پیوندهای مفید
اخبار و اعلانات
آمار
| تعداد نشریات | 158 |
| تعداد شماره‌ها | 6,223 |
| تعداد مقالات | 67,680 |
| تعداد مشاهده مقاله | 114,878,064 |
| تعداد دریافت فایل اصل مقاله | 89,549,904 |
بررسی آنومالی‌های حرارتی و رطوبتی بین زمان حال و پلیئستوسن و بازسازی شرایط اقلیمی با استفاده از شواهد ژئومورفیک (مورد مطالعه: حوضۀ خضرآباد-یزد) | ||
| پژوهش های جغرافیای طبیعی | ||
| مقاله 7، دوره 47، شماره 4، دی 1394، صفحه 583-605 اصل مقاله (1.88 M) | ||
| نوع مقاله: مقاله کامل | ||
| شناسه دیجیتال (DOI): 10.22059/jphgr.2015.56051 | ||
| نویسندگان | ||
| محمد شریفی* 1؛ زهرا فرح بخش2 | ||
| 1استادیار گروه جغرافیا، دانشگاه یزد | ||
| 2کارشناس ارشد ژئومورفولوژی، دانشگاه یزد | ||
| چکیده | ||
| حوضة خضرآباد در فاصلة 30 کیلومتری جنوب غربی شهر یزد واقع شده است. در این حوضه، ژئوفرم‌هایی وجود دارد که به‌احتمال در دورة اقلیمی متفاوتی نسبت به زمان حال به‌وجود آمده است که با تحلیل آنها، برای بازسازی اقلیم گذشته تلاش شده است. برای بررسی وضعیت اقلیمی گذشته، در این پژوهش از نقشه‌های توپوگرافی، عکس‌های هوایی، تصاویر ماهواره‌ای، پژوهش‌های میدانی، سامانة GPS و داده‌های اقلیمی ایستگاه‌های هواشناسی استفاده شد. برحسب همبستگی بین ارتفاع و متوسط دمای سالانه و ارتفاع و مقدار بارش سالانه، گرادیان حرارتی و رطوبتی محاسبه شد. یافته‌های پژوهش نشان می‌دهد خط برف‌مرز دایمی با روش‌های رایت و پورتر، در ارتفاع 2100 تا 2200 متر واقع می‌شده است. باتوجه‌به این خط و افت آهنگ دما به مقدار 65/0 و 8/0 درجه به‌ازای هر 100 متر ارتفاع، مقدار تفاوت دمای کنونی با گذشته، به‌ترتیب معادل 92/12 و 4/13 درجة سانتی‌گراد محاسبه شد. نتایج نشان داد که مقدار بارش سالانه در زمان گذشته 52/176 میلی‌متر نسبت به میانگین امروزی بیشتر بوده است. به‌علاوه، خط تعادل آب و یخ معادل 8/4 درجه، در ارتفاع 1560متری واقع شده است. | ||
| کلیدواژه‌ها | ||
| برف‌مرز؛ پلیئستوسن؛ تغییرات اقلیمی؛ حوضة خضرآباد؛ داده‌های ژئومورفیک | ||
| عنوان مقاله [English] | ||
| Investigation about Temperature and Humidity Anomalies between Pleistocene and Present Times; Reconstruction of Climate Condition Using Geomorphic Evidence (Case Study: Khezrabad-Yazd) | ||
| نویسندگان [English] | ||
| Mohammad Sharifi1؛ Zahara Farahbakhsh2 | ||
| 1Assistant Professor, Physical Geography, Yazd University, Iran | ||
| 2MA in Geomorphology, Yazd University, Iran | ||
| چکیده [English] | ||
| Introduction The study of climate change and its trend have usually been complicated as problems for specific scientists in these subjects. Obviously, climate has been changed during the history of earth many times, and their evidence are landforms in many regions of the world, where we can readily observe now. The landforms could not be justified with the present climate. In fact, any climate creates specific geomorphic systems. Therefore, the existence of different geomorphic systems in different regions of the world shows that climate has changed frequently over time. In the KhezrAbad basin of Yazd Province we can observe landforms that have been created in different periods of climate of different temperature and precipitation conditions. Thus, with studying of present landforms in the basin, it has been tried to reconstruct past climate. The climate could justify such landforms reasonably. KhezrAbad Basin is located in the south-west Yazd city in the slope of Shirkuh Mountain along 31° 48´ 7" to 32° of northern latitudes and 53° 49´ 42" to 54° of eastern longitudes. Materials and Methods For studding the condition of past climate in the research, we have used topographical maps (1/50000), geological map (1/100000), aerial photographs (1/55000), and satellite images. In addition, to study present climate and its changes relative to the past, we have used climate data including temperature and precipitation of 6 stations for 9 years in the region and its surrounding. At first, using topographical maps we have defined the basin. Then, according to the form of contours, aerial photographs, satellite images as well as field study, we marked glacier cirques. For drawing the maps of present isotherm, we created the correlation between altitudes and annual temperature (for 9 years) amongst surrounding stations of the region to obtain the linear equation. Then, using the elevation points extracted from DEM and above equation, we provided isotherm and isohyets maps for present time. As ever, for drawing past isotherm and isohyets maps, we calculated zero C. line (snowline) for the past with Wright and Porter methods. Afterwards, we obtained an equation according to the correlation between altitude and temperature, which replaced once 1000 meters instead of “h” and next time 2000 meters. Therefore, with subtraction of these two numbers, we evaluated adiabatic lapse rate. Using permanent snowline altitude and adiabatic lapse rate it would result in past isotherm map. In the next stage, according to line correlation between temperature and precipitation, we got the equation: P= -15.803T+355.16. On the equation basis, it helps draw past isohyets map. In the Wright method, we used the average of 60% of cirques. In the Porter method, we calculated the snowline of the region according to accumulation area ratio, cirque-floor altitude, and altitude ratios. Results and Discussion Investigation about the region at present shows some landforms such as a number of glacier cirque, a U form origin valley and a few secondary valleys as well as a great fan that could not be created with present climatic processes. Therefore, these landforms indicate a big climatic change in temperature that was lower with higher precipitation. With statistical analysis and also Wright and Porter methods, the snowline has been found between 2100-2200 altitudes in Pleistocene. On the snowline basis as well as adiabatic lapse rate for 0.65 and 0.8 C., we have calculated differences between past and present temperatures in the region orderly 12.92 and 13.4° C. In addition, studies showed that the rate of precipitation in the Pleistocene increased to about 176 millimeter more than present average. Thus, the ice and water equilibrium line has been in 1560 meters equivalent to 4.8° C. With more precise study, the rate of precipitation in Pleistocene has been about 3.38 million cubic meters above 1200 meters height. This volume is about 1.88 as much more than present. The most precipitation volume has been calculated for the altitudes between 2200-2300 meters, and the least for 3000 meters. Conclusion The results of this research in the KhezrAbad Basin show some glacial evidence of past climates. The evidence can be observed as 15 small and big cirques, a glacier broad valley, much volume of moraines such as lateral moraines, medial moraines, and terminal moraines, and also tillites. On the basis of these witnesses, the permanent snowline has been on the height of 2200 meters, but the ice and water equilibrium line on 1560 meters. In fact, glacier’s tongue has been descended more than 600 meters and there has been melted ice; because temperature in the altitude increased to 5° C. The remained erratic in the region affirm the hypothesis. Therefore, with comparison of isotherm and isohyets maps of the basin for present and past times, we estimated about 13°C anomalies. Moreover, research findings show the reduction of 176.52 millimeter of precipitation in comparison with the quaternary. Precise calculation confirms that the volume of precipitation in Pleistocene period has been 3.38 million cubic meters above 2200 m. The volume is about 1.88 as much more than present time. | ||
| کلیدواژه‌ها [English] | ||
| climate changes, geomorphic data, KhezrAbad basin, Pleistocene, snowline | ||
| مراجع | ||
|
1. Abtahi, S.M. (2013). "Studing of Paleoclimate of Jajroud Basin using glaciers evidences". Geographical Researches of desert regions. No. 1: 185-201.
2. ــــــــــ (2012). "The trend of changes in Playas of Salt Lake in the Late Quaternary and Holocene". Ph.D. Thesis. Supervisor Seif, A.. Isfahan University. Department of Geography.
3. Abtahi, S.M., Seif, A. and Khosroshahi, M. (2012). "Investigation of the Last Quaternary Climate from the Geomorphic Evidence in Namak Lake Basin, Central Iran". Journal of Geography and Regional Planning. Vol. 5. No. 3: 93-107.
4. Almodaresi, A. and Ramesht, M.H. (2005). "Traces of Glaciers of Shirkuh mountain in the Sakhvid Region". Geographic Space. No. 19: 2-31.
5. Almodaresi, A. (2005). "Hydrogeomorphology of Sakhvid Basin (Yazd Province)". M.S. Thesis. Supervisor Ramesht, M.H.. Najafabad Azad University. Department of Geography.
6. Afshari Azad, M. and Poursaba, A. (2009). "Studding of glaciers morphology and its spreading in the north Slopes of Sabalan mountain". Geography and regional development. No. 13: 284-300.
7. Amirahmadi. A. (2013). "Traces of glaciers in the Dehbala in the Shirkuh mountain and its role in the Development of Ecotourism". Growth Journal of Geography Education. Vol. 3: 41-43.
8. Bagheri Sadr, F. (2011). "Studding of Evidence of Glacier Morphologic in Lorestan in Quaternary". M.S. Thesis. Supervisor Seif, A.. Isfahan University. Department of Geography.
9. Baghaiynia, A. (2008). "Renovation of Climate Change in the Quaternary using hydrogeomorphology evidence in the Fakhrabad Basin". M.S Thesis. Supervisor Mehrshahi, D.. Yazd University. Department of Geography.
10. Farahbkhsh, Z. (2014). "Hydrogeomorphology of Khezrabad Basin with emphasis on glacier features". M.S. Thesis. Supervisor Sharifi, M.. Yazd University. Department of Geography.
11. Ghezeljeh, B. (2013). "Determine of boundary of preglaciers erosion and studding of its Geomorphological potential in the Gorganrood Basin". M.S. Thesis. Supervisor Amirahmadi, A.. Sabzevari University. Departement of Geography.
12. Hagedorn, H., Haars, W., Busche, D. and Grunert, j. (1978). "Some geomorphological observations from the Shir-kuh, mountains area.Geography". Journalof the Association of Iranin Geographers. Vol. 1: 10-15.
13. Mehrshahi, D. (1999). "Late Quaternary Environments, Ardakan Playa, Central Iran". Ph.D. thesis. Geography Department. Sheffield University. UK.
14. ـــــــــ (2010). "Finding of evidence of Glaciers activities in the mountain of Shirkuh". Roshd Geography Teaching. No. 14: 10-11.
15. Moayeri, M.; Ramesht, M.H., Taghvaiy, M. and Taghizadeh, M.M. (2008). "Glacier Traces in the basin of Safashar of Isfahan". Resaerch magazine of Isfahan University. 32. No. 4: 109-130.
16. Pedrami, M. (1991). "Geology of Quaternary and Paleoclimate of Arac Region (Mayghan Playa)". Internal report of Iran Geology Organization.
17. Pedrami, M, (1982). "Pleistocene Glaciation and Paleoclimate in Iran. Proceeding of the INQUA Conference". Geological Survey of Iran: 1-70.
18. Pourdehghan, D. and Ramesht, M.H. (2005). "Ice in fire, Glacier Traces in the Bam region". Geographical researches. No. 89: 130-143.
19. Ramsht, M.H. and Kazemi, M.H. (2002). "Traces of glacier in the Eghlid basin". growth Journal of Geography Education. Vol. 21. Closed. Issue. 4: 9. Tehran.
20. Ramesht, M.H., Lajevardi, M., Lashkari, H. and Mahmodi Mohamadabadi, T. (2012). "Tracing the effects of glaciers (Tygrani Basin MAHAN)". Geography and environment planning. No. 2 (42): 59–78.
21. Ramesht, M.H. and Shoushtari, N. (2004). "Glacier Traces in the Salafchagan of Qom". Geographical researches. No. 73: 119-132.
22. Rahdanfard, M. (2012). "Studding of glaciers bounds in central Zagros in Late Quaternary". M.S. Thesis. Supervisor Seif, A.. Isfahan University. Department of Geography.
23. Rafiy, Gh.R. (2009). "Traces of Kahak Glacier". M.S. Thesis. Supervisor Ramesht, M. H.. Isfahan University. Department of Geography.
24. Seif, A; Servati, M. R. and Rahedanfard, M. (2015). "Renovation of Quaternary Snowline in the around of Rig Site". Geographical researches. 30. No. 1.
25. Sharifi, M. and Farahbakhsh, Z. (2015). "Studding of evidences of quaternary glaciers geoforms and changes in morphoclimatic and morphodynamic systems in Qezrabad basin". Geography and Environmental planning. accepted for publication.
26. Sharifi, M. and Farahbakhsh, Z. (2015). "The study and analysis of sediments of Qezrabad valley for knowing past morphodynamic processes". Geographical Researches of desert regions. Vol. 2. No.3.
27. Tahouni, P. (2004). "The role of outer dynamic processes in morphogenez Talesh's mountain". No. 47: 31-55.
28. Talebi, H.R. (2002). "Glacial evidence of the Zefreh". M.S Thesis. Supervisor Ramesht, M.H.. Azad University of Najafabad. Department of Geography.
29. Wright, H.E. Jr. (1961). "Pleistocene Glaciation in Kurdistan". Eiszeitalter und Gegenwart. 12: 31–164.
30. Yamani, M. (2007). "The Geomorphological Traces of Glaciers Boundaries in Karkas Mountains". Human science Modares. 11. No. 1: 207-228.
31. Yamani, M., Shamsipour, A.A. and Jafari Aghdam, M. (2011). "Renovation of pleistocene snowline on Jajrorud Basin". Physical Geography research Quaternary 1. No 76: 35-50.
32. Yamani, M., Shamsipour, A.A. and Rahmati, M. (2014). "Determining of climate realms and morphogenetic processes in present and quaternary in the route of Khoramabad-Pole-Zal". Quantitative Geomorphological researches 3. No. 2: 90-103.
| ||
|
آمار تعداد مشاهده مقاله: 2,053 تعداد دریافت فایل اصل مقاله: 1,773 |
||