بررسي زمين ساخت فعال در شمال حوزه آبخيز دشت بيرجند با استفاده از فاكتور‌هاي مورفومتريك

An assessment of active tectonic by morphometric factors in north of Birjand plain watershed

مورفومتري به عنوان سنجش و توصيف كمي شكل‌ها و چشم اندازهاي زمين تعريف شده‌‌اند. دشت بيرجند درشرق كشور ايران و دراستان خراسان جنوبي است. هدف از اين پژوهش ارزيابي تكتونيك مناطق فعال با استفاده از پارامترهاي مورفومتري مي‌باشد. در اين تحقيق از داده‌هاي ميداني و نقشه‌هاي توپوگرافي استفاده گرديده است. نتايج حاصل از محاسبه شاخص‌ها بدين صورت است كه بيشترين ميزان كج شدگي AF در شمال غربي ، كمترين ميزان كج شدگي شمال حوزه مي باشد. شاخص Tداراي نا متقارن‌ترين حالت حوزه در شمال غربي منطقه است. شاخص S بيشترين مقدار در غرب حوزه و كمترين مقدار شمال مركزي حوزه مي‌باشد. بيشترين مقدار Smf در شمال حوزه و كمترين مقدار آن در شمال شرقي حوزه مي باشد. محاسبه شاخص VF نشان داد كه بيشترين تعداد دره ها در اين مناطق واقع شده است. شاخص انتگرال هيپسومتري بيشترين ميزان بالاآمدگي در شمال شرقي و كمترين ميزان در شمال را نشان مي‌دهد، بيشترين مقدار شاخص Dd در شمال وكمترين مقدار در شمال غربي مي باشد. بيشترين مقدار شاخص Te در شمال شرقي حوزه و از طرفي كمترين مقدار شاخص Te در شمال غربي است. بيشترين مقدار شاخص Cدر شمال غربي و كمترين مقدار در شمال حوزه است. بيشترين مقدار شاخص Re در شمال وكمترين مقدار شاخص Re در شمال غربي است. پارامترIat نشان مي دهد كه شمال دشت بيرجند از نظر تغييرات مورفومتريك در درجه فعال قرار دارد و درآينده تغييرات جديدي خواهد داشت.

Introduction Rivers are the first environmental forms that show a relatively rapid response to changes in the bedding or fluctuations in the outflow of the bed. Regarding the fixed-effect photos of the rivers relative to the occurrence of abnormal changes-mainly due to tectonics-can be explained by analyzing them using morphotectonic indices in relation to the occurrence of these changes ( Ramiez Heerea, 1998). Exploring the dynamic processes that affect the formations of Earth and its landscape can be achieved by the Active Tectonics or Active Geomorphology Tectonics One proven and widely used technique is the Morphometric analysis, which helps understand the development of the geomorphic features in the young mountain belt. Morphotectonics can be considered as the knowledge of the study of shapes and patterns created on the ground by tectonic processes .)keller and pinter., 2002.( Mousavi (2006) reviewed the active tectonics in the northwest of Birjand. He points out that structural and morphological factors have been calculated, due to the structural arrangement in the area, the rate of the process of rising in the central part is higher. The principal objective of this study is to Evaluation of active area tectonics using morphometric parameters for the using classification of geomorphological indices considering the geological and physiographic study of watershed and tectonic analysis and geomorphology. Morphometry indicators of active tectonic is concern with the study of the geomorphological conditions of the study area, physical environment and landscape characteristics of the study area which includes drainage pattern, stream order, slope and aspect map. Methodology In this paper, Birjand plain is divided into 36 sub-basins for ease of computing and comparing the results of using indicators which is from sub- basins 1B to 22B of northern part of plain of Birjand, which includes the mountain Shekarab, and from sub- basins 23B to 36B is the southern part of Birjand Plain, which includes the mountain range of Bakhran The data used in this research includes the topographic maps 1: 25000, geological map 1: 100000, fault map 1: 100000. the digital elevation model data (DEM of 30 meters of the region) for mapping the location of the region. We use the 10.3Arc GIS software and modules such as 3D Analyst, Editor, Analysis Tools, and also Google Earth software. Result and discussion The importance of morphotectonic studies is to achieve critical results that are often unavailable through other methods or require a great deal of time and cost. For this purpose, in the course of morphotectonic studies, indicators are being studied that can be of great help in reaching the outcome of the research.The results of calculating the indexes are such that the highest rate of AF in the northwest is the lowest rate of tilting in the north of the area. The T index is the most abnormal case in the northwest of the region. S index is the highest value in the west of the region and the lowest value in the north-central region. The maximum amount of Smf is in the north of the area and its lowest value is in the northeast of the basin. Calculating the VF index in the mountains of Shekarab showed that the highest number of valleys is located in these areas. hypsometric integral is the highest elevation in the northeast and the lowest in the north, the highest is Dd in the north and the lowest in the northwest. The highest value of Te is in the northeast of the basin and the lowest is Te in the northwest. The highest value of C is in the northwest and the lowest in the north. The highest value of Re is in the north and the lowest value of Re in the northwest. The Iat parameter is used to analyze geomorphologic indices and summarize their results in order to determine the relative status of tectonic activities in the region.The Iat parameter indicates that the northern plain of Birjand is morphometric changes in the active class, and in the future will have new changes. Conclusion The results obtained from the study of geomorphic evidence show a relative classification of tectonic activity that is useful for studying and identifying the region. The geomorphic indicators used in this project reflect the tectonic activity of the region. In general, the results of geomorphologic indexes indicate that the study area of the study is active in the field of nautical construction, one of the reasons for which is the trusted fault and the extension of slip, and the activity level of the newly constructed motions in The waters of the basin are more active in this regard than anywhere else.