پديد آورندگان :
مقصودي، مهران دانشگاه تهران - دانشكده جغرافيا - گروه جغرافياي طبيعي , زمان زاده، محمد دانشگاه تهران - دانشكده جغرافيا - گروه جغرافياي طبيعي , يماني، مجتبي دانشگاه تهران - دانشكده جغرافيا - گروه جغرافياي طبيعي , حاجي زاده، عبدالحسين دانشگاه تهران - دانشكده جغرافيا - گروه جغرافياي طبيعي
كليدواژه :
شاخص هاي ژئومورفيك , رودخانه مارون , بهبهان , مورفوتكتونيك
چكيده فارسي :
لندفرمهاي ايجاد شده بوسيله فرايندهاي تكتونيك توسط علم ژئومورفولوژي تكتونيك مطالعه مي شود؛ به عبارتي، ژئومورفولوژي تكتونيك كاربرد اصول ژئومورفيك در حل مسائل تكتونيك مي باشد. اندازه گيريهاي كمي ژئومورفيك با استفاده از نقشه هاي توپوگرافي، عكسهاي هوايي، تصاوير ماهواره اي و بازديدهاي ميداني صورت مي گيرد. نتايج حاصل از چندين شاخص براي ارزيابي ميزان فعاليت تكتونيكي با همديگر تلفيق مي شوند. در اين مقاله به بررسي شاخص هاي ژئومورفيك در اين حوضه پرداخت شد. در اين مقاله به منظور محاسبه شاخص هاي ژئومورفيك از تصاوير ماهواره اي، نقشه هاي زمين شناسي، توپوگرافي، بازديدهاي ميداني و اصول هندسه و رياضي و نرم افزار Arc GIS استفاده شده است. منطقه مورد مطالعه حوضه رودخانه مارون در جنوب غربي ايران و در استانهاي كهگيلويه و بوير احمد و خوزستان مي باشد. طول آبراهه 280 كيلومتر ميباشد. شاخص هاي مورد استفاده در اين مقاله: شاخص گراديان طول آبراهه (SL)، شاخص تقارن حوضه (AF)، شاخص نسبت پهناي كف دره به ارتفاع (Vf)، شاخص شكل حوضه (B)، شاخص سينوسيته جبهه كوهستان (Smf)، شاخص تراكم زهكشي (P)، شاخص سطوح مثلثي شكل (TF)، شاخص تقارن توپوگرافي معكوس (T)، مي باشد. براي بعضي از اين شاخصها روابط جديد و براي برخي ديگر نيز فرمولهايي براي استانداردكردن آنها طراحي شد. در انتهاي مقاله به بررسي تئوري خطاهاي شاخص ها پرداخت شد. طبق نتايج بدست آمده از بررسي شاخص ها حوضه رودخانه مارون از نظر نوزمين ساختي و بالاآمدگي فعال ميباشد. زيرحوض ههاي بالادست بيشتر از زيرحوضه هاي مياني و انتهايي فعال مي باشد تكتونيك منطقه تاثير بسيار زيادي بر لندفرمها و سكونتگاهها دارد. اين نتايج با داده هاي حاصل از لرزه نگاري و ژئوديناميك كه منطقه را منطقه اي لرزه خيز درنظرگرفته اند هم خواني دارد.
چكيده لاتين :
Extended Abstract:
Tectonic geomorphology is defined as the study of landforms produced by tectonic processes, or the application of geomorphic principles to the solution of tectonic problems. (zovoili,2004). These indices have been developed as basic reconnaissance tools to identify areas experiencing rapid tectonic deformation (keller & Pinter, 1996). For study of morphotectonic of region, we must receive the geomorphic indices. These indices are particularly used to study active tectonics.
In this paper we are undertaking a tectonic geomorphology of Maroon River catchment. That the aim of this paper is to determine the most geomorphic indexes such as SL (stream- Length gradient), AF (Asymmetry factor) , Vf (Vf Ratio of valley floor width to valley height), B (Basin shape index), Smf (Mountain front sinuosity index), P (Drainage density),
This paper focuses on the application of morphometric analysis at Maroon River catchment in southwest Iran and geomorphic development of Maroon River in response to the neotectonic movements along catchment.
The stream length-gradient index is correclated to stream power and is defined as , where is the length of the stream from the point of interest, is the change in elevation of the reach and is the length of the reach.the SL index is very sensitive to changes in channel slope, to rock resistance, to topography and to the length of the stream.
The asymmetry factor (AF) is used to indicate tectonic tilting at scale of drainage basin and is calculated by equation where is the area of the right- hand side basin and is total area of the drainage basin.
Triangular facets are interpreted as variably degraded remnants of fault generated footwall scarps. The Vf index is related to the shape of the valley and is calculated by equation , where Is the width of the valley floor, are the elevation of the left and right valley divides, respectively, and is the elevation of the valley floor.
The Smf index reflects the balance between erosional and tectonic forces affecting a mountain front and is defined as where is the length of the mountain front and is the straight line length of the mountain front.
The area of research is located on southwestern of Iran in Zagros Mountains at Khuzestan province. In this research we studied Maroon River that originated in the Zagros Mountain. It forms a large alluvial fan. The start (source) from Sadat-Nil mountains and terminated to Jarahi River. The length of Maroon River is approximately 280km. The Maroon River basin depended on altitude have some different climate. The high land and mountains (up 2500meters) have cold Mediterranean climate, and hill area have Subtropical (2500 – 1000meters) and low land and plains have semiarid. From geomorphology viewpoint, three morphologic faces are dominant on Khuzestan province. At first rocky units which are located in north east of the province. Second; hill units which have coverage in areas located around Dezful, Ramhormoz & Ahwaz cities. Third, alluvial plains & flood plains that form the grounds located in south of Ahwaz to Persian gulf beaches & are a kind of deposited geomorphologies. Mountainous part in Khuzestan is a sample from uniform folded mountainous masses that are named folded Zagros in considering having special lithologic and structural characteristics. Alluvial coverage has hidden geological characteristics of Arabian plat form but regional data especially geophysical data indicates that in this part of the province, sedimentary sequences have clastic facies and a trend of N-S, as very open folds with sides near to horizon have been folded. Geological formations of Khuzestan zone has been thrust as a part of folded Zagros have been formed in sedimentary and tectonic condition hence they have considerable facial differences in terms of time and space.
In this paper we used Arial image, topographical maps, geological maps, Digital Elevation model, field work and applied software such as ArcGIS, Google Earth,
In this paper some of formula of geomorphic indices has improved and some of them have changed. In some indices the authors designed the new formula. The geomorphic indices in this article were calculated. and for any indices the histograms and tables were prepared.
In Behbahan plain and Aghajari plain and the behind of the Maroon River there are some prehistorical settlement and ancient sites and historic sites. The tectonic and geomorphology landscapes influenced in location these sites. During the time some of the sites were abandoned because of tectonic processing and landscapes
In this paper the geomorphic indices have calculated and compared with standard tables and formula and it was concluded that the Maroon River catchment have a high active tectonic and influenced in landscapes.
In the end of paper the authors assessment the theory of errors of geomorphic indices.
