فهرست مطالب

پژوهش های ژئومورفولوژی کمی - سال هشتم شماره 2 (پاییز 1398)
  • سال هشتم شماره 2 (پاییز 1398)
  • تاریخ انتشار: 1398/09/01
  • تعداد عناوین: 12
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  • سید رضاحسین زاده، علی قربانی شورستان*، علیرضا کریمی، مهناز جهادی طرقی صفحات 1-22

    رسوبات لسی در شمال شرقی ایران به شکل پراکنده و با ضخامت کم بر روی دامنه های رو به شمال، شمال شرقی و شرقی نهشته شده اند. مطالعه و بررسی این رسوبات می تواند ما را در بازسازی فرایندهای ژئومورفولوژی گذشته یاری رساند. هدف از این مطالعه شناسایی و تعیین پراکنش رسوبات لسی، بررسی ویژگی های بافت رسوب ها، ویژگی های مورفوسکپی(SEM) و در نهایت منشایابی این رسوبات در محدوده مورد مطالعه می باشد. در مجموع تعداد 119 نمونه سطحی به صورت پراکنده در کل منطقه برداشت و میزان گچ وآهک آنها مشخص گردید. از این تعداد24 نمونه پراکنده از منطقه جهت آزمایش توزیع اندازه ذرات وتعداد 4 نمونه جهت بررسی موفوسکپی(SEM) انتخاب شد. ماسه خیلی ریز ذره غالب در نمونه ها بوده و مجموع سیلت درشت و سیلت خیلی درشت و ماسه خیلی ریز به بیش از 60 درصد می رسند. در بررسی مورفوسکپی دانه های کوارتز مشخص شد که این دانه ها دارای گرد شدگی زیادی نمی باشند و غالب بودن شن خیلی ریز و گرد شدگی کم دانه های کوارتز و هاله مانند بودن اکثر ذرات کوارتز را می توان بعنوان شاهدی از محلی بودن و نزدیکی محل برداشت به محل نهشتگی در نظر گرفت. بین ارتفاع و میانگین اندازه ذرات نمونه های برداشت شده همبستگی منفی قوی وجود دارد(نمودار1) و هرچه به ارتفاع برداشت نمونه افزوده می شود میانگین اندازه ذرات آن کوچکتر می شود و ضریب همبستگی آن 7/- می باشد.

    کلیدواژگان: رسوبات لسی، شمال شرق ایران، توزیع اندازه ذرات، مورفوسکپی، منشایابی
  • سمیه معزز، شهرام روستایی*، توحید رحیم پور صفحات 23-37

    این تحقیق با هدف تهیه نقشه پتانسیل وقوع زمین لغزش در حوضه آبریز نهندچای واقع در استان آذربایجان شرقی انجام شده است. برای تهیه نقشه پهنه بندی از مدل ANP و تکنیک GIS استفاده شده است. ابتدا لایه های اطلاعاتی مربوط به 8 فاکتور موثر در وقوع زمین لغزش شامل شیب، جهت شیب، ارتفاع، زمین شناسی، کاربری اراضی، فاصله از آبراهه، فاصله از گسل و بارش با استفاده از نرم افزار Arc GIS تهیه شد. سپس به منظور وزن دهی هر یک از معیارها از نرم افزار Super Decisions استفاده شد. بدین صورت که ابتدا مدل شبکه ای جهت پهنه بندی خطر وقوع زمین لغزش در این نرم افزار طراحی و ارتباطات داخلی و خارجی معیارها مشخص شده و وزن دهی معیارها صورت گرفت. نتایج به دست آمده از تحقیق حاضر نشان داد که وزن معیارهای هشت گانه مذکور به ترتیب 064/0، 028/0، 044/0، 296/0، 180/0، 134/0، 054/0 و 196/0 است. درنهایت، با تلفیق این لایه ها با توجه به وزنشان، در محیط GIS نقشه ی پهنه بندی خطر وقوع زمین لغزش به دست آمد. در نهایت، نقشه پهنه بندی در 5 طبقه با پتانسیل خطر زمین لغزش خیلی زیاد، زیاد، متوسط، کم و خیلی کم تهیه شد. نتایج تحقیق نشان داد که بیش از 40 درصد از مساحت منطقه پتانسیل بالایی از نظر وقوع زمین لغزش را دارا می باشد که بیشتر منطبق بر مناطق دارای کاربری مرتع، حاشیه آبراهه ها و مناطق دارای سازند مارن است. ارزیابی دقت نقشه پهنه بندی تهیه شده از مدل ANP با نقاط لغزشی رخ داده در سطح منطقه نشان داد که بیش از 80 درصد لغزش ها در مناطق با خطر زیاد و خیلی زیاد اتفاق افتاده است که نشان دهنده دقت خوب مدل ANP در تهیه نقشه خطر وقوع زمین لغزش در منطقه می باشد.

    کلیدواژگان: زمین لغزش-نهندچای، سوپر دیسیژن، GIS-ANP
  • مریم بیاتی خطیبی*، فریبا کرمی صفحات 38-51
    آشفتگی دامنه ها در اثر فرسایش خندقی در کوهستان های نیمه خشک،از رخدادهای مهمی است که با تغییرات اقلیمی تشدید می شود . انواع اشکال خطی به عنوان اشکال ژئومورفولوژیکی، مواد دامنه ای و در واقع تنها خاک قابل کشت کوهستان ها را وارد دره ها می سازند و به این ترتیب ،خندق ها با فعالیت از بخش سر و دیواره ها ،انبوهی از خاک های دامنه ای را بسوی آب های جاری سرازیر می کنند. در دامنه های شرقی کوهستان سهند ،بیشتر سطوح دامنه ها در شکل تسریع شده آن تحت فرسایش قرارگرفته اند .خندق های متعددی در دامنه های حوضه اوجان چای تشکیل شده اند .آبخیز اوجان چایاز محدوده های مهم کشت انواع محصولات دیمی و آبی کوهستان سهند به شمار می آیند،فرسایش خطی تشدید و تسریع شده در این محدوده از نوع فرسایش خندقی ،می تواند خسارات جبران ناپذیری در پی داشته باشد.از این نظر بررسی و شناسائی محدوده های تحت فرسایش خاک در اثر توسعه اشکال خطی از نوع فرسایش خندقی ،از اهمیت ویژه ای برخوردار است. در این مقاله با استناد به روش های کمی ،سعی شده است مقدار فرسایش حاصل از این اشکال برآورد شود.در مرحله نخست سعی شده است با استفاده از مقدار si شکل خندق ها مشخص،سپس با استفاده از معادله فرسایش(E)میزان فرسایش محاسبه شود و با تعیین مقدار فرسایش ،سهم بالاآمدگی ها در سطوح شیب دار با استفاده از رابطه K تعیین شود .
    کلیدواژگان: برآمدگی های تکتونیکی، فرسایش خندقی، فرسایش خاک، حوضه اوجان
  • اسمعیل شاهکویی*، رضا سارلی، یوسف درویشی، سمانه امان پور قرایی صفحات 52-70

    حرکات توده ای، ازجمله پدیده های مورفودینامیک هستند که تحت تاثیر عوامل مختلفی در سطح دامنه های مناطق کوهستانی به وقوع می پیوندد پهنه بندی لغزش ها یکی از روش هایی است که می توان به کمک آن مناطق بحرانی را تعیین کرده و از نقشه های پهنه بندی به دست آمده در برنامه ریزی ها استفاده کرد در این راستا با توجه به موضوع هدف پژوهش حاضر بررسی عرصه های آسیب پذیر در برابر مخاطرات طبیعی با تاکید بر زمین لغزش است. تحقیق حاضر، با توجه به ماهیت مسئله و موضوع موردبررسی، از نوع توصیفی - تحلیلی و از حیث مطالعات کاربردی با تاکید بر روش های کمی است. جهت شناسایی مکان های دارای پتانسیل لغزش بالا معیارهایی از قبیل: (شیب، جهت شیب، کاربری اراضی، فاصله از مراکز سکونتی، انحنای زمین، بارش، ارتفاع، تراکم پوشش گیاهی، زمین شناسی، خاک، تراکم آبراهه، فاصله از جاده مورد ملاحظه قرارگرفته اند به منظور محاسبه تراکم و میزان سبزی پوشش گیاهی از باندهای مادون قرمز نزدیک و باند قرمز (4-5) ماهواره لندست 8 استفاده گردید و خروجی نهایی با روش هم پوشانی حسابی در محیط GIS محاسبه شد تمامی فرایندها و تجزیه تحلیل داده ها در محیط GIS و نرم افزار Super decision استفاده گردید همچنین نتایج بدست آمده در نقشه نهایی نشان دهنده آن است که طبقه 5 با ضریب رانش بالا 15 درصد از کل مساحت منطقه، طبقه4 با ضریب لغزش زیاد 19 درصد، طبقه 3 با ضریب متوسط 35 درصد، طبقه 2 با ضریب کم 22 درصد، طبقه1 با ضریب خیلی کم 8 درصد را به خود اختصاص داده اند درنتیجه بالغ بر 34 درصد از کل منطقه در معرض لغزش شدید قرار دارد.

    کلیدواژگان: لغزش، گرگانرود، شهرستان گرگان، GIS Super decision
  • علی باقریان کلات* صفحات 71-85

    در حوضه آبخیز کاخک واقع در خراسان رضوی، انواع ناهنجاری های طبیعی از جمله فرسایش خاک ، انواع رخساره های فرسایشی (سطحی-شیاری، شیاری و شیاری - گالی) و رسوب زایی متوسط تا بالا دیده می شود. برای انجام این پژوهش، ابتدا 4 واحد همگن (واحدهای کاری) بر مبنای نوع لیتولوژی شامل شیل و ماسه سنگ و گابرو، رخساره های فرسایشی در کاربری مرتعی و در شیب مشابه انتخاب شد. 32 آزمایش در شدت بارش 36 میلی متر در ساعت و به مدت 30 دقیقه با شبیه ساز باران بر روی واحدهای کاری، انجام شد. مقدار رسوب هر یک از آزمایش ها اندازه گیری شد. به منظور بررسی عوامل موثر در تلفات خاک و فرسایش پذیری، نمونه برداری از خاک در لایه 0 تا 15 سانتی متری نیز از مجاور پلات های مورد آزمایش برداشته شد. آنالیز آماری اطلاعات با استفاده از نرم افزار SPSS انجام شد. نتایج نشان داد که لیتولوژی های مورد بررسی از نظر فرسایش و رسوبدهی با یکدیگر تفاوت معنی دار دارند. دو واحد کاری شامل شیل واجد فرسایش شیاری-خندقی (Jsh-RG) و ماسه سنگ واجد فرسایش سطحی-شیاری (Js-SR) به ترتیب با رسوبدهی 12/68 و و 12/45 گرم در مترمربع دارای بیشترین و کمترین مقدار رسوبدهی می باشند. برخی از ویژگی های خاک مانند درصد سیلت، شوری و نسبت جذب سدیم با میزان فرسایش و رسوبدهی خاک دارای همبستگی مستقیم و فاکتورهای درصد پوشش گیاهی و درصد سنگریزه موجود در سطح خاک و همچنین درصد ماسه، کربن آلی و درصد آهک فعال خاک با میزان فرسایش و تولید رسوب، همبستگی معکوس و معنی دار نشان می دهند.

    کلیدواژگان: باران ساز مصنوعی، تلفات خاک، ویژگی های فیزیکوشیمیایی خاک
  • عادل سپهر*، ملیحه پورعلی، محمدحسینl محمودی قرایی صفحات 86-102

    پلایا از عوارض مهم ژئومورفیک کواترنری مناطق خشک و نیمه خشک در ایران است که شناخت ویژگی های آن به تعیین اقلیم و محیط گذشته کمک فراوان می کند. هدف از انجام این تحقیق شناسایی و منشاءیابی کانی های تشکیل دهنده سطوح مختلف ژئومورفیک پلایای سبزوار واقع در شمال شرق ایران با توجه به تغییرات آب و هوایی اواخر هولوسن در منطقه می باشد .بدین منظور 12 نمونه رسوب از سطح و عمق رخساره های ژئومورفیک پلایای مذکور جهت مطالعات رسوب شناسی و ژئوشیمی رسوبی برداشت شد. نتایج آزمایشات فیزیکی_شیمیائی، پراش اشعه ایکس و میکروسکوپ الکترونی روبشی نشان دهنده حضور کانی های آواری و تبخیری همچون کوارتز، آلبیت، اسمکتیت، پالیگورسکیت، سپیولیت، کلسیت، ژیپس و هالیت در منطقه می باشد که در رخساره های رسی متراکم- سخت، رخساره رسی پف کرده و رخساره رسی - نمکی پلایا شناسایی شده اند. روند شکل گیری این کانی ها از عمق به سطح و از شرق به غرب پلایا الگوی رسوب گذاری خاصی را نشان می دهد که بیانگر نوسانات اقلیمی هولوسن پایانی در این پلایا می باشد.

    کلیدواژگان: پلایای سبزوار، ژئوشیمی رسوبی، کانی پالیگورسکیت، کانی های تبخیری، هولوسن
  • فاطمه رحمتی پور، امیر صفاری*، امجد ملکی، فرزاد شیرزادی تبار، علی احمدآبادی صفحات 103-121

    در بیشتر مواقع برای شناسایی گسل های پنهان از روش های ژئوفیزیکی استفاده کرده اند. در پژوهش حاضر قابلیت ژئومورفولوژی جهت شناسایی گسل های پنهان مورد بررسی قرار گرفت. ازجمله مناطقی که رسوبات رودخانه ای آثار گسل ها را مدفون ساخته است شرق استان کرمانشاه است. با بررسی ژئومورفولوژی منطقه و براساس فرضیه جدایی طاقدیس شیرز از سفره رورانده و دیگر شواهد مورفوتکتونیکی حدود کلی گسل های پنهان شناسایی و بر روی نقشه زمین شناسی ترسیم شد. در مرحله بعد با پردازش داده های مغناطیس هوایی، موقعیت دقیق تر گسل ها ترسیم شد. سپس بر روی 4گسل، 5 مقطع برداشت VLF و مغناطیس زمینی صورت گرفت و نتایج مربوط به مراحل پیشین با استفاده از روش های ژئوفیزیکی نیز صحت سنجی شد. اولین گسل از غرب ارتفاعات پرآو و از شمال دشت کرمانشاه به سمت شرق بر روی ارتفاعات پرآو و بیستون امتداد می یابد و با گذشتن از ارتفاعات برناج به سمت غرب وارد دشت شده و پس از عبور از دشت صحنه مجددا با تغییر روند به سمت شمال شرق امتداد می یابد. در فاصله بین ارتفاعات بیستون تا دشت صحنه 5 گسل با جهت شمال- جنوب و منشعب از گسل اول تا حدود طاقدیس شیرز امتداد دارند. گسل دیگر از غرب شهر کرمانشاه آغاز شده و در جنوب ارتفاعات پرآو با تغییر مسیر به سمت جنوب شرق ادامه می یابد و وارد دشت هرسین می-شود. مقایسه نتایج ژئومورفولوژی، ژئوفیزیک و مغناطیس هوایی نشان می دهد که ژئومورفولوژی قادر است گسل های بزرگ و پی سنگی عمیق آشکار و حتی پنهان، که اثرات خود را در مورفولوژی منطقه برجای گذاشته اند، را شناسایی کند.

    کلیدواژگان: گسل پنهان، مورفوتکتونیک، مغناطیس هوایی، ژئوالکتریک، روش vlf
  • مریم عزتی، ابراهیم غلامی*، سید مرتضی موسوی صفحات 122-137

    گسل ها از ساختارهای اصلی کنترل کننده ی هندسه و کینماتیک ساختاری در کوهزادها به شمار می آیند. منطقه ی مورد مطالعه (کوه های شکراب) در استان خراسان جنوبی و قسمت شمالی شهرستان بیرجند قرار دارد. هدف از این پژوهش بررسی تاثیر گسل ها بر تکامل ریخت زمین ساختی منطقه ی مورد مطالعه است. در این پژوهش تحلیل ساختاری کوه های شکراب واقع در شمال بیرجند با استفاده از عملیات صحرایی، ترسیم مقاطع عرضی و شاخص ژئومورفیک طول- شیب رودخانه (SL) انجام شد. برای تحلیل ساختاری و مشخص نمودن تاثیر گسل ها بر تکامل ساختاری ابتدا با استفاده از عملیات صحرایی گسل ها شناسایی گردید و سپس با استفاده از DEM و داده های مربوط به گسل های منطقه مقاطع عرضی ترسیم شد. مقاطع عرضی عمود بر ساختارهای منطقه (گسل های طولی و عرضی) رسم گردید. ترسیم مقاطع عرضی در جهت عمود بر گسل ها نشان می دهد که در مقطع CD که در قسمت غربی منطقه ی مورد مطالعه واقع شده است. شاهد کاهش شیب گسل ها از شمال به سمت جنوب هستیم، بنابراین مقطع CD فعال ترین مقطع می باشد. محاسبه شاخص SL نشان می دهد که بیشترین فعالیت تکتونیکی و بیشترین مقدار شاخص SL مربوط به قسمت غربی کوه های شکراب است که دلیل آن عملکرد اخیر گسل های راندگی می باشد. بیشترین تراکم گسل های راندگی مربوط به بخش غربی منطقه ی مورد مطالعه است و در مناطقی از کوه-های شکراب که بیشترین تراکم گسل های راندگی وجود دارد بالاآمدگی تکتونیکی و فعالیت تکتونیکی نیز افزایش یافته است. نتایج این پژوهش نشان می دهند که با حرکت در روند E-W کوهستان شاهد بیشترین فعالیت تکتونیکی در قسمت غربی می باشیم.

    کلیدواژگان: ساز وکارگسل، مقاطع عرضی، کوه های شکراب، شمال بیرجند
  • محمد زمانزاده*، منصور جعفر بیگلو، پریسا پیرانی، عارفه شعبانی عراقی، فاطمه گراوند صفحات 138-154

    رودخانه ها بر اساس پارامترهای سدی و پیچش، به انواع مستقیم، بریده بریده و مئآندری تقسیم می شوند. مورفولوژی رودخانه ها یکی از عوامل اصلی کنترل کننده شکل هندسی رسوبات است. رودخانه دربرگیرنده رسوبات مختلفی است که از نظر بافت و اندازه دانه و مورفولوژی پشته ها متفاوتند. هدف تحقیق حاضر مقایسه رسوبات پشته های کانال های مختلف از نظر تغییرات در اندازه و بافت رسوب در پشته های انواع کانال های مستقیم، مئآندری و بریده بریده انتخابی، و همچنین تغییرات در قسمت های مختلف یک پشته منفرد  و تفاوت این تغییرات  در بالادست (پشت قلعه) و پایین دست (هزارانی) رودخانه است.در این مطالعه مجموعا 30 نمونه برداشت و کدبندی شدند و در آزمایشگاه به روش غربال مورد آنالیز قرار گرفتند. پس از عملیات گرانولومتری با استفاده از نرم افزارهایEXCEL و GRADISTATE منحنی های موردنیاز ترسیم شد و پارامترهای آماری از جمله متوسط ذرات (MZ)، جورشدگی (Iσ)، کج شدگی (SKI) و کشیدگی (K) به روش ترسیمی و با مقیاس فی به دست آمد و مورد مقایسه قرار گرفت. نتایج نشان می دهد که کانال های بریده بریده بیشترین و مئآندری و مستقیم کم ترین شباهت رسوبی را ب اقرینه خود در سمت دیگر رودخانه دارا هستند. تفاوت های رسوبی مشاهده شده نقش انشعاب های جریان اصلی، سیلاب های دوره ای رودخانه آبدانان و تغذیه رسوبات از دامنه کناری را در تغییر بافت و اندازه رسوب نشان می دهد که گاها سبب شده کانا لمئاندری الگوی رسوبی یک کانال بریده بریده را منعکس کند. بطور کلی در بازه بالادست (پشتقلعه) اندازه و بافت رسوب از شمال به جنوب از گراول با جورشدگی خوب تا متوسط به ماسه با جورشدگی ضعیف تغییر می کند دربازه پایین دست (هزارانی) اندازه و بافت رسوب از شمال به جنوب الگوی بالا دست را نشان نمی دهد که تاثیر جریان های انشعابی و سیلاب را در به همریختن الگوی رسوب و افزایش گراول می توان مشاهده نمود.

    کلیدواژگان: رسوب، رودخانه، بریده بریده، مئآندر، مستقیم
  • فریبا اسفندیاری دارآباد*، مسعود رحیمی، غلامرضا پور مرتضی صفحات 155-171
    امروزه سیل یکی از رایج ترین و پرهزینه ترین بلایای طبیعی جهان است که خسارات و تلفات انسانی و مادی زیادی را بر جوامع انسانی وارد می سازد. برای پیشگیری و کاهش اثرات سیل، اجتناب از قرار گرفتن در معرض این مخاطرات از اهمیت زیادی برخوردار می باشد. پهنه بندی پتانسیل سیل خیزی یکی از روش هایی است که جهت کاهش خطرات ناشی از سیل می توان اتخاذ نمود. در این پژوهش با استفاده از روش L-THIA و مدل منطق فازی اقدام به پهنه بندی پتانسیل سیل خیزی در حوضه آجرلوچای شده است. جهت انجام این کار از نه فاکتور طبیعی (ارتفاع، اقلیم، واحد اراضی، شیب، لیتولوژی، تراکم زهکشی، گروه های هیدرولوژیکی خاک، رواناب و کاربری زمین) استفاده شده است. نتایج به دست آمده از پهنه بندی سیل خیزی در منطقه نشان می دهد که بیشتر مساحت حوضه (حدود 6/65 درصد) دارای پتانسیل سیل خیزی کم، خیلی کم و متوسط قرار دارد. این مناطق بیشتر در بخش های غربی و پست حوضه قرارگرفته اند. بیشتر مناطق سیل خیز حوضه در نیمه شرقی و شمال شرقی حوضه قرارگرفته است. در این مناطق زمین ها ازنظر تراکم شبکه زهکشی در کلاس بالاتری قرار دارند که خود عاملی برای سیل خیز بودن حوضه می باشد. درصد زمین های سیل خیز حوضه در دو کلاس پتانسیل زیاد و خیلی زیاد در حدود 4/34 درصد از کل مساحت حوضه می باشد.
    کلیدواژگان: پتانسیل سیل خیزی، حوضه آبریز آجرلو چای، مدل L-THIA، منطق فازی
  • داود مختاری، محمد حسین رضایی مقدم، پیمان کریمی سلطانی، طیبه عبدالملکی* صفحات 172-188

    ورود گردشگران به غارهای توریست پذیر تغییراتی را در مقادیر عناصر اقلیمی درون غارها مانند دما و درصد رطوبت نسبی و همچنین غلظت دی اکسیدکربن به وجودمی آورد. افزایش غلظت دی اکسیدکربن ناشی از حضور گردشگران سبب، کاهش PH محیط و شکل گیری یک محیط اسیدی می شود. ایجاد محیط اسیدی در درون غارها، انحلال و پوسته پوسته شدن اشکال کارستی درون آنها را به دنبال دارد. جهت بررسی این تغییرات، غارهای کتله خور و سهولان، دو نمونه از غارهای کشور که پذیرای تعداد بالای گردشگر می باشند، انتخاب شدند. برای مقایسه و بررسی نقش گردشگران در تغییر عناصر اقلیمی و غلظت دی اکسید کربن درون غارها، برداشت ها در بهمن ماه به سبب تعداد کم گردشگر و ماه فروردین به دلیل حضور بالای گردشگر در درون غارها با استفاده از دستگاه سه کاره دما، رطوبت وCo2 سنج، مدل (AZ 77535) انجام شد. نتایج مقایسه ی دو ماه بهمن و فروردین نشان می دهد که در هر دو غار در فروردین ماه همزمان با افزایش تعداد گردشگر در درون غارها، مقدار غلظت دی اکسیدکربن بالا رفته و درصد رطوبت نسبی کاهش یافته و دما نیز افزایش یافته است. بطور مثال میانگین بیشترین غلظت دی اکسیدکربن در ماه فروردین در هر دو غار مربوط به دالانهای کم ارتفاع می باشد و مقدار آن در غار سهولان PPM 1503 و در غار کتله خور PPM 1248 است. میزان تاثیر حضور گردشگران بر کاهش درصد رطوبت نسبی در دالان های کم ارتفاع در غار سهولان 5/2 درصد و در غار کتله خور 2/1درصد است.

    کلیدواژگان: غار، گردشگر، غارسهولان، غار کتله خور
  • شهلا عزیزی، علیرضا ایلدرمی*، حمید نوری صفحات 189-209

    امروزه تحلیل و شبیه سازی طغیان و انتقال رسوب با مدل های مهندسی رودخانه کاربرد فراوانی در هیدرولیک جریان دارند. هدف از این تحقیق، شبیه سازی تاثیر تغییر شکل هندسی مقاطع عرضی -رودخانه آبشینه همدان بر فرآیندهای جریان و انتقال رسوب با استفاده از نرم افزار SMADA و شبیه-سازی هیدرولیکی رودخانه با مدل HEC-RAS می باشد. بررسی ها نشان می دهد که تغییرات عرضی رودخانه آبشینه به تغییرات مکانی الگوی کنش (فرسایش و رسوب گذاری) نسبت داده می شود که به دلیل تکرار و فراوانی وقوع سیلاب های منفرد و بزرگ می باشد. همچنین به دلیل فرآیند فرسایش، افزایش سرعت آب و شیب زیاد، مقاطع عرضی بالا دست V شکل بوده و مقاطع میانی به دلیل فرآیند فرسایش و رسوب گذاری به شکل U و در انتهای مسیر به دلیل وجود سد اکباتان و باز شدگی بستر فرآیند انباشت رخ می دهد. نتایج حاصل از مدل HEC-RAS نشان می دهد که مقدار ظرفیت انتقال رسوب با رواناب و سرعت جریان رابطه مستقیم داشته و میزان رسوب از مقدار دبی و بارش تاثیر می-پذیرد و بیانگر این است که در مقطع عرضی از دوازده کیلومتری پایین دست تا مقطع عرضی موجود در نزدیکی سد، میزان جریان رسوب نمی تواند از بستر رودخانه و کناره ها طغیان کند لذا خطری برای مناطق حاشیه رودخانه در پی نخواهد داشت. اما در مقطع عرضی هشت کیلومتری پایین دست حوضه میزان دبی عبوری و رسوب از ظرفیت این مقطع بالا بوده و برای جلوگیری از انباشته شدن رسوبات و بالا آمدن بستر و طغیان رودخانه در این بازه، باید مدیریت لازم و ساماندهی مهندسی رودخانه انجام گیرد.

    کلیدواژگان: مورفولوژی، فرسایش و رسوبگذاری، HEC-RAS، آبشینه
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  • Seyedreza Hoseinzadeh, Ali Ghorbani Shorestan *, Alireza Karimi, Mahnaz Jahadi Toroghi Pages 1-22

    Loess deposits in northeastern Iran are deposited sparsely and with thin thickness on the slope. The aim of this study was to identify and determine the distribution of loess sediments, to study the properties of sediment texture and morphoscopic characteristics (SEM), and finally to identify the origin of these sediments. The fine sand was the dominant particle in the samples, and the sum of coarse silt, very coarse silt and fine sand was more than 60%. In morphoscopic study, quartz grains were found to be not very rounded, and the prevalence of fine sand, low rounding of quartz grains and auricularity of most quartz particles were evidence indicating locality and proximity of the harvesting site to the deposition site. There was a negative correlation between height and average size of the collected particles and its correlation coefficient was -0.7.

    Introduction

    In Kopet Dag region, loess sediments are scattered and of low thickness, and located around the Kalat Naderi, Sarakhs, Torbat-e Jam, Fariman and Mashhad. The goal of this study was to: 1) determine the characteristics of the particle size distribution, 2) determine the properties of the surface texture and the shape of the quartz particles, 3) determine the possible origin of the loess sediments, and 4) determine the distance from the harvest site.

    Materials and methods

    The study area was located at the end of the eastern and southeast of the Kopet Dag mountain range at latitudes of 20'35˚ to 59'36˚ north and longitudes of 50'59˚ to 20'61˚ east and included loesses of Sarakhs, Torbat-e Jam, Fariman and south of Mashhad. In order to do this research, map of loesses distribution was first prepared using geospatial maps, then the range of loess sediment was identified by wide field observations based on the geomorphic and topographic characteristics, and totally 119 surface samples were taken from which 20 samples were selected for particle size distribution and 4 samples for SEM study. For particle size distribution, at first the amount of gypsum and lime of the particles was determined, and after the preparation of the samples, the size of the grains was measured using laser particle size analyzer Malvern mastersizer 2000, and the average grain size, standard deviation, elongation, and skewness were calculated. For morphoscopic study, quartz grains from fine sand part are suitable for quartz morphological analysis and electron microscopy analyzes. To prepare and separate quartz grains before scanning the grains by electron microscopy, the geochemical composition of the grains was determined using Energy Dispersive Spectroscopy X-ray (EDAX) to ensure that only quartz particles were analyzed. Results and discussion The results obtained from the analysis of the particles size showed that silt particles with the average of 62.68% had the highest frequency in comparison to sand and clay particles with the averages of 28.96 and 8.3%, respectively. The results obtained from the scanning of quartz grains indicated that most of the grains had low roundness, and their fractures were angular and the abrasion coefficient of the samples varied from 100 to 210 (low abrasion). With respect to surface texture, quartz grains were mainly aura (semi-luminous) and sometimes opaque.

    Conclusion

    Loess sediments were deposited on slopes with east, north-east and north directions, and their dispersion originating from Turkmenistan had a north-easterly southwest transmission path, while the prevailing wind of the region at the present time (According to the above-mentioned green light) has a north west-south east direction. This shows the different conditions of wind blow direction during the deposition of loess deposits, and based on the slopes that loess sediments deposited on them, wind direction at sedimentation time had a northeast-southwest transmission path. The results of the experiment related to the particle size distribution of the loess of the region revealed that the greatest fashion or facade belonged to 59-micron particles, which include particles with the diameter of coarse silt and fine sands, indicating a small distance from the harvesting source. Furthermore, the results showed that there was strong negative correlation between height and average size of the particles (- 0.7), so that the higher the height of sample collection, the smaller the average particle size. The results obtained from scanning quartz grains showed that most of the grains had low roundness and the fractures were angular, and low abrasion coefficient of quartz samples does not indicate a very long distance. Also, the aura-like nature of the particles represents harvesting from old river beds or alluvial plains, the medium travel distance, and locating in wind sediments areas, and is therefore evidence of the locality of sediments origin. Finally, the frequency particle size curves had almost a uniform and monotonous pattern, and the monoseness and prevalence of sediments with a diameter of 59 microns confirm the belonging of sediments to a single origin. In this regard, it can be assumed that Hari River bed or the dry and desert areas beyond this river in Turkmenistan as well as the beds of dry rivers in the dry and low rainfall Quaternary periods were the origins of the loess sediments of the study area.

    Keywords: Loess sediments, Northeastern Iran, Particle size distribution, Morphoscopy, Identification
  • Somayyeh Moazzez, Shahram Roostaei *, Tohid Rahimpour Pages 23-37
    Introduction

     Landslide is a natural phenomenon which occurs through a fall or the movement of an integrated and often rapid volume of sedimentary materials along the hillsides. This phenomenon causes a lot of economic damages to forests and their growth, farmlands, gas and power transmission lines, mines, engineering structures and buildings. The purpose of this study is identifying the areas prone to landslide and determining the factors influencing the occurrence of landslides in the Nahand Chai basin, located in East Azerbaijan province, using Analytical Network Process (ANP) and GIS technique.

    Methodology

    The study area is located between 38, 08´ and 38, 28´ N and between 46, 21´ and 46, 35´ E in the East Azerbaijan province, Northwest of Iran. According to the current study's hypothetical criteria, practically 8 data layers have been provided in a GIS setting; as they are regarded to be significantly important factors in landslide occurrence in Nahand Chai. The ANP model was introduced to the provided relational database in weighting of data layers and defining a number of related functional criteria and factors.

    Keywords: Landslide, ANP, Super Decisions, GIS, Nahand Chai Basin
  • Maryam Bayatikhatibi *, Fariba Karami Pages 38-51
    Soil erosion is a serious environmental problem around the world .The formation of gully systems is a sign of severe soil erosion, and gullies are an important sediment source in dry lands , also reported that gullies can account for a higher portion of sediment yield in semi arid.Gullies are typical erosion forms in semi-arid and arid landscapes all over the world where high morphological activity and dynamics can be observed. Semi-arid climate conditions and precipitation regimes encourage soil erosion processes through low vegeta-tion cover uplift and recurrent heavy rainfall events.Gully erosion is a threshold phenom-enon and occurs only when a threshold in terms of flow hydraulics, rainfall, topography, pedology , or land use has been exceeded .The North estern slopes of Sahand mountain are severely degraded by rill and gully erosion. In headwater streams in steep land settings, narrow and steep valley floors pro-vide closely coupled relationships between geomorphic components including hill slopes, tributary fans, and channel reaches. These relationships together with small catchment sizes result in episodic changes to the amount of stored sediment in channels. Erosion rate estimates are potentially strongly influenced by the estimation method.A total 11 gullies with various soils and land use types were investigated in Ojan catchement. Field data on gully channel geometry were collected in catchement.The obtained data confirmed the existence of the power relationship for rills and gullies, with the exponent varying from 0.44 for small gully) to 0.5 for gullies . The data did not allow deciding whether the exponent varies consistently with channel width or in a step-wise fashion.Annual sediment yield from gully complexes was derived based on their area using empir-ical equations obtained in the same rock formation and vary formation in headwater catchments of the Ojan River . Major sediment inputs follow high magnitude events. As headwater catchments are major sediment sources, interpretation of sediment delivery processes in these settings is a critical consideration in our understanding of basin-scale sediment dynamics.Analysis of these geomorphic features in steep headwater catchments can also be used to characterize the episodic manner of sediment delivery processes. Narrow valley floors in study area allow sediment to be directly transferred from outside the channels to inside. A data set on soil losses and controlling factors for 11 ephemeral gullies has been collected in the Northestern Sahand mountain . Of the observed ephemeral gullies, gullies. and ephemeral gullies developed on slopes. Analysis shows that E is capable of predicting ephemeral gully cross-sections well. Rather than revealing E ability of predicting ephemer-al gully erosion, this analysis stresses the problematic nature of physically based models, since they often require input parameters that are not available or can hardly be obtained. With respect to the value of simple topographical and morphological indices in predicting ephemeral gully erosion, this study shows that gullies, respectively, over 80% and about 75% of the variation in ephemeral gully volume can be explained when ephemeral gully length is known. Moreover, when previously collected data for ephemeral gullies in study areas and the data for gullies formed in the U form, it appears that one single length vol-ume . A simple procedure to predict ephemeral gully length based on topographical thresholds is presented here. Secondly, the empirical length–volume relation can also be used to con-vert ephemeral gully length data extracted from aerial photos into ephemeral gully vol-umes. The evidence showed that gullying was controlled by faulting and uplifting along the slope. It can be seen that the deep gullies clearly plot higher compared to the shallow gullies. This is also reflected by the intercept of the minimal topographical threshold line. Two bank gullies representing different morphological types of gullies (V-shaped and U-shaped) were chosen from a dataset of gully systems in semi-arid . Gully erosion generates significant volumes of sediment that is delivered to waterways throughout the world . Quantifying gully erosion rates and associated sediment yields is critical for the effective prioritisation of management efforts aimed at reducing the environmental impact of gully erosion .Soil fabric and rock structure and weathering studies were undertaken to establish the in-heritance of soil cracks from the underlying parent material.Two mechanisms of gully de-velopment appear to occur in upland catchement. The first produces stream coupled gul-lies resulting from lateral channel migration and erosion induced at the base of the hill slopes . The second produces more extensive gully networks that are often initiated in the mid slope .In this context, gullies link hill slopes and channels, functioning as sediment sources, stores and conveyors. From a review of gully erosion studies in semi-arid and arid regions, conclude that gullies contribute an average of 50 to 80% of overall sediment production in dry land environments .
    Keywords: Tectonic uplifting, Erosion, Gully Erosion, Soil erosion, Ojan catchement
  • Esmaeel Shahkoee *, Reza Sarli, Yosef Darvishi, Samane Amanpor Gharaee Pages 52-70
    Introduction

    Mass movements are among the morphodynamic phenomena that occur under the influence of various factors at the level of the mountain range. The zoning of landslides is one of the methods that can be used to help those regions Determined the critical situation and used the mapping maps obtained in the planning, the slopes of the movement included the granular and massive movements of the earth, which, in the region, have several natural causes And human beings can interfere in its occurrence, which unfortunately causes some serious financial and psychological damage. Many landslides are quite natural because of copper So large or even small changes can cause landslides. In landslide, the landslide flows downwards. The flow of soil and flowers in the thrust of the ground is quite moldy and occurs where fine grained soil is completely damaged and saturated with water and flows down the sloping surface, although The thrust of the ground can be slow, but it usually has a terrible speed and most of them are fast and very dangerous.

    Methods and material

    The present study is descriptive-analytic with regard to the nature of the problem and the subject matter and is a type of applied studies with an emphasis on quantitative methods. The purpose of this study is to investigate the areas of vulnerable natural hazards with emphasis on landslide ( (Gorganroud sub-region) is used to identify areas with high thrust potential such as: slope, gradient direction, land use, distance from residential centers, land curvature, precipitation, elevation, vegetation density, geology, Soil, water condensation, distance from the road have been considered in order to calculate the density and vegetation cover vegetation of infrared bands The Landsat 8 satellite was used for the red light (4-5) and the final output was calculated using an integrated approach in the GIS environment. All the processes and data analysis in the GIS environment and Super decision software were used, so that each weight Following the criteria of the main criterion in the superconducting software environment, Sepeh was multiplied by using the weighted and linear overlapping methods of each of the sub criteria of the main criteria in their weights, and ultimately by the overlapping of each of the overlapping criteria in The main criterion weight of the multiplication and the final output was determined in the form of a thrust map in 5 floors.

    Results and discussion

    In order to measure the impact of effective factors on landslide, the analytical software mentioned in the research methodology has been used and also to determine the effective indexes in determining low and high risk areas for identifying the degree of drift and land valuation for Types of activities and the importance of each of these criteria in relation to each other according to the current status and the information gathered, as well as the study of books, previous plans and experts' opinion has been taken that ultimately in the form of a layer The information system enters the GIS environment at a later stage, into proportional weights of intelligence layers The importance and the impact of these are given in the appropriate field selection. In order to achieve these indicators, a series of maps and databases were needed that were prepared in the GIS environment and prepared after In order to analyze these maps we used linear and linear overlapping methods.

    Discussion and conclusion

    Accordingly, according to the valuation of each of the criteria above, the main criterion for topography is the highest value in the curvilinear drift with the weight of 0.564323 and in the hydrographic criterion the greatest interference is in the land of the river density zone with a weight of 0.833333 and in the facility standard Substructure of distance from the road with a weight of 0.800000 and in the criterion of utilization and vegetation density, the criterion of density of vegetation with the weight of 0.50000 and also in the ground and soil criterion are the geological layer with the weight of 833333 respectively, respectively, also have the highest value. The area obtained in the final map of the 5th floor with a high runoff factor of 15% of the total area of the area, 4th floor with a drift coefficient 19%, 3rd floor with a mean of 35%, 2nd floor with a low coefficient of 22%, 1st floor with a very low coefficient of 8%, resulting in up to 34% of the total area exposed to extreme poverty.

    Keywords: Slide, Gorganroud, Gorgan, Super decision GIS
  • Ali Bagherian Kalat * Pages 71-85
    Introduction

    Soil physico-chemical properties has a important impact on soil erosion. Shaly originated soils due to the high susceptibility to erosion have high erosion rates in spite of occupying relatively small areas, can make disproportionate contributions to watershed scale sediment budgets. Critical source areas are usually associated with marls, clay rocks, mudstones and shales. Additionally, few reports showed that badland landforms there are on sands or poorly consolidated sandstones.Rainfall simulation is a good method for comparison and quantification of different runoff and erosion processes and factors that influence them. Numerous researchers have used simulated rainfall experiments on a wide range for determination of soil erodibility.The erodible lithologies (shalls) include more than 50 percent of the area of the kakhk watershed basin. Securitizing available literatures about effective factors on soil erosion in eroded soils shows that in spite of numerous reports on different soil erosion processes, little comparative study has been considered on sediment yield originated from soils with different parent material in plot scale under different rainfall intensities. So, there is a need for more detailed investigation on soil physico-chemical and vegetation properties that effect on soil erosion. Accordingly, the present study was carried out to comprehensively compare the effects of environmental factors and rainfall intensities controlling spatial variation in soil loss in kakhk drainage watershed.

    Methodology

    Study Area This research has done in kakhk watershed (3720 ha) which located in the south of Khorasan Razavi province. In this area, half of the area is made up of shale lithologies which are very susceptible to erosion. The annual precipitation is about 220 mm. The predominant lithologies are shale, sandstone and gabbro. The soil profiles are poorly developed. Plot Locations and Characteristics For specifying location of the plots, geology, slop, land use and erosional facies maps were prepared using 1:50,000 topography, geology and dip maps and field surveying. 4 different locations in basis of difference in geology and erosion facies were selected for these experiments. The plots located on different parent materials consist of shale, sandstone and gabbro in the. same slope (20 %) and land use (rangeland) but different lithology and erosion facies. In all of working polygons, the rainfall simulations carried out with intensity of 36 mm h-1 in autumn 2016 . The Experiments Design The rainfall simulator that was used in this study is a portable non-pressurized rainfall simulator which developed at the Soil Conservation and Watershed Management Research Institute (SCWMRI). The 32 rainfall simulation experiments were performed during the autumn of 2016. All runoff and sediment data were collected and analyzed in the laboratory. Before performing the simulations, in order to determine effective factors in sediment production and erosion, 32 soil representative samples from the first 15 cm depth of soil were taken and analyzed. Statistical Analysis The statistical analysis of data was conducted with the software SPSS for Windows. One-way analysis of variance techniques were used by Duncan Multiple Range Test with a level of significance of p≤0.05. For determining the degree and type of correlation between sediment yield and soil physico-chemical properties and soil surface cover used the Pearson's correlation matrix (r) and multi-variable regression method. Stepwise multiple regression analysis was used to assess the effect of soil physico-chemical properties and soil surface cover on soil loss.

    Results and discussion

    The results showed that erosion and sediment yield in lithologies have meaningful differences. Jsh-RG (shale with Rill-Gully facies and Js-SR (sandstone with Sheer-Rill facies ) soil units with 68.12 and 45.12 gr/m2 have the most and the least sediment yield, respectively. It was found that the sediment yield had positive correlations with some soil properties such as silt percent, Ec, pH, and SAR and negative correlations with sand percent, OC, NPV (%), vegetation and rock fragment cover. In this research, regression analysis was used to examine the relative contribution of soil physico-chemical properties on soil loss. The results present that the variables of percent of rock frogment (R.F) and Grass cover (G.C) have greater contribution in explaining the variations in soil loss. Equation (1) with determination coefficients of 0.87 (R2) (p<0.01), selected as appropriate model for predicting soil loss.Sediment Yield=109.112- 1.369 (R.F) -0.988(G.C) (1) In these models, R2=0.87 indicate that 87% of the observed dissipation in dependent variables.

    Conclusion

    In this research, the spatial variability in soil loss for 4 representative selected soil samples derived from different parent rocks analyzed. The results revealed that rainfall simulation is well adapted to the analysis of rainfall-erosion processes within study area. Using a portable rainfall simulator revealed the effects on soil loss under rainfall intensity. Soils derived from shale with Rill-Gully facies and sandstone with Sheer-Rill facies showed the most and the least soil loss, respectively. ANOVAs showed that there are significant differences between treatments (different soils) in soil loss (P<0.01).Multiple regression analysis revealed that rock fragment (R.F) and grass cover (G.C) are the most efficient factors determining soil loss.Pearson’s correlation analysis showed that grass and rock fragment cover, soil vertical resistance and sand fraction are the efficient variables which have negative correlation with soil loss and the variables of silt fraction are the variables that have a positive correlation with soil loss. Meanwhile, the factors of SAR, EC and pH are the efficient chemical variables that have positive correlation with soil loss.In this study, results of the experiments show that the magnitude of soil loss was highly controlled by some soil physical and chemical properties and soil vegetal and rock fragment cover. So, the mechanism of erosion involves the nature of the parent rocks, soil physico-chemical characteristics as well as ground cover.Consequently, the finding of this research indicate that some physico-chemical properties of study soils and soil vegetation and rock fragment cover are suitable indicators for predicting soil loss in the study area.

    Keywords: Rainfall Simulator, Soil loss, soil physicochemical properties
  • Adel Sepehr *, Maliheh Pourali, M.H Mahmoudy Gharai Pages 86-102
    Introduction

    Playa is one of the important geomorphology types in arid and semi-arid regions and it is sensitive to climatic changes. Composition of sediments is varying in playa and sometimes, it can reflect the past climate. Recognition of the minerals and origin of sediments in these regions has a determinative role in geomorphology of playa, for example, existence of paligorskite and sepiolite clay minerals which are formed and become sustainable in alkalic environments such as playa and sediments of arid regions, and they are recognized as an indicator of the past environment and a sign of evaporation conditions in lake sediments. Sabzevar playa, as an old lake sedimentary environment in the north east of Iran, is important from regional and environmental aspects, and recognition of its constituting sediments can significantly help the recognition of the past climate and the current conditions of the playa. This research is aimed at recognizing the minerals constituting different geomorphic surfaces of Sabzecar playa and studying the late Holocene climate in the region by mineralogy of the sediments.

    Materials and methods

    In this research, by using the visual data of satellite images and geological maps of the region with 1:100000 scale, the border of playa was determined and its different geomorphic surfaces were recognized. In the field studies performed during summer, 12 samples of surface sediments and deep sediments were by handy auger along the playa geomorphic areas including clay-flat areas, puffy ground clay area, and salt-clay area, and the location of sampling points was recorded by GPS. Then, sedimentary physical and geochemical analyses were done of the samples. Distribution of the particles size was done after screening by using a 2-mm screen and by laser separation method and statistical criteria of the sediments were done. Analysis and measurement of Potential of hydrogen (pH) and Electrical Conductivity (EC) was done in 1:1 ratio of water to sediment. Calcium Carbonate Equivalent (CCE) percentage of the samples was determined by volumetric method. Mineralogy of the sediments was measured by X-ray diffraction device in the range of 3 to 60 degrees (ϴ2), and for more detailed study of clay minerals, 5 samples of dry intact deposits were studied by scanning electron microscopy.
    Discussion and

    conclusion

    In Sabzevar playa, 3 geomorphologic facies including clay-flat facies, puffy ground-clay facies, and salt-clay facies were recognized which have been formed affected by the surrounding lithology of rocky outcrops, the existing evaporating layers, and the special topography of the playa. Playa (clay-flat facies) has the lowest electrical conductivity which suggests the low level of underground waters in this area. The dominating mineral quartz of this facies is at the surface which suggests the intense wind deposition as a result of increased aridity of the environment. High amounts of sand particles at the surface of this facies approve this assumption. Smectite clay mineral exists at the deep parts of this facies in an autogenic manner which suggests the weak drainage and increased aridity. The central part of the playa (puffy ground-clay facies) has been formed caused by high water table and salty water and lack of seasonal overflows. Low levels of gypsum aggregation at the surface levels and high levels of gypsum aggregation ar the deep parts approve the existence of puffy ground-clay surface. Decreased calcite and increased gypsum and sepiolite in the deep parts and existence of paligorskite can be probably caused by more arid climate and salt changes in this facies. The west part of the playa (salt-clay facies) is the lowest area of the region and it is covered by halite evaporating mineral and clay layers, and it shows the dominating evaporation process. Surface evaporation through capillary force cause upward movement of underground waters and creation of salt layers. The surface of this facies has a high level of electrical conductivity in the region. At the deep parts of this facies, we can see paligorskite and sepiolite fiber minerals in an autogenic form which suggest the dominance of arid and alkaic environment. Distribution of particles size show the highest percentage of caly in this facies which suggests the lowest average of particle size and the lowest amount of environmental energy at the time of deposition.

    Conclusion

    The results of this research suggest the existence of clastic and evaporating minerals such as quartz, paligorskite, calcite, and gypsum in Sabzevar playa. First carbonate minerals (calcite) and then, sulfate minerals (gypsum) have deposited and at the end, chlorides (halite) have deposited. The size distribution chart of particles has the average of 46.20 µm at the surface and 23.98 µm at the deep parts and the average kurtosis of 8.56 µm at the surface and 5.29 µm at the deep parts and the skewness is towards the small particles. The average values of EC and pH in all the deep samples are less than surface samples and it suggests more salt in the surface water. Fiber clay minerals such as paligorskite and sepiolite in playa have been formed in the deep part in an autogenic way and in the surface in an allogenic way, and it suggests the dominance of arid climate of the region in past and present time. Also, surface deposits suggest wind deposition in a quite arid environment and deep deposits suggest deposition in a windy alluvial environment.

    Keywords: Playa of Sabzevar, Geochemistry, Evaporated Mineral, Holocene
  • Fatemeh Rahmatipour, Amir Saffari *, Amjad Maleki, Farzad Shirzaditabar, Ali Ahmadabadi Pages 103-121
    Introduction

    In most cases, faults can be detected by signs; however, in many cases, the outcrops of these structures have not reached the surface of the earth, or deposits have been buried with evidence and indications. Such conditions, although the surface of the earth's crust on both sides of the fault is displaced and drifting up or down, however, the surface out crop of the fault is not observed at the ground or is limited to stacks and mild folds in sections along the fault. To identify these types of faults, geophysical methods, CO2 and soil radon measurements, seismic reflections and electrical imaging, lidar, penetrating ground radar or air geophysics can be used. Researchers who have studied the buried faults of the earth's crust have generally used geophysical methods. According to Giving and colleagues, the results of aerial geophysical data in order to identify hidden faults, if accompanied with evidence of geomorphology and topographic data, have higher scientific value. In this research, the aim is to find hidden faults through geomorphic interpretation methods.

    Methodology

    Among the areas where active tectonics and faults have been buried and the river sediments have buried their works, the east of Kermanshah province is in the Harsin and Bisetoon plain. First, geological maps and topography, geomorphology, and geostructral were explored and interpreted. Based on the hypothesis of the separation of the Shirez anticlinal from the nape as one of the geostructural and morphotectonic evidence, and the flow of the Gamasyaw river and the morphology of the Tsetonic plain of Harsin, the overall boundary of the hidden faults was identified and mapped to geology. In the next step, by studying the data of aeromagnetism and the use of return-to-pole filters, vertical derivatives, analytical signal and tilt, a more precise location of the faults was maped. Then, on the 4 main faults identified, 5 sections of VLF As and Mg As were taken and the results of the previous steps were verified using the geoelectric method.

    Results and discussion

    What is obtained from the results of a total of three methods used to identify hidden faults is a number of faults that have been scattered across the region. The first fault in the almost west to east direction from west of the Taqbostan elevations in the north of Kermanshah plain extends over the Taqbostan elevations, and after passing on the Prao and Bisetoon elevations, with the shift of direction from southwest to northeast to Barnaj, and from there with change the almost east-easterly direction enters the plain and continues in the south of the Khaneh-khode mountain, and after passing through the Sahneh plain, it again extends to the north-east by changing the trend. Between the Bisetoon elevations to the Sahneh plain, 5 faults along the north-south direction extend approximately from the first fault to the shores of the Shirez anticlinal. These faults have been driven by the sliding motion. Another fault that seems to play an important role in the region's morphology and history of geomorphology in the region has started from west of Kermanshah and in the south of the Paro elevations it continues along the southeast to the Harsin plain. Comparison of the results of the three stages of the research showed that what the aeromagnetism and geoelectrics identified as faults, geomorphology, with a small spatial variation, and a negligible distance, as a fault that must exist to justify the region's morphology had identified. Geomorphology is largely capable of treating anomalies and movements caused by faults that are sometimes detected in the field by interpreting geospatial maps and analyzing the geostructural of the area along with simultaneous surveys of geomorphic, topographic, satellite images and remote sensing maps that geologists can not be identified. What is certain is that the effect of hidden faults in the region's morphology is observed only in some areas where the effect of the fault has reached the surface directly and in the expected form; otherwise, in the identification and tracing of the hidden fault by geomorphology, we must look for indirect effects and the effects of long-term faults on morphology, especially geostructural, on a larger scale than the usual methods of morphotectonic studies. It can be said that geomorphology can be successful in finding hidden faults that it has a comprehensive view on geotechnical and past geographic of region. In fact, a thorough examination of the geomorphological nature of the forms is based on the interpretation of the function of the faults, in particular the hidden faults, which themselves sometimes lead to the finding of hidden faults.

    Keywords: hidden fault, Morphotectonic, aeromagnetic, geoelectric, vlf method
  • Maryam Ezati, Ebrahim Ghoami *, Seyed Morteza Mousavi Pages 122-137

    The drainage pattern in tectonically active regions is very sensitive to processes such as upliftment, folding, faulting, and tilting which are responsible for river incision, basin asymmetry, drainage geometry, and river deflection. Shekarab Mountain is located in the East of Iran and north of sistan suture zone. Aim of this research is investigating effect of faults mechanism on structural evolution of Shekarab Mountain. In this study for investigating of structural evolution cross section drowing were used. In this research for evaluation rate of tectonic activity morphometric indices such as stream-gradient index SL were used. The highest amount of SL index is related to western part of Shekarab Mountain that is due to recent operation of trust faults. Field data and geomorphic indices shows that in areas of Shekarab Mountains that have the highest density of thrust faults under pressure operation of trust faults tectonic uplift and tectonic activity also increased.

    Methodology

    Faults and fractures of the study area are extracted from field operations and cross sections were drawed using Digital Elevation Model (DEM) and field data. Structural map of the studied brittle structures (faults and folds) were draw using field operations data. In this research to study the structural evolution of the Shekarab Mountains several investigations used on E-W trend geological cross section and morphometric index such as SL were used. In order to evaluate rate of tectonic activity stream length-gradient index (SL) were calculated. The SL index is very sensitive to change in channel slope, and this sensitivity allows the evaluation of relationship among possible tectonic activity, rock resistance, and topography.

    Result and Discussion

    Shekarab Mountains is located in eastern Iran and is placed in geographical position of 58˚ 37́E to 59˚ 16́E and 32˚ 50́N to 33˚ 09́N. Shekarab Mountains is a terminal splay of Nehbandan fault that is located in the Sistan suture zone. Iran lies on the Alpine earthquake belt which runs west-East from the Mediterranean to Asia. The present tectonics of Iran results from the north-south convergence between the plate of Arabia to the southwest and Eurasia to the northeast. This convergence is accommodated across the Iranian Plateau and adjacent deformed zones, and the deformation, as defined by seismicity and geology is not uniformly distributed. Much of the deformation is concentrated in the Zagros active thin-skinned Fold and Thrust Belt in the southwest, Alborz Thrust Belt bordering oceanic crust of the south Caspian depression, Kopeh-Dagh active thin skinned Fold Belt in the north east, and in East-Central Iranian thick-skinned range and basin province. Results from a regional GPS network indicate that the total convergence across Iran is 25 mm/yr in eastern Iran. Sistan structural zone is a north-south trend and represents the suture between Lut block and Afghan block. The existence of Nehbandan fault system in the border between Sistan suture zone and Lut block has caused several rock units in the margins and within the structural state of Sistan. Nehbandan fault system with strike-slip mechanism by north-south general trend has sub-branches in the North and South terminals. Northern terminal of Nehbandan fault has rotated toward west and its southern terminal toward east. Geometric and kinematic position of identified faults in the studied area show that most faults of study area have a reverse component such as fault F17 Reverse with sinistral strike slip component, fault F6 Sinistral strike slip with reverse component, fault F9 Reverse with dextral strike slip component.

    Conclusion

    Faults and folds are the most important structures in the Shekarab Mountains. For identification of faults and role of faults in structural evolution of Shekarab Mountain field operations were used. After completion field operations of study area Structural map of brittle structures (faults and folds) was prepared. Geometric and kinematic analysis of identified faults indicate that mechanism of most study areas faults are reverse with dextral strike slip component, which indicated the overcoming of compressional stress in Shekarab Mountains. Northern terminal of Nehbandan fault has rotated toward west and its southern terminal toward east. Geometric and kinematic position of identified faults in the studied area show that most faults of study area have a reverse component such as fault F17 Reverse with sinistral strike slip component, fault F6 Sinistral strike slip with reverse component, fault F9 Reverse with dextral strike slip component.The highest amount of SL index is related to western part of Shekarab Mountain that is due to recent operation of trust faults. Field data and geomorphic indices shows that in areas of Shekarab Mountains that have the highest density of thrust faults under pressure operation of trust faults tectonic activity also increased.

    Keywords: Faults mechanism, Cross section, Shekarab Mountain, Northern Birjand
  • Mohammad Zaman Zade *, Mansour Gafar Bighlo, Parisa Pirani, Arefe Shabani Eraghi, Fateme Geravand Pages 138-154
    Introduction

    River morphology is one of the main factors to control the geometric shape of river sediments which is determined by two parameters of braiding and sinuosity (Rust, 1977: 187). Sinuosity or sinuosity ratio represents how much curved a channel is (Charlton, 2007: 138) and braiding parameter represents the number of braids or bars in any wave length of meander. According to these two parameters, rivers are divided into four groups: straight, braided, meandering and anastomosing (Mousavi Herami, 1991: 261-263). There are differences in texture and size of sediments deposited in the channel, braided bars and point bars (Mousavi Herami, 1991: 264). The purpose of this research is to compare sediments from different forms of straight, braided and meandering channel in order to determine the changes of sediment size and texture in: different parts of an individual bar, among bars of three channel forms and between selected locations in upstream and downstream of river.

    Methodology

    The study area is in Abdanan county which is located in Ilam province in the west of Iran on its most important stream which is Abdanan river. At the beginning, two appropriate locations of Abdanan river at the upstream (Posht-qaleh) and downstream (Hezarani) parts of this river were chosen after considering items such as topography, geology map and google earth images and also GIS software. Afterwards on each bar (braided or point) 4 points were chosen for sampling. Then, half a kilogram sediment sample was obtained from each point and after encoding, these samples transferred to the laboratory and granulometry analysis was carried out on the samples. Grains categories and their weight percent obtained using the granulometric analysis and necessary graphs were plotted by Excel and Gradistate. In the next step Statistical parameters such as mean (MZ), sorting (Iσ), skewness (SKI), Kurtosis (K) were calculated and the results were represented in phi unit.

    Result and discussion

    The upstream sediments of river are mostly classified in gravel, sandy gravel and muddy sandy gravel on triangular diagram of Folk (1954), but the downstream samples include sand and muddy sand sediments. Histogram of samples represents some modes on medium and very coarse sand size but the mode on gravel is predominant in all of samples. The latter point shows that samples are poorly sorted and have polygenetic origin. Breaks on cumulative plots represent the different groups of grain sizes which were moving in different mechanisms from suspension to traction. The percentage of coarse grains is high in most samples; and plots are parabolic. This represents the changes of energy in environment. Calculating the statistical parameters such as mean, sorting, kurtosis, skewness using graphical method of Folk and Ward (1957) showed that upstream and riverside parts of the braided channels underwent one-sided washing, so that their sorting is higher and percentage of coarser grains is more than downstream part of these channels which experienced washing from both sides. In the meander bars, sedimentological characteristics of sediments are close to a normal pattern of a meander. The difference, however, is that a newly formed river crossed the flood plain and reduced the sorting of sediments, so that the sedimentological characteristics of these sediments in downstream meander is similar to braided pattern. contrary to what expected, sorting decreases in the straight channels, due to gravels shed from sub-branches and slopes

    Conclusion

    the differences seen sedimentological characteristics of the samples are due to the role of branches of main stream, periodic floods of Abdanan river and sediment-shedding from channel slopes that has changed the texture and size of sediments. These changes in the samples which were obtained from Hezarani location in the meandering channel are due to development of river sub-branches and in the straight channel are because of sediments resulting from channel slopes. generally speaking, sediment texture and size at upstream (Posht-qale) vary from well to moderate sorted gravel in the north to poorly sorted sand in the south but this pattern is not seen in sediment texture and size at downstream (Hezarani) location where effects of river branches and floods are illustrated by increasing gravel and irregularity of sediment pattern.

    Keywords: river sediments, Granulometry, Braided, meander, striaght
  • Fariba Esfandiary Darabad *, Masoud Rahimi, Gholamreza Pourmortaza Pages 155-171
    A flood is a very simple natural phenomenon that occurs when a body of water rises to overflow land that is not normally submerged (Ward, 1978). At the same time, a flood is a very complex phenomenon that connects the natural environment, people, and the social systems of their organization. Flood is the most expensive and devastating natural hazard (Wilby and Keenan 2012; Sanyal and Lu 2004), and it continues to be a concern in many parts of the world (Jha et al. 2012; Kundzewich et al. 2010; Chang and Franczyk 2008). Scenarios of future climate indicate a likelihood of increased intense precipitation and flood hazard in many areas (cf. Kundzewicz et al., 2010). Floods are currently one of the greatest threats to social security and sustainable development, and it is estimated that floods affect around 20–300 million people every year (Hirabayashi and Kanae 2009). In recent decades many studies have been carried out on floods that mainly approached to flood risk management. Flood inundation models are defined as the tools which could simulate the rivers hydraulic and also occurred floods in flood plains (Horrit, 2007, 61). Modern flood management should attempt to analyses the full scope of a flood event, using integrative concepts and taking into account multifaceted expertise from diverse fields. Reliable flood risk assessment and the development of effective flood protection measures require thorough knowledge about flood frequencies at different points in a catchment. In this research, quantitative approaches in order to flood zonation were used for the Ajirloo Chay Basin. Topographic maps with scale of 1: 50,000, digital elevation model (DEM) with 27 m resolution, and satellite imagery (Landsat 3 and 4 :2013) are most important materials in this research. In this study for flood hazard zonation were used the L-THIA method and fuzzy logic quantitative approaches. Fuzzy theory is inaccurate and ambiguous concepts and a variable makes the math. In this study, the operator sum, algebraic product and gamma are used. In order to run the model and research used from a series of climatology data, geomorphology and land surface coating. In flooding zonation an area can be considered many physiographic parameters that can influence. Among these parameters we select nine factors as the most important factors that influence in flooding. These nine factors are: drainage density, hydrologic soil groups, slope, climate, land use, run off, land units, altitude, and lithology.It is important for preventing and decreasing the effect of flood to avoiding expounding these risks. Zonation flooding that can be adopted. In this study we used LHTIA models and fuzzy logic in Ajirloo Chay basin. For this research we got help nine factors includes (altitude – climate – land units – slope – lithology – drainage density –hydrologic soil groups – run off and land use). In this area the results show that more than flood zonation are in very low, low and mediums risk classes (about 65/6 %) that these area are located in western and bathetic water shed and the most high risk area located in the eastern half and the northeast. The high class of land drainage density are in this area of land that is the factor of being prone to flooding The concentration of run off in the Ajirloo chay basin is in the eastern portion and in the upstream of the basin. Natural factors such as high slopes and high altitudes and poor vegetation can aggravated the flooding of the eastern portion of the basin and increase the flood hazard in this portion of the basin. Percent of high risks land is in much and too much potential that included (34/4%) of total area which is remarkable. According to the final map obtained from flooding zonation and for the sustainable development should be prevented from constructions in area with very high and high risk.The concentration of run off in the Ajirloo chay basin is in the eastern portion and in the upstream of the basin. Natural factors such as high slopes and high altitudes and poor vegetation can aggravated the flooding of the eastern portion of the basin and increase the flood hazard in this portion of the basin. Percent of high risks land is in much and too much potential that included (34/4%) of total area which is remarkable. According to the final map obtained from flooding zonation and for the sustainable development should be prevented from constructions in area with very high and high risk.The concentration of run off in the Ajirloo chay basin is in the eastern portion and in the upstream of the basin. Natural factors such as high slopes and high altitudes and poor vegetation can aggravated the flooding of the eastern portion of the basin and increase the flood hazard in this portion of the basin. Percent of high risks land is in much and too much potential that included (34/4%) of total area which is remarkable. According to the final map obtained from flooding zonation and for the sustainable development should be prevented from constructions in area with very high and high risk.
    Keywords: Flood zonation, Agorloo Chay Basin, LTHIA model, Fuzzy logic
  • Dawood Mokhtari, Mohammad Hosein Rezayi Moghadam, Peyman Karimi Soltani, TAYEBEH ABDOLMALEKI * Pages 172-188

    The presence of tourists in the tourist- attracting caves has led to changes in the values of climatic elements in the caves, such as temperature and the percentage of relative humidity, as well as carbon dioxide concentration. Increasing the concentration of carbon dioxide resulting from the presence of tourists decreases the PH level of the environment and forms an acidic environment. Formation of an acidic environment inside the caves will give rise to dissolution and sheeting of the karstic structures within them. In order to investigate these changes, we selected the caves of Katale Khor and Saholan as two examples of caves of the country that are attracting a large number of tourists. In order to compare and investigate the influence of tourist on climate changing and carbon dioxide concentrations in caves, we collected data in February due to the low number of tourists and April due to the high presence of tourists inside the caves, by means of a three-purpose device for measuring temperature, humidity and CO2 (AZ 77535). Comparative findings regarding two months of February and April suggest that in both caves in April, as the number of tourists inside the caves increases, the concentration of carbon dioxide and the temperature have increased and the percentage of relative humidity has decreased. For example, in both caves the average of the highest carbon dioxide concentration in April is found in low altitude halls with its value 1508 PPM in Saholan cave and 1248 PPM in Katale Khor cave. The percentage of relative humidity is decreased in low altitude halls in the Saholan Cave by 2.5% and in the Kotal Khor Cave by 1.2%.

    Introduction

    Caves, as important underground geosites, are considered among sensitive and fragile geomorphological structures (Mokhtari, 2015). The process of breathing in and out by the visitors causes a high accumulation of CO2 in the caves. Entering a great number of visitors into the caves increases the concentration of CO2. The more the time and presence of the visitors in the caves, the higher the accumulation and concentration of CO2 (Maleki et al, 2015). In this study, the Saholan Cave, as the second largest water cave, and the Katale Khor Cave, as the second popular tourist cave in Iran, that annually host a great number of visitors, were examined for changes in climate elements.

    Materials and Methods

    The data related to the concentration of CO2, temperature and relative humidity in maximum and minimum times for visitors’ presence was gathered. Considering changes in temperature, relative humidity and CO2 concentration in the halls and chambers of various sizes, and also for improving the accuracy, the space inside the caves were classed in three categories of low-height (height of ceiling between 0-2 meters from the surface of the ground), average-height (height of celling between 2-5meters), and very high (5 meters or more). Data collecting was done using a three-purpose device for measuring temperature, humidity and CO2 (AZ 77535) during two fifteen-day periods, was carried out, at the same time with, the minimum traffic of tourists in the caves (the Saholan and Katale Khor caves) in February and maximum tourist presence in the caves in April. Data collecting was done on a daily basis three times a day in the morning (before visitors’ arrival), at noon and night (after visitors’ departure) in both caves.
    Discussion and

    Results

    The data analysis showed that the presence of visitors in the cave during spring coincided with maximum walking of the visitors, increases CO2 concentration inside the halls, and the highest amount happens in small halls. Altogether, peak points registered for CO2 in different areas were exactly correspondent with days with highest number of visitors. Regarding the temperature, the range of changes showed an increasing trend from the morning until the night, and high temperatures in the corridors were correspondent with days with high numbers of visitors inside the caves. In the case of relative humidity percentage, there were times with a drop and decrease in humidity, that were exactly correspondent with maximum presence and high number of visitors inside the caves. Overall, relative humidity percentage inside the caves did not show much fluctuation.

    Conclusion

    Changing in climate elements inside the caves can produced following ramifications: corrosion of carbonate formations inside the cave. Impact on visitors’ health.. Maximum entering of the visitors into the caves creates sub-climates that according to the found results can increase CO2 concentration and cave temperature, and decrease the relative humidity. As a result of these changes, the process of karst formations inside the caves will be disrupted, and in some cases might cause destruction and fraction of these formations. Gradual destruction of amazing and well-shaped karst formations inside the caves slowly destroys and desolates the caves, and on the other hand disturbing the balance inside the cave and unleashing little amount of energy might upset the whole ecosystem of the cave. Thus, this phenomenon can endanger the condition of tourist caves of the country including Saholan and Katale Khor caves .
    Keywords: Cave, Tourist, Saholan cave, Katale khor cave.

    Keywords: Cave, Tourist, Saholan cave, Katale khor cave
  • Shahla Azizi, Alireza Ildoromi *, Hamid Nouri Pages 189-209

    The use of river engineering models in flood simulation and sediment transport is a common use in hydraulic flow. The purpose of this study was to simulate the effect of geometric geometric deformation of the Hamedan Aqueduct Ridge on flow processes and sediment transport during different return periods using SMADA software and HEC-RAS model. The results of the HEC-RAS model show that the flow of sediment can not flood the river bed and its sides in a transverse section from a distance of twelve kilometers downstream to the transverse section near the dam, so the danger to the river boundary areas in It will not be. But at a crossroads of eight kilometers downstream of the basin, the amount of discharge and sediment discharge is high at this level and river engineering must be organized to prevent accumulation of sediments and river floods.

    Introduction

    The flow of water in the river is a dynamic phenomenon that is constantly changing and displacing. Various mathematical relations such as HEC-6, HEC-RAS, SSIM, MIKE21, GSTAR, FLUVIAL are used to understand the phenomenon of riverbed displacement and displacement. Using the sediment transport equations and different methods for calculating particle velocity in the HEC-RAS model, river bed transformation can be studied and predicted. The results of the studies show that the sediment transport equations are not very sensitive to the particle velocity calculation in modeling the shape of the river bed shape, and the major difference in the results depends on the type of sediment transport equation used.The purpose of this study is to study the effect of changes in the section of the Abshineh River on the processes governing sediment transport capacity and the determination of flood sections using the HEC-RAS model, so that it can be used to control flood, sedimentation and seismicity Made

    Material and Methods

    The study area
    The catchment area of Ekbatan Dam is located in the south-east of Hamedan city and is one of the sub-basins of the Ghare-Chay River, located in the southwest of Alvand Mountain. Abshineh River is one of the most important sections of the Gharacheh watershed which flows from the northern slopes of Alvand Sarcheshmeh Mountain and enters the dam of Ekbatan-e Hamadan. The river's regime is under a semi-humid semi-humid climate of snowy, rainy and permanent mountains. The average annual rainfall is 312.9 mm and the average annual temperature is 11.3 ° C.
    Research

    Methodology

    In order to simulate the effect of geometric geometric deformation of Abshineh River transverse sections on flow and sediment flow processes, we first selected 6 cross sections of the river, and by sampling the sides and soil mechanics tests, particle diameter and bed gravel, then the maximum discharge Moments with different return periods were calculated using the SMADA software and introduced into the HEC-RAS model for hydraulic simulation of the river. and in Finally, the effect of section changes on the flow velocity, transfer capacity and sediment accumulation were analyzed and evaluated.

    Results and discussion

    The study of discharge and sediment showed that runoff had the most effect on river morphology, which, with the process of erosion and sedimentation, changed transversely. Also due to the size of the particle diameter of the river, the erosion process, the velocity of the water and the slope, the transverse sections of the upper hand V formed and in which the bottleneck was observed. While in the middle sections due to the erosion and sedimentation process, the transverse sections of the river in the shape of U and at the end of the path, due to the presence of Ekbatan Dam and the process of accumulation, have been subjected to a change in morphology. Studies show that runoff has the most impact on river morphology and the amount of sediment transport capacity is directly related to the flow velocity, which increases the flow capacity of the sediment transport, and vice versa. . The results of the model simulated simulation during the 50-year return period show that the flow rate can not flood the riverbed and the sides of the river at a distance of twelve kilometers below the bottom of the dam, resulting in a danger to the areas The boundary of the river and its lands will not be followed. But at the crossroads, located eight kilometers downstream of the basin, the discharge rate and sediment discharge from this section are high. This causes accumulation of sediments and flooding of the river in these places. And can cover the boundaries of the river.

    Conclusion

    Nowday The study of the effect of river cross-sectional changes on the processes governing sediment transport capacity and the determination of flood sections using the HEC-RAS model has been considered by water resource planners and planners. The results showed that the transverse sections of the V-shaped arm and the middle sections were changed to U-shape. In addition, at the end of the Abshineh River, the cross section has been transformed into tensile form. The most important reasons for changing the morphology of the transverse sections of the Abshineh River include the difference in bedding and surface changes, depth and speed of water flow, and erosion and sedimentation. The results of the HEC-RAS model showed that the river is not capable of flooding from its bed at a cross-section of twelve kilometers downstream to the transverse section near the dam. But at a crossroads of eight kilometers downstream, the amount of discharge flowing from this section is high and with accumulation of sediments in this range, the bed will rise and the river flood will occur. Therefore, it is necessary at this point to manage and organize river engineering and engineering.

    Keywords: morphology, erosion, sedimentation, HEC-RAS, Abshinehh