فهرست مطالب

پژوهش های جغرافیای طبیعی - پیاپی 107 (بهار 1398)
  • پیاپی 107 (بهار 1398)
  • تاریخ انتشار: 1398/03/18
  • تعداد عناوین: 12
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  • زهرا خان بابایی، ابراهیم مقیمی*، مهران مقصودی، مجتبی یمانی، سید کاظم علوی پناه صفحات 1-15
    سیلاب‏ های شدید یکی از فاجعه ‏بارترین حوادث طبیعی به ‏شمار می‏روند. این سیلاب‏ ها می‏ توانند به تغییرات مورفولوژیک قابل‏ توجهی در چشم‏ انداز منطقه منجر شوند. در این مقاله به پاسخ ژئومورفولوژیک رودخانه‏های کوهستانی ایلام به سیلاب‏ شدید سال 1394، با ارائه روابط بین تغییرات مورفولوژیک و عوامل کنترل‏ کننده آن در سرشاخه‏ های رودخانه کنجانچم (بالادست سد ایلام)، ‏پرداخته شده است. یک رویکرد یک‏پارچه از جمله تجزیه و تحلیل تغییرات عرض کانال، برآورد دبی اوج، و شاخص ‏های هیدرولیک در بازه‏ های مورد مطالعه، تعیین درجه رسوب‏ دهی در بازه ‏ها، و بررسی نقش عوامل انسانی در تشدید پاسخ سیلاب در مطالعه این واقعه استفاده شد. روابط بین میزان گسترش کانال و عوامل کنترل‏ کننده در مقیاس بازه با استفاده از مدل‏های رگرسیون چندمتغیره بررسی شد. نتایج بیانگر این بود که در این مدل‏ها نسبت عرض رابطه ‏ای نسبتا قوی با پایداری جانبی، عوارض انسانی، درجه رسوب‏دهی، و توان واحد جریان محاسبه‏ شده براساس عرض کانال قبل از سیلاب دارد و ضرایب تبیین چندمتغیره (2R) در محدوده بین 73/0 تا 8/0 قرار گرفت. نتایج نشان داد که متغیرهای هیدرولیک به‏ تنهایی قابلیت توضیح پاسخ کانال به سیلاب‏ های شدید را نداشته و گنجاندن فاکتورهای دیگری از قبیل پایداری جانبی، درجه رسوب‏ دهی، و عوامل انسانی برای افزایش قابلیت توضیح مدل‏های رگرسیون موردنیاز است.
    کلیدواژگان: پایداری جانبی، رگرسیون چندمتغیره، سد ایلام، سیلاب شدید، گسترش کانال
  • شبنم محمودی، داود مختاری*، محمدحسین رضایی مقدم، محمد اکبریان، عباس مرادی صفحات 17-31
    تپه‏ های ماسه ‏ای مانعی در برابر امواج ‏اند و می ‏توانند سواحل را از فرسایش حفظ کنند. بنابراین، حفاظت از این تپه ‏ها امری مهم و نیازمند مدیریت است. هدف از این پژوهش بررسی میزان آسیب پذیری تپه های ماسه‏‏ ای واقع در حد فاصل بندر سیریک تا بندر زیارت در جنوب ‏شرق استان هرمزگان است، زیرا ساخت اسکله‏ های جدید در سال‏های اخیر به تغییراتی در ساحل این منطقه منجر شده است. بنابراین، آگاهی از وضعیت آسیب پذیری تپه های ساحلی می‏ تواند در مدیریت و حفاظت این تپه ‏ها اثربخش باشد. در این پژوهش، عوامل موثر در آسیب پذیری تپه های ماسه‏ ای ساحلی، شامل شرایط ژئومورفولوژی تپه های ماسه ‏ای، عوامل دریایی، فرایندهای بادی، پوشش گیاهی، تاثیر فعالیت‏های انسانی، و عامل مدیریتی، با استفاده از چک ‏لیست، ارزیابی شد. داده ‏های استفاده ‏شده شامل داده ‏های آماری، داده ‏های مکانی، بازدیدهای میدانی، تصاویر ماهواره‏ ای، عکس‏ هوایی، و نتایج گرانومتری است. نتایج نشان داد میزان شاخص آسیب پذیری (DVI) در همه محوطه ‏ها متوسط است. همچنین، مشخص شد در میان عوامل مورد بررسی، عامل وضعیت ژئومورفولوژیک تپه های ماسه ‏ای و سپس فرایندهای بادی به ‏ترتیب بیشترین تاثیر را در آسیب پذیری تپه‏ ها دارند. ارزیابی شاخص تعادل نشان داد تعادل میان آسیب‏ پذیری و مدیریت تپه‏ ها در هیچ کدام از محوطه ‏ها وجود ندارد که دلیل آن می‏ تواند نبود متولی مشخصی در زمینه مدیریت اجرایی حفاظت از سواحل باشد.
    کلیدواژگان: آسیب‏ پذیری، بندر زیارت، بندر سیریک، تپه‏ های ماسه‏ ای ساحلی
  • بهلول علیجانی*، میثم طولابی نژاد، علیرضا کربلائی درئی صفحات 33-50
    این مطالعه با هدف بررسی اثر گرمایش جهانی بر رفتار پرفشار جنب حاره به‏ انجام رسید. بدین‏ منظور، از داده‏ های حداکثر دمای روزانه 49 ایستگاه سینوپتیک طی 1977 تا 2016 استفاده شد؛ با توجه به روند دماهای بالای صدک 95، سال 1996 مرز بین دو دوره قبل و بعد از تشدید گرمایش انتخاب شد. نتایج حاصل از تحلیل‏ ها نشان داد در دوره اول مقدار دما به 39.5 درجه رسیده است؛ درحالی‏که در دوره دوم این مقدار به 40.5 درجه رسیده است و فراوانی دماهای آستانه در دوره اول بسیار کمتر از دوره دوم بوده است. به‏ عبارت ‏دیگر، رفتار گرمایش جهانی ثابت شد و فراوانی دماهای بالای 40.5 درجه در بیشتر ایستگاه‏ها فراگیر و به حالت عادی و نرمال درآمد. نتایج تحلیل سینوپتیک نشان داد میانگین بلندمدت ارتفاع هسته پرفشار جنب حاره طی دوره اول نسبت به دوره دوم افزایشی ده‏متری داشته است؛ اما میانگین بلندمدت اختلاف ارتفاع هسته پرفشار جنب حاره در دوره دوم، نسبت به دوره اول، در ماه جولای، در طول 52.5 درجه شرقی به بیش از 100 متر رسیده است. همچنین، نتایج حاصل از رابطه متقابل دما و ارتفاع جو نشان داد که دلیل افزایش ارتفاع هسته پرفشار جنب حاره افزایش دما در لایه‏ های پایین اتمسفر است.
    کلیدواژگان: پرفشار جنب حاره، فراوانی حداکثر دما، گرمایش جهانی
  • محمد کریمی فیروزجایی، امیر صدیقی، مجید کیاورز* صفحات 51-71
    تغییر خصوصیات بیوفیزیکی سطح زمین یکی از مهم‏ترین اثرهای منفی فعالیت‏های انسانی است. هدف از پژوهش حاضر تلفیق قابلیت‏های سنجش از دور انعکاسی و حرارتی برای بررسی و پایش روند تغییرات خصوصیات بیوفیزیکی سطح منطقه معدن مس سونگون ناشی از فعالیت‏های معدنی طی سه دهه گذشته است. بدین‏منظور، از مجموعه داده‏های انعکاسی و حرارتی تصاویر ماهواره‏ای، ایستگاه‏های هواشناسی، و بازدید زمینی استفاده شده است. در این پژوهش، برای طبقه‏بندی کاربری اراضی از الگوریتم طبقه‏بندی بیشترین شباهت، محاسبه دمای سطح از الگوریتم تک‏کاناله و مدل‏سازی خصوصیات بیوفیزیکی روشنایی، سبزینگی، و رطوبت سطح بازه زمانی 1368-1396 به‏ترتیب از پارامترهای آلبیدو، NDVI، و NDWI استفاده شد. نتایج نشان می‏دهد که بر اثر گسترش و توسعه فعالیت‏های معدنی مساحت جنگل‏ها از 94/995 هکتار به 27/594 هکتار کاهش یافته است. طی بازه زمانی 1368-1396 مقدار میانگین پارامترهای آلبیدو، NDVI، و NDWI به‏ترتیب 1/0 افزایش، 08/0 کاهش، و 12/0 افزایش یافته است. همچنین، تغییر کاربری جنگل به معدن به‏صورت میانگین سبب افزایش 8/5 درجه کلوین دمای سطح شده است. نتایج پژوهش حاکی از کارایی بسیار بالای تلفیق قابلیت‏های سنجش از دور انعکاسی و حرارتی برای پایش و مدیریت پدیده‏های مختلف انسانی، محیطی، و طبیعی است.
    کلیدواژگان: خصوصیات بیوفیزیکی، سنجش از دور انعکاسی، سنجش از دور حرارتی، معدن مس سونگون
  • سعید بازگیر*، مصطفی کریمی احمدآباد، ایوب جعفری صفحات 73-86
    این پژوهش با هدف مطالعه ارتباط الگوهای همدید اولین بارش موثر در زمان کاشت (اولین بارش با مجموع حداقل 5 میلی‏متر طی 24 یا 48 ساعت) و عملکرد گندم دیم در کرمانشاه انجام شده است. در این مطالعه، از تاریخ ‏های مراحل نمو گندم دیم رقم آذر 2 و داده‏ های بارش ایستگاه تحقیقات هواشناسی کشاورزی سرارود از سال زراعی 1384-1383 تا 1395-1394 استفاده شده است. با استفاده از داده ‏های ارتفاع ژئوپتانسیل، باد، و رطوبت تراز 850 و 500 هکتوپاسکال اخذشده از داده‏های واکاوی NCEP/NCAR، الگوهای همدید بارش‏های موثر شناسایی شد. نتایج نشان داد که تاریخ مناسب کشت گندم دیم در کرمانشاه در بازه زمانی 3 تا 14 آبان است. همچنین، الگوهای همدید بارش‏های با آستانه بیش از 5 میلی‏متر در دوره مطالعاتی شامل ناوه فرعی، ناوه مدیترانه، بندال امگا، و کم ‏ارتفاع بریده بوده‏ اند. نتایج این تحقیق نشان داد که کمترین عملکرد محصول نسبت به میانگین بلندمدت (2113 کیلوگرم در هکتار) در سال‏ هایی رخ داده است که الگوی همدید بارشی نوع 4 وجود داشته است. از طرف دیگر، بیشترین عملکرد گندم دیم در سال‏هایی رخ داده که الگوهای بارشی 2 و 3 با یکدیگر اتفاق افتاده است.
    کلیدواژگان: اقیانوس هند، شرایط اقلیمی، کرمانشاه، کشت دیم
  • امید مفاخری*، محمد سلیقه، آذر کرمانی صفحات 87-103
    بارش متغیرترین عنصر اقلیمی است که تغییرات آن پیامدهای زیست‏ محیطی دارد. هدف از این پژوهش بررسی تغییر مولفه ‏های ایجاد بارش ایران در سطح میان‏ تروپوسفری است. نخست داده‏ های بارش 53 ایستگاه‏ همدیدی (1984- 2013) از سازمان هواشناسی دریافت شد. برای ناحیه‏ بندی از نظر دوره تداوم بارشی از تحلیل خوشه‏ ای استفاده شد. براساس معیار روز بارشی، ایران به سه ناحیه طبقه ‏بندی شد. به‏ منظور مقایسه تغییرات مولفه ‏های ایجاد روزهای اوج بارش در دو بازه پانزده‏ ساله، داده‏ های ارتفاع ژئوپتانسیل، باد مداری و نصف ‏النهاری، امگا، تاوایی نسبی، و رطوبت ویژه از مرکز اروپایی پیش ‏بینی میان‏مدت جو دریافت شد. نتایج نشان داد اگرچه میانگین ارتفاع هسته مرکزی کم ‏ارتفاع موثر بر بارش اوج در بازه دوم مطالعاتی از شمال به جنوب ایران کاسته و بر عمق ناوه‏ ها افزوده شده است، قسمت جلوی ناوه اغلب در شرق ایران قرار گرفته و تاثیرگذاری آن‏ها بر بارش اوج نسبت به بازه اول کمتر شده است. موقعیت هسته مرکزی پرارتفاع عربستان، نسبت به محل قرارگیری آن در بازه اول، شرقی ‏تر شده و فرارفت رطوبت کمتری داشته است. همچنین، شیب ارتفاع (اختلاف ارتفاع هسته مرکزی با کنتور بیرونی) از شمال به جنوب کشور افزایش داشته است؛ این امر نشان می ‏دهد بر شدت بارش‏ ها افزوده شده است.
    کلیدواژگان: ایران، مولفه‏ های ایجاد بارش، میان‏ تروپوسفر، ناحیه ‏بندی
  • مرتضی پورزارع، عبدالله سیف*، سیروس فخری، حبیب‏ الله سیاری صفحات 105-122
    برخی عناصر اقلیمی، مانند دمای هوا، فشار هوا، و سرعت باد، در زمره شدیدترین تغییرات کوتاه‏ مدت تراز سطح آب قرار می‏ گیرد. در این پژوهش، تغییرات تراز آب بر پایه داده‏ های ایستگاه هواشناسی و ایستگاه ثبت جزرومد با هدف ارزیابی کارآیی از مدل درخت تصمیم ‏گیری (آنالیز غیرخطی) در برآورد و چگونگی اثرهای پارامترهای مستقل بارومتری، نیروی باد، و دمای هوا بر پیش ‏بینی روند پارامتر وابسته میانگین تراز دریا (MSL) سواحل شمالی دریای عمان (مکران ساحلی- جنوب‏ شرق ایران) در ایستگاه ‏های جزرومدی مناطق جاسک و چابهار در یک دوره  بیست ‏ساله (1997-2016) ارزیابی و محاسبه شده است. براساس رابطه مدل نهایی در منطقه جاسک ((71/0)W 208/7 + (195/0) P 092/11 - (102/1) T 619/5+ 197/13MSL=) و در منطقه چابهار ((316/0) W776/2+(87/0) P596/1-(089/1) T529/1+520/4MSL=) حاصل از الگوریتم درخت تصمیم‏ گیری در پیش ‏بینی MSL با استفاده از داده‏ های موجود تا 95درصد قابل اطمینان است. با توجه به دامنه نوسان جزرومد، به طور متوسط، در منطقه چابهار 1 تا 5/1 متر و در منطقه جاسک بیش از 3 متر برابر بازه زمانی به ‏دست ‏آمده در نمودارها با بررسی اجمالی اشکال ژئومورفولوژیکی در منطقه مطالعاتی از لحاظ آثار مورفولوژیک و داغ آب نیز به‏ خوبی مطابقت می ‏نماید.
    کلیدواژگان: الگوریتم درخت تصمیم، تراز دریا، سواحل شمالی دریای عمان (مکران ساحلی)، شاخص‏های اقلیمی
  • مهدی حیدری، شهریار خالدی*، طیبه اکبری ازیرانی صفحات 123-134
    هدف از این تحقیق بررسی روند بلندمدت رخدادهای گرد و غبار و تاثیر این رخدادها در شهر ایلام بر نگاشت های بروز بیماری های تنفسی است. در این راستا، داده های مجموعه ای از رخداد های گرد و غبار دیدبانی شده روزانه (Total Dust Event)TDE طی دوره آماری 1995-2015 در دو ایستگاه سینوپتیک ایلام و دهلران بررسی شد. نتایج نشان داد که شیب افزایش نگاشت های گرد و غباری در دو ایستگاه ایلام و دهلران به ترتیب 8/0 و 96/0 رکورد در سال بوده است. ماتریس همبستگی بیانگر آن بود که در سطح اطمینان مورد بررسی، ارتباط مستقیم معنی داری بین تعداد نگاشت های سالانه مراجعان بیماری های ریوی و تنفسی ثبت شده در بیمارستان شهید مصطفی خمینی شهر ایلام و رخدادهای گرد و غبار برقرار است؛ به گونه ای که در سال هایی که تعداد نگاشت های گرد و غباری بیشتری در دو ایستگاه ایلام و دهلران ثبت شده است، نگاشت های مراجعان بیماری های تنفسی به طور معنی داری بیشتر بوده است. همچنین، مقایسه نتایج به دست آمده از ارتباط معنی دار بین افزایش تعداد نگاشت های مراجعان بیمارستان و افزایش روند رخداد گرد و غبار در دو ایستگاه سینوپتیک ایلام و دهلران با نتایج سایر محققان در استان کرمانشاه و اهواز مطابقت دارد.
    کلیدواژگان: ایلام، بیماران تنفسی، روند، گرد و غبار، ماتریس همبستگی
  • حسین عساکره*، لیلا حسینجانی صفحات 135-148
    بارش عنصری اقلیمی با وردایی زمانی- مکانی بسیار بالاست. از جلوه‏ های وردایی بارش مقادیر فرین آن است که با پیامدهای محیطی- انسانی و به ‏سبب تاثیرات گسترده در ساختارهای فیزیکی و انسانی در کانون مطالعات اقلیمی است. بنابراین، بررسی این نوع بارش ‏ها در ناحیه ‏ای که قطب کشاورزی است و، از طرفی، این بارش ‏ها یکی از مخاطرات طبیعی است اهمیت دارد. به ‏منظور واکاوی فضایی مجموع فراوانی سالانه بارش شدید (آستانه ‏های صدک 90-95، 95-99) و خیلی ‏شدید (صدک 99 و بیشتر)، از داده ‏های میان‏ی ابی ‏شده بارش روزانه طی بازه 1966-2016 استفاده شد. برای شناسایی الگوی پراکنش مکانی از آماره موران و Gi* استفاده شد. با توجه به مقدار نمایه موران کلی 9/0 (سطح اطمینان 99درصد)، الگوی فضایی برازنده بارش‏ها الگوی خوشه‏ای است. در گروه بارشی شدید، بیشتر الگوهای خوشه‏ ای مثبت در بخش‏های مرکزی و غربی و بارش خیلی شدید بیشتر در بخش شرقی، مرکزی و ناخوشه ‏ها در گروه اول و دوم بیشتر در بخش شرقی و در گروه سوم در بخش‏ های مرکزی و جنوب‏ غربی ناحیه است. آزمون Gi* فراوانی خوشه هایی با ارزش بالا و پایین را تایید می‏‏کند. در بررسی روابط مکانی با آماره دومتغیره موران، طول جغرافیایی و ارتفاعات البرز بیشترین تاثیر را در رخداد بارش‏ ها دارند.
    کلیدواژگان: بارش شدید و خیلی ‏شدید، فراوانی سالانه، نمایه موران و Gi*، ناحیه خزری، واکاوی مکانی
  • سحر نصیری قلعه بین، برومند صلاحی*، علی اکبر رسولی، فرامرز خوش اخلاق صفحات 149-162
    توفان‏ های تندری، به‏ دلیل رفتار بسیار نامنظم در ابعاد مکانی و زمانی، در منطقه شمال‏ غرب ایران از پدیده ‏های آب و هوایی حائز اهمیت به‏ شمار می‏روند، زیرا این نوع بارش‏ ها نقش بسیار مهمی در فعالیت‏ های اجتماعی و اقتصادی مانند تولید محصولات کشاورزی، استفاده از زمین زراعی، و مدیریت منابع آب دارند. در این پژوهش، به‏ منظور شناسایی الگوهای سینوپتیک توفان‏ های تندری طی بازه زمانی 1961-2016، از داده‏ های ایستگاهی بارش شدید بیش از 50 میلی‏متر و داده‏ های فشار ارتفاع ژئوپتانسیل تراز 500 هکتوپاسکال استفاده شده است. روش نقشه ‏های خودسازمان‏دهSOM  و آزمون پتیت در نرم ‏افزار  Rبه‏ منظور شناسایی الگوهای بارش به‏کار گرفته شده است. براساس نتایج، نه الگوی جوی در تراز 500 هکتوپاسکال نشان داده شده و تصاویر مربوط به هر الگو در نرم‏افزار Grads ترسیم شده است. این الگوها نشان می‏ دهند که در بارش ‏های شدید بهاره رخداد بلوکینگ امگایی ‏شکل، تشکیل ناوه عمیقی بر روی شمال خزر، و پدیده بلوکینگ رکس؛ در الگوهای تابستان بلاکینگ حلقه آتش و بلاکینگ کم ‏فشار بریده؛ در الگوی زمستان بلوکینگ رکس؛ و در الگوی پاییز یک ناوه عمیق در بخش شمالی ایران و بلوکینگ کم‏ فشار بریده دیده می ‏شود. بیشترین درصد بارش متعلق به الگوی B3 با 45درصد فراوانی و کمترین مقدار بارش متعلق به الگوی A1 با 20درصد است.
    کلیدواژگان: اردبیل، الگوهای گردش جوی، توفان تندری
  • مهرداد نصراصفهانی، حجت‏ الله یزدان پناه*، محمدعلی نصراصفهانی صفحات 163-182
    وقوع مخاطرات جوی، همچون یخبندان و سرمای دیررس بهاره، سالانه، خسارات زیادی در بخش کشاورزی ایجاد می‏ کند. برنامه ‏ریزی به‏ موقع می‏ تواند خسارت ناشی از بلایای طبیعی را کاهش دهد. امروزه، با استفاده از مدل‏ های پیش‏ بینی عددی وضع هوا، می‏توان از خسارت‏ های ناشی از آن‏ها جلوگیری کرد. در این تحقیق، برای ارزیابی پیش‏ بینی دما توسط مدلWRF  در زمان وقوع سرماهای دیررس بهاره، از یازده ایستگاه هواشناسی واقع در حوضه آبریز زاینده ‏رود، با درجه تفکیک افقی یک کیلومتر، شبیه‏ سازی شد. سپس، با دو رویکرد نقطه‏ ای و منطقه‏ ای دماهای شبیه‏ سازی‏ شده با مقادیر دیدبانی متناظر در پیش‏ بینی ‏های 24 و 48ساعته دمای سطحی (دومتری) ارزیابی شد. براساس نتایج جذر میانگین مربعات خطا، ضریب تعیین اصلاح‏ شده و شاخص میانگین اریبی که برای دمای شبیه‏ سازی 24ساعته بهتر از 48ساعته است به ‏ترتیب 8/2، 88/0، و 48/0 بود. ارتباط قابل قبولی از لحاظ آماری (ضریب همبستگی) بین متغیر مستقل، که همان داده ‏های مدل WRF است، و متغیر وابسته، که همان داده ‏های دیدبانی ‏شده (واقعی) است، وجود دارد.
    کلیدواژگان: پیش ‏بینی دما، تفکیک افقی، راست ‏آزمایی، مدل WRF
  • فاطمه خدادادی، مژگان انتظاری*، فرزانه ساسان پور صفحات 183-199
    مخاطرات زمینی و ژئومورفیک از مخاطرات مهم طبیعی ‏اند که سالیانه خسارات جانی و مالی زیادی در کل کشورهای جهان و به‏ ویژه ایران به ‏بار می ‏آورند. از این ‏رو، مطالعه و تهیه نقشه پهنه‏ بندی مخاطرات امروزه یکی از اولویت‏های هر کشور به‏ شمار می ‏آید. در این تحقیق به بررسی مخاطرات زمین‏ لغزش و سیل در سطح استان البرز پرداخته شده است. برای تهیه نقشه پهنه ‏بندی خطر زمین ‏لغزش استان، از مدل ترکیبی VIKOR-AHP و برای تهیه نقشه پهنه ‏بندی خطر سیل از مدل نسبت فراوانی FR استفاده شد. سپس، به‏ منظور داشتن دیدی کلی و جامع نسبت به وضعیت این مخاطرات، نقشه تلفیقی مخاطرات استان، که از همپوشانی دو نقشه پهنه ‏بندی سیل و زمین ‏لغزش است، با استفاده از مدل FUZZY تهیه شد. طبق نتایج نهایی حاصل از نقشه‏ های پهنه ‏بندی هر یک از مخاطرات، 09/33درصد سطح استان در پهنه با خطر زیاد زمین‏ لغزش و 21/21درصد از سطح استان در پهنه خطر متوسط سیل قرار دارند که شناسایی و پهنه ‏بندی مناطق دارای پتانسیل خطر وقوع این‏گونه مخاطرات اهمیت بسیاری دارد.
    کلیدواژگان: استان البرز، مخاطرات ژئومورفیک، مدل نسبت فراوانی، مدل VIKOR-AHP
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  • Zahra Khanbabaei, Ebrahim Moghimi *, Mehran Maghsoudi, Mojtaba Yamani, Seyed Kazem Alavipanah Pages 1-15
    Introduction A major issue has been the role of large floods in comparison to more frequent floods with lower magnitude. This work addresses the geomorphic response of Mountain Rivers to extreme floods, exploring the relationships between morphological changes and controlling factors. In October 2015, following the occurrence of extreme and sudden rainfall, a large and devastating flood occurred in Ilam province. The floods caused major changes in the morphology of Ilam's rivers and it was accompanied by a considerable extension. The rate of channel expansion in different sections of the studied rivers varied, which led us to examine the influential and controlling factors that led to the diversity of river behavior.The working hypothesis was that explanation of geomorphic effects requires models that include other variables (e.g: lateral confinement, degree of sediment) besides hydraulic related variables (cross-sectional or unit stream power). The main aim was thus to explore the relationship between channel widening and arrange of controlling factors.Other specific aim addressed were which channel width (i.e: pre- or post-flood width) should be considered to calculate unit stream power in order to have a better explanation of channel response? Since few studies have been done in this field, this research was conducted with the aim of investigating the factors controlling the response of Mountain Rivers to extreme flood events in upstream of Ilam dam. Materials and methods The research was conducted on three tributaries of the Konjancham River (upstream of Ilam dam) whose catchments were affected by an extreme flood on 7th October 2015. An integrated approach was deployed to study this flood, including (i) Analysis of channel width changes by comparing aerial photographs taken before and after the flood, (ii) Estimate of peak discharges in studied reaches, (iii) Determine the degree of sedimentation in studied reaches. Delineation of spatial units was carried out according to the approach proposed by Rinaldi et al. (2013), which is a modification of the approach by Brierley and Fryirs (2005).According to that approach, stream sectors were defined as macro reaches having similar characteristics in terms of lateral confinement, while reaches are homogeneous also in terms of channel morphology (channel pattern, width, slope) and hydrology. We used the reach scale (reach length was commonly from 200 to 1300 m) for an overall assessment of magnitude of channel changes and for a preliminary investigation of controlling factors. The dominant process observed in the study reaches was channel widening, which was analyzed in detail by comparing aerial photographs taken before and after the flood. To assess changes in channel width, channel banks, and islands, these features were digitized on pre- and post-flood orthophotos. Channel width was calculated dividing channel area by the length of the reach, and changes in channel width were expressed as a width ratio (channel width after/channel width before the flood).The estimation of peak discharges used to calculate cross-sectional stream power and unit stream power. The last part of the methodological section deals with statistical analysis carried out to explain channel response to the flood event, by exploring the relationships between changes in channel width and controlling factors. Results and Discussion The relationships between the degree of channel widening and possible controlling factors were explored using multiple regression analysis. The analysis was carried out for the widening (width ratio) at reach scale.The whole data set includes 38 reaches. Seven controlling variables were considered (confinement index, percentage of reach length with artificial structures, degree of sedimentation, channel slope, cross-sectional stream power, and unit stream power calculated using pre-flood and post-flood channel width), but each regression model incorporated only three to four variables. Each model included only one of the variables expressing potential or flood flow energy (channel slope, cross-sectional stream power, unit stream power). All four multiple regression models turned out to be significant (p< 0.001) and gave high coefficients of multiple determination (R2and adjusted R2 ranged between 0.73 and 0.8 and between 0.69 and 0.77, respectively). The best model was the one including unit stream power calculated based on pre flood channel width and confinement indexas explanatory variables. Conclusion Results confirmed the main hypothesis of this work that hydraulic variables alone are not sufficient to explain channel response to an extreme flood event. The inclusion of other factors, specifically lateral confinement, degree of sedimentation, and percentage of reach length with artificial structures, led to satisfactory models explaining the observed variability in the degree of channel widening. These results suggest that the widening process is essentially controlled by two factors: flood power and valley confinement. Notably, flood duration above a critical threshold was not included in our analysis, but it is a variable that very likely would increase the robustness of regression models in these reaches. The analysis carried out in the three subcatchments of the Konjancham River basin showed that unit stream power calculated based on pre-flood channel width has stronger relations with channel widening in comparison to unit stream power calculated based on post-flood channel width and to cross-sectional stream power. Because peak discharge was used for stream power calculation, we are aware that neither pre-flood nor post-flood channel width is actually appropriate for the estimation of unit stream power, as the most appropriate would be the (unknown) width at the flood-peak time. The fact that using the pre-flood width gives better relations with the degree of channel widening (width ratio) could suggest that most width changes occurred after the flood peak.
    Keywords: lateral confinement, Multivariate regression, Ilam dam, extreme flood, channel expansion
  • Shabnam Mahmoodi, Davod Mokhtari *, Mohammad Hosin Rezai Moghadam, Mohammad Akbarian, Abbas Moradi Pages 17-31
    Introduction
    Coastal sand dunes are one of the important morphological forms of coastal areas that form behind the coast. These hills have been caused by interactions of sea waves, sea currents, winds and sediment materials on the coast. Sand dunes can protect the coast against waves and erosion, so protecting these hills is important and requires management. Study area is located between the Sirik port and the port of Ziarat, in the southeast of Hormozgan province. Since the construction of new docks in recent years has led to changes in the coast of this region, so awareness of the vulnerability of coastal hills can be effective in managing and protecting these hills. The purpose of this study was to assessing vulnerability of sand dunes by model DVI ( dune vulnerability index). Checklist was used to evalouated to vulnerability index. In this research, effective factors in coastal sand dunes, geomorphologic conditions of sand dunes, marine factors, wind processes, vegetation, effects of human activities and management factor were evaluated using checklist.
    Materials and methods
    In this study, data from Google Earth, Landsat, and aerial photos, and questionnaires and field operations were used to complete the checklist. The steps to complete the checklist are as follows: in the first step, the value range for the quantitative variables was determined on the basis of the available structured checklists .Partial vulnerability indices geomorphological condition (GC), marine influence (MI), aeolian influence (AI), vegetation condition (VC) and anthropogenic effects (AE) were calculated as the ratio between the summations of given variable ranks within each variable class (PVi) and the total maximum possible rank within the class. A total DVI ( total Dune Vulnerability Index) was calculated as the average of the five partial vulnerability indices (PV) as per. The protection measure index (PM) was calculated separately from other factors. Lastly, the residual value as the difference between DVI and PM (DVI-PM) has been calculated to describe the stability of the dune system. In the studies by Davis (1995) to calculate the vulnerability index, referred to as (VI) the calculation of the partial Vulnerability Index is not done, and the vulnerability score from the division of the total variables obtained from all the group of variables, based on the maximum total sum of the concessions of the entire group of variables, is obtained for each site.
    Results and discussion
    Partial vulnerability (Pv), for geomorphologic agent, is above 0.75 in all sites and the degree of vulnerability is very severe because of characteristics of the sand dunes of the region, including low height, slopes over 30 degrees of their upward slopes, fine-to-good sorting. The vulnerability to wind processes in all areas is above 0.5 and shows a high sensitivity to this factor. One of the reasons for wind processes is the small average of the diameter of coastal sediments in this area, because fine sands are exposed to retrogressive waves and are more sensitive to erosion, so beaches with fine sand grains have less resistance to erosion have. The low vegetation of the hills in the side of the sea, in the distance between the hills and the maximum of fashion and the relatively high percentage of uncovered areas, are other factors of high hills' sensitivity to wind processes. The degree of vulnerability to vegetation condition is very severe in sites 4, 5 and 6, and is low in enclosures 1, 2 and 3. Compared with 1966 aerial photos and satellite imagery from 2000 to 2016, vegetation increased than in 1966 and 2000, due to planting and plant care by government office like office of resource natural in Hormozgan. The level of vulnerability to the human factors of sites 1 and 2 is modest and in the rest of the sites is negligible. With the use of aerial photographs and satellite imagery, during the years mentioned above, the amount of roads in this area has been increased and in some areas the road passes through the hills. During these years, some parts of the hill for construction have been cleared. In addition, the construction of three new berths of 3 Sirik (2007), Ziarat (2012) and Taheroi port (2013) has also been associated with shore changes. Due to the field visits and the results of the questionnaires( interviews with local people and experts) show no management action such as specifying areas with access restrictions, and so on to protecting beaches. The only protective action is the planting of seedlings in sites 1, 2 and 3, The only protective action is the planting of seedlings in sites 1, 2 and 3, by natural resources office. Coclusion: The overall vulnerability (DVI) in all areas was moderate. Among the investigated factors, the morphological status of sand dunes, the factor of wind processes, have the most effect on the vulnerability of hills. The results for the DVI-PM index indicate that all sites need quick management. Based on the obtained equilibrium index, there is no equilibrium between vulnerability and hill management in any of the sites indicating lack of management or inadequacy. One of the reasons for lack of management or efficent management seems to be that is not a certain organization responsible in this regard. Comparison of the two methods for the calculation of vulnerability, the first method (DiPanjun, 2014) and the second method (Davis, 1995) shows that In both methods, the severity of the vulnerability of the sites is moderate. There is no difference between the qualitive results obtained in two methods.
    Keywords: coastal sand dunes, &quot, vulnerability&quot, Sirik port, Ziarat port
  • Bohloul Alijani *, Meysam Toulabi, Alireza Karbalaee Doree Pages 33-50
    Introduction Climate change in recent years has led to changes in atmospheric patterns and the appearance of climatic anomalies in most parts of the world. Earth’s climate is a complex dynamic system that involves hydrosphere, cryosphere, biosphere and lithosphere. If any of these system changes, other systems will quickly or slowly align themselves with it, and the outcome of this coordination also affects the system initiated the change. Eventually, an endless chain of links is created between these systems. The interaction between these four systems is responsible for the concern of weather and climate scientists in recent years and propounded the term of "climate change". The result of global warming is climate change. The process of climate change, especially temperature changes, is one of the most important discussions in the field of environmental sciences. Many of our age-old problems, such as floods, storms, droughts, changes in atmospheric patterns, and so on, are rooted in climate change, especially in air temperature increasing. This study aimed to investigate the effect of global warming on subtropical high pressure behavior. Data and Methodology In order to investigate the effect of global warming on the subtropical high pressure behavior, the following steps have been taken. In the first step, maximum daily temperature data of 49 synoptic stations during the period from 1977 to 2016 were used to study the frequency of temperature higher than percentile 95 in each year. Regarding the frequency of temperature higher than percentile 95, this trend has been dramatically has been rose in 1996, so this year has been set as the border between the two pre-warming and post-warming periods. In the second stage, given that global warming is expected to increase these extreme temperature, frequency of temperature higher than percentile 95 was investigated in both periods. In the third stage, changes in the behavior of subtropical high-pressure in terms of height and spatial extent were determined based on 500-hPa geopotential data, derived from European Center for Medium – Range Weather Forecasts (ECMWF). Finally, to prove the existing relationship between the data, the 500-hPa geopotential height anomalies were plotted over the two periods and analyzed to determine that what changes occured in height of the middle level. Result and Discussion By examining the results, it was found that the long-term average of core height of the subtropical high pressure during the second period (1996-1997) has increased by 10 meters relative to the first period (1996-2016). Given the frequency of the thresholds of percentile 95 of the second period, it can be said that most stations have experienced extreme temperatures, so it can be said that global warming has been proven. It can be said that during the current period, a temperature of 40°C is a normal temperature. Therefore, due to the mutual and direct relationship between temperature and height of the atmosphere, it can be said that the reason for increasing the height of the core of the subtropical high pressure is the increase of temperature in the lower layers of the atmosphere. When the temperature increases in the layers near the land surface, thermal low pressure on the land surface and the dynamical high pressure resulting from the subtropical high pressure subsidence and some systems, including Monsoon, are created and for every 1000 meters, while increasing power, it increases air temperature by 6˚C. Thus, the core height of the subtropical high pressure is increased and the maximum temperatures are recorded, especially during the warm months. Pearson correlations also indicate a very strong and positive correlation between the core height of the subtropical high pressure and the maximum temperature in the both periods. Conclusion The results of the analysis of the maximum temperature data showed that during the first period, the temperature reached 30.5 ° C in percentile 95 while during the second period with 1˚C increase it reached 40.5˚C. It can be said that in the first period of global warming we did not have much intensity in our country, but in the second period temperature reached its maximum and the effect of this warming is seen in the recorded temperature. In other words, global warming has been proven and the frequency of temperatures above 40.5 ˚ C has become prevalent in most stations. Spatial analysis of the core of subtropical high pressure indicates that its highest height in the first period over Iran is 5910 m which affect fewer stations. But in the second period, the core height of subtropical high pressure is 5940 meters, which, in comparison with the first period, shows increase in both height and extent resulted in higher temperature. It was found that the long-term average height of the subtropical high pressure core during the second period (1996-1997) has increased by 10 meters relative to the first period (1996-2016). Given the frequency of the thresholds of percentile 95 of the second period, it can be said that most stations have experienced extreme temperatures, so it can be said that global warming has been proven. In other words, during the current period, the temperature of 40 degrees is a normal temperature.
    Keywords: Tropical high pressure, Frequency, maximum temperature, global warming
  • Mohammad Karimi Firozjaei, Amir Sedighi, Majid Kiavarz * Pages 51-71
    1. Introduction Land use has always been one of the most important indicators that humans through its have been influenced their environment.Nowadays, processed mining and related operations are parts of activities that have potential to harm the environment. Mining is in direct contact with nature and the environment, so this will have important effect on the environment. The negative effects of mining activities on changes in surface biophysical parameters such as greenness, brightness, wetness and land surface temperature (LST) depend on the type of minerals, location of the area, extraction method and other factors. Remote sensing technology provides useful information to understand temporal and spatial changes of land use/cover and land development processes. Sungun is a large porphyry copper mine and extraction method of this mine is open pit mining. The important environmental pollutions in this method of mining are land and landscape degradation, mass production of waste mineral extraction and loss of vegetation covers. Due to Sungun copper mine geographic location which it’s adjacent to the Arasbaran forests and Dezmar protected area, the activities of this mine are environmental impact of great environmental importance.The objective of the present study is integrating reflective and thermal remote sensing capabilities to analyze and monitor changes in the surface biophysical parameters of the Sungun copper mine region caused by mineral activities over the past three decades. 2. Data and methods In the current study, the reflective and thermal bands of satellite images acquired by Landsat 4, 5, 7, and 8 have been used to calculate the LST and biophysical parameters. Also, the water vapor products (MOD07) and the LST products (MOD11) of MODIS sensor of TERRA satellite, the air temperature data measured at the meteorological stations and ground data have been used. In the first step, using reflective bands set of Landsat images, the land use change trends in the study area for the period 1989 to 2017 were extracted and analyzed. Satellite images classified based on maximum likelihood classifier. The cross tab model was used to study land use changes trend. In the second step, the changes in biophysical parameters such as greenness, brightness and wetness caused by mineral activities have been investigated. In order to model the surface biophysical parameters of brightness, greenness and wetness for the period from 1989 to 2017, Albedo, NDVI and NDWI parameters were used, respectively. In the third step, by integrating the reflective and thermal remote sensing capabilities, the LST maps are extracted from different years and the trend of LST changes due to land use changes in different time periods has been investigated. For LST retrieval, a single-channel (SC) algorithm was applied. Finally, the zonal analysis has been used to analyze the trend of LST changes caused by land use changes in the studied are. 3. Results and Discussion Over the past two decades, with the increase in the activities of Sungun mine, the area of this land use has increased dramatically. The results indicate that the area of the mine class will increase from 13.41 ha in 1993 to 621.54 ha in 2017. During the same period, as a result of the expansion and development of mineral activities, the area of the forests decreased from 995.94 to 594.27 ha. In the period under study, 2295 ha of forest area has changed to mine land use. Also, more than 2632 ha of pasture land has become mine land. The results demonstrate that during the period of 1989 to 2017, the mean values of Albedo, NDVI and NDWI parameters increased, decreased and increased, respectively. The mean of surface albedo values for the study area has been increased from 0.17 in 1989 to 0.25 in 2017. Also, the mean value of the NDVI index has been decreased by almost 0.09 during the period from 1989 to 2017. The major reason for a decrease in NDVI mean values is the reduction of the forest lands and the conversion of them into the mine and pasture lands in past years. In all dates, the lowest and highest LST mean were related to forest and bare land classes, respectively. In these years, the mean value of LST of the forest is, on average, 6.36 °C below the mean value of the LST of the mine land use. The results revealed that land use changes from forest to mine, pasture to mine, forest to pasture, forest to bare land and pasture to bare land have changed the LST 5.8, -0.1, -1.4, -1.6, 3.3, and 0.9 °C, respectively. 4. Conclusions One of the most important negative impacts of human activities is the change in the surface biophysical parameters. Changing the earth's surface biophysical parameters causes a change in many processes and natural cycles of the earth, including the energy billing cycle. The results of this study are a major warning to environmental authorities to provide appropriate plans and solutions to reduce the negative effects of Sungun copper mineral activities. Also, the results of the study indicate the usefulness and efficiency of the integration of reflective and thermal remote sensing capabilities for monitoring and managing various human, environmental and natural phenomena.
    Keywords: Biophysical parameters, Reflective remote sensing, Thermal remote sensing, Sungun copper mine
  • Saeed Bazgir *, Mostafa Karimi, Ayob Jafari Pages 73-86
    Introduction Understanding of climate parameters and their effects on crop growth is one of the most important agricultural issues. The purpose of this recognition is to increase crop yield and thereby increase production. The position of Iran and its natural geographic features have led to a variety of climate and seasonal variations. These variations in each season has created different conditions for agricultural products. Among the climatic elements, the amount and temporal distribution of rainfall and temperature fluctuations in different stages of crop growth have the greatest impact on the yield of agricultural products, especially rain-fed wheat cultivation. In the growth stages of each crop, especially in rain-fed agriculture, the planting date and the first effective rainfall are an important environmental-managerial factor in production. The main goal of current study was to investigate the relationship of synoptic patterns of effective precipitation with planting date and yield of rain-fed wheat in Kermanshah County. Materials and Methods In this study, data from growth stages (phenology) of wheat, Azar-2 variety, and precipitation of the agrometeorological research station of Sararood, Kermanshah were used from 2004-2005 to 20015-2016. In the next step, the data of geopotential heights, wind speed and direction and specific humidity from 850 and 500 hPa levels were taken from NCEP / NCAR reanalysis dataset. The planting date of rain-fed wheat has been calculated based on 2 methods. In the first method, the starting dates for the first effective rainfall were determined. Accordingly, the date of cultivation was when the total precipitation of 5 mm within one or two consecutive days occurred and after that, the precipitation occurred by 10 days. The second method was to determine the planting date on the basis of climatic data of sowing and germination dates recorded in Sararood agrometeorological research station during the years of study. The effective rainfall was defined as 5 mm rain to wet 5 cm of soil depth for a soil with loamy. Moreover, the staring date of sowing wheat was calculated according to Weibull formula with a 75-percent probability of success. In the following, taking into account the first days of precipitation and based on the number of rainy days, the synoptic patterns of the occurrence of effective rainfall have been derived using a correlation-based method. Results and Discussion According to the results, suitable dates for Rain-fed wheat cultivation in Kermanshah Province were from Aban 3(October 25) to Aban 15 (November 5). In this research, by determining the threshold of correlation coefficient (0.57), 4 general synoptic patterns were found. The features of each pattern were as follows: pattern 1 had the highest share in severe rainfall. This pattern in the pre-germination stage (sowing) had the highest frequency in the occurrence of effective rainfall of 5 mm and more. Pattern 2 was in contrast with Pattern 1, and it was most frequent occurrence in rainfall. Patterns 3 and 4 had characteristics such as limited rainy days and extreme daily rainfall. In addition, synoptic patterns of effective precipitation more than 5 mm were minor trough, Mediterranean trough, Omega Block and cut-off low. The results of synoptic studies of atmospheric patterns also showed that the northern seas of Indian Ocean (Red and Arabian Seas) are the main sources of moisture for all synoptic patterns. Conclusion The main goal of current study was to investigate the relationship of synoptic patterns of effective precipitation with planting date and yield of rain-fed wheat in Kermanshah County. The effective precipitation from synoptic patterns 2, 3 and 4 provided conducive conditions for germination of plant in the next priority after the first pattern. The results indicated that the lowest wheat yield as compared to average yield (2113 kilograms per hectare) occurred in the years with the forth precipitation pattern. On the other hand, the highest wheat yield observed when the synoptic patterns of 2nd and 3rd were occurred simultaneously within a year. For example, the years of 2006-2007, 2014-2015 and 2015-2016 had wheat yield of 2888, 2486 and 2700 kilograms per hectare, respectively. Moreover, the effect of synoptic patterns on planting date showed that the commencement of first effective rainfall with patterns 1, 2, 3 and 4 delayed germination stage with an average of 4, 10, 3 and 5 days, respectively. In conclusion, it should be noted that to take more precise results, it is reasonable to work with long- period data.
    Keywords: Rain-fed Cultivation, Climate Conditions, Indian Ocean, Kermanshah
  • Omid Mafakheri *, Mohammad Saligheh, Azar Kermani Pages 87-103
    Changes effective components in peak rainfall Iran. Introduction Since the spatial and temporal distribution of rainfall in Iran is influenced by the distribution of global circulation systems, the slightest change in its pattern is the severe weather abnormalities. Therefore, spatial and temporal abnormalities of rainfall and extreme changes in rainfall intensity and differences in precipitation types are one of the main characteristics of Iranian rainfall. Climate change is one of the problems of human society and is a threat to the planet Earth. The increase in the temperature of the earth has caused profound and extensive changes in the Earth's climate, causing changes in the time and place of precipitation, which has caused a lot of damage, especially in the last decade. The purpose of this study was to identify and study the changes in the heavy rainfall component of Iran in relation to changes in the systems middle tropospheric. Materials and methods First, the daily rainfall data of 53 synoptic stations were received from the country's Meteorological Organization from 1984 to 2013. The cluster analysis and zoning were done using Euclidean distance method and Ward's method was used. For zoning based on cluster analysis, seven variables of rainy day (one day, two consecutive days, three consecutive days, four consecutive days, five consecutive days, six consecutive days and seven days of continuous rainfall) were used. The final result was the division of the country into 3 regions according to the number of days. In the following, data from the upper atmosphere levels were used to investigate changes in the mechanisms of rainfall formation. Includes discovery data of geopotential heights, u wind, v wind, omega, level, 500 hpa, and specific humidity level 700 at daily average and 1 * 1 degrees from the European Center for Medium Term Forecast ( ECMWF) received. The statistical period of study was divided into two periods of 15 years (first study period 1984-1998 and second study period 1999-2013), The peak days for each area were determined in each of the two time periods. And for each time period The peak of rainfall was 5 days. Then, the synoptic parameters were analyzed and compared in each study period. Discussion In area 1 in the second study period, the range of trough decreased and the depth of trough increased. The central core of geo potential heights in the first time period is greater than the second period of study, in other words, the core in the first period is 5400 geo potential meters, which in the second interval decreased to 5350 geo potential meters. In area 2, in the second period of studies, the high elevation in the convergence region of the Arabian Sea is more shallow and in a more inappropriate position than the first pattern. In area 3, in the second study period, northwest of Iran is located behind the trough, and cold weather is falling and the rainfall in this part of the area is low. In 3 areas, in the second period of studies, the amount of moisture has decreased and caused the rainfall of the second interval to decrease compared to the first interval. Conclusions In the second period of studies (1999-2013), the range of trough has decreased and the depth of trough has increased. The Omega component study showed that in the second study period, the mean omega-negative peak of the peak days of the target area was reduced. The Omega component study showed that in the second study period, the mean omega-negative in the target area was reduced. It was also found that the direction of the wind streams in the second period was reduced due to the flow Linear more of the amount of precipitation. The amount of moisture in the second period of study has also decreased and has caused the second period rainfall to decrease over the first period. In the study of the synoptic components of area two, it was found that in the second period of studies (1999-2013), located on the convergence area of the Arabian Sea, is more shallow and in a more inappropriate position than the first pattern. And caused the maximum moisture content to fall to 5 grams per kilogram. In the study of the synoptic components of the third region, it was found that in the second study period, the study area, especially the northeast of the country, is somewhat ahead of the trough, and the average annual precipitation in this part of the area is increasing in the second period. And the northwest of Iran is located behind the trough and the cold weather has fallen. The rainfall in this part of the area has decreased. Keywords: Zoning, mechanism of precipitation. Middle troposphere, Iran.
    Keywords: Zoning, Components of rainfall, Middle troposphere, Iran
  • Morteza Pourzare, Abdollah Seif *, Sirous Fakhri, Habibollah Sayari Pages 105-122
    Extended Abstract Introduction The relationship between form and process in geomorphology is very important. By changing the process, the forms will be changed and new processes will be created in the form of new forms (Gurabi & Emami, 2017. p:75). Sea level changes mainly include tidal variations and changes due to atmospheric factors. Tidal flows are also affected by coastal washing during their daily advancement and retreat on tidal slopes and tidal zones. The formation of many coastal geomorphologic forms is the result of their involvement. (Nohegar & Hosseinzadeh, 2011. P:131). Climatic factors cause short time fluctuations and tidal cycles and long term fluctuations in medium level of sea (Yamani & MohammadNejad, 2012: p: 87). Torabi Azad and Honarmand (2016) performed a concise investigation about sea level changes in Banda Abbas and Booshehr Stations in a period of 11 years (2000 to 2010) and analyzed and computed barometric effects, wind force and temperature on the sea level mean. The results showed that sea level mean in these stations has incremental trend by 5 cm and 4 cm respectively in the mentioned seaports. Akbari et al (2017) In order to investigate and analyze important tidal components in a vast area including Persian Gulf, Hormuz Strait, Oman sea and Arab sea applied 3D FVCOM Model. The results of this research shows that there is four kinds of tides in Persian Gulf including Daily, semi-Daily, daily compounded and semi-daily compounded tides and on the other regions there is just semi-daily compounded ides.The research aims on investigating the effects of climate change parameters (temperature, pressure, and wind rate) on the sea level fluctuations in an annual, seasonal and monthly changes and 20-year period in northern coasts of Oman Sea and also its physical justifications. Matarials and methods Research domain from geographical networking point of view, Jask port has longitude and latitude of 570 46' in east and 250 40' in north respectively to Gowatre Bay and in the terminal point of southeast of Iran and southwest of Pakistan has longitude and latitude of 570 46' in east and 250 10' in north respectively. Through calculating mean sea level from tide gauges datum belonged to IOC (Intergovernmental Oceanographic Commission) in the stations of hydrography of Jask and Chabhar ports during 1997 to 2016. Tide gauges for mentioned stations during 24 hours presented 1440 datum. In fact they registered sea level in every minutes. Data presented in every minute through averaging changed firstly into hourly data then into daily and finally into monthly data. In order to compute data based on monthly averages, the tidal effect should be deleted and computed into level fragment that means sea level minus tidal effect. According to the presented information in meteorological organization since 1997 to 2016, data about pressure, temperature and wind force were used in research stations as monthly means and the diagrams used monthly, seasonal and yearly means. In this research, Meta heurestic-Algorithm (Decision Tree Algorithm) The CARD regression tree decomposition algorithm (Classification and regression tree) is used as a type of regression decision tree for prediction purposes. Different elements have been used in simulation using decision tree model. In order to verify the relationship between the final decision tree tree based on the statistical index, graphical graphs and correlation coefficients obtained from the field operation method, visual inspection, ground monitoring and verification of control points were made. Result and discussion . The decision tree model in the Jask area has three parameters: wind pressure and wind speed, and the tree has acted on the basis of these two parameters that the model did not use the temperature parameter in the decision tree and was not selected as an effective parameter Is. Also in Chabahar region, all three parameters are used in the model The above-mentioned model has a very high performance in predicting values. In most of the 12-month intervals, the model performed its predictions close to real values; in other words, the tree created using data has a good prediction process and can simulate the changes well Also, according to the above figure, the predictions were evaluated. The results indicate that this model can be predicted with high accuracy and 95% confidence level in the region data. Because the temperature parameter has not been able to predict the response variable in the decision tree, the model has been eliminated, and the final equation of Jask and Chabahar is as follows. MSL(Jask) =13.197+5.619 T(1.102)-11.092 P (0.195)+7.208 W(0.71) MSL(Chabahar)= 4.520+1.529 T (1.089)-1.596 P(0.87)+2.776 W(0.316) Conclusion MSL fluctuations are among the general methods of analysis; therefore, accurate prediction can provide conditions for assessing its status. The purpose of this study was to investigate the effect of data pre-processing on the performance of nonlinear decision tree model in predicting MSL in Jask and Chabahar.The results of this study in all simulations show that pressure and wind parameters are more effective in the final model, which indicates the importance of these parameters in predicting future MSL. Physically, the close relationship between wind speed and water level changes is evident with the strong positive correlation coefficient of the Jask station compared to the Chabahar station in the annual windfall of both regions. Based on the relationship between the final model derived from the decision tree tree algorithm in MSL prediction using available data, it is 95% reliable. Investigating the related geomorphologic forms in the study area, the tidal range fluctuations in the Chabahar region are 1 to 1.5 meters, and in the Jask area more than 3 meters above the time interval are shown well in the diagrams. Therefore, in a closer examination of the processes governing the environments around the coastline, studying and monitoring the status of the tidal region and the influential climatic parameters is necessary.
    Keywords: Climate Indicators, Decision Tree Algorithm, Mean Sea Level, The Northern Coasts Of Oman Sea(Makran Coastal)
  • Mehdi Heidari, Shahriar Khaledi *, Tayebeh Akbari Azirani Pages 123-134
    Extended abstract
    Introduction
    Dust is one of the most important environmental events that can dramatically affect and destroy its living areas. The purpose of this study was to investigate the long-term trends in dust events and to investigate the effects of these events in the city of Ilam on the record of respiratory diseases.
    Materials and Methods
    In this regard, data on recorded events of dusty days during the 1995-2015 statistical periods was taken for two synoptic stations in Ilam and Dehloran. The relationship between time series of dust events could be detected throughout the day as TDE (Total Dust Event), in which total dust storms (including local and overflow and sandstorms and light to medium dust) are used in this research. With the fitting of a linear model at a confidence level of 0.95 (P_value = 0.05), the process of this time series was analyzed. In order to reveal the relationship between the time series of the annual registration of pulmonary and respiratory diseases, which were obtained from male and female patients of Shahid Mostafa Khomeini Hospital in Ilam during the statistical period of 1380-1384, two methods of Pearson correlation of matrix at confidence level of 0.95 (P_value = 0.05) and linear model is used at confidence level.
    Results and discussion
    The results showed that the increase of dust records in Ilam and Dehloran stations was 0.8 and 0.96 records per year, respectively. Correlation matrix indicates that at the confidence level, a significant direct correlation was found between the annual number of patients with pulmonary and perfused patients registered in Shahid Mostafa Khomeini Hospital in Ilam and the occurrence of a recession. In spite of the fact that in the years when the number of records of the higher gathering was recorded at two stations in Ilam and Dehloran, a record of the respiratory examination was significantly higher. Also, models based on the relationship between the number of male patient admissions and the events recorded in the two waves of two synoptic stations in Ilam and Dehloran indicate that these two models, respectively, verified 0.79 and 0.69, respectively, of the variability of the time series of client hospital records. In the case of women with pulmonary and respiratory diseases, the model has been fitted, which according to the number of days with dust in Ilam and Dehloran stations showed that these models could define 0.70 and 0.83 of the number of female patients.
    Conclusion
    The correlation matrix indicated that at the confidence level, a significant direct relationship was established between these two time series so that the number of annual records of patients with respiratory diseases recorded in Shaheed Mostafa Khomeini Hospital in Ilam during the years Which had a higher number of dusty days recorded at two stations in Ilam and Dehloran, was significantly higher. The correlation matrix indicated only the direction and severity of the relationship, so that linear regression models were used to quantify this association and to be aware of the susceptibility function of the records of patients with pulmonary and respiratory diseases. The proposed model can be meaningfully and cognitively able to model the association between dust events (as independent variables) and the records of patients with respiratory diseases (as a dependent variable). A model for recording the number of female patient records during the period 2000-2014 based on the number of dusts recorded at Ilam station has been able to justify 0.62 times of the time records of women referring women in Shaheed Mostafa Khomeini Hospital, while The number of recorded events of the Dehloran Synoptic Station, based on the fitted model, has been able to justify about 0.58 of these changes. The fitted models on the relationship between the number of records of hospital male patients and the recorded dust events of two synoptic stations in Ilam and Dehloran showed that these two models were 0.79 and 0.69, respectively, of the variability of the time series of the records of male patient clients To explain. For the total population of patients with pulmonary and respiratory diseases (without attention), the model was also fitted according to the number of days with dust in Ilam and Dehloran stations, which showed that these models also were 0.67 and 0.83 Describe the records of patients referring. Finally, comparing the results of this study with other researches, it was found that the results obtained in Ilam are in agreement with the results of other researchers in Kermanshah and Ahwaz.
    Keywords: Correlation Matrix, Dust, Ilam, Respiratory Patients, Trend
  • Hossein Asakereh *, Leila Hosseinjani Pages 135-148
    Precipitation is considered as one of the most important climate elements affecting different environmental aspects represented through several different behavioral form among of which is extreme precipitation. Extreme precipitation can occur in the form of flashfloods and draught with considerable negative consequences on humane-environmental. Precipitation extremes follow a geographical pattern like all other climate elements. Recognition of such patterns, specifically in those areas where people’s lives depend on precipitations, can determined the amount of success in environmental management as well as certainty in resources planning. Regarding high extreme precipitation in Iranian coastal region of Caspian Sea, especially in eastern parts, the recognition of spatial auto-correlation of such a phenomenon can facilitate environmental planning and the reduction of vulnerability and also increasing adaptability with such a disaster. Materials &
    Methods
    Therefore, in order to analyze the auto-correlation of the sum frequency of annually extreme precipitations of under investigation region, the 90-95,95-99 and 99 percentile of precipitation for each pixel of the map is considered. Accordingly, 385 stations (synoptic, climatology, and rain gauge of Islamic Republic Organization of Meteorology, and rain gauge of the Ministry of Power) were studied during the time period covering 1966 to 2016. We have used spatial statistics techniques (global Moran index (1), local Moran (2), and Gi* index (3)) to analyze spatial auto-correlation features. Function(1) Function(2) Function(3) In order to investigate the relationship between spatial factors (latitude, longitude, slope and gradient) with the annually frequency of extreme precipitation, we first use the ARCGIS spatial analysis using the Caspian Elevation Digital Elevation Model (DEM) and By applying the following steps, and finally, by sampling for all pixel points that were found in the interpolation of daily rainfall data, calculated on the basis of the following steps: Extracting altitudes, slopes and geographic directions of the subsurface points from the digital elevation model and the slope and the direction of slope obtained during the extraction-sample steps and then the connection of the descriptive table of the layers with the elevation, slope and geographic directions of the slope obtained for the subtropical points. In the last step, the relationship between the spatial factors and extreme precipitation frequency for each month was calculated using general Moran multivariate statistics z_k=[x_k-(x_k ) ̅ ]/σ_k , z_l=[x_l-(x_kl ) ̅ ]/σ_l Function(4) I_kl=(z_k w_zl)/n
    Results and Discussion
    A study of spatial relationships in order to recognize spatial dispersion of spatial complications and spatial auto-correlation is one of the best methods for recognizing the spatial behavior of extreme. The aim of this study is to determine the spatial pattern of the total annual precipitation patterns 90-95, 95-99 and 99 percentile of precipitation using the spatial statistics techniques (global Moran index, local Moran, and Gi* index to analyze spatial auto-correlation features. Accordingly, 385 stations (synoptic, climatology, and rain gauge of Islamic Republic Organization of Meteorology, and rain gauge of the Ministry of Power) were studied during the time period covering 1966 to 2016.. In the study of spatial auto-correlations based on the index used in this study, it shows that the global Moran index is above 0.9, which indicates a statistical significance of this coefficient at a confidence level of 99%, therefore, the pattern governing this behavior The three groups are high based on the Moran profile of the cluster pattern. Frequency maps of the annual occurrence of extreme precipitation show that the highest occurrence of these precipitation is in the first order of the third group and then the second group of precipitation, and the second group of precipitation is less frequent in this respect, as well as the maximum nucleus of this precipitation In the first and second groups, in the central and western parts, and in the third group in the eastern regions, this also shows the extent of the third group's influence in this area Positive and negative auto-correlations spatial clusters have seen the impact of the Alborz Mountains Systems in different parts of the Caspian region, On the eve of the first and second threshold, most cluster patterns of positive auto-correlations in the central and western parts, on the third threshold The most positive auto-correlations is in the eastern and central parts of the Caspian region. Also, negative correlation patterns were observed in the first and second groups more in the eastern part and in the third group in the central and southwestern regions of the district. G* test approved the frequency of clusters with high and low values.
    Conclusions
    In general, it can be said that the Caspian region is more affected by the rainfall of the third and the first group, which covers a large area of the region, especially in the western and central parts, and due to the frequency of occurrence of this type of rainfall in the area that occurs in the event of a flood Effective analysis of spatial dispersion and spatial relationships of this disorder can be effective in identifying areas where flooding is greater and being used to manage and plan environmental hazards to reduce vulnerability and increase adaptability
    Keywords: heavy, very heavy precipitation, annually frequency, Spatial Analysis, Moran, G* Index, Caspian region
  • Sahar Nasirieghalebin, Boroumand Salahi *, Ali Akbar Rasouli, FARAMARZ Khoshakhlagh Pages 149-162
    Extended abstract Thunderstorm is one of the meteorological phenomena seen in most parts of the world and is a major threat to modern societies, which operates in more local-scale. This natural occurrence, despite having advantages in most cases, due to the sudden occurrence, is the most severe and destructive natural disasters in each year, and cause severe damage to different parts of economies and human casualties. Convective storms usually affect small areas than tropical cyclones. Moreover, their destructive effect is often less than the actual value. Basically, thunderstorms are in the most frequent in the warm seasons on the land surface and in the cold seasons on the oceans many factors influencing the occurrence of thunder storms, including thermodynamic and kinematic conditions of the atmosphere, topography, and surface cover, coastal configuration and atmospheric flows. Ardabil province due to its location in northwest of Iran And being in the vicinity of the Caspian Sea and Gilan province have a several extreme precipitation days in each year, which causes severe damage to the agricultural and livestock sector. In this study, daily large-scale circulation patterns are firstly characterized in the northwest area of Iran, Ardabil province, through the use of SOMs technique. Then, the potential implications of circulation types to explain variability and change of the Ardabil precipitation are also attempted. Therefore studding of this phenomena and identifying of synoptic patterns have Great importance for the region. Materials and method The observed daily extreme precipitation records over 50mm used in this study are provided by the Ardabil Meteorological Data Sharing Service System. There are 4 stations in the data sparse Ardabil but their operations started in different years (most are from January 1 in 1961) and there are missing values at some stations in the early decades during the 1961–2016. Additionally, the daily geopotential heights at 500 hPa isobaric level (GH500) with the spatial resolution 2.5° latitude × 2.5° longitude based on extreme precipitation days used for circulation types are obtained from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR,.http://www.esrl.noaagov/psd/data/grided/data.ncep.reanalysis.html reanalysis dataset to identify circulation types. Some of the circulation patterns in Ardabil area were objectively evaluated with Pettit test. Based on this method, a significant abrupt change point is detected in the series of the sum of q-error and t-error, which indicates 9 distinct circulation patterns with a 3 × 36 SOM topology can describe the changes in synoptic positions in the Ardabil area. In addition, the maps created in the Grads software are also presented. Result and discussion The large-scale circulation classification provides an ideal tool to understand the circulation dynamics and their association with local climate variability. In this study, daily circulation types are objectively studied through the use of SOM technique and are further linked to the extreme precipitation over 50 mm characteristics in the northern area of Iran, Ardabil , during the period 1961–2016. Results show that the SOM method adopted could reasonably classify the daily geopotential height field at the 500 hPa vertical level over Ardabil province. By using an objective determining method (the Pettit test), 9 circulation types are qualified. Most of the severe precipitation patterns in Ardebil are related to the spring and April months, which is the time of the occurrence of thunderstorm in Ardebil. The 500 hpa HGT patterns during spring rainfall are associated with Omega Block, Rex Block and deep wave on Caspian Sea. This atmospheric pattern at the level of 500 Hpa has a completely baroclinic and unstable atmosphere in Ardabil which produced thunderstorm. In summer patterns, Ring Of Fire Block and Cut off Block are seen. This type of Block occurs during the summer, the conditions of high pressure system centre are very stable. Cut off Block, is a deep craft, occurs when high-altitude winds change to high latitudes and leave a low-spin (low pressure) behind them. In autumn pattern, a deep wave in the northern part of Iran and a cut off block are seen. Deep Wave, supplemented by cold weather in northern latitudes. In winter pattern is a Rex Block, which is a set of systems with a strong high stack in the vicinity of a low-altitude strong lane. Ardebil is located on the eastern side of the wave, is the location of the western winds ascent that creates barocilinc atmosphere and precipitation. In the A1 group, the highest frequency is in May with 30%, in the A2 group with 34% the highest frequency is in April and the lowest frequency is in October with 5%. In the A3 group, the frequency is 15% in February, March, April and May. Also in group B2, the frequency of April, May and August are 8% .In group B3, the highest frequency with 25% and 15% are for October and November. In the C1 group, the July-September months are over 16%. In the C2 group, January-April are 16% and 8% and in the C3 group, May, June and September are 8%. In the spring, the highest percentage of precipitation belongs to the B3 model with 45% fluctuation and the lowest amount of precipitation belongs to the A1 pattern with 20%. The patterns of A1 and C1 (45%), B1 (35%) and C3 (20%) are summer season patterns, The C1 pattern with (45%) has only some rainfall in winter. The C3 pattern has a rainfall of only 25% and 15% in spring and summer. In autumn, the patterns of A1 (28%), A2 (10%), B1 (15%) and B3 (45%) are high-end models. In winter, only A3 patterns with (35%) and B3 with (20%) are rainfall patterns.
    Keywords: Self-organized SOM maps, Circulation patterns, Thunderstorms, Ardabil province
  • Mehrdad Nasr Esfahani, Hojjatollah Yazdanpanah *, Mohmmad Ali Nasr Esfahani Pages 163-182
  • Fatemeh Khodadadi, Mojgan Entezari *, Farzaneh Sasanpour Sasanpour Pages 183-199
    Introduction Natural hazards with their varieties and their extent of influence as repetitive and destructive phenomena have always been present through the life in the planet; they have always been a serious threat to human beings since the advent of mankind. Accordingly, it can be said that no community claims immunity from natural hazards, and humans always suffer from objective and subjective harmful effects. Natural hazards by destroying income sources, biological resources, and people activity centers (houses, workshops, farms, etc.), increase their economic and physical harms. Related to the history of the hazards studies, the following notes could be mentioned. Materials and Methods In this research, in order to zone the flood and landslide hazards in the Alborz Province based on the used models, the indices of each model were extracted to be utilized in providing the risk map of these hazards as follows: for the landslide hazard zonation of the Alborz Province, one of the outranking methods, entitled VIKOR consensus optimization method, based on calculation of maximum utility and minimum losses was utilized and the susceptibility map of the sub-basins of the Alborz Province was prepared according to the occurrence of the landslide phenomenon. IN order to study the flood hazard of the Alborz Province, the Frequency Ratio Model (FR) was used. In order to perform these two models, it is necessary to extract the most important indices affecting the occurrence of the hazards; for this purpose, based on a deep investigation on previous studies in this field as well as the features of the study area, 9 indices were determined for landslide zoning using VIKOR-AHP compound model as follow: lithology, drainage density, soil type, precipitation, altitude, distance from the fault, land use, dip gradient, vegetation As well, for the flood zoning, using the frequency ratio model, 11 indices were applied which are: lithological factors, land use, distance from the river, soil type, dip gradient, dip direction, surface curvature map, Topographic Wetness Index (TWI), drainage density, altitude and amount of precipitation. Discussion and results In order to zone the risk of the landslide in the Alborz Province, initially nine criteria were considered regarding the basin tendency to land-sliding in sub-basins. After selecting the main criteria, in the next stage, the maps for each one of the selected criteria for weighting and evaluating sub-basins in the GIS environment were prepared and mapped. Considering the effect of the nine criteria in the occurrence of landslide (distance from fault, precipitation, vegetation, land use, soil type, lithology, height, drainage density and dip) distance from fault and vegetation criteria have a decreasing effect and the other seven criteria have an increasing effect. After preparing the selected criteria map, the significance coefficient of the mentioned criteria was determined by the AHP hierarchical algorithm, based on the importance level of the landslide occurrence and basins susceptibility to this phenomenon. In this investigation, in order to weight options based on the role of each criterion in the considered option, the definitive weighting range of one to ten is used; so that weight 1 has the least effect and weight 10 indicates the most effect in the landslide risk. After determining the importance coefficient of the criteria, weights decision matrix was prepared for the VIKOR algorithm. As it is known, nine criteria are efficacious in evaluation of the watershed basins. Table 2 shows the decision matrix based on the effective parameters in the sub-basins. After weighting and preparing the weight matrix, the matrix values were normalized. Conclusion The results of the landslide study in the Alborz Province indicates that in Taleghan and Karaj counties, the occurrence possibility of landslide is high due to the natural conditions of the region in terms of considered indices; since in these counties, the precipitation conditions are relatively good and vegetation is mainly of poor pasture type, there are no proper drainage conditions. The presence of less developed soils and almost impermeable bedrock, high altitude and relatively steep slope in these areas and the presence of frequent faults, provided the occurrence condition of landslide phenomenon. Therefore, as the output of the landslide zoning map shows, more than 60% of the area of these two counties are located in high-risk areas. Also, the natural conditions in relation to the flood risk is persistent and some indices such as susceptibility to erosion, land use, rivers distance, amount of precipitation, altitude, precipitation, slope angle and slope direction have led to the presence of possibility of flooding in the Alborz Province; consequently, due to the dominance of these indices in Taleghan, Karaj and Savojbolagh counties, the highest flood risk could be observed respectively. The situation of Taleghan and Karaj counties are more susceptible and vulnerable to geomorphic hazards; because the area percentage of the high and high risk classes in these two counties is considerable (high). On the other hand, most of the habitat areas of the Province are situated in high risk places in terms of flood and landslide hazards; it shows the necessities of more detailed planning to prevent the hazards and the related damages. In the following, in order to investigate the status of residential centers of the Alborz Province in relation to geomorphic hazards and the degree of adaptation and correct location-defining of these centers (urban and rural), a study was conducted; it indicates the establishment of most urban and rural centers in high-risk areas. For example, 52% of the Karaj County with 28% of the Province’s area and about 2 million populations are located in very high flood and landslide risk zones; in order to reduce their probable losses, people should be aware of probable risks and necessary plans should be considered.
    Keywords: Geomorphic hazards, Landslide, Flood, VIKOR-AHP, Fr model Alborz province