پديد آورندگان :
گورابي، ابوالقاسم نويسنده , , كيارستمي، فاطمه نويسنده كارشناس ارشد مخاطرات طبيعي، دانشگاه تهران ,
كليدواژه :
الگوي TecDEM , تكتونيك ژيومورفولوژي , حوضه رودك , مورفوتكتونيك , تكتونيك فعال
چكيده فارسي :
شناخت نواحي زمين‌ساختي فعال، به‌ويژه در زون‌هاي ساختاري همگرا به‌سبب قابليت مخاطره‌آميز بودن شايان توجه آنها اهميت زيادي دارد. از سوي ديگر، به‌دليل محدوديت‌هاي فيزيكي، بررسي‌هاي ميداني در اين نواحي با توپوگرافي خشن و متعارض، دشوار است. در اين پژوهش، با استفاده از روش‌هاي دورسنجي، ژيومورفومتري و كارهاي ميداني، اختصاصات مورفومتريك و ژيومورفولوژيك حوضه رودك در شمال شرق تهران در قالب الگوي TecDEM كه در نرم‌افزار متلب اجرا شده، از داده‌هاي رقومي (الگوي رقومي ارتفاع) استخراج و تجزيه و تحليل شده است. در اين الگو، از شاخص‌هاي نو مانند چولگي و كشيدگي نمودار هيپسومتري، شاخص فرورفتگي ?، شيب S و نقشه همپايه IsoBase MAP بهره گرفته شده است. نتايج بررسي و تجزيه و تحليل عناصر ساختاري مورفوتكتونيكي استخراج‌شده مانند نيمرخ طولي رودخانه، جهت‌هاي جريان، مورفولوژي حوضه آبريز، نقطه‌هاي عطف و تغيير شيب، منحني‌هاي هيپسومتري و مقدار كشيدگي و چولگي آن كه حاصل كنش و واكنش نيروي‌هاي زمين‌ساختي است، بيان‌كننده تغييرات مورفوتكتونيكي فعال حوضه و كنوني آن است. نتايج بررسي‌ها در قالب الگوي TecDEM، پژوهش‌هاي ميداني و شواهد به‌دست‌آمده از طريق داده‌هاي ايستگاه ژيوديناميك گرمابدر، درستي الگو را در نشان دادن شرايط نيوتكتونيك مناطق نشان مي‌دهد.
چكيده لاتين :
Extended abstract
Introduction
Identification of active tectonic areas, especially in Convergent zone because potentially risky of them are very important. Nowadays there are several algorithms that are used for tectonic analysis; one of them is TecDEM that used in this research. In this study, using Remote sensing techniques, Geomorphometry analysis and fieldwork were analyzed Morphometric and geomorphologic characteristics for Roodak basin in northeast of Tehran in the TecDEM model within Matlab software. This model is used from new indices such as Skewness and Kurtosis of hypsometry diagram, concavity and steepness indices and finally IsobaseMap. The obtained results from this calculation; Represents Morphotectonic changes on the watershed. The results in the TecDEM model Comparison with field studies And obtained evidence through Garmabdar Geodynamic station data show accuracy of model at Description and Analysis neotectonic terms area.
Material and methods
To investigate active tectonics in the study area, beginning through geological map(Tehran, MarzanAbad ,Baladeh, Fasham) of the area the faults zones was diagnosed. Then, evidence of active tectonics in the basin Studied by regional presence. Also the data analysis of Garmabdar geodynamic permanent station Based on data from 5 years (2006 to 2010) was used. Then through a Kartosat 2.5 meter resolution satellite image approximate range of Roodak basin and sub basins specified, Finally To extract Roodak basin and sub-basins and calculate the indices; was used from ArcGIS and TecDEM software beside the digital elevation map (DEM).
Result
The values obtained from indices besides field study and analysis of Garmabdar geodynamic station show that Roodak Basin is in early stage. Lack of sediment on some areas, fractured rocks by fault, Steep slopes, Narrow valleys and high mountains, high potential of mass movement in the basin and etc., Along with calculate tectonic indices which is consistent with observations, Reflect this subject.so the TecDEM is a powerful tools to understand the nature of tectonic zones. Based on concavity and steepness and Gradient slope River indices, fourth sub basin of Garmabdar basin has highest rate of activity and Meygoon basin has lowest rate of activity, while based on Transverse topographic symmetry index, first and third sub basins show the maximum tilt. Also IsoBase map of area, Tectonic effects on topography changes and change in the classification of stream basin Confirms. Hypsometry curves for all sub-basins show young Terms in the Roodak basin and its sub basins and fourth sub basins of Garmabdar has most Convexity. Despite the difference in values of parameters, averages represent active tectonic regime in the basin. Accommodation of field study, Library Studies and geodynamic data with model results demonstrate the proper use of this model in tectonic analysis. Especially in relation to areas that may not be possible to field study.
Conclusions
Roodak basin of geological division is part of Alborz-Azarbaijan seismotectonic .also this basin is in southern highland of central Alborz and much of it is green tuff of Karaj Formation. In terms of hydrological this basin is part of the Jajrood basin and eastern branch of Jajrood River flows in that. The river originates in the highlands clone Basatk and after passing through the Darbandsar and Shemshak, Meygoon and Fasham with Another branch Nika, Lalani Ruteh busted water tributaries binds and called the name Jajrood. Ahar river from south and Amameh river from north Attached to it and create eastern Jajrood river .In this study, using Remote sensing techniques, Geomorphometry analysis and fieldwork were analyzed Morphometric and geomorphologic characteristics for Roodak basin in northeast of Tehran in the TecDEM model within Matlab software. The analysis results of structural elements Extracted as Longitudinal profile of the river, flow directions, basin morphology, slope changed , IsoBase map, geomorphic indices and Skewness and Kurtosis of hypsometry diagram that is resulting from the interaction of tectonic forces; Represents Morphotectonic changes on the watershed. The results in the TecDEM model Comparison with field studies and obtained evidence through Garmabdar Geodynamic station data show accuracy of model at Description and Analysis neotectonic terms area. So the TecDEM is a powerful tool to understand the nature of tectonic zones.
Key words: Tectonic geomorphology, tectonic activity, Roodak Basin, Morphotectonic, TecDEM Model.
