فهرست مطالب

نشریه جغرافیا و مخاطرات محیطی
پیاپی 8 (زمستان 1392)

  • تاریخ انتشار: 1392/12/21
  • تعداد عناوین: 8
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  • محمد امین حیدری، فرامرز خوش اخلاق، محمد امین مرادی مقدم، اصغر مولایی پارده صفحات 1-18

    وضعیت پوشش سطح زمین نقش بسیار مهمی در دمای هوا و در لایه خرد و محلی دارد. بطورکلی هرگونه تغییر در سطح زمین پیامدهای آب وهوای شدیدی در این مقیاس ها خواهد داشت. خشک شدن دریاچه های داخلی از مسائل نوظهور آب وهواشناسی می باشد که خشک شدن احتمالی دریاچه ارومیه در شمال غربی ایران یکی از این نمونه هاست. در این پژوهش از مدل شبیه ساز آلودگی هوا (TAPM)، جهت شناخت اثر خشک شدن دریاچه ارومیه بر تغییرات دمایی ایستگاه مراغه در سال های 2003 و 2006 استفاده شده است. بر اساس نتایج به دست آمده در این پژوهش، متوسط دمای سالانه ایستگاه مراغه در اثر خشک شدن دریاچه 0.25 درجه سلسیوس افزایش، و در ماه های گرم سال به ویژه اوت و ژوئیه در ساعات میانی روز به طور متوسط افزایش حدود 4 درجه سلسیوس و همچنین در ماه های سرد به ویژه دسامبر و ژانویه حدود 3.5- درجه سلسیوس در متوسط دمای شبانه، کاهش را نشان می دهد. بر این اساس با خشک شدن دریاچه ارومیه دماهای کمینه و بیشینه سالانه در منطقه مورد مطالعه تغییرات محسوسی را نشان می دهند.

    کلیدواژگان: ارومیه، شبیه سازی عددی، رژیم دما، TAPM
  • فاضل ایران منش، مهران مقصودی، ابراهیم مقیمی، مجتبی یمانی، امیرحسین چرخابی صفحات 19-31

    از ویژگی های بارز رودخانه کرخه در غرب استان خوزستان به ویژه در دشت آزادگان، دینامیک فعال آن است. بررسی این پویایی و تعیین نقش آن در ایجاد مخاطرات محیطی و ساختار فضایی منطقه، مستلزم شناخت مورفودینامیک رودخانه از گذشته تا حال بر اساس شواهد رسوبی و هیدرومورفولوژی است؛ زیرا مورفودینامیک رودخانه ها به خصوص در دشت های سیلابی معلول شرایط رسوب گذاری و وقایع محیط شناسی مانند تغییرات آب و هوایی و تغییرات سطح اساس آب هاست. بدین منظور، پس از جمع آوری داده ها، تغییرات مسیر رودخانه و شرایط محیط های رسوبی به عنوان متغیر مستقل و عناصر فضایی مانند تغییر در اندازه ذرات رسوبی، تپه های ماسه ای، کاربری های کشاورزی، مسکونی و غیره به عنوان متغیرهای وابسته در نظر گرفته شدند. ابتدا با استفاده از روش های پردازش رقومی بر روی تصاویرماهواره ای لندست سال های 1990،1993،1998،2002 میلادی و سنجنده Liss از ماهواره IRS هند سال 2006 میلادی و ثبت نقاط شاخص در بازدیدهای میدانی، مسیرهای متروکه بازسازی و مسیرهای فعال بررسی شدند. در ادامه با تطبیق مسیرهای رودخانه با سایر لایه های اطلاعاتی، دو مغزه رسوبی در محل های رفیع و جفیرتا عمق 10 متری به منظور تعیین رابطه بین قطر ذرات رسوبی با شرایط سیلابی و محیط های رسوب گذاری گرفته شد. نتایج نشان داد، سه توالی رسوبی با شرایط اقلیمی مرطوب و کاهش قطر ذرات رسوبی در اعماق(10-6، 5-4، 3-0 متری) و دو دوره با شرایط اقلیمی خشک به همراه افزایش قطر ذرات رسوبی در اعماق(6-5 و 4-3 متری) را می توان در مغزه ها تشخیص داد. شرایط اقلیمی خشک به همراه عقب نشینی خط ساحلی در هولوسن میانی سبب شد، دلتای کارون و کرخه توسعه پیداکرده و جابجایی و تغییر مسیرهایی نیز در بستر این رودخانه ها پدیدار شود. این تغییرات در مسیر روستای عبدالخان تا تالاب هویزه دارای حداقل دو تغییر شکل پلان خم رودخانه و چندین مسیر متروکه طبیعی می باشد. به دلیل سرعت و تنش برشی، خم ها با پدیده انتقال وگسترش همراه بوده و ضمن ایجاد خسارت به اراضی کشاورزی و مسکونی، موجب جابجایی آن ها نیز شده است.

    کلیدواژگان: دشت آزادگان، کرخه، رسوب، ساختار فضایی، مخاطرات محیطی و مورفودینامیک رودخانه
  • فریبا صادقی، هوشمند عطایی، سادات هاشمی نسب صفحات 33-47

    با توجه به ماهیت عناصر اقلیمی که در قالب مقیاس های مختلف زمانی مورد استفاده قرار می گیرند، تغییرات زمانی عناصر اقلیمی از اهمیت زیادی برخوردار است که یکی از مولفه های مهم مورد مطالعه، تغییرات گرایش دار یا روند می باشد. در این پژوهش به منظور بررسی روند حداقل دمای ایران، حداقل دمای 78 ایستگاه در طی دوره آماری 2008- 1958 مورد بررسی گرفته است. با توجه به سنجش حداقل دمای سالانه ایستگاه های ایران با استفاده از آزمون جوینر و اسمیرونوف، نتایج حاصله بیان می دارد که حداقل دمای 19 ایستگاه ایران دارای توزیع نابهنجار است. ایستگاه هایی با توزیع نابهنجار با آزمون ناعاملی دنیلس و سایر ایستگاه-ها به دلیل بهنجاری توزیع حداقل دما، با آزمون عاملی tr مورد بررسی و سنجش قرار گرفته-اند. نتایج حاصله نشان می دهد از بین 78 ایستگاه، حداقل دمای 26 ایستگاه که عبارتند از بردسیر، سقدار، اردبیل، آباده، بجنورد، دامنه فریدن، همگین، کاشان، پل زمانخان، اصفهان، قزوین، ارومیه، همدان نوژه، گرگان، سقز، زنجان، خوی، دزفول، کروندار، برازجان، برنیشابور، نصرت آباد، خوانسار، بیرجند، سنندج و اراک بدون الگوی روند هستند. میل تغییرات روند حداقل دما در 4 ایستگاه شهرکرد، خرم آباد، بندرعباس و فسا به صورت نزولی و تغییرات روند در 48 ایستگاه ایران به صورت مثبت یا صعودی بدست آمده است. برازش و پیش بینی سری های حداقل دمای روند دار ایران با مدل هموارسازی هولت نشان دهنده افزایش حداقل دما در مناطق غربی بین 02/0 تا 32/0 درجه، در مناطق شرقی بین 27/0 تا 45/0 درجه، در مناطق شمالی بین 35/0- تا 28/2 درجه و در نواحی جنوبی ایران بین 27/0- تا 28/0 درجه می باشد.

    کلیدواژگان: روند، مدل های گرایش دار، آزمون های پارامتری، آزمون های ناپارامتری، شیوه هولت
  • مریم سادات میرعابدینی، شعبان شتایی، مریم آق آتابای صفحات 49-64

    یکی از کاربردهای دورسنجی در زمین شناسی تهیه نقشه خطواره هاست که به عنوان یکی از مهم ترین موضوعات در مطالعات زمین شناسی مناطق مختلف در نظر گرفته می شود. هدف از این تحقیق، استخراج خطواره های (گسل) البرز مرکزی با استفاده از تصاویر ماهواره ای سنجنده ASTER به روش بصری و رقومی خودکار است. بعد از انجام تصحیحات هندسی تصاویر تکنیک های بارزسازی مکانی شامل فیلترگذاری، تجزیه مولفه های اصلی و نسبت گیری باندی بر روی تصاویر سنجنده ASTER اعمال شد. استخراج خطواره ها بر روی این تصاویر پردازش شده به دو روش تفسیر بصری و رقومی خودکار انجام شد. سپس خطواره های استخراج شده به دو روش بصری و رقومی خودکار با یکدیگر و با خطواره های (گسل) استخراج شده از نقشه زمین شناسی منطقه مقایسه گردید. نتایج نشان داد که میزان گسل های استخراج شده با روش تفسیر رقومی خودکار با میزان گسل های نقشه زمین شناسی همخوانی ندارد و روش تفسیر رقومی خودکار نتوانسته سبب استخراج و شناسایی خطواره های گسلی منطقه (گسل خزر و شمال البرز) شود. ولی میزان خطواره های استخراج شده به روش بصری با میزان گسل ها در البرز همخوانی بیشتری نشان می دهد. بنابراین روش رقومی خودکار به علت دقت پایینی که دارد، برای مطالعات زمین شناسی که بر مبنای مطالعات صحرایی دقت بالایی دارد، پیشنهاد نمی شود. در نتیجه، بهترین روش برای انجام مطالعات زمین شناسی و بررسی های ساختاری در مناطق وسیع و یا مناطقی که دسترسی به آنها مشکل است، استفاده از روش تفسیر بصری و رقومی سازی دستی برای استخراج خطواره هاست.

    کلیدواژگان: استخراج خطواره، ASTER، تفسیر رقومی خودکار، تفسیر بصری، البرز مرکزی
  • حمید زارع ابیانه صفحات 65-86
    این مطالعه با هدف مدل سازی تغییرات مکانی پارامترهای کیفی آب زیرزمینی دشت همدان-بهار با روش های زمین آماری انجام شد. پارامترهای هدایت الکتریکی املاح محلول (EC)، pH، قلیائیت (SAR) و باقی مانده جامد املاح (TDS) از خصوصیات اصلی آب زیرزمینی انتخاب شدند. مدل سازی با استفاده از روش کریجینگ، روش معکوس فاصله وزنی و روش شبکه توابع پایه شعاعی انجام شد. برای انتخاب روش مدل سازی، دو آماره میانگین مجذور مربعات خطای نرمال (NRMSE) و میانگین خطای سوگیری (MBE) در قالب تکنیک اعتبارسنجی متقابل به کار گرفته شد. نتایج نشان داد روش کریجینگ با نیم تغییرنمای کروی در مدل سازی عوامل کیفی برتری دارد. مقدار NRMSE در نیم تغییرنمای کروی برای هر چهار عامل بین 95/0 تا 96/0 بود که نسبت به سایر نیم-تغییرنماها (96/0 تا 98/0) کمتر بود. کمترین خطای مدل سازی به پارامتر pH و بیشترین خطا معادل 42/0=NRMSE و 01/0-=MBE به پارامتر EC تعلق داشت. بر همین اساس پهنه بندی ها به منظور درون یابی عوامل کیفی در سطح آبخوان و برون یابی عوامل کیفی براساس اطلاعات آبخوان در سطح دشت صورت گرفت. پهنه بندی تغییرات مکانی نشان داد مقادیر EC و TDS دارای روند تغییراتی مشابه است. یکی از دلایل اصلی تشابه تغییرات EC با TDS ارتباط خطی این دو پارامتر است. نتایج پهنه بندی نشان داد مقادیر EC، TDS و SAR، از امتداد جنوب شرق به شمال شرق کاهش یافته است؛ به طوری که مقادیر SAR از بازه 8/2-9/1 به 2/1 – 8/0، EC از بازه 3/2395 – 4/1266 به بازه 5/823-3/483 میکروموس بر سانتی متر و TDS از بازه 3/1591-3/826 به بازه 2/526-7/295 میلی گرم بر لیتر کاهش یافت. تغییرات پارامتر pH غیریکنواخت تر از سه پارامتر دیگر بوده و حداکثر آن در ناحیه شمال غربی دشت در بازه 93/7 تا 75/7 است. هم چنین نتایج حاصل بیان گر دقت کمتر روش زمین آمار در برآورد پارامترهای کیفیت آب زیرزمینی در نقاط حداکثر بود. در مجموع می توان اظهار داشت با داشتن مقادیر یک کمیت کیفی آب در یک نقطه می توان مقدار همان کمیت را در نقطه ای دیگر با مختصات معلوم با دقت بالا برآورد نمود.
    کلیدواژگان: کیفیت آب زیرزمینی، کریجینگ، نیم تغییرنما، دشت همدان، بهار
  • عباس مفیدی، محسن حمیدیان پور، محمد سلیقه، بهلول علیجانی صفحات 87-112

    باد سیستان به عنوان برجسته ترین جریان ترازهای زیرین جو در فلات ایران، بنا به ماهیت، گستره ای محلی تا منطقه ای را در شرق این فلات اشغال می نماید. اگرچه محلی و یا منطقه ای بودن باد سیستان موضوعی باز تلقی می گردد، اما آغاز و خاتمه ناگهانی وزش باد سیستان در شرق ایران و تغییرات سال به سال قابل ملاحظه در زمان آغاز و خاتمه این باد، نقش برجسته عوامل بزرگ مقیاس و مقیاس منطقه ای را در شکل گیری باد سیستان متذکر می گردد. پژوهش حاضر سعی دارد با بهره گیری از روش هایی موسوم به «نقطه تغییر»، زمان آغازگری (Onset)، زمان خاتمه و طول مدت وزش باد سیستان را مورد بررسی قرار دهد. مطالعه با بهره گیری از داده های روزانه شدت و جهت باد در ایستگاه زابل، به عنوان ایستگاه معرف باد سیستان، برای یک دوره 41 ساله (2012-1972) به انجام رسید و جهت تعیین زمان آغازگری و خاتمه باد سیستان از سه روش Pettitt، SNHT و Buishand استفاده شد. در این تحقیق با بهره گیری از سری زمانی روزانه شدت و جهت وزش باد، زمان آغاز، خاتمه و طول مدت وزش باد سیستان تعیین گردید. یافته ها بیانگر آن است که از میان سه روش تخمین نقطه تغییر، روش پتیت در تعیین زمان آغاز و خاتمه باد سیستان از کارایی مناسب تری برخوردار است. بر اساس روش پتیت باد سیستان بطور متوسط در روز 122 ام (2 می) از سال میلادی آغاز شده و تا روز 287 ام (14 اکتبر) تداوم می یابد. بر این اساس، متوسط طول دوره وزش باد سیستان 165 روز در سال تعیین گردید. یافته ها همچنین بیانگر آن است که زمان آغازگری، زمان خاتمه، شدت و طول مدت وزش باد سیستان تغییرات قابل ملاحظه ای را از سالی به سال دیگر نشان می دهد. از دیگر نتایج این مطالعه، نبود یک روند معنی دار در رفتار تمامی ویژگی های باد سیستان است.

    کلیدواژگان: باد سیستان، نقطه تغییر، آغازگری، زمان خاتمه، مدت وزش باد
  • عزت الله قنواتی صفحات 113-131
    در این مطالعه، خطر سیلاب(سیل خیزی و سیل گیری) در محدوده شهر کرج و نواحی پیرامون آن، با استفاده از منطق فازی با درجات مختلف معین شده است. در پهنه بندی سیلاب از لایه های شیب، خاک، ژئومورفولوژی، کاربری اراضی، انحنای طولی(تغییرات شیب در امتداد جریان)، انحنای عرضی(واگرایی و همگرایی جریان)، بارش، تراکم زهکشی، فاصله از رود و زمین شناسی استفاده شده است. سپس به هر یک از لایه ها با توجه به نوع روابط شان با پدیده سیل خیزی و سیل گیری و بر اساس توابع تعیین شده، مقدار عضویت تعیین و وارد مدل گردیدند. نتایج این تحقیق نشان داد مدل فازی با وجود پیچیدگی هایی که دارد، دارای مزایای بسیاری در مطالعه پدیده های مختلف مرتبط با سطح زمین است. با توجه به نقشه نهایی بدست آمده، در سیل خیزی پهنه های با خطر بسیار زیاد در بخش شمالی، شمال شرقی و شرقی منطقه مورد مطالعه واقع گردیده اند. نواحی با خطر کم نیز اغلب در دشت ها، دره ها و خط القعرها که شیب کمتری دارند، واقع گردیده اند. با توجه به نقشه نهایی بدست آمده سطوح سیل گیر با خطر بسیار زیاد اغلب در قسمت های جنوب غربی و جنوب شرقی منطقه مورد مطالعه واقع شده اند. پهنه های با خطر زیاد نیز اغلب در قسمت های مرکزی و غربی قرار دارند.
    کلیدواژگان: ژئومورفولوژی، سیلاب، کرج، منطق فازی
  • مهناز جهادی طرقی سید رضا حسین زاده صفحات 133-162
    به دلیل تازه تاسیس بودن بسیاری از ایستگاه های آب سنجی و یا تخریب و انهدام کلی آنها در اثنای وقوع سیلاب های بزرگ، گزارش دبی های ثبت شده اینگونه وقایع کاتاستروفیک کم بوده و داده های مربوط به آن ها یا حاصل تخمین های غیرمستقیم دبی بعد از وقوع سیلاب و یا تعمیم سیلاب های مشاهده شده 40- 30 سال گذشته است. به همین دلیل، روش های متداول هیدرولوژیک برای تخمین حداکثر سطح، حجم و دوره برگشت این سیلاب ها نتایج قابل اطمینانی بدست نمی دهد و فاقد دقت لازم برای برنامه ریزی های کنترل سیلاب است. لوگ پیرسون تیپ 3، روش برآورد گامبل، حداکثر بارش محتمل(PMP) و سایر فنون آماری زمانی قابل اعتمادند که دوره برگشت مورد محاسبه کوتاه تر و یا معادل دوره آماری پایه باشد. ضعف اساسی روش های آماری و نیاز به تخمین های دقیق تر باعث ترغیب ژئومورفولوژیست ها به استفاده از معیارهای ژئومورفولوژیک برای بازسازی سیلاب های قدیمی و بهره گیری از نتایج آن در پیش بینی سیلاب های احتمالی آتی گردید؛ بطوری که از دهه 1980 شاخه ای در ژئومورفولوژی رودخانه ای تحت عنوان هیدرولوژی پالئوسیلاب در آمریکا پایه ریزی گردید و به سایر مناطق جهان گسترش یافت. این مقاله از نوع مروری بوده و هدف کلی آن آشنایی با موضوع هیدرولوژی پالئوسیلاب و ترغیب محققین علوم زمین به استفاده از آن به عنوان یک راه حل عملی خوب برای تخمین دوره های برگشت سیلاب های بزرگ، ارزیابی و تهیه نقشه-های خطر، برنامه ریزی بهتر برای نواحی مستعد سیلاب (بر مبنای داده های واقعی) و حفظ محیط زیست است.
    کلیدواژگان: هیدرولوژی پالئوسیلاب، شاخص های دیرینه تراز، رسوبات آب راکدی، بازسازی سیلاب های قدیمی
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  • Mohammad Amin Heidari, Faramaz Khoshakhlagh, Mohammad Amin Amhadmorad Mog, Asghar Molaei Pardeh Pages 1-18
    Introduction

    The Atmosphere is characterized by phenomena whose space and time scales cover a very wide range. The space scales of these features are determined by their typical size or wavelength، and the time scales by their typical lifetime or period. In reality none of these phenomena is discrete but part of a continuum; therefore it is not surprising that attempts to divide atmospheric phenomena into distinct classes have resulted in disagreement with regard to the scale limits. Most classification schemes use the characteristic horizontal distance scale as the sole criterion. The thermal and dynamic property of water bodies (oceans، seas، lakes، etc.) makes them very important stores and transporters of energy and mass. The exchanges occurring at the air/water interface are، however، complicated by the fact that water is a fluid. This means that heat transfer within water is possible not only by conduction and radiation، but also by convection and advection. As in the atmosphere these modes of transfer greatly facilitate heat transport and mixing، and thereby allow heat gains or losses to be spread throughout a large volume. Although water is not compressible like air، it can be deformed، giving surface waves (Oke،1978:85) Such conditions lead to the development of special instability phenomena such as miniature whirlwinds known as ‘dust devils’، and a whole range of unusual optical effects. These include the ‘shimmering’ of objects viewed through the lower atmosphere، and the well-known mirage، both of which are due to the refraction of light as it passes through media of different density. Shimmering is caused by multiple refraction of light as it passes from the object through a field of vertically-arranged filaments of air of differing density. A mirage is caused by the refraction of light from the sky as it passes through the horizontal temperature (density) stratification of the lower atmosphere، and the amount of bending depends on the lapse rate. Land cover and land use are included in influencing factors on climatic elements in particular temperature regime in spatial and temporal scales. Lakes are considered as natural controls on temperature and moisture regime in interior continents. However، any change in hydro climatic conditions of lakes such as increase or decrease of their levels is reflected into climatic conditions of lake surroundings. Nowadays in Iran there is a national challenging debate because severe fall of water level of Lake Urmia and its likely drying up in near future. This paper analyses the temperature regime of surroundings area of Urmia Lake while it drying up by using TAPM model. Of course، it is obvious the changes will not be limited to temperature regime and involved all of the climatic elements and factors. Study Area: The Lake Urmia is located in northwest of Iran and Maraghe city location is in southeast of lake with distance 30 km. Whole area is mountainous and some rivers were discharge to Lake Urmia. Climatic conditions of lake area is humid and cold in winter and moderate to semi warm and arid to semiarid in summer.

    Material And Methods

    Temperature data of synoptic station of Maraghe in southeast of lake was analyzed by using TAPM model for simulation and then for calibration of model outputs. TAPM model is a model for air pollution simulation that made by CSIRO in format comprehensive software. This software had been used and recommended by more than 190 users in 25 countries in different parts of world. In this research for purposes of simulation and evaluation the monthly data of two years; 2003 and 2006 were used. For computing the occurred changes and as such as estimating the errors the observed and simulated data were compared with together. For modeling purposes the water body of Lake Urmia was substituted by an area having coverage of gravel and sand with a texture of loam.

    Results And Discussion

    The classical climatology practiced in the first half of the twentieth century was almost entirely concerned with the distribution of the principal climatological parameters (e. g. air temperature and humidity) in time and space. While this information conveys a useful impression of the state of the atmosphere at a location it does little to explain how this came about. Such parameters are really only indirect measures of more fundamental quantities. Air temperature and humidity are really a gauge of the thermal energy and water status of the atmosphere respectively، and these are tied to the fundamental energy and water cycles of the Earth-Atmosphere system. Consequently، any change in land cover made by both natural and anthropogenic factors mainly can exacerbate the climate change. The results of this research show that the drying up Lake Urmia will cause significant increase or decrease of temperature in different months in Maraghe station. Also، because of increased temperature differences the continental conditions will increase. Status of land cover have important role in the air temperature and in local and micro climate layer. The overall any change in the surface ground In These scales will be have severe consequences of climate. Shrivel domestic lakes is a newly emerging matters in the climate، and shrivel possible Lake Urmia in northwestern of Iran is one of examples. In this study، to understand the effect of shrivel Lake Urmia on the temperature changes in Maragheh station in the years 2003 and 2006 used The simulation model TAPM. Based on the results obtained in this study the mean annual temperature will increase about 0. 25 ° C the effect of shrivel Lake، and in hot seasons especially in July and August in mid-day hours، the average temperature is increases about 4 ° C. The simulation results in the colder months especially in December and January show Temperature decrease during cold nights To - 0. 5 ° C. Accordingly in effect of the shrivel lake Urmia annual minimum and maximum temperatures In the study area Show significantly the change.

    Conclusion

    Based on results of this research the mean annual temperature of Maraghe station will increase up to 0. 25o C if the Urmia Lake completely be dried up. In summertime particularly in august and July the increase of maximum temperature will be 4o C. And in wintertime particularly in December and January the decrease of minimum temperature will be 3. 5o C and less. Due to above mentioned temperature differences the continental conditions in study area will increase dramatically

    Keywords: Environmental Change, Temprature Regime, Numerical Simulation, Urmia Lake, TAPM Model, Maraghe
  • Fazel Iranmanesh, Mehran Maghsoudi, Ebrahim Moghimi, Mojtaba Yamani, Amir Hossein Charkhabi Pages 19-31
    Introduction

    One of the main characteristics of Azadegan plain in the west of Khuzestan province is active instability of geomorphic features of Karkheh River This instability caused extensive variations in the sedimentary setup in the western parts of this plain، such as buried and abandoned river beds، which are repeated over time. Therefore، these variations should be studied in more details in the upper Holocene، since they can help us to better understand the changes and sedimentation details to reduce the environmental hazards in the region. Morpho dynamic characteristics of this river in the flood plains of Khuzestan are influenced by the sedimentation conditions، climatic changes، and hydraulic base levels of the Persian Gulf and in this context the two dynamic river systems of Karoun and Karkheh in Khuzestan are very important to be studied in much detail (Ramesht، 22، 1382). These rivers have been changed the routes in the past in Khuzestan and consequently caused complex sedimentation systems. The morphologic characteristics of these rivers indicate their longitudinal profiles are higher than the main level of the flood plain of Khuzestan. The Karkheh River changed its route in Hamidieyeh position about 100 yrs ago and at the present is running by Sosangard City in Khuzestan. Diopin (2011) studied the routes of the Karkheh، Karoun and Jarhi Rivers in Khuzestan and he found a good correlation among these river dynamics and human developments in this province. He found four different routes for Karkheh River in his study. The objective of this study was to further lighten the route changes and dynamics of the Karkheh River which will help us to better manage the spatial settings and predict the environmental risk in the province. Study Area: Azadegan plain is located in the west of Khuzestan province. This region is about 7500 km2 bordered from north by Shoush and Ilam cities، Iraq from the west، and Ahvaz City the east. Sosangerd is located in the center and the Karkheh River is the major river which drains this extensive plain. The Karkheh rises from the Zagros Mountains and، after pouring into the plain in the northwest، it crosses the Ahwaz anticline near the village of Hamidiya. The river turns into two parallel channels; both ending in the Hawiza Marshes which are located near the Iraq-Iran border. The area has some low hills، named Alaho-ahakbar and Mishdagh، with 173 m above sea level. Active sand dunes are extended from northwest of the province، i. e.، Fakeh and Mousian area. It contains most part of the plain and develops in west of Karkheh، Molla sani، and Maroon Rivers. The average of annual precipitation and temperature are 266 mm and 31 degrees (C°)، respectively. Annual evaporation in lowlands and coastal areas is 2500 mm، which almost more than 10 times of annual precipitation.

    Material And Methods

    In this research the quantitative data، are grouped into two groups of independent and dependent variables. According to the purpose of the study، the river coarse and sedimentary environments are used as independent variables and some other data including particle size، land use، sand dunes extent، and urban areas as dependent variables. The enhancement of abandoned stream channels and scrutiny of active courses of Karkheh River was conducted by using Landsat satellite images of 1990، 1993، 1998، 2002، as well as IRS LISS images of 2006. In this process we used spectral and spatial enhancement indices and recording index points. One of the main indices، which were used for edge enhancement، was gradient filter. The filter was applied in band 7، due to absorption of wavelengths of 2. 08-2. 35 micrometer due to sensitivity to moisture، vegetation، and soil. Given the direction of flows in the rivers in Azadegan، four linear filters of horizontal، vertical، northwest-southeast، and northeast-southwest have were applied for the enhancement process. To better understand the relationship between the condition of sedimentary environments and the sediment types in river dynamics، drilling operation and core sampling were performed. The coring was done by a rotary drilling method up to the depth of 10 meters in Rafi Area in the vicinity of Hoveyzeh Wetland to represent a lake environment and the abandoned channels of the Karkheh fluvial environment in Jafir Region. From these cores، 20 subsamples were selected for granulometric analysis.

    Results And Discussion

    Grain size analysis showed interesting results. The grain size in Roafyeh core indicated the percentage of clay fraction (less 0. 002 mm) showed increasing trend with depth، while on the contrary، the sand fraction showed a decreasing trend with depth. Cristian (1997) and Slina (1998) believed stable condition indicates decreased in flow energy with sedimentation of fine grained particles such as silt and clay particles، while unstable condition shows increase in flow energy with lager particle sizes. The results of grain size analysis on the cores in the area showed a both the stable and unstable sedimentation conditions indicating fluctuations in percentage of particles sizes with depth with Three sedimentary sequences in the depths of (0-3، 4-5 and 6-10 meters) could represent humid conditions at the time of sedimentation and. While two periods of dry climate condition were presented with increased sediment particles size in the depths at 3-4 and 5-6 meters،) can be detected in the Rofayeh core. More arid condition along with recession of sea-level could cause Karoun and Karkheh delta to develop with their channel changes during mid Holocene in the area. However، the changes in the Karkheh route from Hamidieh area to Hovaizeh lagoon along with bed deformation and canal displacements occurred naturally and artificially. Due to rapid changes and shear stresses in the river systems، the bends associated with the expansion of sediment transport phenomena، could cause significant damages to agricultural lands and residential areas.

    Conclusion

    Morphology of the Karkheh River، bed formation، and its translocations in different parts of the Zagross folding belt are dependent upon a variety of factors such as hydraulics، sediment، and tectonic processes. The morphodynamics of Karkheh in proximity of Azadegan Plain is mainly function of folding types and internal factors of tectonic such as uplifting in the area. Moreover، relative sea level changes in the Persian Gulf and sedimentation in of the Karkheh River delta played a main role in its paleo-morphodynamics. Due to global sea level rise in 6000 years ago in the Persian Gulf area (Kent and Kent، 2006)، shoreline of the Persian Gulf was near Ahvaz City up to Hoveyzeh Wetland. Then، with the beginning of shoreline recession from 5500 years ago، in the middle of Holocene، the Karun River delta was developed and experienced movements over the bed of Karkheh River. The shoreline recession was synchronic with cold climatic conditions in high and middle latitudes and with relatively temperate climatic conditions in low latitudes and coastal areas. In such conditions، sedimentary environments were stable with low energy state that allows deposition of fine particles such as clay. Therefore، the changes in climatic conditions altered the situation of sedimentary environments and river morphology in the area. The hazards caused by these changes had significant influences on natural and human spatial features، i. e.، agriculture، civilization، and geomorphologic features. The extended meanders along the margin of the Karkheh River are cut through the sand dunes، caused the translocation of sand sediments onto the point bars along the river path. This process widened the channel beds through generation of developmental meanders which provided suitable lands for agriculture among the sand dunes. The cuttings are stable until the channel beds are not abandoned.

    Keywords: Azadegan Plain, Environmental Hazards, river morphodynamic, spatial
  • Fariba Sadeghi, Hooshmand Ataei, Sadat Hasheminasab Pages 33-47
    Introduction

    Climate is a large system which is produced due to the relation and action between other large systems. If a change occurs in one of these systems، other systems will coordinate themselves with the change fast or slowly. The consequences of this coordination will impress the system that is starter of this change and an endless continuum of the links connects these systems together. According to the nature of the climate elements used in the form of different time scales، the time variations of climate elements are very important. Study of the time changes are performed via different models such as trend، seasonal، periodic and random models.

    Material And Methods

    The statistical population in this study is monthly، seasonal and annual minimum temperature of 236 Synoptic and Climatology stations in Iran، which samples with 78 Synoptic and Climatology stations were randomly selected due to their minimum temperature with high statistical period (higher than 30 years) and during 1958-2008. The lost minimum temperature of some stations was reconstructed using the least square method. The first step in a research for using tendency models is the measurement of series. Joiner and Smirnov tests were used for normal and abnormal measurement، Tr parametric test was used for the measurement of trend models، proportionate with data nature for stations with minimum normal temperature and Daniels nonparametric test was utilized for stations with minimum abnormal temperature. Tr test: The above-mentioned test is considered as one of the important parametric tests. The value of Tr test can be calculated using the following equation: (1) Daniels، test One of the most important nonparametric tests is Daniels test. For the calculation of this test with frequency more than 30، the following equation can be used: (2) The application of fitting، smoothing and prediction models: The series with trend and seasonal changes can be smoothed and predicted with Holt method.

    Results And Discussion

    Regarding to the Joiner and Smirnov tests used for the evaluation of data distribution، among 78 stations، minimum temperatures of 19 stations have abnormal distribution. The Daniels nonparametric test was used for the evaluation of the series with abnormal distribution and the Tr parametric test was used for the evaluation of minimum temperature of other stations with normal distribution. The obtained results of Tr test show that the minimum temperature has tendency changes or trend for stations of Chadegan، Noushahr، Hamedan، Shargh Esfahan، Khoshkedaran، Zabol، Bandar Torkman، Talasar، Kalaleh، Jask، Miandouab، Iranshahr، Hamandabsard، Bajestan، Sedeh Brjand، Mahmoodabad، Semnan، Chabahar، Emamghais، Tashkouyeh، Rineh larijan، Bandar Lengeh، Ahvaz، Bam، Torbat heydareh، Abadan، Boushehr، Tabriz، Kerman، Khoramabad، Banadr Anzali، Bandar abass، Kermanshah، Sabzevar، Shiraz، Ramsar، Shahroud، Tehran، Shahrekord، Zahedan and Yazd. Among these، the obtained value for the minimum temperature of Khoramabad، Bandar abass and Shahrekord is negative. It shows that there are negative trends in minimum temperature for these stations and positive trends for other stations. Using Daniels test for the stations with abnormal distribution، minimum temperature has tendency changes for stations of Bahookalat، Lahijan، Pilimbra، Sarbaz، Dargzin، Zardgol، Fassa، Rasht، Mashhad، Babolsar and tabass. Since this value is positive for all of stations except Fassa، the minimum temperature of these stations has an increasing trend. Compared to the obtained predictions using Holt method and the minimum temperature average during the past years، we will have an increase in minimum temperature in different regions of Iran during period of 30، 40 and 50 following years. The predicted values will show an increase of 0. 16 degree for the minimum temperature in the northwest areas، 0. 02-0. 32 degree or an average of 0. 17 degree in west، 0. 12-0. 27 degree or an average of 0. 19 degree in southwest، 0. 27-0. 45 degree or an average of 0. 36 degree in east، -0. 27-0. 28 degree in south، -0. 35-. 28 degree in north، 0. 09-0. 47 degree southeast in and 0. 03-0. 67 degree in central areas.

    Conclusion

    The results of this study show that among 78 stations، the minimum temperature for19 stations have abnormal distribution. The minimum temperature for these stations was measured with Daniels nonparametric test and the annual minimum temperature for other stations with normal distribution was measured with Tr parametric test. According to the two applied tests (Tr and Daniels) on the stations of Iran، the results show that the minimum temperature for 26 stations are without any trend pattern. Tendency changes for 48 stations are shown as positive and tendency of trend changes for minimum temperature of 4 stations of Khoramabad، Bandar abass، Shahrekord and Fassa are obtained as descending. Also the series of annual minimum temperature for 52 stations in Iran have been measured and predicted with different Alpha coefficients. The forecasts show that minimum temperature will increase in the west areas between 0. 02-0. 32 degree، east areas between 0. 27-0. 45degree، south areas between -0. 27-0. 28 degree and north areas between -0. 35-2. 28 degrees.

    Keywords: Trend, Tendency Models, Parametric tests, Nonparametric tests, Holt method
  • Maryam Sadat Mirabedini, Shaban Shataee, Maryam Agh Ataby Pages 49-64
    Introduction

    Nowadays، remote sensing is considered as an important subject in many field studies، like agronomy، hydrogeology، mineral exploration، geography and geology. This knowledge has been applied in most of the geological fields. The significant application of remote sensing is preparation of lineament maps that is an important issue in the geological studies. In the remote sensing study، geological structures (e. g. cracks، fractures، faults، shear zones and foliations) are illustrated as a lineaments (Kamali et al.; 1390،2). Therefore، tectonic and structures of different areas can be investigated with use of remote sensing techniques and providing these maps. Lack of access to some areas as well as necessity to spend a lot of money and times for studying large areas have been forced researchers to find a solution for these problems. The first remote sensing studies related to geological applications dates back to first aerial photo studies in the early 20thcentury (Koç; 2005، 6). The lithology، structures and geology units had been identified with using aerial photographs، and finally geological maps had been drawn. After the Landsat images were published in 1972، the use of remote sensing was increased in the earth studying. Recently these images are largely applied in the geological researches. Since satellite images are obtained from varying wavelength intervals of the electromagnetic spectrum، they are considered to be a better tool to discriminate the lineaments and to produce better information than conventional aerial photographs (Casas et al.; 2000، 2011). The purpose of this research is to apply the remote sensing techniques and ASTER images for lineament extraction (faults) using both visual (manual) and automated methods in the central Alborz، map faults preparation، and then comparison of these maps with geology maps and with together. Study Area: Iran is located within the Alpine–Himalayan folded belt in a zone of continental convergence between Eurasia and Arabia platforms which is mostly accommodated by shortening and strike-slip faulting in the mountain belts such as the Great Caucasus، Zagros، Alborz، KopehDagh and also the active Makransubduction zone (Javidfakhr et al.; 2011، 290). The Alborz range is an active mountain belt that surrounds the South Caspian Basin. The deformation of the Alborz is due to the northward shortening between the central Iranian block and the Eurasian plate (Vernant et al.; 2004، 179). The researches show that the present-day deformation in Alborz is characterized by range-parallel left-lateral strike-slip and thrust faults (Djamour et al.; 2010، 1). The study area is located in the northern part of the Central Alborz Mountain range between longitude of 51. 19 -52. 13 E and latitude of 36. 01 -36. 68 N. The main structures of the study area are the North Alborz and Khazar faults، which are only separate structures east of 51°30''E. The North Alborz Fault is mapped as a south-dipping thrust (Geological Survey of Iran 1991a، b، Allen et al.; 2003، 662). It changes strike at 53° E from ENE to WNW. The Khazar Faultwith a southward dip direction is the longest fault in the northern edge of the Alborz Mountains. This structure separates the Caspian Sea to the north from the Alborz Mountains in the south (Motaghi et al.; 2010، 790).

    Material And Methods

    In this study، three data sets have been used: 1) ASTER Digital Elevation Models (DEMs) of central Alborz (between longitudes of 51. 19 -52. 13 E and latitudes of 36. 01 -36. 68 N). 2) 1:25000 contour line maps of central Alborz. 3) 1:100000 geological maps of Baladeh and Marzan AbadBefore the lineament extraction، a set of image processing techniques should be done that are including radiometric and geometric images correction and image enhancement techniques. Since the radiometric correction had been performed in the ground stations on the satellite images، this correction wasn’t necessary for our ASTER images. The geometry correction and geo-referencing have been done only on VNIR images due to be high spatial resolution. The image enhancement techniques that applied on VNIR band are including filtering (directional)، PCA (principle component analysis) and band rationing (OSAVI (Rondeaux et al.; 1996، 102)). Then، lineaments have been extracted using both visual (manual) and automated digital interpretation method.

    Results And Discussion

    After lineament extraction the fault maps، rose diagram، density and length-density maps have been drawn. The comparison analysis of obtained faults maps by both methods (visual and automated) with faults maps that obtained from geology maps was done in points of estimating frequency، length، direction and density of line aments. The frequency of automatically extracted lineaments (3886) are greater than the manually ones (1912). The first reason for this results is that short lineaments have been identified by the program (LINE module of PCI Geomatica)، and the second one is that this program can’t distinguish faults from other lineaments (roads، rivers، etc.). The amount of identified lineaments with filtering، PCA and band rationing are respectively 1440،411 and 57. As you see، the frequency of identified lineaments with filtering and PCA are greater than the band rationing ones. The reason is due to further lineaments enhancement using directional filters as well as 80% information in the first component of the PCA. With using band rationing some of the lineaments in the southern part of the study area which could not be recognized by directional filters and PCA have been identified. The average length of the manually extracted lineaments (2. 19 km) that are close to the geology map lineaments (1. 93) are far from the average length in the automatically extracted ones (0. 18). The maximum length of lineaments for the manually extracted (25 km) which is as long as fault lengths in the central Alborz (e. g. 150 km for Mosha fault) is 0. 36 km in the automatically ones. Orientations of lineaments for both maps are illustrated with rose diagrams. The dominant orientations for the manually extracted lineaments are in the east-west and northwest-southeast directions. These orientations are as a result of deformation in the region. Dominant deformation in Alborz is characterized by range-parallel left-lateral strike-slip and thrust faults. Deformation is due to the north–south Arabia–Eurasia convergence، and westward motion of the adjacent South Caspian relative to Iran. Roughly north–south shortening occurs on thrusts that dip inwards from the range margins (Allen et al.; 2003، 659). The density (Zakir et. al.; 1999، 1073) and length-density maps indicate increasing of lineament density in the northern parts and in east-west direction (in the direction of Khazar and North Alborz faults). This means that there is a fracture zone in the area (Sarp; 2005، 58).

    Conclusion

    In this research، lineaments (faults) of central Alborz are extracted from the ASTER images by using remote sensing techniques and both visual (manual) and automated methods. The results show that directional filters and PCA had a main role in faults identification and extraction. The reason is due to further lineaments enhancement using directional filters as well as 80% information in the first component of the PCA. Some of the lineaments in the southern part have been identified by using band rationing. The extracted lineaments are consistent with the geology maps’ faults (Saidi; andGhassemi; 1381; VahdatiDaneshmand، 1379). These images processing techniques and lineaments identification indicate that directional filters (Sarp; 2005، 43. Koçal; 2004، 15) are the most important factors for lineaments recognition in the vegetated areas. Frequency، length and orientation of the automatically extracted lineaments have no consistency with the geology maps’ faults. Since the program (PCI geomatica) can’t distinguish fault lineaments from the others، the Khazar and North Alborz faults which are the most important structure in the Alborz region have not been recognized. So، for geological researches that always have been based on field studies and require high precision، the automated method because of the low accuracy isn’t recommended. In the visual (manually) method، length، orientation، density and length density are consistent with fault’s status in central Alborz. Consequently، the best way for geological and structural studies on large areas or areas that are difficult to access، is the visual method for lineament extraction.

    Keywords: Fault line Extractions, ASTER, Automatic Digital Interpretation, Visual Interpretation, Central Alborz
  • Hamid Zreabyaneh Pages 65-86
    Introduction
    Inflation of population and rising living standards in many countries need to be enhanced the high quality water suitable for different uses such as agricultural، industrial and drinking sections. Groundwater is one of the most important water supply sources which are encountered with many problems such as drawdown، recharge reduction due to low rainfall and different natural and man-made pollutions. Therefore، monitoring of groundwater quality is very important. Chemical hazards are one of the major environmental hazards in the field of water quality issues and other areas that jeopardizes the health and security of human. Researchers report results from the application of geostatistics in hydro-solving processes، increase accuracy، and reduce the number of samples collected from the economic point of view. Study Zehtabian et al. (2010:61) with the aim of modeling spatial variation of groundwater quality using geostatistical methods، showed that Co-Kriging method is more accurate than radial basis function and the inverse distance weighting methods. Maghami et al. (2011:171) for groundwater quality zoning in Abadeh city used kriging and inverse distance weighted. Comparing the results of this study showed that kriging method with semi variogram of circle is compared to other methods. Spatial prediction of fluoride concentration in groundwater resources in the North West of Iran indicated that Kriging method with r= 0. 73 was less than Co-kriging (r= 0. 86) (Asghari Moghaddam et al.، 2008:1). Survey data and the findings indicate human use of chemical fertilizers and reduce the quality of water resources. Such a situation is not only caused environmental sustainability، sustainable development، but also to the environment will be broken. Therefore، unsustainable human development، along with its non-application of chemical fertilizers is one of the most important environmental hazards at all levels of society. The purpose of this study was the spatial variability modeling of water quality parameters in Hamedan - Bahar plain by geostatistical methods. Study Area: Hamadan – Bahar plain، called Siminehrood، with an area of 2459 km2 along 48° 17'' to 48° 33 E and 34°49'' to 35°02'' N is located in the northern highlands of Alvand. For zoning of aquifer parameters used data of 25 observation wells during the spring and summer in during 2009-2010 years (Fig. 1). Fig. 1 Location of the study area Lack of adequate surface water، rainfall and rainfall duration mismatch causes excessive pressure on groundwater resources for supplies more than 80 percent of agricultural water and 50 percent of drinking water aquifer is above (Balali et al.، 2010:194). On the other hand، indiscriminate and inappropriate use of fertilizers to increase agricultural production can alter the quality of groundwater resources. For zoning of the aquifer quality، the data of 25 observation wells during the spring and summer of the years 2009 and 2010 were used. As the season of spring probe picked up in order to perform the irrigation of crops، and the importance of summer as the season of low water، picked up، and the spring is to provide drinking water for the cities of Hamedan.
    Material And Methods
    The parameters studied were EC، pH، SAR and TDS as the main characteristics of groundwater. For interpolation of data in locations without measurements، were used three methods of geostatistical including ordinary kriging (OK)، inverse distance weighting (IDW) and radial basis function networks (RBF). For choice modeling method، Normal Root Mean Square Error (NRMSE) and Mean Bias Error (MBE) in the form of cross-validation technique was used.
    Results And Discussion
    The results showed that kriging with spherical semi-variogram are useful for modeling qualitative factors (Fig. 2). NRMSE of the spherical semi-variogram for each of the four parameters was 0. 95 to 0. 96 that was lower to other semi-variogram (0. 96-0. 98). The lowest error was modeled on the parameters pH، and the maximum error was awarded to EC parameters with NRMSE=0. 42 and MBE= -0. 01. Fig. 2 The semi-variogram of each of the quality parameters Accordingly، the zoning was done for the interpolation of aquifer quality parameters based on the information of plain aquifer. The map of zoning showed that trends of EC and TDS are similar. One of the main reasons of similarity changes is because of a linear relationship between these parameters. The results of zoning indicated EC، TDS and SAR values has increased form the South East along the North East. So that SAR from 1. 9-28 to 1. 2-0. 8، EC from 2395. 3-1266. 4 to 823. 5-483. 3 µmoh/cm and TDS from 1591. 3-826. 3 to 526. 2-295. 7 mg/L decreased (Fig. 3). But change of pH was non-uniform than the other three parameters and its maximum was in the north-west plains (7. 75-7. 93). Also، The accuracy of geostatistical methods in the estimation of the area under study (non-peak) was higher. The reason is due to lack of measurement points in border studies، and regional climatic factors in causing maximum points، which is not in the geostatistical methods.
    Conclusion
    The results showed that kriging with spherical semi-variogram are useful for modeling qualitative factors. Also، the results show that the statistical accuracy is low in estimation of water quality parameters at maximum points. In general it can be stated، with water quality values at one point، can estimate amount to the same quantity at a point with known coordinates and high precision.
    Keywords: Groundwater Quality_kriging_Semi_Variogram_Hamedan – Bahar plain
  • Abbas Mofidi, Mohsen Hamidianpour, Mohammad Saligheh, Bohloul Alijani Pages 87-112
    Introduction

    Wind is one of the important meteorological parameters which have an extensive application in environmental studies. The winds have various spatial and temporal scales regarding to their characteristics and structures. Sistan wind as an outstanding low level flow in eastern Iran is playing an important role to creation of local and regional climatic features. The Sistan wind initiates and ends with an abrupt change in wind speed and wind direction which mostly related to a regional scale atmospheric circulation pattern. Study Area: The Sistan area is located at the tail end of a large closed inland basin (Fig. 1)، in one of the driest regions of the world (Smith، 1974). The area has very varied climatic conditions. The annual precipitation in the lower Sistan basin is about 50 mm. The Helmand river plays a major role in the Sistan region by draining the snowmelt waters from the mountains of the southern Hindu Kush. The basin has no outlet and receives drainage from an area of about 335،000 sq km. Its floor occupies about a third of this area and lies at elevations that range from 500 to 900 m.، the west end of the Hindu Kush، with peaks more than 4000 m a. s. l.، borders the basin on the north. Mountains as much as 2000 m high border the basin on the west، south and east. The climate of this area is arid. Mean monthly low temperatures are near 5°C، and mean high monthly temperatures are near (35°C).

    Material And Methods

    This research aims to clarify the onset and the withdrawal dates of Sistan wind by using a change point approach. The meteorological dataset، i. e. surface wind at 10 m above ground level (agl)، was obtained from the Zabol meteorological station، located well within Sistan basin and in close proximity (~10 km) from the Hamoun lakes. The dataset corresponds to 3-hrs and/or daily-averaged observations covering the whole period 1972-2012 with specific emphasis on wind velocity and wind direction. Three most popular change point techniques including Pettitt، SNHT and Buishand were applied to estimate the onset and withdrawal dates of Sistan wind during the whole period of the time. All three techniques are used wind velocity time series to clarify the specific time for each year. Also، the wind direction time series were used to confirm the results which obtained by change point techniques.

    Results And Discussion

    The result indicates that the wind over the Sistan basin experiences two types of abrupt changes during the warm period of the year. The first type of abrupt change is related to the eastward movement of synoptic systems originated from extra-tropics which can affect the region for a short term (i. e. for a couple of days). In contrast، the second type of the abrupt change can recognized as a sign of the onset and withdrawal of Sistan wind over eastern Iran. In the beginning of summer، when the wind over Sistan basin suddenly changes from an irregular and low intensity wind to a stable and strong northwesterly wind، one can suppose that the onset of Sistan wind is occurred. On the other hand، the withdrawal of Sistan wind is related to an abrupt change in direction and the intensity of wind where the stable and strong northwesterly wind replaces by an irregular and low intensity wind over the Sistan basin only during a few days at the end of warm period of the year.

    Conclusion

    The results indicate that the Pettitt is the most reliable method among three change point techniques، regarding to estimation of onset and withdrawal dates of the Sistan wind. The Sistan wind is initiated on 122nd Julian day (May 2)، and is ended on 287th Julian day (October 14)، on the base of Pettitt method. Therefore، the average duration of Sistan wind blowing is about 165 days in the year which is apparently longer than the duration which former researchers has been estimated. The results also indicate that the inter-annual variations of Sistan wind intensity are significantly high. Also، it should note that، there is no any significant trend in the behavior of Sistan wind، (i. e. onset، withdrawal and wind blowing duration)، when the wind velocity and direction of Sistan wind is analyzed. It should also conclude that the inter-annual variations of wind velocity and its onset and withdrawal times over Sistan basin are mostly related to the variation of regional to large scale atmospheric circulation over southwest Asia.

    Keywords: Sistan Wind, Change Point, Onset, Withdrawal, Wind blowing duration
  • Ezatallah Ghanavati Pages 113-131
    Introduction
    Flood is one of natural hazard which ranks the most one just like earthquake and drought according to the report of the natural hazard program of the United Nations. Besides physical factors، and lack proper management will increase the flood potential. Therefore، in order to prevent flood damage it seems to be necessary to provide essential requirements before physical expansion of cities. Floods not only in developing country but also in developed country cause life and property damages. Such as these disasters was hurricane Katrina that had serious damages for the united sated of America. Occurrence of several flood disaster in Karaj city during few last years، such as 31March 2009 disaster flood that cased many life and property damages، indicate that flood researches are necessary for this area. Many studies had done by researchers related to flood in Iran and around the world. The flood map zonation for Helmand basin in Afghanistan was produced by using revers engineered flood hazard (Hagen، et al.، 2010). Another studies related to flood had done by (Sinnakaudan، et al.، 2003، Hudson، et al.، 2003، Wolski، et al.، 2006، Baldassarre، et al.، 2003). Hossain zadeh and Jihadi (2009) were studied the effects of physical urban expansion on drainage natural pattern and urban flood intensity of Mashhad city in Iran. By using HEC-HMS hydrological simulation method characters of flood were studied in Kron plain in Iran (Amir Ahmadi، et al.، 2011). The result of this research shows that it''s not necessary to relate the characters of final flood to the pick flood sub basins. The flooding areas in Farahzad basin of Tehran، Iran were studied by using analytical hierarchy process (Ghanavati، et al.، 2012). Study Area: The Karaj as the fourth biggest city of Iran is situated between 35 39′ latitude north and 51 10′east longitude in the Alborz province. This area has 1108m minimum altitude and 3239m maximum altitude. Yearly average precipitation in this area is 251mm and about 42 percent of them raining in winter season. Karaj city has moderate climate and its mean yearly temperature is 14. 1 degree in centigrade scale. The Karaj plain is situated between Kane and Karaj river basin. So، the physical bed of this area was formed by deposited of fluvial cone of these rivers.
    Material And Methods
    In this research to identified areas of high risk flooding and high risk prone to flood، teen factors as: slope، profile curvature، plan curvature، precipitation، drainage density، distance to river، geology، geomorphology، land use and soil that affect flooding were used for preparing flood risk map of Karaj area. These data layers provide and extract by many sources such as geology maps of the area، satellite imagery، and data of climatology and hydrology stations. The fuzzy model was used to weighting each factor related to their effects on flooding. Fuzzy model is based on fuzzy logic that used in fuzzy condition. According to fuzzy logic each member belongs to different sets but in different grade. Membership grades are between 0-1 and also zero and one themselves. The fuzzy theory has been developing from the beginning to now and has had different usages. This theory has been used widely in modeling the physical phenomenon، survey and classification. In the theory of exact set if we consider a set each member of the mother set is in the set or it isn’t and we can define the below function for each set like (A). In this function each member of (A) set is attributed to (1) and the members out of the set are attributed to (0). A fuzzy set is represented by membership function. This function is indicating the member''s grade of dependency by a real number between [o-1]. So، before executing the fuzzy model، membership function is determined for each layer (below table). By determining the functions to each layer، the value of each layer is located between [0-1]. As the area are having the most effect on flooding attributed to (1) and the areas having the less effect on flooding attributed to the less possible number or (0). By using Arc GIS sum and product fuzzy operators on layers، the fuzzy sum and product maps are provided. To adjust the maximum and minimum values of risk، the gamma operator was used to provide the final map.
    Result And Discussion
    The final mapping flood risk is provided according to determine fuzzy membership for each layer and performing flood model based on Gama 0. 9، 0. 7 and o. 5. To find the most appropriate Gama for flooding map، between effective factors and the flood maps that provided by different Gama correlation were calculated using ArcGIS software (table No. 1). Gamma slope soil geomorphology landuse profile curvature plani metric curvature precipitation drainage density distance to river geologyGamma 0. 9 0. 74 0. 05 0. 82 0. 1 -00. 3 0. 06 0. 78 -0. 2 0. 26 -0. 69Gamma 0. 7 0. 67 0. 03 0. 72 0. 11 -0. 09 0. 09 0. 76 -0. 24 0. 34 -0. 68Gamma 0. 5 0. 56 0. 02 0. 6 0. 1 -0. 1 0. 11 0. 67 -0. 21 0. 33 -0. 63According to the evaluations، the Gama 0. 9 has the most correlation with effective factors and so Gama 0. 9 was selected for providing the final flood map. Based on the natural fraction method، the final risk zonation flood map is classified in five categories from very high risk areas to very low risk areas.
    Conclusion
    According to the final flood map (Gama 0. 9)، the areas which caused the most flood situated in north eastern، north and east of Karaj city. These areas have slope between 30-75 % and precipitation between 600- 900mm. Their location is between 1500-3000m far from the rivers. The drainage densities of these areas are between 0-0. 5. Also، the flat and low area such as valises، stream channels، terraces and flood plains have the highest potential for flooding. These landmarks are located mostly in western south and eastern south of the studied area. These areas have slope between 1-5 % and height between 1000- 1400m. Their location is between o-1500m far from the rivers.
    Keywords: Flood Risk Mapping, Fuzzy Logic, Flood Geomorphology, Karaj
  • Mahnaz Jahadi Toroghi, Seyed Reza Hosseinzadeh Pages 133-162
    Introduction
    Current statistical methods may be unable to accurately predict recurrence intervals of rare، large magnitude floods. The usual procedure involves extrapolation from gauged hydrological records documenting 30–40 year records of observed (normally small) floods to the estimation of the quantifies and recurrence intervals of very large، rare floods. This Conventional approaches become less reliable as recurrence intervals exceed the length of the data base. If anything that happened in the past can happen at any instant with the same likelihood، then history provides no meaningful information and conventional method of addressing flood risk assessment can be improved by including information on past floods. Past flood information can be obtained from palaeoflood and from historical information. Documentary records can provide a catalogue of the largest flood events that curried during periods of settlement، while palaeoflood investigations using palaeostage geological indicators can document the magnitudes of the largest floods over well defined periods of time (usually from decades to millennia)، and provide evidence of all other events below or above specified flow stages or thresholds. For historical flood data، human observation is required، but the modern hydrological procedures employed at gauging stations do not apply. Both sources are types of non-systematic information and use the same statistical analysis approach. palaeoflood and historical flood data provide a feasible solution for assessing and mapping flood risks، and planning flood-prone zones. These improved flood-potential estimates using palaeoflood and historical flood data also have significant beneficial economic and environmental implications، related to floodplain planning، management design of hydraulic structures، management of critical water-resources and environmental conservation issues. This paper is focused on introducing of paleoflood hydrology as an approach of modern geomorphology in flood risk assessment with emphases on using the technique in Iran. Therefore the present paper has a review substance which is based on all results throughout the world and 6 case studies in Iran. Paleoflood Hydrology: Definition and Background The term of paleoflood first came into prominent use in the 1970s (costa 1974; patton and Baker 1977; Baker et al 1979). The recordings of palaeofloods are natural، not human، and this distinguishes them from instrumental/systematic and from historical floods measurements. Paleoflood hydrology is the science of the study of paleofloods، which is emerged from divers studies in quaternary geology and fluvial geomorphology. In definition Palaeoflood hydrology is the study of past or ancient flood events which occurred prior to the time of human observation or direct measurement by modern hydrologic procedures. Most studies involve prehistoric floods، although the methodology may also be applicable to historic or modern floods in remote areas not subject to either modern hydrologic analysis or to human observation. These indices include various effects on the landscape، sediments، or vegetation. Then Sources of palaeoflood data are geological indicators such as flood deposits، silt lines and/or erosion lines found along a river’s channel، valley walls and/or terraces etc. The background of paleoflood studies during the 1970s to recent years has been summarized in table 2 with a dividing the age into 3 following stages: 1. the origin of the discipline (before 1980)، 2. The Evaluation period and regional development (1980-2000)، 3. Globalization phase. The origin based on a review from Baker (2008:2) is returned to Dana (1882)، Tarr (1892)، flint (1933)، (Fuller، 1917) and specially Harlen Bretz (1923،1928 and 1929). then in 1982 paleoflood hydrology received its name by Kochel and Baker (Baker، 2008:5). Baker (2006، 2008 and 2013) reviews the origin and progress of the discipline in all around the world، the below records are been summarized directly from his papers with referring to table 2 in the Persian section of this paper. Paleoflood studies were started with an extensive program of investigations in central Texas during the early and middle 1970s (Baker، 1975; Patton and Baker، 1977). During the early 1980s، the focus of southwest US paleoflood research moved to Arizona and adjacent portions of Utah (Ely and Baker، 1985; Webb et al.، 1988). About this same time، a related program in paleofloodhydrology was initiated in Colorado (Costa، 1983; Jarrett، 1990)، California (Ostenaa et al.، 1996) and Utah (Ostenaa et al.، 1997، Greenbaum et al.، 2005). Then paleoflood investigations has been pursued for many years in the north–central United States (Knox، 1985، 1993، 2000)، northeastern US (Brown et al.، 2000)، and limestone caves in the AppalachianAreas (Springer and Kite، 1997; Aldred،2010). Paleoflood studies are also finding application in the northwestern US (O’Connor et al.، 2003) and in Canada (Gottesfeld، 1996; Saint-Laurent et al.، 2001، 2010). paleoflood investigations based on SWD and PSI developed to northern Australia during the early 1980s (Baker et al.، 1983، 1985 and Pickup، 1987; Pickup et al.، 1988) and followed in India during the lately 1980s to the beginning of 2000s (Baker،1988; Ely et al.، 1996; Kale et al.، 1997، 2000، 2003) More recent studies have been accomplished in southern India (Thomas et al.، 2007; Kale 2008). Studies have also been conducted in nearby Thailand (Kidson et al.، 2005) and Nepal (Wohl، 1995). The best settings for SWD-PSI paleoflood hydrology occur in southern Europe. Extensive work has been conducted in Spain (Benito et al.، 2003; Thorndycraft et al.، 2005). More localized studies were done in Greece (Lewin et al.، 1991; Macklin et al.، 2010)، Italy (DeWaele et al.، 2010)، and southeastern France (Sheffer et al.، 2003، 2008) Paleohydrological investigations in northern Europe have predominately focused upon interpretations of alluvial stratigraphy in floodplain and terrace sequences. Extensive work has been done in the UK (Brown et al.، 2001; Macklin and Lewin، 2003)، Germany (Hoffmann et al.، 2008)، and Poland (Starkel et al.، 2006). Werritty et al. (2006) described a study in Scotland. Luo (1987) reported the detailed records of extraordinary floods on major Chinese rivers and results used in paleohydraulic calculations of peak discharges at appropriate cross sections (Shih، 1985). Subsequent Chinese paleoflood research has generally followed the paleoflood analytical techniques employed internationally by other paleoflood researchers (e. g.، Yang et al.، 2000; Yu et al.، 2003; Zhu et al.، 2005). Paleoflood studies in Japan are summarized in papers by Jones et al. (2001)، Grossman (2001)، and Oguchi et al. (2001). In the early 1990s، a detailed program of paleoflood investigationswas begun in the Negev Desert of southern Israel (Wohl et al.، 1994، Greenbaum et al.، 2000، 2001،2008). In Iran a catastrophic flooding in the northeastern of the country caused Iranian researchers looked for a new way to calculate of large flood discharges and asses the highest flood level in the Channel Rivers، so they used the paleoflood techniques in many bedrock canyons in the country (Hosseinzadeh and Jahadi toroghi 2007، 2013، Hosseinzadeh et al، 2013 and 2014). The paleoflood investigations in southern Africa were accomplished by Smith and Zawada (1990)، Zawada (1994، 1997، 2000)، and Zawada and Hattingh (1994). Slack Water Deposits (SWD) and Paleostage Indicators (PSI): Slack-water deposits and palaeostage Indicators are used to infer the past flood stages. River channels cutting through hard bedrock or other resistant boundary materials (e. g.، cemented terraces) provide the most suitable settings for reconstructing the palaeoflood record as they are the most conducive to the accumulation and preservation of flood deposits and palaeostage indicators (PSI’s). Slack-water deposits consist of sand and silt (occasionally gravel) that accumulate relatively rapidly from suspension during major floods، particularly where flow boundaries result in markedly reduced local flow velocities. For palaeoflood studies، a slack-water sedimentation site should be optimum for both the accumulation and preservation of the relatively fine-grained flood sediments carried high in flood flows at maximum stage. They may develop at abrupt channel expansions، in the lee of bedrock protrusions، at meander bends and at various channel-margin alcoves (in shallow caves along bedrock walls). These fine-grained deposits can be preserved in stratigraphic sequences، providing detailed and complete records of flood events that extend back several thousands of years. Tributary mouth slack-water sites are among the most easily recognized in a reconnaissance study of potential palaeoflood investigations. Tributary junction angles relatively close to 90 ° are optimum for facilitating deposition by backflooding up tributary mouths. However many investigators stipulate the tributary mouths are the best sites for SWD accumulations، but our studies in the bedrock canyons located at the kopet-dagh mountain range show mostly sites are been informed in the caves and bedrock alcoves (Hoaaeinzadeh and Jahadi Toroghi 2012:92). The thickness of slack water deposits different from a few centimeters to tens centimeters based on geomorphic situation and watershed characteristics. In the North American large rivers the tick sediment layers are common but in the rivers which located in the European and Iranian mountain ranges thin layers are dominated. Comparisons of slack water sediment thickness in different sites show a relationship between slack water deposit thickness and duration of flooding، the deposit thickness increases by increasing of the peak discharge duration. Mean slack water deposit size is partially inherited from the lithology of the mainstream upstream from the depositonal site. The grain size of sediment samples were obtained from she-hezar river in the north of Iran ranges between medium to coarse sands، the mainstream originated from Alam- Kuh Batolith with coarse grain granite and frost weathering produce a large amounts of procedures for flood transportation. In contrast the samples which collected from kopet- Dagh mainstreams include of silt، clay and very fine sands because large areas in the catchment region have covered by marl and clay formations. In addition، grain size is controlled by the fluvial regime of the main river. Paleoflood dating
    Methods
    Once the discharges of paleofloods are determined along a river reach، the absolute flood chronology can be established using by one of dating methods. These methods included Dendrogeomorphology، radiocarbon dating، lichenometry، Thermal luminescence (TL)، Optically Simulated Luminescence (OSL) and cesium137. However Dendrogeomorphology is the best accurate method to precise even the year or season flooding but this technique faces with limitations in the length of the dating. Radiocarbon dating is more popular because its possible to date the paleoflood for longer period of time more than to 40 thousands years. Early works in paleoflood hydrology relied almost extensively on conventional radiocarbon dating for its geochronology. Since the 1980s، however، spectacular advances have been made in geochronological techniques for precisely determining the ages of ancient floods. Most important have been tandem accelerator mass spectrometry (TAMS) and OSL dating (Baker، 2008:7). The first method permits the precise dating of tiny carbon-rich material that was transported by a flood and secondary one permits the dating of individual sand or silt grains that were transported in suspension by flood vent. Cesium137 is also used for dating of very young deposits (Ely et al.، 1992; Thorndycradt et al.، 2005). Unfortunately there are not any laboratories inside of Iran to dating the samples in own country. It should be fine if large universities make enough funds to establishment of dating laboratories. Hydraulic Modeling: Hydraulic flow models can be used to predict peak flood discharges when field surveys of channel geometry permit the association of palaeostages with discharges in channels. Computerized procedures for hydraulic flow modeling are used to tie the elevations of the highest slackwater deposits to surveyed river cross sections. Correlation of multiple SWD-PSI sites along a river reach is used to identify the maximum palaeostage achieved by a given flood. The early paleoflood hydrology investigations used the slope-area equations. The largest probable floods have been calculated in 6 Bedrock Rivers in Iran by using manning formula and paleoflood stages based on slack water deposit elevations (table 2 In the Persian section). Important advances have accrued since 1980s in various aspects of computational hydraulics. Various two-dimensional models، particularly depth-averaged approaches، are increasingly being employed for paleoflood studies (Baker، 2008:7). Paleoflood Hydrology in Iran: Iran is located in the particular climatic and geomorphic location which causes catastrophic flooding in many regions every year. Flash floods in small catchments as Tajrish (capital Tehran)، Masuleh (a historic village in Gilan) and Bujan (a village in Khorasan Razavi); large floods in larger rivers as Neka، Tajan (northern slopes of Alborz)، Madarsoo (National park of Glestan) and Ghareh Aghaj basin (in Zagros) are showed the flooding capability of this country. Gage station records are not long enough to calculate the interval recurrences of large floods but it is possible to find many paleoflood sites in most of rivers. Based on Our observations in bedrock canyons in Kopet-Dagh and Zagros mountain areas there are many paleoflood slack water deposit sites in the channels that preserved in a very good condition. However it''s difficult to find confident slack water deposit sites in the humid climate of northern Iran but the reorganization of past floods is probable using dendrogeomorphology (Hosseinzadeh and Jahadi Toroghi، 2013). The comparison of large flood discharges obtained by paleoflood data with discharges calculated by statistic methods suggested large differences between these methods. Conclusion and Prospect: Paleoflood hydrology was separated from quaternary geology and fluvial geomorphology in 1980s. After nearly three decades research in paleoflood hydrology، it has found a global development and many countries using the methods for assessing the flood hazard and environmental managements. One of new approach is reorganization of the origin of sediments to understanding of the paleostorm spatial distributions، especially in European and Iranian watersheds which they have a very clear slack water deposit units. In other words the slackwater deposit layers at these rivers can be separated in color، grain size، mineralogy and thickness، which help to illustrate the origin of sediments. Paleoflood hydrology can detect of climatic changes، explain the drainage network response to these changes and the effects of atmospheric circulation patterns on flooding for a long period of time. Planning for establish of global database for paleoflood data will help researchers to find a global view of paleofloods for further studies. Flood hazard studies in Iran are mostly involve statistical methods by analyzing of yearly peak discharges to calculate the recurrence of large flood events. Other works like watershed management projects use the experimental equations or computer modeling for hydrological analyses. Since 1980s، Turning of processes geomorphology to using the historic geomorphology methods has made modern geomorphology by combination of process and historic geomorphology، inside of this paradigm، paleoflood hydrology emerged from modern geomorphology. Iranian academic centers and governmental organizations who work on natural environment were stopped in the process geomorphology stage، not passed to using modern geomorphology techniques، similarly in flood studies they were using the traditional hydrologic methods for analyzing، predicting and planning. It’s the time to select a new approach for flood risk analyzing in our country، the rivers are historian can help us to reconstruct the flood stages and flood discharge for a longer calendar. Young geomorphologists should be better to pick-up their equipments and do filed work for getting truly data from nature to make them able for accurate predicts.
    Keywords: Paleflood Hydrology, Paleostage Indicators, Slack Water Deposits, Paleoflood Reconstruction