تحولات مورفولوژيكي و الگوي پيچان رودي بستر رودخانه مرزي هريرود با استفاده از RS

The morphologicevolution and meandringof Harriroud bed with geostatistical method and RS

تكنيك هاي سنجش از راه دور نقش بسيار مهمي در شناخت تحولات مورفولوژيك بستر رودخانه ها و تحولات پيچان رودي آنها از نظرجابجايي مرز دارند.از سوي ديگر مياندري شدن يكي از مهم ترين مسايل مهندسي رودخانه است كه فعاليت ها و سازه هاي عمراني را در حاشيه رودخانه ها تحت تاثير قرار مي دهد. بنابراين ، مطالعه تغييرات مورفولوژي كانال هاي رودخانه اي به منظور راهكارهاي كنترلي مناسب جهت حل مشكلات ديناميكي اين نواحي اهميت دارد . هدف اصلي اين مقاله ، بررسي روند تحولات بستر و الگوي پيچان رودي هريرود با استفاده از تكنيك هاي سنجش از راه دور، شاخص هاي هندسي و تصاوير ماهواره اي است. براي رسيدن به اين هدف ، با توجه به گستردگي مسير رودخانه و مرزي بودن آن ،از مقايسه عكس هاي هوايي سال 1353 و تصاوير ماهواره اي لندست و گوگل ارث سال 1390با پردازش در محيط جي آي اس استفاده گرديده است. با رقومي سازي مسير رودخانه در محيط اتوكد ، شاخص هاي هندسي(ضريب خميدگي،زاويه مركزي شعاع نسبي و واريانس و انحراف معيار آنها) بر روي تصاوير هوايي و ماهواره اي محاسبه شد و در 25 نقطه از مسير با عمليات زميني كنترل گرديدند تا خطاهاي احتمالي برطرف شوند . نتايج آشكار نمود كه تعداد پيچان رودها از 172 در سال 1353 به 166 در سال 1387 كاهش يافته و نيمرخ عرضي هريرود در طول اين دوره زماني تغييرات زيادي داشته و الگوي پيچان رودي بويژه در بازه دوم مسير به شدت افزايش يافته است كه منجر به تخريب 12 ميله مرزي ، يك پاسگاه مرزباني ، آسيب ديدگي اراضي زراعي 8 آبادي و سامانه جاده مرزي در مسير رود گرديده است . بيشترين تراكم پيچان رودي ( با ضريب همبستگي 998/0 ) مربوط به مسيرهايي است كه جنس سازند زمين شناسي بستر از لس ها ، مارن هاي رسي و آبرفت سست بوده است.

Introduction : Rivers and waterways are dynamicfullysystem and morphological pattern variescontinuously over time. Therefore, lateralerosion and damage to coastal infrastructure and displacement boundary follows .Although several factors such as the diversion channel at sides, palms up, the antropogenactivities, different bed formation and flooding, damage to walls, bedfloor and canals are changing pattern (Yamani and Sharafi2012) . But usually one or two dominant factor control the changes . Riverbeds due to dynamic evolution over time arelarge changes relatively, especially in rivers that flood Considered as the boundary line can bring serious damages tohuman infrastructure, and agricultural land . This river is the main source in Afghanistan . The total length of 1,888 km border rivers . Of this amount, 31% of the Azerbaijani border, the border with Turkmenistan 21.5%, 18.6% related to the Iraq border, 12.5% of the Afghanistan border, Pakistan and the remaining 12% of the river that borders Armenia and Turkey (Hafez Nia 2007) . In this sense the study of the evolution is one of the most important issues meander boundary river river border control and management. Harriroudlocated between the PishRobatTaibad the border point YazTappehSarakhs needs a lot meander of which there are a lot of changes over the past 40 years and Any knowledge about the evolution of Control Engineering rivers is essential . The main question was to investigate the morphological changes of context and meander pattern Harriroudriver as a boundary river During the period from 1974 to 2011, and how this changes the way in which part of it is more? Methodology and materials : Research to date - experimental data using the 1974 aerial photographs and Landsat satellite imagery and Google Earth in 2011 with ground control operations have been achieved . The most important research tools include: A – aerial photography 1/20000year 1974 and digitization Harriroudblocks in AutoCAD environment (B) Landsat MSS imagery and Google Earth images to digitize them in GIS C. Preparation of the tails carefully SRTM 30 m from the track bed in a GIS environment (D) controlling the withdrawal of the 25 points of the track bed Results and Discussion: For identification and classification of meanders and geometric parameters are calculated to be encoded in the border Meander TaibadTorbatejam and were SarakhsEast . The coding of Meanders has been in place PishRobat to meander No. 166 at the YasTappehSarakhs in the south to the north. Due to the various geomorphological characteristics of the river, it has been separated into two different periods in their geometric parameters are compared And meanders strongly indicate areas . The first period, from 1 to 99 meanders takes the place of the PishRobat to the mid-line Torbatejam. The second period started of Meanders No. 100 and continue to TappehSarakhs. Geometric parameters of the calculations show that the total number of rivers meandering path goes from 172 in 1974 to 166 in 2011 dropped Meander . In other words, over the past 37 years, 6 Meanders removed and each of the six second interval is In other parts of the Meander River bend under pressure and are volatility. Harriroudcurvature coefficient calculation data during the period 1974 to 2011 show that the average ratio is 39/1 times the bend of the river in 1974 . In 2011 that increased to 73.1 and represents a pattern of meandering river Even in 2011, during the second period of the river, the average rate increased to more than 2 severe meandering pattern tends towards the river . Calculated based on the radius of the inscribed circle radius of the bend of the river meanders has been relative to the width of the AutoCAD software. In the first period the relative radius of 7.5 in 1353 to 1.4 in 2011Harriroudreduced and limited indicator of disruption and volatility curve is in the second period of relative radius of 5.6 to 4.3, which indicates the pressure is reduced congestion and is severe instability meanders in this section. Comparison of satellite images and aerial photographs in 2011 showed that most ancient Meander Route 1974Harriroudhave arisen in the country . This leads to the enslavement of water border road and border facilities have been damaged . Conclusion: Identifythepattern ofriverboundarymeanderthroughgeostatistical methods have more accuratelythanothermodels .Geometric parameters of the statistical indicators show that the river Harriroudduring 1974 to 2011 the number of meanderrivers dropped from 172 to 166 And the boundary line changes, particularly in the second period with a mean coefficient of curvature is also the first in the range of 28.1 to 51.1 river and the second period of 44.1 to 70.1 was increased Meanders and indicates disruption of the river, especially in the second period. The results also revealed that the angle of the beam relative Harriroudduct morphology has changed a lot in the 37 years . As the central angle of 112 to 223 Harriroudreached the changes in the second period, especially the Pole Khatoon has been more needs YazTappehSarakhs. Therefore, due to the increasing flood discharge and sediment load in the river border Harriroudcontrol and exacerbate arterial pattern and meandering pattern river has become severe . The most important factors controlling the pattern of sedimentary processes and flood discharge conduit at the interval of most the second period of the loess formations - loose alluvial bed and uses resonance to the edge of the river Leading to severe pattern of meandering river is the river channel . These changes can cause damage, including damage to road infrastructure facilities Border Water Bondage number of bars and have been cultivated land border villages.