per
انجمن ایرانی ژئومورفولوژی
پژوهشهای ژئومورفولوژی کمّی
22519424
2018-11-18
5
1
1
13
78027
بررسی شواهد ژئومورفولوژیکی یخچالی کواترنری در ارتفاعات شمال شرق ایران (مطالعه موردی: رشتهکوه بینالود )
Investigating Quaternary Glacial Geomorphological Evidences at the Northeast Heights of Iran (Case Study: Binalud Mountain Ranges)
علی قربانی شورستانی
1
عذرا خسروی
2
علی نورمحمدی
3
دانشگاه فردوسی مشهد
دانشگاه فردوسی مشهد
دانشگاه فردوسی مشهد
پژوهش حاضر تلاش دارد تا با بررسی شواهد ژئومورفولوژیکی یخچالهای کواترنر در ارتفاعات بینالود، تعداد و محدوده پراکندگی سیرکهای یخچالی و همچنین برفمرز آخرین دوره یخچالی را در ارتفاعات بینالود تعیین کند. بدین منظور با استفاده از تفسیر نقشههای توپوگرافی مقیاس 1:50000 و تصاویر ماهوارهای و عکسهای هوایی 1:20000 منطقه، موقعیت شواهد یخچالی ازجمله سیرکها بررسی و در مرحله بعد با انجام بازدید میدانی موقعیت آنها شناسایی گردید. در گام بعدی با استفاده از دو روش رایت و پورتر حد برفمرز آخرین دوره یخچالی محاسبه گردید. همچنین در این تحقیق با استفاده از دادههای اقلیمی ایستگاههای هواشناسی و سینوپتیک موجود در منطقه و به کمک رابطهسنجی بین دما، بارش، ارتفاع و همچنین با در نظر گرفتن ارتفاع خط برف، نقشههای همدما و همباران حوضه در شرایط کنونی و در کواترنر بازسازی و ترسیم گردید. نتایج نشان میدهد افزون بر 39 سیرک بزرگ و کوچک بر روی ارتفاعات بینالود شکلگرفتهاند که بین ارتفاع 2100 تا 3380 متری توزیعشدهاند. تراکم سیرکها در ارتفاع 2350 تا 2500متر بیش از بقیه ارتفاعات است بهطوریکه حدود50 درصد آنها در این ارتفاع تمرکزیافتهاند. همچنین حداقل دمایمتوسط سالانه بینالود در زمان حاکمیت یخچالها برابر8/5- درجه سانتیگراد در ارتفاع 3308 متری و حداکثر دمای متوسط سالانه منطقه برابر با 5/9 درجه سانتیگراد در ارتفاع 870 متری بوده است. مقایسه نقشه همدمای فعلی و گذشته منطقه حاکی از آن است که رشتهکوه بینالود در کواترنر حدود 8/8 درجه سانتیگراد نسبت به زمان فعلی سردتر بوده است. نقشه همبارش منطقه در کواترنر حاکی از آن است که حداقل بارش در آن زمان برابر با 369 میلیمتر در پستترین نقطه و حداکثر مقدار بارش برابر با 832 میلیمتر در مرتفعترین بخش بوده است.
1. Introduction
The effects of climate change in the Quaternary period, especially in glacial periods of Iran, is less-known and under-studied. Although there have been some studies on some quaternary glaciers in Iran such as Alborz, but no study has to date investigated the East and North East regions of Iran in this regard. Binalud altitudes in the Northeast of Iran are amongst the regions which have the potential for the creation of glaciers and glacial conditions due to an altitude of more than 3000 meters and being located in the pathway of cold Siberian currents, especially in the cold periods of the year.
2. Materials and methods
The aim of this study is to identify glacial evidence and determine the permanent snow line of the last Quaternary period in Binalud heights. At first, the border area was determined using 1: 50000 topographic maps. In order to create the current isorain and isothermal maps of the region, the temperature and precipitation data of the stations of Mashhad, Nishaboor, Torogh, Akhlamad, Chenaran, Shandiz, Torqabeh, Kang, Golmakan, Arsalan, Ami Abad, Soltan abad and Chakaneh were used. With the help of this data and the digital elevation model of the area and according to the correlation between elements of temperature, rainfall and altitude, the current isorain and isothermal maps were drawn in the Arc GIS software.
Then, according to the form of curves on topographic maps of 1:50000, satellite images, and aerial photographs of the region, the areas under the ice sheet and glacier Cirques that mark the rule of glacial climates in the past were determined. Also, the previous permanent snowline of Binalud Mountain was estimated through Wright and Porter’s method. Then, the isothermal map of the area in the past was obtained using the height of the snow line and the adiabatic temperature drop. In order to prepare the past isorain map, after overlaying the current isothermal and isorain maps of the area in the Arc GIS software, their correlation spot was determined and using the relationship between precipitation, current temperature and the past temperature data, the past isorain map of area was prepared. Then, through field operations, the forms created by glaciers, including glacial valleys, Cirques and moraines were identified and finally, the data were analysed.
It is worth mentioning that in order to control and gather complementary information from field works and to study the literature and various methods of studying glaciers, the library method has been employed. In general, the current study is a fundamental research in which the analytical – historical, descriptive and experimental methods have been used.
3. Research findings
Morphological evidence
The first step for following the effects of Quaternary glaciers in the mountain ranges of Binalud is the evaluation of forms based on the morphic indicators on topographic maps of 1: 50,000 and the use of satellite images. Over 39 large and small Cirques were counted on the heights of Binalud that have been distributed between 2050 to 3380 meters of height. The density of Cirques in the elevation of 2350 to 2500 meters is more than the other heights, such that about 50% of them are concentrated in this elevation. Among the important factors based on which the existence of late Quaternary glaciers in the studied area may be proved is climatic evidence. To investigate the changes in climatic elements such as temperature and rainfall, the quantitative amounts of these parameters are needed. The current isothermal map of the area demonstrates that the minimum annual average temperature in the region at an altitude of 3300 meters is 3 ° C and the maximum annual average temperature at an altitude of 870 meters is 15.5 ° C. To estimate the past ambient temperature, after determining the permanent snow line border of the area in the past, the correlation between the temperature and altitude of the station was calculated using linear relationship and its linear equation was T = -0/005 H + 19/148 . Then, using this equation, the adiabatic temperature drop of 0.62 ° C was calculated for every 100 meters. Afterwards, using the altitude of the past permanent snow line border of Binalud and its adiabatic drop, the past isothermal map of the area was prepared. The minimum annual average temperature of Binalud at the time of the dominance of glaciers was -5.8 ° C in the altitude of 3308 m and the maximum annual average temperature was 9.5 ° C at the 870 meters altitude. Comparison of the current and past isothermal maps of the area indicates that in the Quaternary period, Binalud Mountain was about 8 ° C colder than the Present. Of course, the difference has not been the same for all parts of the region and it increased under the effect of altitude, such that the maximum temperature difference has occurred at the highest part and the minimum difference is related to the lowest point of the area. Also, the current isorain map of the region demonstrates that the minimum average annual rainfall is 196 mm, while the maximum average rainfall is 551 mmm in the highest point of the region. The isorain map of area in the Quaternary period indicates that the minimum precipitation in Quaternary was equal to 369 mm in the lowest points and the maximum amount of precipitation was 832 mm in the highest parts. Comparing the current and past isorain maps shows that in the period in which ambient temperature was 8.8 ° C less, the amount of ambient humidity was significantly different from the current rainfalls. Accordingly, during the glacial period, the precipitation was observed more than twice at lower altitudes and approximately 1.5 times more at high altitudes. This amount of change in the environmental temperature and humidity, along with the existing formation of (schists and shale) the region has created fundamental changes in the area’s morphogenesis system, in a way that there are currently no evidence of the Glacier morphogenesis system.
Wright’s method which is known as one of the most popular methods for determining the permanent snowline is based on counting small Cirques and calculating the height of their output entries (Ramesht quotes Parizi, 2013, 117). Based on the Cirques counted through Wright’s method, the 60% line of the region’s Cirques was determined. This altitudinal line determines that 60% of the Cirques are located above this line. By calculating this line, the permanent snow line in the studied area during the dominance of glaciers at an altitude of 2345 meters is estimated.
Discussion and conclusion
The results of this study suggest that the minimum average annual temperature of Binalud during the reign of glaciers at an altitude of 3308 meters has been 8.5 ° C and the maximum annual average temperature of the region has been equal to 5.9 ° C. Comparing the current and past Isothermal maps of the area, it is indicated that in the Quaternary period, Binalud mountain had been about 8.8 ° C colder than the current time. Of course, the difference has not been the same for all parts of the region and it increased under the effect of altitude, such that the maximum temperature difference has occurred at the highest parts, while the minimum difference has been related to the lowest point of the area. The minimum precipitation in the Quaternary period was equal to 369 mm in the lowest points and the maximum amount of precipitation was 832 mm in the highest parts. Comparison of the current and past isorain maps of the area indicates that in the period that ambient temperature was 8.8 ° C less, the amount of ambient humidity was significantly different from the current rainfalls. Accordingly, during the glacial period, precipitation was observed more than twice at lower altitudes and approximately 1.5 times more at high altitudes. According to our surveys, about 39 glacial cirques have been identified in the area, the minimum height of which is 2100 meters. According to the results, the permanent snow line in the region is located at the altitude of 2360 meters.
https://www.geomorphologyjournal.ir/article_78027_f1c006753f66be585afd3e81aa80087e.pdf
ارتفاعات بینالود
سیرک یخچالی
یخچالهای کواترنر
تغییرات اقلیمی
Binalood Heights
Glacier Circus
Quaternary Glaciers
Climate change
per
انجمن ایرانی ژئومورفولوژی
پژوهشهای ژئومورفولوژی کمّی
22519424
2018-11-18
5
1
14
26
78028
بررسی پیامدهای برداشت شن و ماسه بر مورفولوژی رودخانه (مطالعه موردی: رودخانه ده بالا-کرمان)
Geomorphic effect of instream gravel mining
Case study (Dehbala River â Kerman)
شیرین محمدخان
1
فاطمه نرماشیری
2
احمد یزدان پناه
3
دانشگاه تهران
مجتمع آموزش عالی سراوان
مرکز تحقیقات بینالمللی بیابان کرمان
رودخانهها سیستمهایی کاملاً پویا بوده و مشخصههای مورفولوژیکی آنها بهطور پیوسته تغییر میکند در این پژوهش پیامدهای برداشت شن و ماسه بر مورفولوژی رودخانه ده بالا در استان کرمان با استفاده از روش مقایسه زمانی- مکانی، موردبررسی قرارگرفته است. جهت مقایسه زمانی از عکسهای هوایی و جهت مقایسه مکانی، طول رودخانه به چهار بازه تقسیم و پارامترهای هندسی رودخانه مانند طولموج، ضریب خمیدگی، شعاع نسبی و زاویه مرکزی اندازهگیری شد. تغییرات زاویه مرکزی نشاندهنده افزایش پیچانرودی شدن از سال 1367 الی 1384 میباشد. بر اساس شاخص ضریب خمیدگی میزان خمیدگی رودخانه در طول این دوره افزایش داشته است. افزایش طولموج و طول دره در این دوره نشان از افزایش قدرت مانور رودخانه دارد. کاهش زاویه مرکزی در این دوره نشان از تحت فشار قرار گرفتن رودخانه و متعاقباً افزایش ناپایداری، توسعه و گسترش فرسایش کناری میباشد. عرض بستر دارای بیشترین تغییرات نسبت به سایر پارامترها میباشد. درمجموع میزان تغییرات مورفولوژی رودخانه اندک بوده و ممکن است به علت وجود شن و ماسه زیاد اثرات برداشت مصالح کوتاهمدت بوده باشد اما به علت روند کاهشی بارش و کاهش آورد رسوبی لزوم احتیاط بیشتر در میزان برداشت شن و ماسه ضروری میباشد.
Rivers are completely dynamic and active systems. In this study, we have investigated the effects of gravel mining on river morphology in Dehbala River of Kerman. First, basic researches including physiographic, geological, meteorological, erosion and sediment studies were conducted, then morphology of Dehbala River was studied using time- location comparison method. River bed was digitized by ILWIS software, in three periods of time, using the aerial photos of 1989, 1999 and satellite image of 2006 from river bed, and then geometrical parameters of river such as wavelength, the coefficient of curvature, relative radius and central angle was computed by AutoCAD software to evaluate changes, using fitting circles tangent method. According to the situation of gravel mines, the drainage path was divided into 4 pieces and then these parameters and changes were compared along the river. Changes in central angel demonstrate increased meandering from 1989 to 2006. According to the coefficient of curvature index, curvature of river was increased in this period. Increase in wavelength and length of valley of the river show increase in maneuverability of the river. Decrease in central angle of the river from 1989 to 2006, demonstrates increased instability of the river and subsequently development of lateral erosion. Width of bed shows the most changes in comparison with the other parameters. Piece 2 shows more changes in width of bed, which can be caused due to locate gravel mines in this piece and subsequently direct derivation. Finally, morphological changes of river was few and probably due to presence of large amounts of sand and gravel, the effects of gravel mining were short-term, but because of decreasing trend of rainfall and consequently decrease in bed load, more caution in gravel and sand mining is required.
Average rainfall is 152.9 during the selected period. The lowest amount of rainfall is 26.6% and the highest is 144.4. The moving average rainfall the first show decreasing trend and then fixed trend. Spatial analyses of the river in 1367 show all sections are extended meander except one section but in 1377 this section extends and the other sections have been marked changes. In 1388 we can see decrease meandering in all of section except section 2. But in general, we are witnessing an increasing of meandering from 1367 to 1384.
The curve of the river has been rising during the period under study. Valley wavelength and valley length have been increased which represents increasing maneuverability Dehbala River. The central angle is reduced in this period; that means the river has been under more pressure. This issue shows unstable platform and extend the margin erosion. Changes the width of bed has been increasing trend. River depth changes over time and place were not significant.
Geometric parameters obtained from Dehbala River also indicate the changes in the time series in the period of the study. Increasing meandering, instability, bank erosion and increase the width of bed is one of those changes. These changes may be a risk of river flooding in wet years in Dehbala River. Also, due to the proximity of farms and residential areas next to the river should be considered the effects and mixing river bed and residential areas. We should not be taken less than 500 meters from residential areas at the edge of the river. The amount of erosion and sediment assessment especially in the area based on EPM is about 65 million cubic meters per year and Mine removal is permitted according to the table (9) is currently 150 thousand cubic meters per year. The rivers have a lot of sediment, for example Dehbala River effect of sand mining may be short time. But in the form of reduced rainfall will have many problems.
https://www.geomorphologyjournal.ir/article_78028_3c99cfbedc4b720bd7f486de6079a3a3.pdf
مورفولوژی
شن و ماسه
رودخانه
پارامترهای هندسی
کرمان
morphology
Gravel mining
Geometric parameters
Kerman
per
انجمن ایرانی ژئومورفولوژی
پژوهشهای ژئومورفولوژی کمّی
22519424
2018-11-18
5
1
27
42
78029
پایش تغییرات خط ساحلی با استفاده از سنجشازدور در محدوده ساحلی دریای عمان از چابهار تا بندر تنگ
Monitor shoreline changes using remote sensing in coastal areas of Oman from the Chabahar to port Tang
سعید نگهبان
1
دانا رستمی
2
حمید گنجائیان
3
دانشگاه شیراز
دانشگاه تهران
دانشگاه تهران
نواحی ساحلی بهعنوان مناطقی که بین دو نوع محیط شکل زایی متفاوت قرار دارند همواره دارای تنوع فرآیندهای مختلف طبیعی بوده و دارای اهمیت هستند که این مناطق در طول زمان تغییر میکنند. پایش ویژگیهای مختلف نواحی ساحلی ازجمله تغییرات خط ساحلی، یکی از عوامل اساسی در جهت استفادهی بهینه از این منابع طبیعی و مدیریت پایدار آنها میباشد این پژوهش سعی دارد که به بررسی تغییرات خطساحلی چابهار تا تنگ به کمک تصاویر ماهوارهای بپردازد و نقشهها و نمودارهای مربوط به این تغییرات را استخراج کند. پژوهش از نوع توصیفی – تحلیل مبتنی بر روشهای کتابخانهای، نرمافزاری، آماری و میدانی است، بدینصورت که ابتدا به کمک فعالیتهای میدانی، نقشهها و مدارک موجود، منطقه مورد شناسایی قرار گرفت، سپس از طریق تصاویر ماهوارهای TM , ETMو OLI مربوط به سالهای 1988 تا 2015 تغییرات خط-ساحلی با استفاده از روشهای مبتنی بر طبقهبندی برای فاصله زمانی موردنظر بررسی شدند. نتایج حاصله بیانگر این است که محدوده موردمطالعه در طی 30 سال گذشته دارای تغییرات چشمگیری بوده است. بهطوریکه در طول دوره اول (1988-1998) 67/1 کیلومترمربع کلاس خشکی به کلاس آب تبدیلشده است. در همین دوره 75/8 کیلومترمربع کلاس آب به کلاس خشکی تبدیلشده است. در طول دوره دوم (1998-2008) 58/6 کیلومترمربع کلاس خشکی به کلاس آب و 2/260 کیلومترمربع کلاس آب به کلاس خشکی تبدیلشده است. همچنین در دوره سوم (2008-2015) 7 کیلومترمربع کلاس خشکی به کلاس آب و 12 کیلومترمربع کلاس آب به کلاس خشکی تبدیلشده است. تغییرات بهصورت پسروی نیز بیشتر ناشی از فعالیتهای انسانی در این منطقه بوده است. بهطوریکه بیشترین تغییرات در محدوده شهر چابهار،کنارک و اسکلهها و بنادری است که در محدوده ساحلی این منطقه ایجادشده است. عامل مهم و تأثیرگذار دیگر در پسروی خط ساحلی این منطقه حجم زیاد رسوبگذاری در مصب رودخانههای این محدوده میباشد. عامل دیگر که باعث بالاآمدگی ساحل این منطقه شده تکتونیک میباشد.
Monitoring the various features of coastal areas, including changes in the coastline, one of the main factors for the efficient use of natural resources and their sustainable management. To this end, new approaches such as the use of satellite data and image processing techniques, could be an ideal method, because it saves on time, money and other resources.
Coastal geomorphology is the study of the dynamic interface between the ocean and the land, incorporating both the physical geography (i.e. coastal geomorphology, geology and oceanography) and the human geography (sociology and history) of the coast. It involves an understanding of coastal weathering processes, particularly wave action, sediment movement and weather, and also the ways in which humans interact with the coast. The main physical Weathering process on beaches is salt-crystal growth. Wind carries salt spray onto rocks, where it is absorbed into small pores and cracks within the rocks. There the water evaporates and the salt crystallises, creating pressure and often breaking down the rock. In some beaches calcium carbonate is able to bind together other sediments to form beachrock and in warmer areas dunerock. Wind erosion is also a form of erosion, dust and sand is carried caround in the air and slowly erodes rock, this happens in a similar way in the sea were the salt and sand is washed up onto the rocks.
Methodology
In this study, data from satellite sensors TM, ETM, OLI dated 1988, 1998, 2008, 2015 were used, prior to the use of data, geometric and radiometric corrections were made on them.Then, beginning with the help of maps and documents, regional (Chabahar to narrow coastline) were identified. The method of classification of images, changes in the coastline for the study was determined intervals.
Result and discussion
The results showed that the method-classification capabilities for monitoring changes coastline. Using the results of the classification of the images showed that the coastline of the study area during the study period (30 years old), is subject to significant fluctuations. The greatest changes during the three periods examined for regression of coastline, or a class of water to drought and most of these changes are sandy beaches. So that during the first period (1988-1998), 67/1 kilometers drought class to class in the same period, the water has become, 75/8 kilometers grade water to drought. During the second period (1998-2008), 58/6 square km of land, water has become the class. During the same period, 2/260 square kilometer water to drought class has become. During the third period (2008-2015), the 7 square kilometers of water into the soil class in the same period, the amount of water to land conversion is 12 km from the class. Changes coastline this area has been the result of human-activity. So that most of the changes in the city of Chabahar, Konarak and ports and docks in the coastal area of this area has been created.
https://www.geomorphologyjournal.ir/article_78029_948b502258cd9db0148a681f07b68f71.pdf
ساحل
تغییرات خطساحلی
تصاویر ماهوارهای
چابهار
بندرتنگ
Coast
shoreline changes
image Satellite
per
انجمن ایرانی ژئومورفولوژی
پژوهشهای ژئومورفولوژی کمّی
22519424
2018-11-18
5
1
43
59
78030
مطالعه تغییرات ژئومورفولوژی بستر رودخانه کارون و علل آن از سال 1954 تا 2011 (1334تا 1391)
The study of geomorphological changes in Karun river and its reasons in the period of 1954-2011(1334-1391)
سیدرضا حسین زاده
srhosseinzadeh@um.ac.ir
1
مریم رشیدی
2
عادل سپهر
adelsepehr@um.ac.ir
3
حیدر زارعی
4
محمد خانه باد
5
دانشگاه فردوسی مشهد
دانشگاه فردوسی مشهد
دانشگاه فردوسی مشهد
دانشگاه شهید چمران اهواز
دانشگاه فردوسی مشهد
مطالعه تغییرات مورفولوژیک رودخانهها و رابطه آن با عوامل تأثیرگذار طبیعی و انسانی بهطور گستردهای بهعنوان یک ابزار مفید بهمنظور مشخص نمودن روند تکاملی رودخانهها و برنامهریزی درست برای حفاظت و بازسازی رودخانهها شناختهشده است. استان خوزستان با برخورداری از جریان رودخانههای دائمی بزرگ، نقش مهمی را در چرخه حیاتی آب کشور ایفا نموده و سهم قابلتوجهی از اهداف توسعه پایدار در بخش آب و کشاورزی را به خود اختصاص داده است. در این میان رودخانه کارون بهعنوان بزرگترین رودخانه ایران همهساله حجم آب قابلتوجهی را به دشت خوزستان و نهایتاً خلیجفارس روانه میسازد. این مطالعه به بررسی تغییرات ژئومورفولوژیکی رودخانه کارون با استفاده از تفسیر عکسهای هوایی و تصاویر ماهوارهای تجزیهوتحلیل آماری هیدرو اقلیمی و آنالیزهای رسوبشناسی در محدوده شهر اهواز میپردازد. ابتدا با استفاده از عکسهای هوایی، تصاویر ماهوارهای Landsat و IRS تغییرات مکانی و زمانی بستر رودخانه طی سالهای 1954، 2000 و 2011 مورد تجزیهوتحلیل قرار گرفت و سپس به بررسی علل این تغییرات پرداخته شد. نتایج حاصل از بررسیها نشان داد که طی 57 سال تغییرات چشمگیری در مورفولوژی رودخانه ازجمله تغییر در عرض رودخانه بهویژه در محدوده شهر اهواز، تغییر در مئاندرها و ایجاد جزایر رسوبی به وجود آمده است. همچنین آنالیز رسوبات جزایر نشان داد رسوبات تشکیلدهنده جزایر حاصل سیلابهای متعدد بوده که در محیطی آرام نهشتهگذاری شدهاند. علل اصلی ایجاد تغییرات کاهش دبی به دلیل ساخت سدهای متعدد در بالادست، ساخت پلهای متعدد در مسیر رودخانه بهویژه در محدوده شهر اهواز، عوامل زمینشناسی و پوشش گیاهی میباشد. بهطورکلی انسان و دخالتهای آن مهمترین عامل تغییرات مورفولوژی بستر رودخانه کارون میباشد.
Introduction
The study of the past morphological changes in floodplain unconfined reaches and the relationship with the natural and human-induced controlling factors is widely recognized as a useful tool to define the evolutionary trend in order to plan correct river management or sustainable river restoration. Morphological evolution involves bed level fluctuations, as a consequence of incision and aggrading, as well as plan form changes, concerning channel width, position and pattern. Following appreciable variations of boundary conditions, due to either natural (e.g. climate change) or anthropogenic (e.g.water extraction, damming or sediment mining) causes, rivers may experience long-term morphological evolution, which will eventually affect large portions of their watersheds Karoun is the biggest river of Iran which is emanate from the Zagros mountain and empties into the Persian Gulf. During the past two decades, numerous sedimentary islands have been made in Karoun river bed within Ahvaz city that caused the river ecosystem faced with various issues and has created some changes for Ahvaz city. This study examines geomorphological changes of the river and also the reason of creation and development sedimentary islands within the city.
Methodology
In the first phase of this study, Landsat7 satellite images of 2000 and IRS (internal revenue service) of 2011 and aerial photos of 1334 and also statistics hydro metric stations have been used. According to aerial photos, the base map and geomorphology were produced in ArcGIS environment. Then, by comparing satellite images, geomorphological changing procedure of river bed was extracted from 1954 to2011.
In this study, check path length of110km is divided into 4phases (periods) and then geomorphological map was produced for 1354.In next years, the other changes were measured against the base year. In the next level (phase), the statistics on the rate of hydro metric stations and rainfall data were analyzed by software excel. This analysis ,6th linear regression polynomial and drawing diagrams monthly and yearly average , average maximum instantaneous flow rate of each of the stations was drawn from 1961to2011. Preliminary observation was done during several stages for more and better recognition and understanding of the region in Farvardin94. And after that the sediment samples of islands were taken selectively. After transferring the deposits to the lab, a depth isolated from the sediments were taken into granulometry analysis and its sedimentology variables like cumulative frequency percent, tilt and sorting were revealed.
Results and discussion
The river's path has suffered changes and many displacements from 1334, the period which has been studied, to 1391. According to the territorial sections of the river that its value given in table1, it is seen that there has been lots of landscape changes in river channel.
The average changes show that in overall, during the period of study of this research, the least amount of landscape changes during the 57year old period were in the first interval with average 330m and the most amount of landscape changes were in the third interval of the river which means metropolitan area of Ahvaz with average 430m.
In term of river channel pattern and its relationship with changes rate has been seen in the second level. Evaluation of historical maps shows that arterial pattern (the second interval) in the first level and meander patterns (the third and fourth intervals) has the most amount of changes and displacements while the direct intervals (the first interval) is more stable than the other intervals.
Conclusion
Result show significant changes in the river's morphology during these 57years. Including width changes in river bed and river channel especially within Ahvaz city. mendar variations and formation of bar islands were formed. River islands in this area can be divided into the following 3categories:
1. Longitudinal islands which are long and droplet like are formed in the middle of the channel. Their overlapping structures (they consists of both large and small sediments) indicates various flood period.
2. Transverse islands which widen rather suddenly, occurs when sediments are deposited in the center of the river due to gradient losses.
https://www.geomorphologyjournal.ir/article_78030_70a5b89da48ff6a728f02f230d8b2bbc.pdf
رودخانه کارون
جزایر رسوبی
ژئومورفولوژی رودخانهای
بستر رودخانه
اهواز
Karun river
Alluvial islands
River geomorphology
Riverbed
Ahvaz
per
انجمن ایرانی ژئومورفولوژی
پژوهشهای ژئومورفولوژی کمّی
22519424
2018-11-18
5
1
60
74
78031
ارزیابی و پهنهبندی خطر زمینلغزش با استفاده از فرآیند تحلیل شبکه و شبکه عصبی مصنوعی (مطالعه موردی: حوضه آذرشهر چای)
Evaluation and zoning landslide hazard by using the analysis network process and artificial neural network (case study Azarshahr Chay basin)
معصومه رجبی
mrajabi@tabrizu.ac.ir
1
خلیل ولی زاده کامران
2
حسن عابدی قشلاقی
3
دانشگاه تبریز
دانشگاه تبریز
دانشگاه تبریز
ارزیابی حساسیت زمینلغزش مهمترین گام در تهیه نقشه خطر زمینلغزش است. هدف اصلی از این مطالعه، بررسی و مقایسه نتایج حاصل از دو مدل شبکه عصبی مصنوعی(ANN) و فرآیند تحلیل شبکهای(ANP < /span>) در پهنهبندی خطر زمینلغزش در حوضه آذرشهر چای میباشد. برای انجام این تحقیق با بررسی منابع و نظر کارشناسان، فاکتورهای مؤثر در وقوع زمینلغزش (شیب ، جهت شیب ، طبقات ارتفاعی ، لیتولوژی ، کاربری زمین ، فاصله از رودخانه ، فاصله از گسل ، فاصله از جاده) در محیط Arc GISآمادهشده و با لایه پراکنش زمینلغزشها تطابق داده شد و اطلاعات مربوط به زمینلغزشها در هر یک از لایههای اطلاعاتی بهصورت کمی به دست آمد. سپس با استفاده از ابزار Arc GIS و تجزیهوتحلیلهای صورت گرفته در هر دو مدل ، اهمیت هرکدام از لغزشهای رخداده بررسی و نقشههای پهنهبندی زمینلغزش تولید شد. ارزیابی نتایج بهدستآمده از فرآیند تحلیل شبکهای و شبکه عصبی مصنوعی با استفاده از ضریب آماری کاپا نشان میدهد که شبکه عصبی مصنوعی با ضریب 74/۰ نسبت به فرآیند تحلیل شبکهای با ضریب 72/0 از دقت بیشتری در پیشبینی زمینلغزش در حوضه آذرشهر چای برخوردار است. همچنین بر اساس پهنهبندی صورت گرفته با استفاده از مدل فرآیند تحلیل شبکهای نتایج بهدستآمده نشان میدهد که 13/7، 44/28، 13/37، 14/23، 27/3 درصد از مساحت منطقه به ترتیب در کلاسهای خطر خیلی کم، کم، متوسط، زیاد و خیلی زیاد قرارگرفته و در مدل شبکه عصبی مصنوعی به ترتیب 49/5، 61/32، 05/32، 22/23، 73/5 درصد از مساحت منطقه در کلاسهای خطر خیلی کم، کم، متوسط، زیاد و خیلی زیاد قرارگرفته است.
Introduction
Mass movement is as relocation large amounts of masses of soil, stone or a combination of them down the hillside is, in effect of force gravity. In the process and how to mass movements in hillside are presented multiple classifications. Carson and Corby, mass movements materials on hillside have divided to three floors slip, flow and creep (Moghimi et al., 2008). Since predict the time and location of the landslides are out of the current human knowledge. Therefore, for expressing sensitivity slope to landslide hazard zonation is in different areas(Shadfar et al., 2007). Of the most common of natural hazards at Sahand mountainous masses are a landslide. However, despite such abundance, exhaustive research has been done in this case. In these mountains, are harsh climatic conditions and context's sovereignty of materials susceptible to landslide such as pyroclastic materials and old alluviums is considered of landslide prone areas of the country. Azarshahr Chay basin as one of the drainage basins of Sahand mountain due to steep hillside's soil and surface materials not consolidate the lack of full-scope protection by vegetation and being active different processes over the years, feet walls of valleys cut by the waters flowing and in recent decade's manipulation human, the environment one of the area's susceptible mass movements(Bayati khatibi, 2011).
Methodology
In this study, landslide hazard zonation under study was checked at eight factors influencing to include: slope, aspect, lithology, distance from the road, distance from the fault, distance from the river, elevation and land use. These factor's maps prepared by ARC GIS software, and for zoning has been used in artificial neural networks and analysis network process. For this purpose the topographic map in scale 1: 50000 , geological map 1: 100000, 30-meter SRTM DEM been used the study area. By using satellite images Landsat 8 ETM+ 2014 (34 row; 168 Path), Google Earth software and field studies, were diagnosed 35 slide point. Then, the coordinates of the slide point transferred to the software Arc GIS landslide distribution map was produced in the context of these Apps. Also, the study points of non-slide, for use in artificial neural network training and testing are provided in the slope of less than 5 degrees.
Results and discussion
As mentioned, one of the models used in this study is network analysis. For preparation, the map zoning the landslides uses analysis network process model, you first need effective factors coefficients calculated in landslides in the study area. Then, use the coefficients obtained, proceed to Creating map landslide susceptibility was based on the analysis network. To do so, first in ARC GIS information layers that already been prepared and Digital to become raster formats or network and then reclassified and eventually coefficients obtained from ANP model in the Raster Calculate were imposed on the aforementioned layers and finally zoning map were obtained from a network analysis model. And map was classified in five classes: very high, high, medium, low, very little.
The neural network model, after determining the basic structure of the neural network and providing the information needed to train designed the neural network. Also, to achieve an acceptable error, is ready for the network, to do the logical analysis of information that has not been encountered previously and done forecasting and simulations the necessary. For this purpose, using the weight of the final stage of the training network, The total area, including 56040 pixels and each of pixel has eight features a landslide. Enter the network. After performing network analysis on this data, for each pixel was obtained value between zero and one. By category the values obtained from the network, Areas to different parts divided of opinion landslide risk. Eventually, hazard maps by a margin of 0.2 were classified to five zones of very low, low, medium, high and very high.
Conclusion
In this study, we examined the 8 factors the landslide hazard zonation. These factors include slope, aspect, lithology, land use, elevation, distance from the road, distance from the fault, and distance from the river, which results from these studies are as follows. The results of the network analysis process as one of the multi-criteria decision-making models, the most important factors in the occurrence of landslides Azarshahr Chay basin in order of priority were identified as follows: 1. Lithology, 2. Land use, 3. Slope, 4. Elevation, 5. distance from fault, 6. distance from river, 7. Aspect, 8. distance from road.
For landslide hazard zonation using Neural Network, In the first stage of training in order to avoid increasing the error, Each of artificial neural network parameters (number of repetitions, then learning and the number of neurons in the hidden layer) is determined based on trial and error. Then 1-15-8 structure of meaning 8 input neurons, 15 neurons in the hidden layer and one output neuron have been prepared landslide maps; the results show that is located 5.49, 32.61, 32.05, 23.22, 5.73 percent of area are at risk classes very low, low, medium, high and very high. For landslide hazard zonation using a network analysis process, the formed paired comparison matrix factors and then was calculated weight each factor. Eventually, using the functions overlaps in geographic information system software for landslides in was prepared the final maps Azarshahr Chay the basin. The results show that is located 7.13, 28.44, 37.13, 23.14, 3.27 percent of the area are at risk classes very low, low, medium, high and very high. The results of the analysis network process and artificial neural network, using the coefficient of kappa statistics shows that artificial neural networks with coefficient 0.74 compared to network analysis process with coefficient 0.72 more accurate is in predicting the risk of landslides in Azarshahr Chay basin.
https://www.geomorphologyjournal.ir/article_78031_094d802b0adb46dca38accb44bfef9a1.pdf
زمینلغزش
پهنهبندی
فرآیند تحلیل شبکه
شبکه عصبی مصنوعی
حوضه آذرشهر چای
Landslide
Zoning
analysis network process
Artificial Neural Network
Azarshahr Chay basin
per
انجمن ایرانی ژئومورفولوژی
پژوهشهای ژئومورفولوژی کمّی
22519424
2018-11-18
5
1
75
88
78032
تحولات ژئومورفولوژیکی پلایای میقان در کواترنر
Quaternary Geomorphological Evolutions in Meyghan Playa
میر اسداله حجازی
1
آتنا عسگری
2
بهاره میرزاخانی
3
دانشگاه تبریز
دانشگاه تبریز
دانشگاه محقق اردبیلی
ایران کشوری است که در بخشهای داخلی آن، شواهد ژئومورفولوژیکی متعددی را از تغییرات اقلیمی بهصورت تناوب اقلیم خشک و بارانی دارا است. دریاچه میقان، یکی از بسترهایی است که این شواهد را بهصورت سطوحی از رسوبات آواری و تبخیری حفظ کرده است. این دریاچه، حوضه آبریز خود به مساحت حدود 5528 کیلومترمربع را زهکشی میکند و در حال حاضر دارای اقلیمی خشک، با تبخیر بیش از بارش است. شرایط اقلیمی و همچنین شرایط زمینشناسی آن سبب شده است که این دریاچه به شکل پلایا تحول یابد. درحالیکه بسترهای سیلابی اطراف دریاچه، حکایت از اقلیم با بارش بیشتر را در این حوضه، دارد. این پژوهش باهدف شناسایی تغییرات دریاچه میقان انجامشده است. از نقشههای توپوگرافی 1:50000،مدل رقومی ارتفاع منطقه در مقیاس 1:50000 تصاویر ماهوارهای ETM+ و IRSP6 ، نقشه زمینشناسی 1:50000 و مشاهدات میدانی استفادهشده است. تکنیک تحلیل مؤلفههای اصلی برای شناسایی سطوح اطراف دریاچه انجامشده است و نتایج آنالیز به کمک مشاهدات میدانی و نمونهگیریهای موجود، ارزیابیشده است. نتایج بهدستآمده نشان داد که دریاچه میقان در آخرین دوره سرد، باران بیشتری دریافت نموده است و مساحتی معادل 129 کیلومترمربع را داشته است. به دلیل وجود کانیهای تبخیری ازجمله کلسیت، ژیپس و هالیت در بستر زمینشناسی حوضه و با تغییر اقلیم، کاهش بارش و افزایش تبخیر، دریاچه کوچکتر شده و کانیهای تبخیری بر اساس میزان حلالیت خود رسوب نمودهاند و سطوح آهکی، گچی و نمکی را در اطراف دریاچه تشکیل دادهاند و دریاچه میقان بهصورت پلایا تحولیافته است. در هریک از سطوح نامبرده، واحدها و رخسارههای ژئومورفولوژیکی خاصی شکلگرفته است که نشانگر تحول ژئومورفولوژیکی این دریاچه در طول زمان است.
Introduction
Nearly two-thirds the area of the country is desert. Playa or holes as well as units from the desert area of Iran occupy substantially and Due to their economic and ecological potential and requires careful and thoughtful be evaluated. Meyghan is a playa. Playa undeniable importance of studying in Iran. The other side is located near the city Meyghan and geomorphological undeniable impact on the city and other nearby towns led to this research, studied watersheds. Overall, in this study, the landforms are identified. The active processes are assessed to identify areas Morphogenetic and morph tectonic. In the next stage due to a bug off and heritage areas Morphogenetic climate in the climate of the last glacial period, these territories will be determined in the past. Finally, based on changes in landforms checked. According to a survey by researcher of research on these topics in our country is very small compared with the world.
Area of study
The main central drainage basin of the 5 sub-basin - Qomroud, Ghare Chay, salt (Khoshkrud), Meyghan and is composed Kashan desert. Meyighan sedimentary basin that Taleghani (1375) referred to as Arak plain, covers an area of 5528 square kilometers, of which 2,000 square kilometers and 3528 square kilometers it plain to the heights overlooking the plain form. The basin of the lake with an area ranging up to 106 seasonal Meyghan square kilometers and the elevation 1660 to 1700 meters above sea level, Farah and Arak alluvial plain, alluvial fans and piedmont basin is a watershed contour Qom and cranberry tea with low-lying mountains to the south, east and north, with the hilly areas located in the west basin has emerged. Meghan with an area of 135 square kilometers, including 94 percent of the lake's salt level is the average height of 1675 meters above sea level and is located in the Alborz and Zagros Mountains, 15 km north and northeast of the city of Arak is located. It covers an area of 143 square kilometers of desert in the pits or Meyghan playa is located in the center of the basin and is surrounded by relatively high mountains. The closest town to Meghan is Arak. Desert surrounding villages at different distances relative to seasonal lake surrounded by Meyghan
Data and Methodology
Meyghan Basin based on DEM and topographic maps at a scale of 1: 50,000 has been set. To obtain changes in the Quaternary surface of the lake, the main component analysis (PCA) was used based on the correlation matrix. In this way, aimed at identifying the level that had arisen as a result of changes in mineralization. For this purpose, reflective bands of ETM image data 6 was used. To increase the spatial resolution panchromatic band with the same image sensor with a pixel size of 15 m were combined. Then they calculated the correlation matrix. Most correlation between the bands 1 and 2 are equivalent to 9699/0 is the ETM image.
6 persons, sensor-based component bands 1 to 7 ETM (with the exception of band 6) was calculated as the percentage share of each PC of total variance changes (or eigenvalues) were compared.
For the above analysis with higher accuracy can be performed, the same operation on the pictures) III IRS- P6 (LISS - with pixel dimensions of 27 meters and four reflective bands was carried out.
Levels obtained respectively from the inside out with areas of salt, gypsum and lime playa Meyghan have coincidence.
Conclusion
Satellite images of the area, a large lineaments in the basin Meyghan, are identifiable. There are three clauses that are based on the three sides of Meghan, shows that the desert is probably along three fault, and has fallen But Tabarteh and Talkhab in the marginal basins in the margins of tectonic uplift and fall Pasadenian for the middle section appears which results in the formation of sedimentary basins and independence Meyghan and ultimately create Meghan at its center the size of today.
Meyghan Lake drainage basin with an area of 5528 square kilometers, which is more water volume to get the last cold period that has been more widely. Given the existence of a considerable part of limestone, gypsum and salt compounds in the rocks of the basin, in cold periods of lower temperatures and more precipitation, these dissolved minerals and water flow the basin is drained by the end. With global warming and increased evaporation than precipitation, sedimentation and dissolved minerals and as a result Meyghan just a playa lake has evolved.
Given the existence of a considerable part of limestone, gypsum and salt compounds in the rocks of the basin, in cold periods of lower temperatures and more precipitation, these dissolved minerals and water flow the basin is drained by the end. With global warming and increased evaporation than precipitation, sedimentation and dissolved minerals and as a result Meyghan just a playa lake has evolved. Smaller level from the third component part of the evaporate deposits along the lake correspond with the field observations showed that the part with a maximum accumulation of gypsum. Field observations in addition to sediment gypsum, calcite and halite mineral zones with predominant accumulation around the lake showed. Open correspond with the dominant mineral calcite surface Meyghan biggest playa. This level may indicate that precipitation since the last cold period is higher or lower temperature than is the present time. Now as the wet and dry climatic fluctuations in lake levels Meyghan just changes the expanse of salt and gypsum appear wet and dry. The maximum difference in height between the deepest points of the lake with the greatest surface obtained from the above analysis, 7 meters. In general it can be said that whenever a more humid climate and rainfall was higher, the central part of damp and salt Meyghan, expanded and more dry periods soluble salts have precipitated; therefore, in zones around the lake as well as lime and gypsum salt deposits can be seen. In this way, aimed at identifying the level that had arisen as a result of changes in mineralization.
https://www.geomorphologyjournal.ir/article_78032_f529c9918a95eef3530907bcaba52c97.pdf
پلایا
تحولات ژئومورفولوژیکی
دریاچه میقان
PCA
playa
Geomorphologic Evolution
Lake Meyghan
PCA
per
انجمن ایرانی ژئومورفولوژی
پژوهشهای ژئومورفولوژی کمّی
22519424
2018-11-18
5
1
89
109
78033
استفاده از تکنیکهای پیکسل مبنا و زیر پیکسل مبنا جهت شناسایی مناطق دگرسانی (مطالعه موردی: محدوده تنگ بستانک استان فارس)
Using pixel basis and subpixel based techniques to identify alteration zones(Case study: Tange Bostanak Region)
احمد نوحه گر
1
محمد کاظمی
2
سیدجواد احمدی
3
حمید غلامی
4
رسول مهدوی
5
دانشگاه تهران
دانشگاه هرمزگان
سازمان انرژی اتمی
دانشگاه هرمزگان
دانشگاه هرمزگان
آشکارسازی طیفی کانیها با استفاده از تصاویر چند طیفی سنجندهها، بهمنظور شناسایی و اکتشاف کانیهای هر منطقه با بهرهگیری از رفتارهای منحصربهفرد کانیها شیوهای نوین در زمینه علوم محیطی محسوب میگردد. تحقیق حاضر با استفاده از دادههای سنجنده لندست 8 و با روشهای مختلف پیکسل مبنا و زیرپیکسل مبنا مانند روش نسبت گیری باندی، آنالیز مؤلفههای انتخابی)کروستا(، نقشهبردار زاویه طیفی(SAM)، برازش مشخصه طیفی (SFF) ، روش ACE و فیلتر انطباقی تعدیلیافته(MTMF)به مطالعه و شناسایی زونهای دگرسانی در منطقه تنگ بستانک در استان فارس میپردازد. انجام پردازشهای لازم و استفاده از تکنیکهای ذکرشده منجر به شناسایی دگرسانیهای مختلفی ازجمله آرژیلیک، فیلیک و پروپلیتیک شده است. همچنین در این تحقیق با در دست داشتن نقشه واقعیت زمینی منطقه دولومیتی از سطح منطقه، دقتهای طبقهبندی ازجمله دقت کلی، کاپا، دقت ناظر و دقت تولیدکننده محاسبه گشت. همچنین با استفاده از نمونهبرداری تصادفی از سطح منطقه و انجام آزمایش ICP-MASS ، مجموع مربعات باقیمانده برای هرکدام از روشهای پیکسل مبنا و زیرپیکسل مبنا محاسبه و آنالیز XRD جهت تدقیق نتایج شناسایی اهداف با استفاده از نمونهبرداری تصادفی روی مناطق مختلف انجام شد. نتایج نشان داد روش SFF با مجموع مربعات باقیمانده 5/1 و ضریب کایا و کلی 679/0 و8/84 بیشترین دقت در شناسایی زونهای دگرسانی و روش PCA با مجموع مربعات باقیمانده 46/3 و ضریب کاپا و کلی 279/0 و 4/44 کمترین دقت را در شناسایی این مناطق دارد. همچنین بعد از گزینش مناسبترین روش شناسایی مساحت مناطق مختلف محاسبه گشت که مناطق دولومیتی، کلسیتی و کوارتز(سیلیسی) به ترتیب با 144/37، 32/33 و 86/27 کیلومترمربع بیشترین مساحت از سطح منطقه موردمطالعه را به خود اختصاص دادهاند.
Introduction
advanced remote sensing has been used in the past few decades in geology, mineral and hydrocarbon exploration. In the initial stages of remote-sensing technology development in the 1970s, geological mapping and mineral exploration were the commonest applications. Both multispectral and hyperspectral datasets can be used for mapping the alteration zones. alteration zones are commonly associated with certain minerals, such as propylitic assemblage (chlorite, epidote, and calcite), argillic minerals (kaolinite, dickite, montmo- rillonite), phyllic alteration minerals (sericite, illite), and advanced argillic minerals (alunite, pyrophyllite). Many studies reported the importance of remote sensing for mapping alteration minerals with ASTER data through image processing techniques, such as band rationing, principal component analysis (PCA), linear spectral unmixing (LSU), matched filtering (MF), mixture tuned matched filtering (MTMF), and constrained energy minimization (CEM). Most of these studies determined hydrothermally altered minerals at regional scale through per pixel analysis with little attention to subpixel analyses. However, an image pixel is often a mixture of the energy reflected or emitted from different materials that cannot be detected by per pixel classification algorithms. Rare publications are available for mapping alteration minerals using subpixel algorithms. Landsat 8 data can detect the altered rocks and ferrous minerals throw the OLI (Operational Land Imager) part of the image due to the absorption and reflectance characteristics of these rocks which appear in this range.
Methods
The Spectral Angle Mapper (SAM) algorithm is based on an ideal assumption that a single pixel of remote sensing images represents one certain ground cover material, and can be uniquely assigned to only one ground cover class. The SAM algorithm is a simply based on the measurement of the spectral similarity between two spectra. The spectral similarity can be obtained by considering each spectrum as a vector in q -dimensional space, where q is the number of bands. The SAM algorithm determines the spectral similarity between two spectra by calculating the angle between the two spectra, treating them as vectors in a space with dimensionality equal to the number of bands. (SFF) method. This is one of the algorithms nowadays used for satellite spectral analysis. Here, the similarity and conformity between the unknown image spectrum and the reference spectra are studied by investigating the reference spectra of the known signature and the recorded spectrum for each pixel in the satellite image. MTMF is a partial subpixel unmixing hybrid method based on the combination of well-known signal processing methodologies and linear mixture theory. This method combines the strength of the matched filter (MF) method (no requirement to know all the end members) with physical constraints imposed by mixing theory (the signature at any given pixel is a linear combination of the individual components contained in that pixel). The adaptive coherence estimator (ACE) estimates the squared cosine of the angle between a known target vector and a sample vector in a transformed coordinate space. The space is transformed according to an estimation of the background statistics, which directly effects the performance of the statistic as a target detector. Also we used RMSE to evaluation these method with actual dolomite zones. root mean square error (RMSE) analysis was performed for 50 alteration-mapped pixel points derived from the image processing results and compared with real points on the ground obtained in the global positioning system survey(where Preal is realpointsonthegroundand Pestimated is alteration-mapped pixelpointsatpoint i). Also we listed errors of commission, omission, Kappa coefficient and overall accuracies. Errors of commission result when we incorrectly identify pixels associated with a class as other classes, or when we improperly separate a single class into two or more classes. Errors of omission occur whenever we simply don’t recognize pixels that we should have identified as belonging to a particular.
We studied the applicability of data from the recently launched Landsat-8 for mapping alteration areas and litho- logical units associated with SAM, MTMF, ACE, SFF, PCA and BR to identification alteration zones in the region in Fars province's Beheshte Gomshodeh.
Result and discussion
In Landsat8 Band 2 is positioned in the blue(0.450–0.515 _m), band 3 in the green(0.525–0.600 _m) and band4 in the red (0.630–0.680 _m) region of the electromagnetic spectrum. The natural RGB colour combination image was assigned to bands4, 3and2 for a full view of the image. Geological features and the geomorphological framework can be distinguished at regional scale. Using confusion matrix showed that among the various methods SFF least error and ACE has the maximum error. The SFF method is based on the comparison of absorption features in the image and the reference spectra. The distribution map of the indicator clay minerals, such as kaolinite, muscovite, illite , montmorillonite, alunite, pyrophyllite, dickite, chlorite, and epidote in Beheshte Gomshodeh exploratory area has been prepared with the help of this method. SFF method. This is one of the algorithms nowadays used for satellite spectral analysis. Here, the similarity and conformity between the unknown image spectrum and the reference spectra are studied by investigating the reference spectra of the known signature and the recorded spectrum for each pixel in the satellite image. We have used the SFF algorithm (for the processing of satellite images in this study) because it gives users the best results, compared with all other spectral analysis methods (in the ENVI software) used for satellite image processing Another advantage of SFF method (compared with other classification methods and spectral analysis algorithms) is that it has sensitivity to recording precise and subtle mineral absorption features in the spectral diagram of the mineral under consideration. In other words, in this method, even the smallest and the most suibtle absorption features are highlighted for the purpose of a thorough and precise study.
https://www.geomorphologyjournal.ir/article_78033_4cb0b48c1680463f737bad7dcf4c5ac2.pdf
دگرسانی
برازش مشخصه طیفی
پیکسل مبنا
سنجشازدور
تنگ بستانک
Alteration
spectral
pixel-based
Remote Sensing
Tange Bostanak
per
انجمن ایرانی ژئومورفولوژی
پژوهشهای ژئومورفولوژی کمّی
22519424
2018-11-18
5
1
110
128
78034
ارزیابی تغییرات اقلیمی بین زمان حال و پلئیستوسن و بازسازی شرایط اقلیمی گذشته با استفاده از شاخصهای ژئومورفیک(نمونه موردی: حوضه دشت ابراهیم آباد-یزد)
Study of Landforms of Pleistocene glaciation in the central of Iran (Case study: Kazab-Yazd)
محمد شریفی
1
کاظم طاهری نژاد
2
فاطمه زارع
3
دانشگاه یزد
دانشگاه یزد
دانشگاه یزد
ایران مرکزی در حال حاضر از شرایط آبوهوایی گرم و خشک و بعضاً بسیار خشک برخوردار است. بااینوجود، آثار لند فرمهای موجود در منطقه حاکی از آبوهوای بسیار سردتر و البته مرطوبتری درگذشته است. هدف این پژوهش ارزیابی شرایط اقلیمی گذشته و محاسبه تفاوتهای آن با شرایط دمایی و بارشی حال حاضر است. برای انجام این تحقیق، از نقشههای توپوگرافی 50000/1، نقشه زمینشناسی 100000/1، عکسهای هوایی، نقشه رقومی ارتفاعی زمین باقدرت تفکیک 20 متر، گوگل ارث و نرمافزارهای Excel، GIS، سامانه GPS و همچنین بررسیهای میدانی استفاده شد. یافتهها حاکی از آن است که برفمرزها در این منطقه برحسب روشهای رایت و پورتر در ارتفاع حدود 2200 متری و خط تعادل آب و یخ نیز در سهطبقه ارتفاعی 1570 متر، 1700 و 1800 متر قرار داشته است که احتمالاً مربوط به شکلگیری سه دورهیخچالی یا دستکم پسروی یخچالها در سه دوره متناوب بوده است. مقایسه نقشههای همدمای حال و گذشته حاکی از تفاوت دمایی 14.4 درجه سانتیگراد دارد. درواقع، متوسط دمای حال حاضر 11.4 درجه بوده اما این میزان برای گذشته 3- درجه بوده است که این مقدار نیز در ارتفاعات مختلف نیز تغییر میکرده است بهگونهای که بین 10- در ارتفاعات تا 4.1 در بخش پاییندست حوضه متغیر بوده است. ازنظر شرایط بارش نیز، مقایسه نقشههای همبارش حال و گذشته نشان میدهد که بارش گذشته در حدود 350 میلیمتر (2.5) برابر بیشتر از حال حاضر بوده است که با افت دمایی 14 درجه سانتیگراد، قاعدتاً بیشتر بارشها بهصورت برف نیز میباریده است.
Introduction
Present Landform has been affected by climate conditions duration the time, and also the characteristics of sequence and periodicity of the condition. Thus, using the landforms, we can reconstruct climate condition and its changes. Geomorphological glacier relicts are one the most terraces that show the changes of climate in the past. Nevertheless, Central of Iran has located in a dry region at the moment, especially central of Iran, but there are some specified landforms in the region that represent spreading the glacier in the center of Iran in Pleistocene. These includes abrasive and depositional relicts. The goal of the study is the investigating of present landforms in the central of Iran-Kazab Basin in the west of Yazd City- to know processes that have created them in the past, especially the landforms that have created by glaciers. Kazab basin has located in the south-west of Yazd city in the west slopes of Shirkuh Mountain along 31° 53´ to 32° 7´of northen latitudes and 53° 52´ 42" to 54° 7 of eastern longitudes.
Materials and Methods
This research has been performed on basis of field studies and direct observation of glacial landforms. But, we studied topographical and geological maps, DEM, satellite images as well as aerial photographs, at first. The resulted information of the maps controlled with GPS System in the field. Then, we measured some boulders and pick up some sample of sediments and examine them in the geomorphological laboratory in the department of geograpgy in Yazd University.
Discussion and results
Findings show many landform that has created by a glacier morphogenetic system. These landforms was categorized in two classes includes abrasive and deposition processes. The relicts of abrasive of the glacier activity involve 28 small and great rcirques and some wide valleys as well that the width some of them reach to 200 meters in height 2000 meters. The most important of deposition traces of the glacier in the region involve tills, moraines, tillite and erratic stones. We have discussed both classes in more detail in the following:
abrasive traces
-Cirques: using topographical map and its contours characteristics we marked cirques on the map. Cirques appear on the map with stretched contours as sinusoidal form. Accordingly, we defined 28 small and great rcirques, and then checked them on the field using GPS system. More of them have laid between 2000 to 2500 meters height.
-Glacial valley: A valley carved by glaciers is normally U-shaped. A glacial valley becomes visible upon the recession of the glacier that forms it. Glacier valleys are the biggest abrasive forms glacier in mountains that become broad towards peak. Because a glacier has a much greater viscosity and cross section than a river, its course has fewer and broader bends, and thus, the valley becomes straighter and smoother. In the Kazab there are 3 wide valleys that the Hamane Valley, in the west of the basin, is the greatest so that the width of it reches about 200 meters.
Depositional traces
-Tills and moraines: Moraines are landforms created directly by glacier. In other words, moraines are a formation composed of unsorted and unbedded rock and soil debris called till, which was deposited by a glacier. After the retreat of a glacier the moraines remain as prominent features of the topography. Present moraine often have deposited in Pleistocene epoch. Kazab moraines usually have lay within main valley and include different sizes. They often observe between 1750 to 2050 meters as lateral, medial and terminal moraine. The medial moraines in the region are shown spiral hills with about one kilometer length and 20 M height. Besides, they are one of the most typical relicts of glacier in the center of Iran. The most properties of moraine are nonhomogeneous, angular, and have vertical direction to the river.
-Tillite: Sedimentary rock that consists of consolidated masses of unweathered blocks (large, angular, detached rock bodies) and glacial tills (unsorted and unstratified rock material deposited by glacial ice) in a Conglomerate form. The presence of tillites in a region provides evidence of former intense and widespread glaciation; recent tillites (about 10,000 years old) can be directly connected with glaciation, and Pleistocene tillites (10,000- 2,500,000 years old) can be convincingly related to glaciation. In other words, tillites are a kind of conglomerates that their sediment is created by glaciers. The rocks are deformed, poorly sorted and comprise quartz, feldspar and mainly sedimentary lithoclasts. The pebbles are relatively nonhomogeneous regarding their size. In the Kazab basin, tillites are observed in the left and right of the valley. In the region, tillites has located as terraces on both besides the river channel on the bedrock. They probability belong to the first glacial period that in another glacial periods sediments have stick together by calcium carbonate and established conglomerate and also has covered by tills and slopes sediment, they have remained unweather till now The height of the tillite layer in the Qezrabad valley is about 10 meters.
-Erratic stones: An erratic is a boulder transported and deposited by a glacier that differs from the size and type than the bedrock or native rock to the area in which it rest. Erratic stone are useful indicators of of former ice flow, and setting of glaciers. Erratic stones in the Kazab valley has located in three different height like 1750, 1850 and 2170meters that could show represent three glacial periods in the region by reducing their intensity from old to new.
Conclusion
Results show glacial traces for three periods In the Kazab basin in Pleistocene. Tillites and moraines located on them show two glacial periods at least, but the erratic stones, which has located in three different height indicates to three glacial periods. Besides, tills, moraine, tillites, wide walleyes, and cirques affirm glacial prevailing in the region. Nevertheless, granulometry studding on the medial moraines as well as tiillites confirm glacier processes in the region too.
https://www.geomorphologyjournal.ir/article_78034_a0299cb8ef0503398e5ac2004de91381.pdf
تغییرات دمایی
تغییرات رطوبتی
حوضه آبریز ابراهیم آباد
برفمرز
Kazab
Glacier
Geomorphological relicts
Tillite
Quaternary
per
انجمن ایرانی ژئومورفولوژی
پژوهشهای ژئومورفولوژی کمّی
22519424
2018-11-18
5
1
129
141
78035
ارزیابی شاخص موقعیت توپوگرافی (TPI) در زون سنندج - سیرجان و زاگرس شکسته
An Analysis of Topographic Position Index (TPI) in Sanandaj â Sirjan Zone and Broken Zagros Zone
امجد ملکی
1
هاجر مارابی
2
حمید رحیمی
3
دانشگاه رازی کرمانشاه
دانشگاه رازی کرمانشاه
دانشگاه رازی کرمانشاه
مطالعه کمی ناهمواریها، یکی از بخشهای نوین و کم سابقه در مطالعات داخلی محسوب میشود که با توجه به این واقعیت، اعتبارسنجیهای این نوع مطالعات نیز به همین منوال جایگاه مهمی را به خود اختصاص داده است. در این راستا در تحقیق پیشرو آنالیز شاخص موقعیت توپوگرافی (TPI) بهصورت خودکار در دو ناحیه زون سنندج – سیرجان و زاگرس شکسته جهت دستیابی به نتایج صحیحتر، موردبررسی قرار گرفت. در این تحقیق با توجه به صحت سنجی و انطباق با شرایط مشاهداتی از بین سایر روشها از روش Dickson & Beier استفاده گردید. پس از تهیه لایه TPI با تفکیک 4 طبقه (ارتفاعات، شیب تند، شیب ملایم و دره) به روش Dickson & Beier از لایه رقومی ارتفاعی (DEM) با دقت 10 متر از کل شهرستان صحنه در استان کرمانشاه، در گام بعدی بهصورت پایلوت از هر دو ناحیه ژئومورفولوژیک زاگرس دو قسمت (A= زون سنندج – سیرجان و B= زاگرس شکسته) با ابعاد 07/6 × 07/6 کیلومتر انتخاب شدند. در قسمت پایانی پروژه نیز نتایج حاصل از شاخص موقعیت توپوگرافی با توجه به تصاویر ماهوارهای و بازدیدهای میدانی بررسی شد. نتایج بیانگر تطابق مناسب مقادیر TPI=1، با درهها و کانیونها (حضور شبکه زهکشی)، TPI=2، با قسمتهای سکونتگاهی، زراعی و شیب ملایم، TPI=3، بر دامنههای با شیب تند و پوشش اندک گیاهی و TPI=4، با ستیغ است. در دو قسمت نیز بخشهای با شیب تند، حداکثر مساحت از هر دو زون موردمطالعه (پایلوت) را شامل شده است و سپس لندفرمهای شیب ملایم و ارتفاعات و درنهایت نیز درهها نیز حداقل مساحت را به خود اختصاص دادهاند.
Automatic analysis of morphometric of topography is one of the new sections and unprecedented internal studies. Due to this fact, the validation of this type of studies are also similarly important to their assigned position. Hereof, the leading research, analysis of the topography position index (TPI) automatically in two regions of Sanandaj – Sirjan zone and broken Zagros zone to achieve most correct results, were studied. In this study, according to verify and adaptation with condition of observations was used of Dickson & Beier within through of the other methods. After preparing of TPI layer with separation to 4 classes (ridgetop, steep slope, flat-gentle slope and canyon bottom) approach by Dickson & Beier from DEM layer with a resolution of 10 m of the total Sahneh township in Kermanshah province, in the next step typically from two parts of the geomorphologic Zagros region selected two part with dimensions of 6.07 × 6.07 km. In the final part of the project as well as the results of the topographic position index with respect to satellite images and field visits. The results represent the perfect match the values of the TPI = 1, with valleys and Canyon (Exist of Drainage Network), TPI = 2, with the residential part of the crop, and the slope gentle, TPI = 3, fitted with steep slopes and sparse vegetation and TPI = 4, with ridgetop. In two parts areas of steep slope has been included maximum area parts of the both regions (pilot) and then the landforms of slope gentle and the ridgetop and finally also canyon bottom as well as the minimum area.
Introduction
Landform is a feature of land or face of its a complicated that formed it to be formed by natural processes formed that it can be described and defined with features of distinctive, and present of various landforms and diversity of their controlled mainly by changes in the shape and position of the land. So, classify and identify different areas according to morphometric characteristics is essential. In this study, accuracy and TPI model classes at the first by given the actual conditions, and in the next measured in accordance with a resolution of DEM. The present research with new assumptions, the validity of this model in two different regions of Zagros and given the realities of the region, work epigraph put.
Materials and Methods
In this part, analysis of the topography position index (TPI) automatically in two regions of Sanandaj – Sirjan zone and broken Zagros zone to achieve most correct results, were studied. After preparing of TPI layer with separation to 4 classes (ridgetop, steep slope, flat-gentle slope and canyon bottom) approach by Dickson & Beier from DEM layer with a resolution of 10 m of the total Sahneh township in Kermanshah province, in the next step typically from two parts of the geomorphologic Zagros region selected two part with dimensions of 6.07 × 6.07 km. In this study, according to verify and adaptation with condition of observations was used of Dickson & Beier within through of the other methods.
Results and discussion
Sanandaj – Sirjan zone (A)
By analysis this area to the conclusion that 8.52 % of the zone is valleys, 22.74 % is gentle slope, 57.64 % is steep slope and 11.1 % ridgetop included. By analysis of the drainage network achieve as well as the adaptation of drainage on gentle slopes and valleys. The river beds are located within TPI = 1 and by following in this topographic feature continues themselves route. In addition to we will by satellite image analysis on adaptation TPI = 1, on valleys, TPI = 2, on settlements and agricultural areas, TPI = 3, on steep slopes and poor coverage of plant and TPI = 4, on the steep sections and ridgetop.
Broken Zagros zone (B)
By analyzing this area to the conclusion that 8.01 % of the zone is valleys, 15.42 % is gentle slope, 66.46 % is steep slope and 10.1 % ridgetop included. By analysis of the drainage network achieve as well as the adaptation of drainage on gentle slopes and valleys. The waterways in the area are located within TPI = 1 and by following in this topographic feature, will be going on. In addition to we will by satellite image analysis and field studies on adaptation of TPI = 1, on valleys, TPI = 2, on residential and agricultural sectors, TPI = 3, the= 3, on steep slopes and sparse vegetation and TPI = 4, the ranges and steep ridge, approved. In this zone the same as the previous zone, b by studying satellite images to overlap TPI = 1, the valleys, TPI = 2, the built-up area ranges and crops, TPI = 3, on steep slopes and low vegetation cover and TPI = 4, the steep and uphill sections.
Conclusion
In this study, the accuracy and TPI model classes, at first with real conditions (field data) and second proportional to the measured resolution of DEM. Select two locations in two construction zones and different morphology and get results of According to environmental conditions is bodes of the reliability of the method used in this research and its applicability. Nevertheless, for analyses was used of models Dickson & Bear (4 classes) in two broken and folded Zagros zones with a further variety of geomorphologic, and a perfect correspondence established values TPI = 1 on valley, TPI = 2, on settlements and agricultural areas, TPI = 3, on steep slopes and low vegetation cover and TPI = 4, on the steep part and ridgetop. In both areas as well as areas with steep slopes where the largest ratio of any Two zones (pilot) is then taken and at the next gentle slopes and ridgetop, and at the finally the valleys lowest area accounted.
https://www.geomorphologyjournal.ir/article_78035_9939280f5ae33690b0ad2b15cf456d37.pdf
TPI
Dickson & Beier
زون سنندج – سیرجان
زاگرس شکسته
TPI
Dickson & Beier
Sanandaj – Sirjan zone
broken Zagros zone
per
انجمن ایرانی ژئومورفولوژی
پژوهشهای ژئومورفولوژی کمّی
22519424
2018-11-18
5
1
142
159
78036
پهنهبندی حساسیت وقوع زمینلغزش با استفاده از مدل هیبریدی قضیه بیز –ANP (مطالعه موردی: کرانه جنوبی حوضه آبریز اهر چای از روستای نصیرآباد تا سد ستارخان)
Landslides susceptibility mapping using hybrid model of Bayes' theorem & ANP,
Case Study: Ahar drainage basin South boundary (From Nasirabad to Sattar Khan dam)
موسی عابدینی
1
شهرام روستائی
roostaei@tabriz.ac.ir
2
محمدحسین فتحی
3
دانشگاه محقق اردبیلی
دانشگاه تبریز
دانشگاه محقق اردبیلی
نقشههای حساسیت وقوع زمینلغزش یکی از مهمترین ابزارهای لازم برای برنامهریزان و تصمیم گیران محیطی بهویژه در مناطق کوهستانی است. در این پژوهش، پهنهبندی پتانسیل وقوع زمینلغزش در کرانه جنوبی حوضه آبریز اهرچای از روستای نصیرآباد تا سد ستارخان با استفاده از روش تحلیل شبکهای بر پایه زمینلغزشهای رخداده درگذشته که بهوسیله روش شی گرا استخراج و شناسایی گردیده است، و تئوری احتمالات شرطی (قضیه بیز)، موردمطالعه قرارگرفته است. تئوری بیز ، بهعنوان مدلی سودمند و آزمایششده در زمینههای مختلف، همچون مطالعه حرکات تودهای، تحقیقات معدنی و نقشهکشی چشمههای آب زیرزمینی میباشد. جهت وزن دهی به لایهها در این روشها، از10 پارامتر شیب زمین (به درجه)، جهت شیب، کاربری زمین، سنگشناسی، بارش، شاخص تراکم پوشش گیاهی(NDVI)، شاخص طول شیب(LS)، شاخص رطوبت توپوگرافیک (TWI)، شاخص قدرت آبراهه (SPI)، فاصله از گسل و فاصله از آبراهه استفاده شده است. تعداد 70 درصد زمینلغزش ها (25 عدد) برای اجرای مدل و 30 درصد (10 عدد) دیگر برای اعتبارسنجی بهکاررفته است. نتایج حاصله از روش مذکور و اعتبار سنجی میدانی مؤید دقت شناسایی 71.11٪ و دقت کلاسبندی 91.4٪ میباشد. با توجه به نتایج بهدستآمده 02/34 درصد از اراضی محدوده موردمطالعه از پتانسیل بسیار بالایی برای وقوع زمینلغزش برخوردار میباشند. همچنین، درصد قابلتوجهی از زمینلغزشها در طبقه با حساسیت زیاد (05/57) قرار دارند. لذا میتوان گفت دقت مدلهای بکار رفته در پهنهبندی حساسیت وقوع زمینلغزش قابلقبول و خوب است.
Introduction
Mass movements and landslides are considered the most destructive natural hazards. The study predicts landslide location using conditional probability theory (Bayesian theorem), on the southern edge of the Ahar drainage basin (From Nasirabad to Sattar Khan dam),, on the landslide occurred in the past by the object-oriented approach extracting and identifying been conducted. Using Bayesian probability theory correlation between parameters and landslide areas (two-thirds of landslide areas) to determine the weight of all categories of parameters were obtained. According to the map obtained by any of the parameters weight class, class of high silt old alluvial terraces are in layers, average pasture land in between classes, directions north and northwest, steep grade 5-25 the distance of 270-125 meters from the river greatest impact on weight and landslides in the area. The accuracy of landslide susceptibility maps using a third (12 points slip) landslide areas were evaluated. The result showed that the model with the predictability and kappa coefficient 0/93 and 0/945 percent of high and very high risk of landslides in class acceptable accuracy in evaluating and landslide susceptibility mapping.
Materials & Methods
In this study, object-oriented method to extract landslides, the IRS P 6 bands of satellite images were proper. Multiresolution segmentation algorithm was then applied for the segment. Among the different scales, scale 35 was chosen as the appropriate scale and form factor and compression factor each respectively 0.2 and 0/5 were selected and specific conditions of each class at the end of the definition, classification was carried out in the last stage to win to assess the landslide susceptibility in the region of evidence weight method is used. This model is useful as a model and tested in different fields, such as the study of mass movements, mineral research and mapping underground springs.
ANP Method:
Network analysis process is one of the MCDM techniques and in behalf of the compensation models. This model of hierarchical control, clusters, elements, and elements is an interaction between clusters. In general, the implementation of network analysis process model can be described in four stages as follows. 1. Build the model and create a lattice structure 2 binary comparison and determine the priority vectors that are actually similar to those in the analytic hierarchy process in the network analysis process repeated measures conducted in the screw. 3. The formation of primary and uneven super matrix. 4. The weighted matrix (5) formed Super eventually formed the super matrix.
weight of evidence(WofE):
weight of evidence(WofE) is a statistical method based on probability theory. This model represents relationships between an event landslides occurred and causative factors predisposing factors landslide estimates. In 1988, the model was used for mineral exploration. It is used to assess the landslide susceptibility. If causal factors (predisposing factors landslide) to B, class B i and landslides occurred in each parameter to consider S, then the Bayesian theory to calculate the conditional probability of landslides (S) in certain class (B i), can be used the following equation:
In this study, using 10 natural and human parameters (lithology, distance from fault, distance from the river, rainfall, land slope, slope, land use, density of vegetation(NDVI) and sediment transport index(STI) stream power index (SPI) and topographic wetness index (TWI) zonation action has been taken.
Discussion of Results
According to maps and information provided by a layer formation, and are old alluvial terraces conglomerate, the greatest impact and the weight to be allocated. Tuff, silt-ignimbrite alternating with layers of sandstone and conglomerate is the next category. Pyroxene and andesite rock formations as well as the other layers of the lowest weight and effect in landslides in the region. Among the different classes of land, pasture medium with the most weight had the greatest impact on landslide occurred that can focus in relation to human activities and population centers in these areas. Among the different tilt directions, directions north and northwest and the southern and south-eastern most minimal impact on land sliding. Also, the slope of 15-5 and 25-15 have the highest impact and landslides have weight. Class 270- 125 meters away from the river layer also have the greatest impact on landslides.
Conclusion
In this study, potential zoning landslides type South Bank Ahar drainage basin to the dam of the village of Nasirabad Khan, was evaluated. To do this, set the parameters of natural and man and landslides type occurred in the area (70 percent landslide) and ANP and Bayes' theorem is used to combine the two models. According mapped the western and southern parts of the North East region in terms of range and landslides has the greatest potential landslides. According to Table 3, 29/17% of the land as a regional study area with high potential for landslides have been considered. To assess the final map of 30% was used for regional landslide to the accuracy of the model used for zoning. Based on the results obtained from the assessment and placement of a significant percentage of the landslide in the floor with high sensitivity and very much (57/05) the accuracy of the model used in the occurrence of landslide susceptibility zoning acceptable and good.
https://www.geomorphologyjournal.ir/article_78036_84159cf8508a86805b79a38f0868eedf.pdf
پهنهبندی
زمینلغزش
قضیه بیز
فرآیند تحلیل شبکه
اهر چای
Landslide
Bayes' theorem
Network analysis process
Aharchay
Zoning
per
انجمن ایرانی ژئومورفولوژی
پژوهشهای ژئومورفولوژی کمّی
22519424
2018-11-18
5
1
160
180
78037
تأثیر نو زمینساخت و تغییر اقلیم در تحول پهنههای ماسهای شمال خاوری اهواز
مهران مقصودی
maghsoud@ut.ac.ir
1
امیر احمدی
2
سیاوش شایان
3
دانشگاه تهران
دانشگاه تهران
دانشگاه تربیت مدرس
پهنهها و لندفرمهای ماسهای بارزترین ویژگی مناطق بیابانی در روی زمین میباشند که در شناخت و بازسازی تغییرات پالئوژئومورفولوژی و پالئوکلیماتولوژی کمک شایانی میکنند. در این پژوهش بهمنظور تأثیر نو زمینساخت و تغییر اقلیم در تحول پهنههای ماسهای اهواز، نخست با بررسی و اثبات زمینساخت بهوسیله چهار فاکتور ژئومورفولوژیکی – مورفوتکتونیکی شامل: پارامتر تراکم زهکشها (P < /span>)، شکل حوضه (BS)، عدم تقارن حوضه زهکشی (AF) و ضریب پیچوخم جبهه کوهستان(SMF) پرداخته شد. در ادامه جهت بررسی تأثیر اقلیم بر پهنههای ماسهای، جمعاً ۶ نمونه رسوبی، (۳ نمونه از ماسههای فسیل و ۳ نمونه از ماسههای روان) بهوسیله دستگاه XRF تعین جنس و مقدار کربنات کلسیم هر نمونه بهوسیله دستگاه کلسیمتری برنارد مشخص گردید. نتایج بدست آمده از فاکتورهای ژئومورفولوژیکی – مورفوتکتونیکی نشان از بالا بودن زمینساخت جنبا در منطقه مورد مطالعه در محدوده خطوط گسلی و تاقدیس کوپال بهویژه در بخش خاوری منطقه میباشد. دادههای رسوبی ۱۱ عنصر را شامل: Na2O، MgO، AL2O3، SiO2، P2O5، SO3، K2O، CaO، Fe2O3، Sr و Br در همه نمونهها نشان داد. درمجموع از یازده کانی مورد مطالعه در نمونههای ماسههای فسیل و روان، ده عنصر دارای تغییر میباشند و میانگین CaO در ماسههای فسیل تقریباً ۲۰٪ کمتر از ماسههای روان میباشد. این تغییر درصد عناصر از ماسههای فسیل به روان نشان از یک فاز تغییر اقلیم میباشد که در کانیهای حساس به هوازدگی شیمیایی مانند Fe2O3 (۱۲٪ بیشتر) و AL2O3 (۱۸٪ بیشتر) در منطقه بارزتر میباشد. نتایج این پژوهش نشان از تکامل پهنههای ماسهای بخش خاوری اهواز بهوسیله زمینساخت و تغییر اقلیم میباشد.
https://www.geomorphologyjournal.ir/article_78037_5d0cf623e07068bb93373883a49f5150.pdf
زمینساخت جنبا
تغییر اقلیم
ماسههای بادی اهواز
کربنات کلسیم
.XRF
per
انجمن ایرانی ژئومورفولوژی
پژوهشهای ژئومورفولوژی کمّی
22519424
2018-11-18
5
1
181
190
78038
پتانسیل سیلخیزی حوضههای آبریز استان کردستان با بهکارگیری شاخصهای مورفومتری و تحلیلهای آماری
هادی نیری
1
ممند سالاری
2
اسرین میرزا مرادی
3
دانشگاه کردستان
دانشگاه کردستان
دانشگاه کردستان
سیل یکی از مهمترین مخاطرات تهدیدکننده جامعه بشری محسوب میشود. در دهههای اخیر با افزایش جمعیت و تغییر اقلیم اثرات این مخاطره بیشتر شده است. مطالعه ویژگیهای حوضهها که میزان سیلخیزی با آن در ارتباط است میتواند به مدیریت صحیح این مخاطره کمک نماید. استان کردستان با اقلیم نیمهخشک و تغییرپذیری زیاد بارش از پتانسیل بالایی برای این مخاطره برخوردار است. در این مقاله پتانسیل سیلخیزی حوضههای استان کردستان شامل حوضههای قرارگرفته در داخل استان و مشترک با استانهای مجاور با استفاده از شاخصهای مورفومتری و هیدروگرافی محاسبه گردید. با این هدف و بر اساس عوامل توپوگرافی و هیدرولوژی سطحی 18 حوضه شناسایی و مورد ارزیابی قرار گرفتند. در ادامه پژوهش آبراههها بر اساس روش استرالر طبقهبندی و سپس 12 پارامتر شاخص در ارتباط با سیلخیزی شامل طول حوضه، تراکم زهکشی، نسبت انشعاب، فراوانی آبراههها، طول جریان سطحی، ضریب فرم حوضه، شکل حوضه، ضریب کشیدگی، ضریب گردی، ضریب فشردگی، نسبت بافت و مساحت برای تمام حوضهها محاسبه گردید. از نرمافزارهای GIS و Excel بهمنظور تسهیل محاسبات و استخراج دادهها و SPSS برای طبقهبندی و نیز استاندارد کردن دادهها استفاده شد. نتایج نشان داد که حوضههای آبخیز موردمطالعه بر اساس پارامترهای موردمطالعه در دو خوشه قرار میگیرند. به ترتیب خوشه 1 دارای 11 حوضه شامل حوضههای بیجار، گلتپه، تپه اسماعیل، بوکان، رزاب، سقز، انگوران، قروه، سنندج، تکاب و شاهیندژ و خوشه 2 دارای 7 حوضه شامل حوضههای پاوه، سردشت، بانه، روانسر، کامیاران، مریوان و قزلچه میباشد. همچنین نتایج مقایسهای بیانگر قرارگیری حوضههای خوشه 1 در شرق و حوضههای خوشه 2 در غرب محدوده موردمطالعه است. مجموع برآوردها و تحلیلهای آماری نشاندهنده پتانسیل سیلخیزی بیشتر حوضههای شرقی با وجود بارندگی بیشتر حوضههای غربی است که دلیل بارز آن ناشی از شرایط توپوگرافی، پوشش گیاهی و لیتولوژیکی خاص حوضههای شرقی است.
https://www.geomorphologyjournal.ir/article_78038_80126bca744239bdc2a223dae181238e.pdf
سیلخیزی
مورفومتری
شاخصهای آماری
استان کردستان