold seasons, by spreading the west wind over the country and the appearance of variations pressure patterns, more temperature advections happen. Materials and Methods In order to obtain the temperature advection patterns during the cold years, first, based on the time series, the average annual temperature of the country in a 30- year course of 1970- 2000 was selected and then the years of 1976, 1982, 1992, 1974 and 1975, were determined as the cold years. After that, three of U wind, V wind, and the Air temperature in the level of 1000 HP were determined for the hour of 12GMT in the aforementioned course in the geographical limit of 20? to 50? North latitude and 35 to 70 east longitude, with the spatial resolution of 2.5*2.5? and from the NCEP/NCAR climatic database. The temperature advection of each year calculated using programming in the Grads software environment. Finally, the data matrix is arranged with the dimension of 1827*56 in an S- mode. In the next step, a principal component analysis is done on the data matrix of the temperature advection. This analysis showed that with 15 components more than 93% of the variance in data can be explicated. Based on this method, two matrices with the dimensions of 56*15 for the spatial pattern, and 1827* 15 for the tempo pattern were provided. The component loadings matrix (56*15) was converted to the map, and the components score matrix, with the dimension of 1827*15, that resemble the temporal pattern, were converted to 15 charts. In the next stage a cluster analysis with the integration ward method on the components scores matrix (1827*15) was data. This review showed that according to the scores of the 15 main components in 1827 days (5 years), 12 advection patterns can be determined. Results and Discussion After determining the representative days, the temperature advection maps of the levels of 1000, 700 and 500 HP 12 hour GMT of these days were collected from the climatic data base of NECP/NCAR and were measured and plotted with grads software. In these maps, the solid line with positive scores and is the warm advection and the dotted lines the negative numbers represent the cold advection. This study reveals that low temperature in the cold years has an external origin and is due to the spread of cold temperature advection in the style and form of atmospheric pressure systems. The reviews showed that the temperature advections, devastate the country in two forms of eastern advection (from the east and north east) and the western ones (from the north west, west and south west). The eastern advections are related to how Siberian high pressure happens, while the western advections are due to the spread of the western winds across Iran. Conclusion This study revealed that eastern advections are stronger, while the western advections are a little mild. On the other hand, the eastern advection in the maps of 1000 level, has a wider view and spread, while in the maps of 700 level, their intensity is reduced and it represents that the eastern advections are moved in lower levels of the atmosphere. Evaluating the map of representative days shows that the patterns No. 1, 5, 6, 8, 11 and 12 have an eastern origin and No. 2, 4 and 7, have a western origin and the patterns No. 3, 9 and 10, have a western- eastern origin. Accordingly, it can be concluded that the cold advection, has a more eastern origin. And also the reviews demonstrated that during the study of cold advections, a more abundance available than the warm advection. It means that the coldness of the air during the cold period, is not only because of the local elements, but also is due to the cold advections, while the warmness of the air during the warm period is due to the local factors and the pressure of an almost stable air that is due to the subtropical high pressure. Evaluating the frequency of the temperature advection in the months of the year showed that the patterns of 9, 11 and 12, are in the summer and in 32% cases are in the second group. Therefore, it can be said that the temperature advections happen more during the cold period of the year, as they are dependent to the pressure patterns and these patterns are stronger in the cold time and they are more abundant, too, and moreover, they expanded to the lower latitudes.}, keywords = {Advection pattern,Cluster Analysis,Iran,Principal component analysis,Temperature advection}, title_fa = {شناسایی الگوهای فرارفت دمایی ایران در سال‌های سرد}, abstract_fa = {برای دستیابی به الگوهای فرارفت دمایی در سال‌های سرد، ابتدا براساس متوسط دمای سالانه کشور، پنج سال سرد مشخص گردید. سپس برای تعیین فرارفت‌های دمایی سه مؤلفه باد مداری، باد نصف‌النهاری و دمای هوا در تراز 1000 هکتوپاسکال، برای ساعت 12 GMT و در محدوده جغرافیایی 20 تا 50 درجه عرض شمالی و 35 تا 70 درجه طول شرقی، از پایگاه داده‌های اقلیمی استخراج گردید. فرارفت دمایی برای هر سال با استفاده از برنامه‌نویسی در محیط‌ نرم‌افزار گرادس محاسبه گردید و در مرحله بعد تحلیل مؤلفه اصلی بر روی ماتریس داده‌های فرارفت دمایی انجام گرفت. این تحلیل نشان داد که با پانزده مؤلفه می‌توان بیش از 93 درصد تغییرات داده‌ها را تبیین کرد. سپس تحلیلی خوشه‌ای با روش ادغام وارد، بر روی ماتریس نمرات مؤلفه‌ها انجام گرفت و براساس مقادیر پانزده مؤلفه در 1827 روز، دوازده الگوی فرارفتی شناسایی گردید. برای هر الگوی فرارفتی یک روز نماینده مشخص شد که معرف فرارفت دمایی در زمان حاکمیت آن الگوست. با مشخص شدن روز نماینده، نقشه‌‌های فرارفت دمایی این روزها محاسبه و ترسیم گردید. تحلیل نقشه‌های روزهای نماینده الگوهای فرارفت دمایی نشان داد که در طی دوره مورد مطالعه، الگوهای فرارفت سرد، به مراتب غلبه بیشتری دارند و از این‌رو پایین بودن دما در سال‌های سرد ناشی از فراوانی فرارفت‌های سرد و یورش توده‌های هوای سرد و گسترش آن بر پهنه ایران‌زمین بوده است. فرارفت‌های دمایی در قالب دو گروه فرارفت‌های شرقی ناشی از گسترش فراباری سیبری و فرارفت‌های غربی در نتیجه استقرار بادهای غربی، کشور را در بر می‌گیرند. بررسی نقشه‌های روز‌های نماینده، نشان می‌دهد که فرارفت‌های شرقی سطحی‌اند و شدت بیشتری نیز دارند و در لایه‌های پایین جَو جابه‌جا می‌شوند. این در حالی است که فرارفت‌های غربی، ملایم‌ترند و در ترازهای میانی جَو نمود بیشتری دارند. بررسی بسامد فرارفت‌های دمایی در ماه‌های سال، نشان داد که الگوهای شماره 9 و 11 و 12 تابستانه‌اند و در 31 درصد موارد در دوره گرم حادث شده‌اند. از این‌رو می‌توان گفت که فرارفت‌های دمایی در دوره سرد سال بسامد بیشتری دارند.}, keywords_fa = {Advection pattern,Cluster Analysis,Iran,Principal component analysis,Temperature advection}, url = {https://jphgr.ut.ac.ir/article_22204.html}, eprint = {https://jphgr.ut.ac.ir/article_22204_eee3e69ae11790122f0d8d77c09500dc.pdf} } @article { author = {zareabayneh, Hamid and Bayat Varkeshi, M and Sabziparvar, A.A. and Marofi, S and Ghasemi, A}, title = {Evaluation of Different Reference Evapotranspiration Methods and their Zonings in Iran}, journal = {Physical Geography Research}, volume = {42}, number = {4}, pages = {95-109}, year = {2011}, publisher = {University of Tehran}, issn = {2008-630X}, eissn = {2423-7760}, doi = {}, abstract = {Introduction Iran is characterized as arid and semi-arid climates due to low annual precipitation, high frequencies of flood and high rate of evapotranspiration. Evapotranspiration as one of the main components of hydrologic cycle is affected by atmospheric conditions and plant physiology. The complex of weather factors and plant physiology has encouraged the researchers to use numerous approaches for estimation reference evapotranspiration rate (ET0). Although lysimeters are the only direct methods for measuring ET0, the high costs of installation and maintenance are among the main problems for its popular use. Nevertheless, lysimeters are the most reliable tools for ralidation outputs of the ET0 models. The main objective of the present study is to assess various reference evapotranspiration models in order to provide Iso-ET0 maps as useful tools for water resources managers. Materials and Methods This study contains the UNESCO approach to classify the climates of 91 weather sites. The authors have also used lysimeyer data for selecting the most accurate ET0 model. All 91 sites of case-studies were classified in six different groups accordingly and the ET0 values were determined for 13 different ET0 models by using Ref-ET software. Computation ET0 methods include seven combination Penman type methods, two temperature-base ones, three radiation-temperature ones and at last one radiation method. In the next stage, among the 13 ET0 models, the best performance ET0 model was selected for each climate type according to the lysimeter data. The selection of the best ET0 method was done by different statistics such as coefficient of determination (R2), root mean square error (RMSE), and mean bias error (MBE). The authors used geo-statistical Kriging approach to prepare the estimated ET0 maps. The Iso-ET0 maps were plotted by means of geographical information of the weather site, the GIS and Surfer tools. Results and Discussion The results highlighted that among the 91 weather sites and 9 lysimeter stations, in 55.6 % cases, Penman type methods perform the most accurate ET0 estimates for most parts of Iran (Rahimi Khoob, 2008; Dehghani Sanij et al, 2007; Jensen et al., 1990). In 22 percent of the stations Blaney-Cridle and Hargrive Samani two methods were appropriate. The comparison of model results with those of lysimeter data showed reasonable deviations (RMSE=1.1 mmday-1, MBE= -0.23 mmday-1, R2=0.85) suggesting the accuracy of the each selected ET0 model. The geostatistic Kriging Iso-ET0 maps indicated that 23% of the country (mainly northern parts) experiences mean ET0 values of less that 4.48 mm per day. For the rest of the country (77%), the mean daily ET0 was more than 10.7 mm. It seems that the low rates of evapotranspiration in the northern elevated sites is a result of higher precipitation (higher humidity) and relatively lower temperature in this region. In arid and semi-arid sites, the irregularity of precipitation time series and dramatic changes in precipitation variability are the main reasons of higher evapotranspiration a water resources deficit in these regions. According to the extent of many countries, and the limited number of stations Laysymtry, estimated evapotranspiration, water management in the agricultural sector is required. Therefore, having the best model to estimate evapotranspiration in different areas and its interpolation with the most appropriate method helps a lot more accurate estimation in areas without measuring. Conclusions In consistence with the results addressed by Farshi and Shariati (1999) and Dehghani Sanij et al. (2004), our model results showed that Penman type models are the most reliable ET0 models for estimation of reference evapotranspiration in most parts of Iran. The Kriging-GIS maps of ET0 values showed that 23% of the country mainly located in high altitude of north Alborz mountain range experience low evapotranspiration. In contrary, about 77% of Iran show high evapotranspiration rates. The existence of Alborz mountains, north forests and high humidity are the major reasons for lower evapotranspiration rate in the northern areas (Rahimi Khoob and Khoshkam, 2003, 55). In comparison with the ET0 of the north, geographical maps of Iso-ET0 values showed higher potential of ET0 in southern parts of the country. Overall, water is a valuable commodity for Iran, especially in the areas with high potential ET0, in agriculture and consumer other sectors. Watershed management plans as well as plans for surface water storage, given the lack of precipitation and high average ET0, is essential.}, keywords = {Iran,Kriging,Penman,Reference Evapotranspiration,zoning}, title_fa = {ارزیابی روش‌های مختلف برآورد تبخیر تعرق گیاه‌مرجع و پهنه‌بندی آن در ایران}, abstract_fa = {کشور ایران دارای اقلیم خشک و نیمه‌خشک است که ریزش‌های کمِ جوّی، رگبارهای شدید، وقوع جریان‌های سیلابی و تبخیر (تبخیر تعرق) زیاد از ویژگی‌های آن به شمار می‌آید. پژوهش حاضر سعی در ارزیابی و پهنه‌بندی تبخیر تعرق گیاه‌مرجع (ETo) و ارائه آن در قالب نقشه‌های پهنه‌بندی و هم تبخیر تعرق (مرجع) به عنوان ابزاری اساسی برای مدیریت آب دارد. در این بررسی با گروه‌بندی مناطق هم‌اقلیم براساس اقلیم‌نمای یونسکو از میانگین‌های درازمدت متغیرهای اقلیمی 91 ایستگاه هواشناسی و داده‌های لایسیمتر، برای تعیین روش مناسب تخمین ETo استفاده شد. تبخیر تعرق گیاه‌مرجع برمبنای اطلاعات اقلیمی هر یک از ایستگاه‌ها به کمک نرم‌افزار RefET به 13 روش محاسبه شد. روش‌های محاسباتی شامل هفت روش ترکیبی بر پایه روش پنمن، دو روش دمایی، سه روش تشعشعی ـ دمایی و یک روش تشعشعی بودند. مناسب‌ترین روش محاسباتی از بین 13 روش، در مقایسه با مقادیر تبخیر تعرق لایسیمتری در هر اقلیم انتخاب شد. انتخاب روش محاسباتی براساس آماره‌های ضریب تبیین (2R)، جذر میانگین مربعات خطا (RMSE) و میانگین خطای اریبی (MBE) صورت گرفت. مقادیر RMSE، MBE و 2R در 9 ایستگاه لایسیمتری به ترتیب 1/1 میلی‌متر در روز، 23/0- میلی‌متر در روز و 85/0 به دست آمد، که نشان‌دهنده دقت مناسب کار در گستره جغرافیایی کشور ایران است. در نهایت هر یک از روش‌های محاسباتی انتخاب شده، برای سایر ایستگاه‌های هم‌اقلیم فاقد مقادیر لایسیمتری مبنای برآورد ETo قرار گرفتند. نتایج نشان داد که روش‌های با پایه پنمن در اکثر مناطق ایران مناسب‌ترین روش برای برآورد ETo به‌شمار می‌آیند. در ترسیم نقشه هم‌تبخیر تعرق مرجع (ISOETo) و پهنه‌بندی آن براساس نقشه‌های توپوگرافی رقومی شده، اطلاعات جغرافیایی ایستگاه‌های هواشناسی و بهره‌گیری از نرم‌افزارهای GIS و Surfer براساس داده‌های تبخیر تعرق مرجع روزانه صورت گرفت. نتایج پهنه‌بندی به روش کریجینگ، نشان داد میزان ETo در 23 درصد از سطح ایران که در مناطق مرتفع شمال کشور قرار دارند، کمتر از 48/4 میلی‌متر در روز است؛ و در مقابل 77 درصد از سطح کشور در پهنه ETo بیش از این مقدار تا سقف 70/10 میلی‌متر در روز قرار دارد. به نظر می‌رسد که پراکنش مناسب زمانی و مکانی بارش‌های مناطق شمالی، رطوبت نسبتاً بالا و برودت هوا در کاستن از پتانسیل تبخیر تعرق این مناطق نقش اساسی دارد. در مجموع وجود بی‌نظمی و نوسانات زیاد در سری‌های زمانی بارندگی سالانه از عوامل اصلی کمبود منابع آب و به تبع آن افزایش تبخیر تعرق در مناطق خشک و نیمه‌خشک ایران است.}, keywords_fa = {Iran,Kriging,Penman,Reference Evapotranspiration,zoning}, url = {https://jphgr.ut.ac.ir/article_22205.html}, eprint = {https://jphgr.ut.ac.ir/article_22205_95b1759bfea49a95798852a010e8a780.pdf} } @article { author = {Solaimani, Karim and Azmoudeh, A.}, title = {Investigation of Land Use Change Effects on some Physical and Chemical Properties, as well as the Soil Erodibility}, journal = {Physical Geography Research}, volume = {42}, number = {4}, pages = {111-123}, year = {2011}, publisher = {University of Tehran}, issn = {2008-630X}, eissn = {2423-7760}, doi = {}, abstract = {Introduction Different land-uses are being changed every day by the man, all over the world. Nowadays the increase of population and request for agricultural products causes natural vegetation such as transferring forests to farmlands. Rapid population growth in northern Iran requires additional farmlands for food production leading to clear cutting of forests and converting to the agricultural land. Land-use changes, mainly through conversion of natural vegetation may influence many natural phenomena and ecological processes and leading to a remarkable change in soil properties. There is a considerable concern that land-use changes can lead to an alteration of the soil organic carbon. Conversion of natural vegetation to agricultural land uses leads to a significant decrease of soil organic matter (SOM) content and conversely, reversion of cultivated land to natural vegetation can reliably replenish SOM and return lost soil carbon via increased soil carbon storage. Understanding the effects of land use and land cover changes on soil properties include many implications for devising land management strategies for identifying sustainable practices in each region with the intention of land degradation, sustainable development of agriculture and environmental protection. Therefore this study has been conducted to assess the impact of conversion of native forests into cultivated land (Wheat) and garden (Orange) on some soil properties and soil erodibility and investigate the effects of some soil properties on soil erodibility in northern Iran. Materials and Methods The study has been conducted in the Berenjestanak watershed of Mazandaran. The altitudinal range of the study site is between 153 and 777.2 m above sea level with a mean annual precipitation of 905 mm. Most precipitations are during the winter and spring seasons (November–May), and means annual temperature ranges from 16°C. Soil samples were taken at two depth of 0-10 and 10- 20 cm to characterize the physical and chemical properties, in particular soil texture, soil organic carbon, total N, bulk density, PH and EC. Soil erodibility measured by Wischmeier method. One-way Analysis of Variance (ANOVA) (SPSS 15) was used to compare the effects of land- use changes to selected physical and chemical properties and soil erodibility. The DUNCAN procedure was conducted to compare soil properties mean at P < 0.05. Pearson correlation coefficients were performed for response and explanatory relationships between soil erodibility with selected soil properties in three given land-uses. Results and Discussion The Conclusions show that land-use changes lead to significant changes in soil properties and its erodibility. Soils under three land-use types in the north of Iran have been shown to differ markedly in their contents of soil organic carbon, total N, bulk density, sand, and PH and soil erodibility. The organic carbon and total nitrogen content of the natural forest situation were significantly higher than the organic carbon and total nitrogen content of the garden and cultivated land. These results confirm the conclusions from several other experiments that have also shown a decrease in soil organic carbon and total nitrogen after cultivation. The bulk density of the soils was at the lowest level in areas under natural forest and the highest in cultivated areas of wheat. The result showed that land-use affected the measured content of sand in 0-10 cm of soil, but did not have a significant interactive effect on clay and silt contents. Also reduction of the permanent vegetation, loss of SOM, destruction of soil structure and the soil stability in the process of these alterations on the forest areas were caused increasing the soil erodibility 2 times more than the forest conditions soil. The correlation matrix revealed that soil organic carbon, total N and clay showed negative correlation with soil erodiblity, while silt and fine sand showed positive correlation whit soil erodibility. Conclusion Overall results indicated that conversion of natural forest and cultivation in the given area caused a degraded the soil properties, great decrease in soil quality and made the surface too sensitive for soil erosion. In conclusion, when these systems are converted for agriculture without proper practices of securing organic matter and soil stability, they are easily threatened. Therefore, conservation and good management after natural forest removal and reforesting can go some way to provide a solution to the problems of soil degradation, nutrient depletion as well as improving the soil quality}, keywords = {Brenjestanak basin,Erodibility organic material,land use change,soil}, title_fa = {بررسی نقش تغییر کاربری اراضی بر برخی از خصوصیات فیزیکی، شیمیایی و فرسایش‌پذیری خاک}, abstract_fa = {تغییر کاربری جنگل به اراضی کشاورزی، عموماً تأثیر جدّی بر میزان ماده آلی و دیگر ویژگی‌های فیزیکی و شیمیایی خاک می‌گذارد. این پژوهش با هدف بررسی نقش تغییر کاربری جنگل بر برخی از خصوصیات فیزیکی و شیمیایی خاک و در ادامه شناخت شماری از متغیرهای مؤثر خاک بر شاخص فرسایش‌پذیری در بخشی از حوضه آبخیز برنجستانک صورت گرفته است. بدین منظور سه کاربری جنگل، زراعت دیم (گندم) و باغ مورد بررسی قرار گرفت. نمونه‌های خاک از دو لایه سطحی 10-0 و 20-10 سانتی‌متر در قالب طرح بلوک کاملاً تصادفی برداشته و مقایسه شد. نتایج نشان از آن داشتند که میزان ماده آلی در اراضی زراعی و باغ، به ترتیب 24/44 و 45/45 درصد در لایه 10-0 سانتی‌متر، و 69/42 و 43 درصد در لایه 20-10 سانتی‌متر کمتر از اراضی جنگلی بوده است. حداکثر نیتروژن کل در لایه 10-0 سانتی‌متر در کاربری جنگل به میزان 303/0 درصد و حداقل آن در لایه 20-10 سانتی‌متر در اراضی باغ به میزان 190/0 درصد مشاهده شد که کاهشی معادل با 32/37 درصد را نشان می‌دهد. وزن مخصوص ظاهری و اسیدیته خاک طی تغییر کاربری جنگل افزایش یافت. این در حالی است که تغییر کاربری جنگل به اراضی زراعی و باغ تأثیر مشخص و معنی‌داری بر درصد ذرات رس و سیلت نداشت و تنها در لایه 10-0 سانتی‌متر تفاوت معنی‌داری از لحاظ درصد ذرات شن مشاهده شد. نتایج نشان داد که فرسایش‌پذیری خاک به دلیل کاهش پوشش گیاهی پایا، ماده آلی خاک، تخریب ساختمان خاک و پایداری خاکدانه‌ها طی تغییر کاربری جنگل، افزایشی حدود دو برابر داشته است. همچنین متغیرهای رس، ماده آلی و نیتروژن کل دارای همبستگی معنی‌دار منفی؛ و در مقابل، درصد سیلت و شن ریز نیز دارای ارتباط معنی‌دار مثبت با میزان فرسایش‌پذیری‌اند.}, keywords_fa = {Brenjestanak basin,Erodibility organic material,land use change,soil}, url = {https://jphgr.ut.ac.ir/article_22206.html}, eprint = {https://jphgr.ut.ac.ir/article_22206_b87643c9b42ac2e3aeb8264d3bd8f1cb.pdf} } @article { author = {Seif, A and khosravi, ghasem}, title = {Investigation of Active Tectonics in Zagros Trusth Belt Farsan Region}, journal = {Physical Geography Research}, volume = {42}, number = {4}, pages = {125-145}, year = {2011}, publisher = {University of Tehran}, issn = {2008-630X}, eissn = {2423-7760}, doi = {}, abstract = {Introduction Concerns of earth sciences, tectonic geomorphology with its own methodology is too. The main subject in tectonic geomorphology science is the study of measurable forms and landforms produced by tectonic signals. Since judgment about paleoseismological characteristics of an area cannot be only based on instrumental paleosizemology records and/or historical earthquake, so the study of surfacial landscapes and landforms is very important. Active tectonics indexes are advantageous tools for assessment and investigation of tectonic status of mobile zones. Active tectonics indexes are such as stream length gradient, drainage basin asymmetry, drainage basin shape, hypsometry integral and ratio of valley- floor width to valley height. The, main Zagros fault is one of the major as well as active faults of our country which has been prudes many earthquakes in around area. In this study Farsan basin, which consists of two zone structural of Sanandaj-sirjan and high-Zagros, was tested by seven different indexes and active tectonic rate was measured. Farsan and Hafshijan basin with 32.5-32.9 latitude in north hemisphere, and 50.33-50.78 longitude. By is located in Chahar Mahal and Bakhtiari province Paying attention to paleosizemology situation on the zone and comparing it with field observation, the results have been evaluated. Materials and Methods All the indexes have been measured with high resolution DEM (10 meters) within GIS software. Finally, the results of the active tectonic indexes were converted to IAT index and the active tectonic rate map of Farsan basin has prepared. The aims of this study are as follows: First, to study the tectonic status of the Farsan Basin along the Zagros fault margin based on active tectonic indexes. Second, to show the status of this zone by comparing the results from the active tectonic indexes at both sides of this fault and at the structural zone, i.e. Sanandaj-Sirjan and high-Zagros. Third, to show that which index gives better and more reliable results, considering the geomorphologic and field observations. It should be noted here that measurements have been done by GIS software using digital elevation models (DEM) with 10-meter-pixel resolution. For studying this basin, it was divided to 30 sub-basins. Sub-basins 1-16 and 30 were located inside high Zagros zone, and 17-29 inside Sanandaj-Sirjan zone. These sub-basins had also been categorized into 3 classes (1, 2, and 3) based on their tectonic activity. Class 1 has the highest activity and class 3 has the lowest. Results and Discussion Shape-ratio Index (Bl): This index is calculated by dividing length of the basin (B) by greatest width of the basin (L), Bl=B/L. Based on this index, the results showed that 27.88% of basins are in class 1, out of which 15.38% are in Sanandaj-Sirjan zone and 12.5% in high Zagros zone. Drainage Basin ASymmetry Index (Af): This index shows the tilting caused by tectonics and is calculated by Af =100(Ar/At), Ar: the area at the right side of the channel, At: the total area if the basin. The results showed that 71.93% of the basins have a tilted shape and are in class 1 out of which 30.76% are in Sanandaj-Sirjan zone and 41.17% in high Zagros zone. Hypsometric Integral Index (Hi): It is calculated by , in which , Hmax, and Hmin are the average, maximum, and minimum height of the basin, respectively. According to the results, totally 27.14% of the basins have active tectonics and are in class 1, out of which 15.38% are in Sanandaj-Sirjan zone and 11.76% in high Zagros zone. Mountain-front sinuosity Index (Smf): This index is calculated by the direct distance (Lmf) divided by indirect distance (Ls), Smf=Lmf/Ls. The results based on this index showed that 77.7% of the mountain fronts are in high Zagros zone and 63.6% of them in Sanandaj-Sirjan zone, both of them in class 1. Ratio of Valley-floor Width to Valley Height Index (Vf): This index is calculated by Vf =2VFW/[(ELD-ESC)+(ERD-ESC)], VFW: Valley-floor width, ESC: Valley-floor height, ERD,LD: Elevations of right and left valley divides. Based on this index, narrow and deep valleys have active tectonics. The results showed that only 37% of the measured valleys in high Zagros are in class 1 and no valley from Sanandaj-Sirjan zone is in class 1. Stream length-Gradiant Index (SL): it is calculated by SL= (?H/ ?L)L, in which ?H is change in elevation of the reach; ?L is length of the reach, L is the total channel length. According to the results, 23.52% of the streams are in high Zagros zone (class 1) and 15.3% are in Sanandaj-Sirjan zone (class 1). To produce the IAT index, the authors have added all the results from these 6 indexes, calculated S/n, and finally drawn the zoning map of the Farsan basin in 4 classes. The results showed that 3.18% of total basin areas (25.85 km2) have active tectonics. Conclusion The average basin area categorized in class 1 is around 13 km2, while the average area of inactive basins is around 37.27 km2. The average height of the basins in class 1 is about 2650 m., while that of in class 3 is around 2470 m. So, in this basin the main Zagros fault has very active tectonics along 8350 meters and tectonically high-Zagros zone is more active than the Sanandaj-sirjan zone.}, keywords = {Active tectonics indexes,Farsan basin,High-Zagros,IAT index,Main Zagros fault,Sanandaj-Sirjan}, title_fa = {بررسی تکتونیک فعال در قلمرو تراست زاگرس منطقه فارسان}, abstract_fa = {شناسایی مناطق دارای پتانسیل خطر زمین‌لرزه همواره از دغدغه‌های اصلی رشته‌های مرتبط با علوم زمین بوده است و محققان مختلف با نگرش‌های گوناگون آن را مورد مطالعه قرار داده‌اند. دانش تکتونیک ژئومورفولوژی نیز با روش‌شناسی خاص خود به مطالعه این پدیده محیطی پرداخته است. از این رهگذر تعبیر و تفسیر شواهد بر جای مانده از لرزه‌ها و حرکات تکتونیکی جدید بر چشم‌اندازها اصول موضوعه این دانش نوپاست. شاخص‌های تکتونیک فعال از ابزارهای کارآمد برای شناسایی وضعیت تکتونیکی و ارزیابی احتمالی مناطق لرزه‌خیز به‌شمار می‌آید. شاخص‌هایی چون سینوس جبهه کوهستان، شاخص‌های دره‌ای چون شاخص نسبت V شکل دره‌ها، شاخص پهنا به عمق دره‌ها، گرادیان طولی رودخانه، شاخص‌های حوضه‌ای چون شاخص تقارن حوضه زهکش، شاخص نسبت V شکل و شاخص انتگرال هیپسومتری، از این دست‌اند. از سویی هم ابرگسل زاگرس در زمرة گسل‌های فعال و اصلی کشورمان است که همواره منشأ لرزه‌های بسیاری در حاشیه خود بوده است و مرز دو زون ساختاری سنندج ـ سیرجان و زاگرس مرتفع است. در این پژوهش حوضه فارسان، که شامل دو زون سنندج ـ سیرجان و زاگرس مرتفع است، به‌وسیله شش شاخص متفاوت در محیط سیستم اطلاعات جغرافیایی (GIS) و از مدل رقومی ارتفاعی (DEM) با دقت 10 متر مورد آزمایش قرار گرفته و نرخ تکتونیک فعال آن سنجیده شده است. سپس نتایج به دست آمده، با بررسی میدانی مقایسه گردیده‌اند. نتایج شاخص‌های متفاوت تبدیل به شاخص IAT شده‌اند و نقشه پهنه‌بندی تکتونیکی حوضه فارسان در چهار کلاس بسیار فعال، فعال، نیمه‌فعال و غیرفعال ترسیم گردیده است. نتیجه به‌دست آمده این است که در این حوضه گسلی فرعی منشعب از گسل اصلی زاگرس در طول حدود 8350 متر دارای فعالیت تکتونیکی در حد بسیار فعال است. همچنین بخش‌های زیادی از حاشیه این گسل دارای تکتونیک متوسط است. دو شهر باباحیدر و فارسان در حاشیه گسل‌های فعال واقع شده‌اند.}, keywords_fa = {Active tectonics indexes,Farsan basin,High-Zagros,IAT index,Main Zagros fault,Sanandaj-Sirjan}, url = {https://jphgr.ut.ac.ir/article_22207.html}, eprint = {https://jphgr.ut.ac.ir/article_22207_5e3bdda2b60933b400b866d56edf3084.pdf} }