Environmental Erosion Research

fa بررسی تغییرات مورفولوژی و الگوی پیچان‌رودی رودخانه‌ی‌زهره با استفاده از تصاویر Google Earth Study of the morphological changes and meander pattern of the Zohre River using satellite images مدلسازی و تحلیل زمانی و مکانی رخداد انواع مختلف فرسایش محیطی مستخرج از پایان‌نامه / رساله / طرح پژوهشی فرسایش و رسوبگذاری دو پدیدهای است که به تغییرات مورفولوژیکی در رودخانه‌های آبرفتی منجر می‌شود. تغییرات مورفولوژیکی در رودخانه‌ها می‌تواند مشکلات عدیدهای را در پی داشته باشد؛ از این رو، مطالعه و بررسی شکل رودخانه‌های آبرفتی در علم مورفولوژی اهمیت به سزایی دارد. در این تحقیق، تغییرات مورفولوژی رودخانهی زهره واقع در جلگه‌ی هندیجان، برای طول حدود 23 کیلومتر در بین طولهای جغرافیایی ´30 °49 و ´38 °49 و عرضهای جغرافیایی ´2 °30 و ´6 °30 شمالی مطالعه و بررسی شد. بدین منظور، تصاویر Google Earth مسیر رودخانه برای سه دوره‌ی زمانی شامل مسیر قدیمی، سال 2000 و 2014 میلادی بررسی شد. ذکر این امر لازم است که مسیر قدیمی بر مبنای آثار به‌جای مانده از رودخانه، در تصویر Google Earth سال 2000 میلادی در محیط GIS بازسازی شد. سپس این تصاویر در محیط GIS، تجزیه ‌و تحلیل و پارامترهای مهم در تغییرات مورفولوژی رودخانه از قبیل ضریب خمیدگی، زاویهی مرکزی، طول قوس و شعاع انحنا نیز محاسبه شد. نتایج نشان داد که درگذشته‌ در این رودخانه، چهار قطع‌شدگی یا میانبر رخ دادهاست و در آینده نیز ایجاد یک میانبر، قابل پیشبینی است. تعداد پیچش‌ها در طول این سه بازه زمانی، از 35 به 21 کاهش یافت و میانگین ضریب خمیدگی از 64/1 به 58/1، شعاع انحنا از 1/450 به 3/632 متر، زاویه‌ی مرکزی از 6/196 به 3/193 درجه و طول قوس از 1197 به 6/1154 متر تغییر داشت. بر اساس معیار ولفرت، بر حسب ضریب خمیدگی رودخانه‌ها (به نقل از راهنمای مطالعات ریخت‌شناسی رودخانه‌ها، نشریه‌ی شماره‌ی 592 وزارت نیرو: 96) و زاویه‌ی مرکزی کورنایس، رودخانه‌ی زهره واقع در جلگهی هندیجان در رده‌ی رودخانه‌های پیچانرودی و پیچانرود بیش از حد توسعه‌یافته قرار می‌گیرد. Extended abstract 1- Introduction The Hedijan coastal plain around the Zohreh River is a hub for essential agriculture, fisheries, trade, and the military. Any change in the regime and territory of the Zohreh River will have significant economic, social, and security effects in the region. Due to the privation of the region and preserve the available resources and capital, it is necessary to carefully study the hydraulic parameters affecting the morphological changes and the complex pattern of the meandering of the Zohre River. In this study, considering the special conditions of this coastal plain, it has been tried to study geometric features such as curvature coefficient, curvature radius, central angle, and river arc length in three time periods by studying and examining satellite images in a GIS environment.   2- Methodology In this study, to study the morphological changes and meandering pattern of the Zohre River in the coastal plain of Hindijan, Google Earth satellite images from 2000 and 2014 were used. Based on these two images, the old route of the Zohreh River can be identified in the study area. In the next step, to investigate the meandering and morphological changes of the river, the route drawn from Google Earth entered the GIS environment. Using the ArcMap 10.2 software, to examine essential parameters in river morphological changes, circles with a suitable radius tangent to the existing curves in the river path were drawn. In the old route, 35 meanders were detected, and in the 2000 and 2014 routes, 21 meanders were identified and examined.   3- Results  In order to study the morphology and meandering pattern of the Zohre River in the study area, various parameters such as bending coefficient, central angle, arc length, half-wavelength, and radius of curvature were calculated. According to Wolfert (2001), four types of rivers, including direct, sinusoidal, meander, and more meander, have been introduced in terms of the degree of curvature of rivers. According to this criterion, the Zohre River can be placed in a meandering river in the study area. Also, the number of meander from previous years, 2000 and 2014, was 35, 21, and 21. The maximum radius of the meander of this river was 450.1, 661.8, and 632.3 m. The lengths of the arch were 1197, 1118.2, and 1154.6 m, respectively. There have been alternating positive and negative changes in the values of the central angles in all three study periods. The average central angle from the old route to 2000 has been declining, and from 2000 to 2014, it has been increasing. In the old route, based on the size of the central angles, 57.14% of the torsions are in the overdeveloped area, 14.30% of the torsions are in the developed inverted 11.42% are in the undeveloped area. 17.14% was the size of a cow's horn, and no percentage was found for quasi-twisting curves. In 2000, based on the size of central angles, 42.86% of turns were over-developed, 14.30% of the turns were over-developed, and 23.80% of the turns were twisted. The average amount of radius in the old path increased from 450.1 to 66.81, and from 2000 to 2014, it decreased to 632.3. In total, this parameter has increased over three time periods. Finally, the obtained values for this parameter indicate that the river is meandering and the morphological changes in these three periods.   4- Discussion & Conclusions The results showed that significant changes have taken place and are taking place over the years under study. During the three times of periods, four significant shortcuts and other significant morphological changes occurred. It is predicted that in the place of the 18th meander at the location of the existing bottleneck, there will be a shortcut in the future, which will eliminate the existing meander and create new ones. Also, according to the Wolfert classification criterion based on the bending coefficient (1.5-2) and the Corneiss classification based on the central angle (158-296), the Zohreh River is located in the Hindijan Plain is in the category of meandering and the meander is overdeveloped. گوگل ارث, رودخانه‌ی زهره, زاویه‌ی مرکزی, ضریب خمیدگی. Satellite image, Zohre River, morphology, central angle, bending coefficient. 113 131 http://magazine.hormozgan.ac.ir/browse.php?a_code=A-10-415-1&slc_lang=fa&sid=1 Fateme Darvishzadeh فاطمه درویش زاده fatemehdarvishzadehpn@yahoo.com 10031947532846005967 10031947532846005967 No Department of Water and Soil, Faculty of Agriculture, Shahrood University of Technology, Shahroud گروه آب و خاک، دانشکده‌ی کشاورزی، دانشگاه صنعتی شاهرود Samad Emamgholizadeh صمد امامقلی زاده s_gholizadeh517@yahoo.com 10031947532846005968 10031947532846005968 Yes Department of Water and Soil, Faculty of Agriculture, Shahroud University of Technology, Shahrood گروه آب و محیط زیست، دانشکده‌ی مهندسی عمران، دانشگاه صنعتی شاهرود Khalil Ajdari خلیل اژدری azhdary2015@yahoo.com 10031947532846005969 10031947532846005969 No Department of Water and Soil, Faculty of Agriculture, Shahroud University of Technology گروه آب و خاک، دانشکده‌ی کشاورزی، دانشگاه صنعتی شاهرود Mohammad Sayari محمد سیاری m.sayari@gmail.com 10031947532846005970 10031947532846005970 No Isfahan regional water شرکت آب منطقه‌ای اصفهان