فهرست مطالب

  • پیاپی 106 (زمستان 1397)
  • تاریخ انتشار: 1398/01/20
  • تعداد عناوین: 12
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  • مقاله علمی پژوهشی
  • سینا صلحی، عبدالله سیف * صفحات 611-638
    ژئومورفولوژیست ‏ها برای نمایش ناهمواری‏ ها و اشکال ژئومورفیک سطح زمین از مدل‏های مختلفی استفاده می‏کنند؛ یکی از پرکاربردترین آن‏ها مدل سایه- روشن است که با تابش فرضی نور از یک منبع از آن برای تشخیص و نمایش عوارض مختلف ژئومورفیک و فرم ‏های خطی استفاده می‏شود. ثابت‏ بودن منبع نور و تنوع و پیچیدگی سطوح زمین در بسیاری مواقع مدل‏ها و الگوریتم‏ های استاندارد را با محدودیت روبه ‏رو و تفسیر عوارض سطح زمین را دشوار می ‏کند. برای تصحیح، بهبود، و نمایش هدفمند توپوگرافی از مفهومی با نام «مورفولوژی نوری» استفاده شد. مولفه‏ های ژئومورفولوژیکی مانند شیب، جهت شیب، فراوانی، و توزیع جهات و میزان و نوع همگرایی- واگرایی سطوح زمین مد نظر قرار گرفت. از چهارده مدل مختلف انحنا و شش مدل نوسان زوایای آزیموتی و سمت‏الراسی برای آشکارسازی و تصحیح نمایش عوارض استفاده شد. آنالیز جهتی، مورفولوژیک، و کنتراست بر روی همه مدل‏ ها انجام و با نتایج مدل استاندارد مقایسه شد و نحوه عملکرد و ارتباط هر یک با لندفرم ‏ها تحلیل شد و کاربردهای رایج آن‏ها در شناسایی لندفرم‏ها تحلیل گردید. همه مدل‏ها در محیط پایتون اجرا و توسط واسط گرافیکی پایتون طراحی شد. نرم‏افزار Optical Morphology برای اجرای همه مدل‏ها ارائه شد.
    کلیدواژگان: برنامه‏ نویسی پایتون، ژئومورفولوژی، سایه- رن گ‏زنی محاسباتی، مورفولوژی نوری
  • فاطمه ستوده، بهلول علی جانی، محمد سلیقه *، مهری اکبری صفحات 639-653
    در این پژوهش برای شناخت تاثیر رشته‏ کوه زاگرس در تغییرات چرخند‏هایی که از غرب وارد ایران می‏شوند از رویکرد محیطی به گردشی استفاده شد. بدین منظور، داده ‏های سیزده ایستگاه سینوپتیک غرب ایران و داده‏های ساعتی ERA-Interim با تفکیک مکانی 125/0×125/0 درجه، طی سال‏های 1984 2013 دریافت شد. با این رویکرد، 203 روز بارش فراگیر شناسایی شد. با اعمال تکنیک تحلیل عاملی بر روی داده‏های تراز دریای متناظر با این روزها، عامل دوم بیشترین پراش بارش ‏های حاصل از چرخند را توجیه می‏کند. روزهای چهاردهم تا هجدهم آپریل 2003، که بیشترین همبستگی را با سایر روزهای این عامل دارد، الگوی نماینده انتخاب شد. در این الگو، چرخند‏ رسیده به کوه ‏های زاگرس از زمان شکل‏ گیری تا زمان رسیدن بر روی عراق و ادغام با سامانه سودانی، به لحاظ دینامیکی، تقویت می‏شود. به هنگام نزدیک‏ شدن به زاگرس، از تاوایی مثبت و سرعت قائم هوا کاسته می‏شود؛ اما با عبور از زاگرس بر تاوایی مثبت آن افزوده می‏شود. رابطه چرخند تقویت‏ شده با منطقه واگرایی ترازهای میانی وردسپهر در همه مراحل مشاهده شد. زاگرس نخست باعث تضعیف و دوقطبی‏ شدن چرخند می‏شود. سپس، با دور شدن از کوهستان، چرخند مجددا تقویت می‏شود. این چرخند‏ها را چرخند‏ زاگرسی می‏توان نامید.
    کلیدواژگان: تاوایی، زاگرس، سرعت قائم هوا، شار رطوبت، چرخنده ای بادپناهی
  • فاطمه عابدی، داریوش رحیمی *، سید ابوالفضل مسعودیان، محمد صادق کی خسروی کیانی صفحات 655-667
    سامانه‏ های بندالی پدیده‏ های مقیاس همدید منطقه برون‏حاره‏اند که موجب انقطاع و تضعیف بادهای غربی می‏ شوند و در رخداد فرین‏های آب‏وهوایی نقش مهمی دارند. برای بررسی فراوانی، توزیع زمانی و مکانی سامانه ‏ها از داده ‏های ارتفاع ژئوپتانسیل تراز 500 هکتوپاسکال با تفکیک مکانی 5/2 × 5/2 و تفکیک زمانی شش‏ ساعته برای دوره 1951 تا 2012 در نیمکره شمالی و نمایه فیلترشده (TM) استفاده شد. یافته‏ ها نشان داد که رخدادها در اطلس دو برابر آرام و سه برابر امریکا و غرب اروپا است و کمترین رخدادها در شرق آسیا و شرق اروپا است. همچنین، از نظر زمانی، در اقیانوس اطلس سال 1954 بیشترین و‏ 1968 کمترین و در اقیانوس آرام سال 2011 بیشترین و 1957 کمترین فراوانی رخداد را دارند. در ایران یازده سال بدون رخداد و سال 1975 بیشترین درصد فراوانی مشاهده شد. توزیع فصلی نشان داد بیشترین فراوانی رخداد به ‏ترتیب در فصل تابستان، پاییز، زمستان، و بهار است. رخدادهای بندالی در فصل زمستان بیشتر روی مناطق اقیانوسی و سواحل و در فصل گرم روی مناطق قاره ‏ای نیز مشاهده شد. همچنین، مشخص شد که رخداد سامانه‏ های بندالی در 90 موقعیت از 144 طول جغرافیایی با کاهش بارش سالانه در ایران ارتباط معنادار دارد.
    کلیدواژگان: ایران، سامانه ‏های بندالی، نمایه (TM)، نیمکره شمالی
  • چیمن حاتمی ژار آباد، مهدی عرفانیان *، سحر بابایی حصار صفحات 669-684
    تخمین تابش خالص روزانه در مدیریت منابع آب، به‏ویژه در برآورد میزان تبخیر و تعرق، کاربرد گسترده ‏ای دارد. در این پژوهش از مدل رقومی ارتفاع سنجنده ASTER داده‏های ماهواره‏ای سنجنده MODIS و یک مدل هندسی (مبتنی بر شیب و جهت) در تهیه نقشه‏های تابش خالص روزانه (Rn) در حوضه آبریز دریاچه ارومیه استفاده شد. در تخمین مولفه‏های تابش از محصولات مختلف سنجنده MODIS شامل آلبدو، ضریب گسیلندگی زمین و اتمسفر، دمای سطح زمین و هوا استفاده شد. به دلیل وسعت زیاد حوضه، مولفه‏ های تابش فقط برای چهار تاریخ در شرایط آسمان صاف تهیه شد. برای اعتبارسنجی نتایج، از داده‏های تابش طول موج کوتاه ایستگاه‏های سینوپتیک ارومیه و تبریز استفاده شد و معیارهای خطای RMSE و MAE به ترتیب برابر با 29/30 و 19 وات بر مترمربع به‏دست آمد. مقادیر تابش خالص طول موج بلند روزانه (Rnl) با روش چهارزمانه مشاهدات دمای سطح  زمین برآورد شد. به دلیل فقدان داده ‏های مشاهده‏ای تابش طول موج بلند، از روش فائو (پنمن) برای تولید مقادیر Rnl در ایستگاه ‏های سینوپتیک ارومیه، تبریز، بناب، مراغه، و سهند استفاده شد. نتایج نشان داد مقادیر تابش طول موج کوتاه 24ساعته ورودی در پیکسل‏های هموار و شیب‏دار دارای اختلاف زیادی است.
    کلیدواژگان: ارومیه، تابش خالص، مدل هندسی، مودیس
  • فاطمه جعفری شندی، سعید جهان بخش اصل*، مجید رضایی بنفشه، سید ابوالفضل مسعودیان صفحات 685-696
    بحران آب به همراه اثرهای منفی تغییر اقلیم یکی از دغدغه ‏های بشر در سطح جهانی است. تغییرات بلندمدت فراسنج‏ه ای اقلیمی در نتیجه انتشار گازهای گلخانه‏ ای تاثیر معنی‏ داری در منابع آب تجدیدپذیر داشته است. در این پژوهش به بررسی تغییرات زمانی تبخیر- تعرق واقعی (ETa) و ارتباط آن با دما و بارش استان آذربایجان شرقی پرداخته شد. برای این ‏کار از داده‏های‏ فرآورده دورسنجی MOD16A2 سنجنده مودیس در بازه زمانی 20002014 استفاده شد. تفکیک اسمی داده ‏های به‏ کارگرفته‏ شده سنجنده مودیس 1000 متر است. در این پژوهش، علاوه ‏بر داده ‏های فرآورده MOD16A2، داده ‏های دماهای بیشینه، کمینه،‏ و بارش 11 ایستگاه همدید استان نیز به ‏کار گرفته شد. هدف از این پژوهش مقایسه مقادیر ETa پایگاه ntsg با دما و بارش استان است. نخست میانگین داده ‏های رقومی تبخیر- تعرق واقعی استان بر روی 124548 یاخته برآورد شد. سپس، به روش همبستگی و تحلیل رگرسیون پیوند بین دماهای بیشینه، کمینه، و بارش ایستگاه‏ های هم دید با تبخیر- تعرق واقعی ارزیابی شد. نتایج نشان داد که همبستگی خطی دماهای بیشینه و دمای کمینه با تبخیر- تعرق واقعی یاخته نماینده ایستگاه‏ ها به‏ صورت مستقیم و منفی بوده و با افزایش هر C°1 دما، مقدار تبخیر- تعرق واقعی به اندازه 02/0 میلی‏متر در روز کاهش می ‏یابد.
    کلیدواژگان: بارش، تبخیر- تعرق واقعی، تغییر اقلیم، دما، سنجنده مودیس تررا
  • محمد علی نژاد، محسن حسین علی زاده *، مجید اونق، علی محمدیان بهبهانی صفحات 697-712
    نبکا نقش‏های متعددی در پایداری اکوسیست م‏ های مناطق خشک و فرا‏خشک دارد؛ مهم‏ترین نقش آن‏ حفظ پوشش گیاهی و تثبیت ماسه‏ های روان است. تحقیق حاضر بر اساس روش میدانی شمارش 147 نبکا در دشت صوفی کم استان گلستان انجام شده است. به‏ منظور بررسی تعیین نوع الگوی پراکنش نبکاها و عوامل تاثیرگذار در پراکنش مکانی آن‏ها، خصوصیات مورفومتریک نبکا‏ها (طول، عرض، و ارتفاع نبکاها) در عرصه تعیین شد و موقعیت مکانی آن‏ها ثبت گردید. همچنین، برای تعیین خصوصیات فیزیکی و شیمیایی خاک از راس نبکاها خاک نمونه‏ بردار شد و سپس تحلیل‏ مکانی نبکاها با استفاده از توابع k رایپلی، g تک‏ متغیره، و تابع همبستگی نشان‏دار انجام شد. پراکنش مکانی نبکاها در فاصله‏ های بین 0 تا 50 متر به ‏صورت کپ ه‏ای تعیین شد. همچنین، تحلیل تابع همبستگی نشان‏ دار با احتمال 95درصد و در سطح 5درصد برای پارامترهای طول نبکا، کج ‏شدگی رسوبات، اسیدیته، و ماده آلی خاک نبکاها بیانگر تاثیر این عوامل در الگوی پراکنش بود و سایر پارامترهای مورد مطالعه تاثیری نداشتند. با توجه به نقش مثبت نبکا در کاهش اثر فرسایش بادی، بررسی پراکنش مکانی و عوامل موثر در پراکنش و توسعه نبکاها و ضرورت آگاهی از فرایند‏های طبیعی آن‏ها می‏تواند در مدیریت بهتر به‏ منظور کاهش میزان فرسایش بادی کاربردی باشد.
    کلیدواژگان: آمار مکانی، استان گلستان، تابع همبستگی نشان‏ دار، دشت صوفی کم، نبکا
  • فرشاد صفرپور، سید ابوالفضل مسعودیان، جواد خوشحال دست جردی * صفحات 713-729
    میزان بارش اندازه ‏گیری‏ شده توسط رادار با میزان بارش دریافت‏ شده در سطح زمین تفاوت دارد. در نتیجه، برای تعیین میزان بارش با استفاده از داده ‏های رادار، باید داده ‏های رادار را بر اساس داده ‏های زمینی تصحیح کرد. پیوند میان بارش و بازتابندگی رادار نمایی است از Z=aRb . اگر مقادیر ضرایب این مدل درست انتخاب نشود، برآورد مقدار بارش توسط رادار با اشتباه همراه می شود. در این پژوهش بارش‏ های 26 تا 27 آبان 1394 و 10 تا 12 آذر 1395 در ده ایستگاه‏ استان کرمانشاه بررسی شد. در بارش اول زاویه ارتفاع بهینه پرتو انتخاب و رابطه مربوط به آن استخراج شد و ضرایب تصحیح به‏دست آمد. با استفاده از این رابطه، مقدار بارش برآوردی رادار از 31درصد به 96درصد افزایش یافت و میانگین مجموع بارش برآوردی رادار از 9/8 به 4/32 میلی‏متر رسید که از میانگین واقعی فقط 1 میلی‏متر کمتر است. در بارش دوم، با استفاده از داده ‏های بارش رادار، فقط یک معادله استخراج شد و ضرایب تصحیح رادار به‏دست آمد. نتایج برآورد بارش رادار به این روش نیز مورد قبول بود و میانگین مجموع بارش برآوردی رادار از 6/9 به 5/23 میلی‏متر افزایش یافت که 4 میلی‏متر از مقدار واقعی کمتر بود.
    کلیدواژگان: استان کرمانشاه، برآورد بارش، رادار هواشناسی، صحت‏ سنجی
  • مهران فاطمی*، حمیده دهقان صفحات 731-746
    دما یکی از مهم‏ترین متغیرهای هواشناسی موثر در رشد و نمو موجودات زنده است. برای کمی‏سازی اثر دما در رشد و نمو گیاهان عموما از شاخص ‏های درجه- روز رشد استفاده می‏شود. از این رو، هدف از این تحقیق اندازه ‏گیری میزان روند تغییرات درجه‏- روز رشد دماهای 5 و 10 درجه سانتی‏گراد در طول فصل رویشی در 31 ایستگاه سینوپتیک منتخب با 25 سال دوره آماری مشترک (1364 1389) در سطح کشور است. برای محاسبه واحدهای گرمایی طول فصل رشد از روش دمای میانگین روزانه منهای دمای پایه استفاده و نقشه ‏های پهنه‏ بندی آن تهیه شد. با استفاده از آزمون من‏- کندال، چگونگی و زمان آغاز روند یا تغییرات واحدهای گرمایی مشخص و مقدار تغییرات محاسبه شد. نتایج تحقیق تغییرات بیشتری را در سری‏ های مربوط به واحدهای گرمایی با آستانه‏های دمای 10 درجه نسبت به سری‏هایی با آستانه 5 درجه نشان داد. ایستگاه ‏های آبادان و اهواز در دمای 10 درجه، برخلاف ایستگاه ‏های دیگر، دارای روند کاهشی بودند. نقشه پهنه ‏بندی واحدهای گرمایی نشان داد که واحدهای گرمایی در پایه دمایی 5 درجه از جنوب به شمال کشور و از غرب به شرق افزایش می ‏یابد و کاهش آن در پایه دمایی 10 درجه است.
    کلیدواژگان: آزمون من- کندال، ایران، روند واحدهای گرمایی طول فصل رشد، طول فصل رشد
  • حمید بابلی موخر، کوروش شیرانی، علیرضا تقیان* صفحات 747-773
    شکل زمین نقش اساسی در فرایند رخداد زمین ‏لغزش ایفا می‏کند. هدف اصلی از این پژوهش، ارزیابی و مقایسه دو مدل احتمالاتی دمپسترشفر و وزن شاهد با تاکید بر شاخص ‏های‏ مورفومتری در پهنه‏ بندی حساسیت نسبت‏ به زمین‏لغزش در حوضه آبخیز رودخانه فهلیان است. بدین منظور، هجده عامل موثر در وقوع زمین‏ لغزش شناسایی و ارزیابی شد. سپس، نقشه ‏های این عوامل در محیط GIS تهیه و با لایه پراکنش زمین ‏لغزش‏های منطقه همپو‏شانی و بر‏اساس دو مدل فوق وزن‏ دهی شد‏. نقشه ‏های پهنه ‏بندی حساسیت براساس دو مدل تهیه شد. نتایج نشان داد که در هر دو مدل شیب‏ های بیش ‏از 40درصد و شاخص ناهمواری زمین بیش‏ از 14 بیشترین وزن را به خود اختصاص داده‏ و مهم‏ترین نقش را در وقوع زمین‏ لغزش‏ های منطقه داشته‏ اند. به‏منظور ارزیابی دقت و صحت مدل‏ها، از منحنی ویژگی عملگر نسبی (ROC) استفاده شد. نتایج اعتبار‏سنجی حاصل ‏از سطح زیر منحنی برای مدل دمپسترشفر و وزن شاهد به‏ ترتیب 79/0 و 76/0 به‏دست آمد. بنابراین، اعتبار هر دو مدل خوب برآورد شد. همچنین، نتایج حاصل از محاسبه نسبت FR و شاخص SCAI مبین طبقه‏ بندی مناسب در پنج طبقه حساسیت است. با‏ توجه به نتایج کمی اعتبار‏سنجی، مدل دمپسترشفر، با بهره ‏گیری از شاخص ‏های مورفومتریک، مدل مناسبی برای پهنه ‏بندی حساسیت نسبت به زمین‏ لغزش معرفی می‏شود.
    کلیدواژگان: حوضه آبخیز رودخانه فهلیان، زمین‏ لغزش، مدل دمپسترشفر، مدل وزن شاهد، مورفومتری
  • حمید نوری*، علیرضا ایلدرمی، مهین نادری، سهیلا آقابیگی امین، حسین زینی وند صفحات 775-790
    در این تحقیق به منظور بررسی اثر تغییر کاربری اراضی و تغییر اقلیم بر رواناب یک حوضه کوهستانی برف ‏گیر در زاگرس مرکزی از مدل هیدرولوژی SWAT استفاده شد. کاربری اراضی حوضه آبخیز گرین در سال 1986 از اداره منابع طبیعی همدان استخراج و در سال‏های 2000 و 2014 از تصاویر ماهواره لندست 8 تهیه شد. نقشه کاربری اراضی در سال 2042 با استفاده از مدل مارکوف و CA مارکوف پیش‏بینی شد. برای پیش‏بینی اقلیم آینده از مدل HadCM3 استفاده شد و خروجی ‏های آن با مدل LARS-WG ریزمقیاس‏نمایی شد. با توجه به ضریب نش‏- ساتکلیف، ضریب تبیین، P-factor، و R-factor به‏ دست ‏آمده در مرحله واسنجی (به‏ترتیب برابر با 59/0، 60/0، 47/0، و 09/0) و مرحله اعتبارسنجی (به‏ ترتیب برابر با 71/0، 72/0، 59/0، و 02/0)، این مدل دارای کارایی قابل قبولی است. نتایج نشان می‏دهد که این منطقه تا سال 2042 شاهد افزایش 28/2درصدی مساحت جنگل و کاهش 07/2درصدی مساحت مرتع، روند کاهشی میانگین بارش ماهانه و روند افزایشی میانگین دما خواهد بود. همچنین، کاهش میزان رواناب ناشی از تغییر کاربری اراضی (5/6درصد) نسبت به اثر تغییر اقلیم در این حوضه کوهستانی (7/10درصد) کمتر است.
    کلیدواژگان: تغییر اقلیم، حوضه گرین، رواناب، کاربری اراضی، مدل SWAT
  • صدیقه کیانی سلمی *، سید حجت موسوی، پریسا یگانه دست گردی صفحات 791-811
    گردشگری اسکی یکی از شاخه‏ های گردشگری ورزش‏های زمستانی است که، از دیدگاه جهانی، به یک صنعت تبدیل شده است؛ اما، در حال حاضر، با تبعات ناشی از تغییر اقلیم و گرمایش جهانی به‏ خطر افتاده است. در چنین شرایطی، برنامه ‏‏های گردشگری ورزشی باید در جهت انتخاب مناسب ‏ترین مکان برای احداث پیست ‏های اسکی باشد که از لحاظ میزان برف‏ یری و سایر فراسنج‏ های مورد نیاز با کمترین مشکل مواجه شود. راه‏ حل مناسب در پهنه‏ بندی، انتخاب، و تعیین مکان‏ های مناسب احداث تاسیسات ورزش‏ های زمستانی و پیست‏ های اسکی استفاده از سیستم اطلاعات جغرافیایی است. بنابراین، هدف از اجرای پژوهش حاضر پهنه ‏بندی مناطق مستعد احداث پیست اسکی با رویکرد گردشگری ورزشی در استان چهارمحال و بختیاری است. این پژوهش از نوع کاربردی است و شاخص ‏های به ‏کاررفته عبارت است از: میزان بارش، روزهای برفی و یخبندان، شیب، راه ‏های ارتباطی، تراکم راه ‏های ارتباطی، فاصله از راه‏ های ارتباطی، ارتفاع، طبقات شیب، جهت شیب، سرعت باد غالب، پوشش گیاهی، تراکم مراکز شهری و روستایی، فاصله از مراکز شهری و روستایی و اماکن، سالن، پیست و مراکز ورزشی. پس از وزن‏دهی و محاسبه وزن نهایی، هر یک از مولفه ها با فرایند تحلیل سلسله‏ مراتبی وارد نرم ‏افزار ArcGIS شد و در ترکیب با روش ارزیابی، توان اکولوژیک مناطق مستعد احداث پیست اسکی تعیین گردید. نتایج نشان داد حدود 77/802 کیلومتر مربع (93/4درصد) از سطح استان چهارمحال و بختیاری پتانسیل احداث پیست اسکی را دارد که بخش وسیعی از آن در شهرستان کوهرنگ گسترده شده است. پیست اسکی چلگرد، معروف‏ترین پیست فعال استان، در پهنه شناسایی‏ شده واقع شده است.
    کلیدواژگان: استان چهارمحال و بختیاری، پیست اسکی، گردشگری ورزشی، مناطق مستعد، پهنه‏ بندی
  • الهام یوسفی روبیات *، فاطمه جهانی شکیب، علی نخعی صفحات 813-827
    آمایش سرزمین پایدار سازوکار تنظیم سیاست ‏های کاربری اراضی و بهبود شرایط فیزیکی و مکانی است و می‏تواند برای استفاده بهینه و حفاظت بلندمدت منابع طبیعی نقش ایفا کند. از طرفی، به‏ کارگیری مدل‏ های بهینه‏ سازی امری ضروری است؛ زیرا دارای تعامل با اهداف چندگانه، حالت فضایی، منطقه تحقیقاتی بزرگ، الزامات کارایی و تاثیرات آن‏هاست. بنابراین، الگوریتم ‏های فرا ابتکاری ابزار کارآمدی برای حل مشکلات پیچیده فضایی شناخته شده است و قابلیت ارائه فناوری بالا و قابل اعتماد برای حل مسائل بهینه‏ سازی غیرخطی را داراست. در این پژوهش، از الگوریتم جست‏وجوی گرانشی (GSA) به‏ منظور به ‏گزینی کاربری‏ کشاورزی در حوضه آبخیز بیرجند استفاده شده است. در این الگوریتم، بر اساس توابع برازش، اهدافی نظیر بیشینه‏ کردن تناسب محیطی، بوم‏ شناختی، فشردگی و سیمای‏ سرزمین، و کمینه‏ کردن تغییرات کاربری با قیودی مانند محدودیت توسعه فضایی و میزان تقاضا مناسب ‏ترین مکان‏ ها انتخاب شد. همچنین، به‏ منظور ارزیابی کارایی الگوریتم GSA در به‏گزینی اراضی کشاورزی آینده، نتایج حاصل با الگوریتم تخصیص چندهدفه سرزمین (MOLA) مقایسه شد. یافته ‏های حاصل از مقایسه بصری، پارامترهای آماری، و تحلیل سنجه‏ های سیمای‏ سرزمین حاکی از کارایی و برتری نسبی نتایج الگوریتم GSA نسبت به MOLA است، که این مناطق بیشتر در حال حاضر دارای کاربری مرتع کم‏تراکم و اراضی دیم هستند.
    کلیدواژگان: الگوریتم جست‏وجوی گرانشی (GSA)، الگوریتم ‏های فرا ابتکاری، به‏ گزینی کشاورزی، بیرجند، MOLA
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  • sina solhi, Abdollah Seif* Pages 611-638

    Optical Morphology and its Application in Geomorphology
    Introduction
    Geomorphologists use different models to illustrate topography and geomorphic features which, one of these common model is hillshading, that is a effective tool to detect and represent morphological shape of the terrain. This model uses a light source to make a contrast between bright sections and the parts that fall in the shadows. Many researchers have worked on the hillshade modelling. Some of them work on the azimuthal and zenithal angle of light source illumination on the earth surfaces. Some others focus on the direction and the gradient of the earth and their effect on the quality of the shadows and bright areas representations. In this research new concepts named optical morphology introduced which is considerred as a set of methods, models and technics, for representing geomorphologic and topographic features more accurate and visible. 14 terrain curvature models and 6 models regarding to azimuthal and zenithal angle adjustmernt performed. For running these models, Digital Surface Model (DSM) extracted from ALOS satellite data, was used in the large varieties of Iran geomorphological landforms. Then, these models scripted in the python programming language and graphical user interface (GUI) designed, using using Python Tkinter library. A GIS-Based toolkit named Optical Morphology prepared for calculating all introduced models in the form of raster file format. Finally, numerical analysis (Including statistical, morphological,directional and contrast analysis) run on the all model outputs and then, performances and some general applications of these models are describe in the field of geomorphology.
    Materials and methods
    In this research Digital Surface Model, published by Japan Aerospace Exploration Agency (JAXA), with a spatial resolution near 23m, is used. The data is obtained from ALOS satellite image. The database is based on the global 3-D topographical DSM, which is currently the most accurate elevation data on the global scale. Several hill-shade modeling is used to enhance terrain feature’s representation. For this purpose, Python programming is used for preparing all these models.
    Main local terrain descriptors such as slope and aspect used to enhance terrain morphology appearance. 6 models run based on changing azimuthal and zenithal angles of light source position which are included Aspect Frequency Distribution Analysis (AFDA), Un-weighted Multi-Directional Light Source (UMDLS), Weighed Multi-Directional Light Source (WMDLS), Vertical Light Source Illumination (VLSI), Slope Shading Model (SSM), and Sinusoidal Light Source Fluctuation (SLSF). 14 models run according to the terrain curvatures which are included Profile Curvature Shading Model (PCSM), Tangential Curvature Shading Model (TCSM), Plan Curvature Shading Model (PCSM), Un-sphericity Curvature Shading Model (UCSM), Mean Curvature Shading Model (MCSM), Differential Curvature Shading Model (DCSM), Maximal Curvature Shading Model (MaCSM), Minimal Curvature Shading Model (MiCSM), Horizontal Excess Curvature Shading Model (HECSM), Vertical Excess Curvature Shading Model (VECSM), Total Gaussian Curvature Shading Model (TGCSM), Total Accumulation Curvature Shading Model (TACSM), Flowlines Curvature Shading Model (FCSM), Total Ring Curvature Shading Model (TRCSM). All these models programmed using python (V.2.7 and Tkinter for GUI programming).
    Results and discussion
    In this research optical morphology of terrain performmed, using basic geographic information system concepts. Python programming used to execute different hillshade models. Some topographical factors such as terrain slope and aspect considered with regards to light source directions (Azimuthal and zenithal directions). In general 20 different shading models programmed for calculating optical morphology and prepared as GIS toolkit named Optical Morphology. This tool could be able to uses Digital Elevation Model as an input, process and analysis its raster structure and then store results as an ASCII file format. Finally, results, applications, advantages and disadvantages of these models explained.
    Conclusion
    light source direction modeling combining to the geomorphological attributes, is a powerful tool for recognizing and detecting landforms more accurate and could help geomorphologist in different field of studies. In this research, optical morphology modeling was done using Python programming language to enhance representation of the geomorphological terrain features. The results of these efforts are abstracted in the GIS-based toolkit which is applicable in the quantitative geomorphology area. These models have different approaches against local topographic properties, local conditions of each place and aims of shading. Some geomorphological factors such as slope and aspect, topographic characteristics, terrain curvatures and, pixel distribution was considering in running and performing suitable and adjusting model.
    Keywords: Optical Morphology, Geomorphology, Python Programming, Analytical Hill-shading
    Keywords: Optical Morphology, Geomorphology, Python Programming, Analytical hill-shading
  • Fatemeh Sotoudeh*, bohlol alijani, mohammad saligheh, mehry akbary Pages 639-653
     
    Introduction
    The activity of synoptic cyclones plays an important role in determining the local climate and the formation of large-scale atmospheric circulation through the vertical and horizontal exchange of heat, humidity and momentum, coupled with interaction with large scale circulation centers (Zhu et al, 2001: 1523). The cyclones generally are transmitter the bad weather conditions and also represent the initial mechanism of transmitter moisture and heat to the pole. Systematic changes in geographical location or the intensity / frequency of cyclone activity will have significant disparities among other regional climate impacts (Wang, 2006: 3145).
    The effect of mountainous obstacles on synoptic systems, especially the cyclone systems, has known. The mountain range is one of the factors, In addition to disrupting the face of the earth's uniformity, also disrupt the climatic uniformity. The purpose of this study is to determine the effect of thermodynamics of Zagros Mountain on the changes in cyclones entering the country from the west.
    Materials and methods
    For this purpose, the daily precipitation data of 13 stations of the Meteorological Organization in West of Iran were received. Also geopotential data were extracted from the NCEP / NCAR databases with spatial resolution of 2.5 × 2.5 degrees and ERA-Interim data from ECMWF databases with spatial resolution of 0.125 × 0.125 degrees, thier framework is 0 to 80 degrees east and 0 to 60 degrees north.
    Using the Factor Analysis method, April 14th-18th, 2003 was selected as the best pattern. After selecting the sample day, sea level pressure maps and geopotential heights of different levels were prepared and analyzed.
    Results and discussion
    The result of the study of these maps showed that the cyclone reaching the Zagros Mountains, dynamically strengthened from the day it formed until it arrived in Iraq. When approaching the Zagros, the vorticity and its omega are reduced, but crossing Zagros, a positive vorticity increase happens. These types of cyclones call Zagros cyclones. The relationship between the amplified cyclone with the divergence region of the middle and middle levels were observed at all stages. The Zagros roughness, like a wall, initially causes the cyclone reached with Iran to weaken and become bipolar. But the passage of the cyclones from it, the thermodynamic conditions of the descending air in the lee mountain range, that makes them revival. As the roughness collides, a weak core remains in the Zagros range, and another nucleus is formed by passing through the mountains in the central regions of the country, and is reinforced in the next hours; and finally, the cyclone is amplified and it leaves Iran completely. These cyclones can be called zagros second cyclones.
    Conclusion
    Mountain barriers consider as the factors destroying the homogeneity of the local climate.
    Sometimes they act as the planets like the Rocky Mountains. Iran's land are heterogeneous due to elevations in the north, west, and other areas, Iran is heterogeneous in term of geomorphology and climatology.
    One of the most outstanding effects of roughness on the climate is the change in the structure of systems passing through these barriers. Zagros Mountains is one of the main mountain ranges of Iran, with an almost northwest-southeast direction with a maximum height of about 4,400 meters zardkuh, has a significant impact on immigrant systems in the country.
    A study on the cyclone on April 14th , 2003 showed that this cyclone was formed on the April 12th on the northwest of Europe, moving towards the Mediterranean Sea. its trough arrives in the country on the April 14th and it reaches the slopes of Zagros on the 16th. As Zagros is approaching, changes in pressure in the back and the lee of Zagros are increasing. Vorticity and divergences are completely different in two parts. In the altitudinal areas in the Zagros line, during a few days and during the passage of the cyclone, there is a negative vorticity. The vertical velocity also demonstrates subsidence in Zagros altitudinal areas. The results vividly prove that the cyclone is(get) weakened in collisions with the Zagros, and its movement gets slowness(slow), but it does not disappear. But also it is re-reinforced on the Zagros lee in the central of regions, and continued its route to outside the borders of the country.
    Keywords: Lee cyclones, cyclonic vorticity, Vertical Velocity, humidity flux, Zagros
    Keywords: Lee cyclones, cyclonic vorticity, Vertical Velocity, humidity flux, Zagros
  • fatemeh abedi, Dariosh Rahimi*, Seyed Abolfazl Masoodian, mohammad sadeq kianykikhosravi Pages 655-667

    The Climatology Analysis of Blocking System in Northern hemisphere and Iran
    1. Introduction
    Blocking is one of the most protruding flow patterns and has received attention during the last decades due to its effect on seasonal weather characteristics. The first qualitative conditions for the blocked atmospheric flow was introduced by Rex in 1950 telling the atmospheric jet becomes divided in two separated parts with a considerable connected mass transport, the flow to be meridional at the splitting point and downstream, and the state to continue for at least ten days with a zonal width of at least 45 degrees. The new ideas formulated by Rex became the basis for several blocking indices. Most of the indices detect typical atmospheric patterns. For shorter time series particular criteria have been used. Although, the majority of the analyses study the 500 hPa geopotential height.
    In the face of the differences between the index classifications, they draw similar conclusions regarding the patterns of the Northern Hemisphere blocking climatology. However, the blocking frequency, which is the percentage of time steps an assured longitude, is blocked, can be as low as 5%, or higher than 20%. The main aims for this wide range of frequencies in automatic recognition are modifications of the Rex criteria and the use of different parameters (Schalge and et al,2011, Elliott, R.D., T.B., Smith, 1949, Knox, J.L, J.E., Hay, 1984, Pelly, J.L, 2001, Antokhina and et al,2016, Rex, D.F, 1950).
    Due to its simplicity, the index of Tibaldi and Molteni (TM-Index) has become a standard in automated blocking detection analyses. An important problem of the TM-Index is that it cannot effectively distinguish between blocking and cut-off low patterns, since both fulfill the TM-Index criteria. The adapted TM-Index MTM has a higher rejection rate for cut-off lows. Limits in the Rex conditions can be measured as implementations of independent filters which show synergetic effects if they are used in run (Tibaldi, S., F., Molteni, 1990, Schalge and et al,2011, Barriopedro and et al,2006).
    2. Data and methodology
    The data used is the 500 hPa geopotential height of the NCEP/NCAR reanalysis dataset (1951–2012) with
    a spectral truncation of (2.5*2.5 on a Gaussian grid) (Tibaldi, S., F., Molteni, 1990, Schalge and et al,2011).
    We used to define blocking in north hemisphere Tibaldi and Molteni index. For blocking define at a longitude are GHGS > 0, GHGN < −10 m lat, with the geopotential height gradients in a northern and southern region (1)   In the present study, the TM-Index is modified by introducing different ranges for the gradients (this will be denoted as the basic setup in the following):
    And for Iran:
    Which:Z is the geopotential height and φ indicates latitudes.
    So, the 500 hPa geopotential height field is analyses for a pattern with a positive geopotential height gradient in the southern region and a strongly negative gradient in the northern region. The explanation of a range for Δ leads to a larger number of detected blocking events.
    According to this definition, it is possible to find blocking structures with a maximum between the center and southern region. If, for example, only the southernmost latitude in the mid-latitude region has higher geopotential height than one of the more northern latitudes of the southern region, GHGS > 0 and blocking will be detected. Without this modification, such a combination is not possible and blocking is not identified, because the high geopotential is too far south and the lower geopotential too far north, associated with a relatively small meridional extent of the block. The increase of the blocking frequency by the variable gradient ranges in the basic setup amounts to 20% in regions with high blocking frequency and to 50% in regions with low blocking activity compared to the original TM-Index.
    3.Discussion
    3.1. Location Blocking system:Most of the blocking systems in the northern hemisphere are in all seasons and their continuity in the Atlantic and Pacific. The analysis of the frequency of blocking systems in (2012 -1951) finding that most of the blocking systems occurred in the Atlas region 11.2%, the 4.8% traffic, Europe 3.9%, the United States 3.7%, and Asia 0 .75%. The highest frequency of blocking systems was observed in the central part of the Atlantic on the W ° 30, then the Pacific in the western and central part on W ° 140, in the west of the United States on W ° 125, west Europe on the W ° 10 and in Asia between the region (E ° 85 - E60) (Figure1 and 2).   The location of the blocking systems in the northern hemisphere.   3.2. Duration of Blocking System:Between 1951-2012, the Atlantic was 20.8% in 1954 and 19.5% in 1998, with the highest annual rates in 1968 and 4.6% in 1987, and 5.5% in 1987, with the lowest incidence of 5.5% Block diagrams (Figure 3) and Pacific Ocean in 1985 with 12.9% and 1998 in 10.7% were highest in 1957 with 3.6% and in 1968 and 1997 with 3 .8% of the days of the year had the lowest incidence (Fig. 4).
    Fig (3) Blocking System Frequency at 1954
    Fig (4) Blocking System Frequency at 1985
    4.Results
    Blocking is one of the most protruding flow patterns and has received attention during the last decades due to its effect on seasonal weather characteristics. Moreover, finding show that Most of the blocking systems in the northern hemisphere are in all seasons and their continuity in the Atlantic and Pacific. The analysis of the frequency of blocking systems in (2012 -1951) finding that most of the blocking systems occurred in the Atlas region 11.2%, the 4.8% traffic, Europe 3.9%, the United States 3.7%, and Asia 0 .75%. Over the years (1951-2012) in Iran, 11 years without a blocking system, 1975, the highest frequency of blocking systems has been observed in the east of the country. Also, seasonal distribution of systems showed that the highest frequency of occurrence of blockade systems is in summer, autumn, winter and spring
    Keywords: Northern hemisphere, Iran, Blocking System, Index TM
  • Chiman Hatami, Mahdi Erfanian*, Sahar Babaei Hessar Pages 669-684
     
    Introduction
    Daily average net radiation (DANR) is necessary for hydrological modeling, water resources management and planning, in particular for prediction of daily evapotranspiration (ET). Recently, some remote sensing based methods have been developed at watershed and regional scales to help researchers for estimating DANR and ER under both clear and cloudy conditions. DANR is a critical variable linking estimates of instantaneous latent heat flux (satellite overpass time) from energy balance based models. Radiation modeling based on ground or station data is actually point scale estimation. On the other hands, application of geostatistical methods to produce radiation maps at watershed scale, are often associated with remarkable errors due to the limited number of stations. In this study, net daily radiation maps was created based on newly developed geometric radiation model based on land and atmospheric MODIS data in the Urmia Lake Basin (ULB) under clear-sky condition for four selected dates in 2006 and 2007.
    Materials and Methods
    In this study, the ULB, located in northwestern Iran, was selected as the study area that extending in latitude from around 35.67° to 38.47° N and in longitude from around 44.22° to 47.89° E. The basin has an area of approximately 52700 square kilometers. This study attempts to estimate the DANR maps for four selected days under clear sky. Long et al. (2010) developed a geometric model considering slope and aspect effects to improve parameterization schemes to estimate daily average net shortwave radiation (Rns) and daily average net longwave radiation (Rnl). In present study, the same methodology applying a characteristics model based (slope, azimuth and elevation) based on daily MODIS data products and the global ASTER DEM. The DANR is total of the daily net short wavelength radiation and daily net long wavelength radiation. Long wave radiation was estimated using MODIS products including surface albedo, land surface temperature (LST), atmospheric temperature, pressure and emissivity. A four-observation based method using Terra-MODIS and Aqua-MODIS LST data was applied to estimate daily average LST in order to improve the accuracy of estimates of Rnl. In the study, we applied the 24-hour incoming direct solar radiation (Sin24) measurements of Tabriz and Urmia synoptic stations for validation. The RMSE and MAE measures were used for model evaluation. In addition, due to the lack of ground-based Rnl observations; we utilized the FAO (Penman) method to generate corresponding ground data for model validation.
    Results and Discussion
    In order to compare the amount of incoming Sin24 on flat and sloping surface, the whole study area was assumed a flat and the Sin24 maps were produced. The different between Sin24 on flat (Sin24,s) and sloping surfaces (Sin24,f) were calculated for all pixels. The histogram plot or frequency of Sin24,s - Sin24,f quantity at different intervals of slope showed that by increasing slope degree, the frequency of pixels at all slope classes becomes greater. This reflects the importance of the slope for estimating Sin24. In addition, the values of Sin24 at flat are higher than sloping surfaces especially for where slopes < 30 degree. Aspect is another influencing factor on the amount of receiving and absorbed radiation. The RMSE and MAE for observed and estimated Sin24 values were 30.29 and 19w.m-2, respectively. The models in average overestimate Sin24 about 10.5%. The results showed that the eastern and western aspects receive more daily net radiation during day and sunshine hours or day length has its impact on radiation. For Rnl estimates, the RMSE was 36w.m-2
    Conclusions
    In present study the Sin24 was parameterized by taking into account the effect of terrain factors, such as slope, azimuth and elevation on direct solar radiation. The sunrise and sunset angles for a given sloping surface (pixel) are different in geometric radiation model. Results indicate that the model has the capability to characterize the variability in Sin24. The incoming solar radiation for flat surface is higher than sloping surface. We founded that southeast and southwest aspects receive grater net radiation. The DANR values decrease with an increase in elevation. The geometric model used in this research needs to be evaluated in different watersheds in Iran without data availability problem especially daily Rns, Rnl and LST measurements, a high number of meteorological stations with proper spatial distribution. This research was done under limited data in the ULB.
    Keywords: MODIS, Net Radiation, Geometric Model, Urmia
  • Fatemah Jafari shandi, Saied Jahanbakhsh*, Majid Rezaiebanafsheh, Seyed Abolfazl Masoodian Pages 685-696
     
    Introduction
    The increasing expansion of industries and the use of fossil fuels have led to an increase in greenhouse gas emissions and, consequently, global warming and the occurrence of climate change phenomena. Climate change is a change in the climate behavior of an area relative to the behavior that is expected during a long-term period of observed or recorded information in that area ( Karamoz and Iraqi Nejad, 1384 : 450 ). The ET element is considered to be one of the most important components of water balance in nature; it is strongly influenced by important climate components such as temperature and under the influence of climate change, it can exhibit various reactions (Goyal, 2004:1) Therefore, in calculating the water balance of each basin, ET calculation is important (Jafarpur, 2001: 110). Because ET along with the surface flow and water penetration in the soil are considered as components of the water balance. Due to the temporal variations of climate variables and consequently ET, the use of remote sensing methods that considers these changes is more favorable. Using Landsat satellite imagery and energy balance model, Using the NOAA, AVHRR and SEBS algorithms, Baba Jafari et al (2015) estimated monthly ETA values for agricultural use in the Akhole region located in Tabriz plain area. Comparison of the results of the algorithm with observation values indicates the accuracy of the model with a coefficient of 0.8 and the mean square root of the error is 9.64 millimeter per month (Baba Jafari et al., 2015: 1).
    Materials and methods
    In this study, for the analysis of the ETa of the East Azarbaijan province, MOD16A2 remote sensing data in a time interval of 8 days in the period 2014-2000 were applied. Data on maximum, minimum and precipitation temperatures of 11 stations of the province were also used. Since the relationship between temperature and ETa is linear, the correlation between the average of the maximum and minimum temperatures of 8 days in the stations of the province with the mean values of 8 daily ETa for representative cells was calculated. As the purpose of the current research is to estimate ETa for explaining the water balance of the province, the correlation between precipitation of the stations in the province with the ETa of the representative cells was also evaluated. Given the fact that the data of the MODIS are 8 daily scales, with programming in MATLAB software, the data of the maximum, minimum and precipitation temperatures of the stations was converted to eight days interval. Investigations showed that MODIS provides only ETa data of the representative cells of Ahar, Jolfa, Sarab, Sahand, Marand and Meyaneh stations, and for other stations due to the placement of the cell in the class of ground cover construction, ETa data has not been recorded.  
    Results and Discussion
    The findings of this study indicate that the average maximum and minimum mean and total mean of ETa data on 124546 pixels in the province for the period from 2000 to 2014 were 2.3, 0.5 and 0.8 millimeter per day. The time series ETa of the cells within the boundaries of the province also showed the highest changes in 2003 and 2010, at 9.1 millimeter a day, and the lowest in 2001, at 0.1 millimeter per day. In this regard, the time series of the ETa of the stations in the study years showed that the highest and lowest values of ETa changes were in the Sarab and Sahand stations, and the value was 3.3 (millimeters per day) in 2012 and 0.01(millimeters per day) in 2001. Due to the fact that the temperature relationship with ETa is linear, the correlation between the average maximum and minimum temperatures of 8 days in the stations of the province with average ETa values of 8 days for representative cells of the station was calculated. Investigations showed that there was a negative relationship between the mentioned parameters. Basically, there must be a positive and direct relationship between temperature and ETa. The only factor that can disrupt this relationship is the lack of adequate water in the area. Regression analysis on min and max temperature data matrix with ETa of 8 days at stations at 95% confidence level showed that with increasing temperature of 1 degree Celsius in the province, ETa decreases by 0.02 mm per day. The ETa variation slope in relation to precipitation stations showed at the 95% level of confidence, with an increase of 1 millimeter of precipitation, the ETa would increase by 0.9 millimeter per day.
    Conclusion
    In this study, the correlation between the mean maximum and minimum temperature of ground stations with the mean of 8 daily ETa of the representative cells of the stations was investigated. Investigations showed that there is a negative relationship between the mentioned parameters. The existence of a negative relationship between the above mentioned parameters reflects the fact that when the warm season approaches, the water resources are decreasing, as a result of decreasing water, ETa values decrease with increasing temperature. Because there is not enough water to evaporate in the area, the correlation between mean precipitation and ETa also showed a positive relationship between them. In other words, the higher the rainfall, the higher the water available to the plant and the soil will increase Eta. Given that the average annual rainfall in the province is 267.27 mm, and the annual loss of ETa is 32.4 mm. This amount of evaporation is significant compared to 267.27 millimeters of annual rainfall. The province's climate leads to desert and dry land
    Keywords: Key words: actual evapotranspiration, MODIS Terra, Climate change, precipitation, temperature
  • mohammad alinezhad, * Mohsen Hosseinalizadeh, majid Ownegh, Ali Mohammadian behbahani Pages 697-712
     
    Introduction
    Nebakas are single dunes formed by the accumulation of aeolian sediments under the bushes and shrubs. They play an essential role in the stability of arid and hyper-arid ecosystems, mostly by preserving the vegetation. Moreover, they are very important in stabilization of moving sand in deserts and semi-arid areas, as well as in protecting human settlements and facilities from sand infestation. The spatial point pattern analysis of natural or manmade effects provides useful information about the effects of competition between environmental conditions. The spatial point pattern of every phenomenon and their impacts on environment is being considered as a basic criterion for decision making, especially in risk management. For instance, spatial pattern of plants is a context in ecological theory, and a data-set consisting of a series of mapped point locations is a main example of a spatial point pattern. The methods for quantifying these characteristics of point pattern are known as summary statistics. From a statistical point of view, the methods are also appropriate for phenomena that represent various types of geomorphologic features. So, to better understand the factors controlling the pattern of Nebakas, univariate and bivariate summary statistics have been used. Moreover, a more promising approach in such analyses is to complement point position with quantitative size attributes and use mark point patterns (i.e., Nebakas with a quantitative characteristic such as physical and chemical properties of the soil). In fact, the spatial distribution of Nebakas in the semi- arid regions can be described and modeled by point pattern processes where the points are given by locations of the Nebakas. Investigations which have not done so far on the spatial analysis of the Nebka dunes, given the importance of spatial statistics in obtaining useful information for better management in all fields.
    Materials and methods
    In the present study, a 197ha area was selected and the maps related to 147 Nebkas in the Sufikam plain, northwest of Golestan province, Iran were obtained. In order to study the distribution pattern of Nebkas and also the factors influencing their spatial distribution, morphometric characteristics of the Nebkas, including length, width and height were recorded. The physical and chemical properties of the soil were assessed and the spatial pattern of Nebkas were analyzed using R and Programita softwares based on Ripley’s K and G univariate functions and Mark Correlation Function (MCF).
    Results and discussion
    Results showed that by using Ripley K function, the spatial distribution of Nebkas in Sufikam plain is clustered and most of them located in the North of area of interest. Density of Nebkas and also their mean spatial distance (distance between Nebkas) was 0.75 per hectare and 33m in turn. Regarding the results of g(r) in Sufikam plain, the significant aggregation of Nebkas was observed at all scales (0–50 m). As the function failed to be in the bounds of respective 95% simulation envelope, the aggregation of Nebkas in all of the scales was a significant departure from random labeling at the significance level of 0.05 (Fig. 8). Furthermore, regarding the results of mark correlation function (MCF), Nebkas and parameters of the length of the Nebka, sediment deposition, pH and organic matter of the Nebka soil, were highly correlated. Moreover, the parameters of width, volume and height of Nebka, EC, SAR, ESP, sorting and mean diameter of sediments did not affect their distribution pattern.
    Conclusion
    Considering the results of the spatial analysis of the Nebkas, factors affecting the distribution of these facies were identified. In this study, it was also found that soil acidity has a significant effect on the distribution pattern of Nebkas. In addition, a greater organic matter content has a greater effect on the growth of the plant species, which can also affect the distribution pattern. Soil textures such as clay, silt and sand did not affect the neighboring Nebkas in the study area. The sediment deposition and the distribution of the Nebkas indicates a positive correlation; which means that the larger its value (or the symmetry of the sediments towards fine particles), the denser the distribution of the points. According to the results which show the positive role of Nebka landform in reducing the effect of wind erosion, the investigation of their spatial dispersion and factors which affect their dispersion, development and natural processes, can be a guide for natural resource managers for controlling and reducing the wind erosion
    Keywords: Nebaka, Spatial statistic, Mark Correlation Function, Sufikam plain, Golestan province
  • Farshad Safarpour, Abolfazl Masodian, javad khoshhal* Pages 713-729
     
    Introduction
    Kermanshah Province is one of the western mountainous provinces located in the middle Zagros mountains.The rainfall in this province is similar to other mountainous regions orographic and rugby.
    Forecasting rainfall in terms of severity, amount and continuity in the usual way is often not precisely possible and requires very expert forecaster and familiarity with local conditions.This leads to severe, destructive and sometimes catastrophic floods in the province.
    Today, weather radars can be predicted by experts as a valuable tool for forecasting rainfall, provided that they are calibrated in accordance with local conditions and calibrated over time with climate change.
    If the calibration of weather radar is good, radar can estimate the amount of rain over the vast areas with good accuracy. Relationship between rain and reflectivity radar exponential Z=aRb, where a and b are coefficients radar. And the amount of R depends on factors such as: the type of rain, rain season, latitude and topography. Variation range of a is few tens to few hundred, and the range of variation b is 1 to 3. Drop size and distribution of rainfall, the coefficient of this.
    Materials and methods
    The purpose of this study is to measure the Kermanshah weather radar with the conditions of the province, so that the specialists predict that using this radar can predict the characteristics of rainfall before its occurrence, provide warnings to the people and authorities and the damage to the dwellings Historic buildings, administrative centers, urban and rural facilities, farms, humans and animals to the extent possible
    In this study, rain from 17 to 18 November 2015 and 30 November to 2 December 2016 at the stations, Kermanshah, Eslamabad, Sarpol, Ghasre Shirin, Harsin, Javanroud, Tazabad, Songhor, Ravansar, Ghilan Gharb and Soumar at distance of 30 to 100 kilometers from Kermanshah’s radar are investigated.
    Results and discussion
    Linear regression method using hourly rain data and the amount of reflectivity, linear equations and the coefficient R2, reflectivity, respectively. For rainfall of 17 to 18 November 2015 for all stations different angle radar beam and the reflectance was measured. And the amount of rain gauges in the same period was obtained. The radar beam elevation angle optimized for each station, a separate line equation was obtained. Using the coefficients of the equation and radar, rain intensity level was determined Surface Rainfall Intensity (SRI) and the total rainfall was an hour and finally total rain was estimated for each station. Radar estimated rainfall amounts for the first part was more than the amount measured by rain gauges.
    Because the error was found in all stations, it is assumed that the size and distribution of rainfall in the first part of rainfall vary with the next step. So to solve this problem, rain at all stations was divided into two parts. For the first part of the conflict between rainfall radar and rain gauge rainfall, there was a common linear equations and coefficients a and b were obtained again for all stations. The amount of rainfall was estimated again. A result showed that the amount of rainfall was estimated in this way is better than before.
    Use this relationship to estimate the amount of rain 31 percent to 96 percent and the average total rainfall radar estimated that 8.9 to 32.4 millimeter Increased than before calibration. and only was 1 millimeter less than of the actual average obtain by gauge. Since acquiring the optimum beam angle the radar for any location, time-consuming and difficult. So when the time is not enough, it is better for each rainfall radar obtained a relationship. So in the following for rain 30 November to 2 December 2016, using rainfall data of all stations, for correction factors radar, only one equation was obtained. and The results of this way was good, and the mean rain radar to estimate rainfall radar calibration 9.6 to 23.5 millimeter increased and only 4 millimeter less than of the actual rain that obtain by gauge.
    Conclusion
    The results showed that the coefficients radar for any location and at any time is different. So to increase the accuracy of radar rainfall it is better for each separate equation obtained. However, to obtain a separate equation for each location is the best. Finally, it is suggested that the radar equation coefficients for each region of Iran, which is covered by the weather radar, are calculated, so that they can accurately predict the precipitation and give warnings to the different centers.
    Keywords: Radar, Rainfall, calibration, Kermanshah
  • mehran fatemi*, hamidah dehghan Pages 731-746

    One of the challenges of the 21st century is the issue of climate fluctuations. The increased average global temperature and its pursuing changes are part of the climatic changes that have been addressed in all ecological theories. In addition to this global increase in the air temperature, many of the phenomenological, meteorological and satellite-based studies have reported a surge in the length of the growing season caused by the augmented temperature in northern areas during the twentieth century. Any crop requires a minimal temperature for its germination and growth below which the growth process is impeded or stopped. This temperature is specific for each plant variety. One of the critical effects of this phenomenon (global warming) is a change in the degree-days of plants. A plant growth is a variable of the temperature. The growing degree day index and its availability for a crop plays a vital role in the process of the growth and enhanced productivity of inputs, including cultivation date and greater yield. Thus, the growing degree-days vary relative to the temperature fluctuations. Investigating the effects of temperature in different time periods on the growth and development of organisms, especially plants is of paramount importance.
    The objective of this paper is to investigate whether there are specific trends in the number of heat units during the growing season using temperature indices to determine indicators, capacities and limitations of the agricultural climate in planting varieties with different adaptation styles.
    In this paper, daily temperature data (minimum, maximum and average) reported by 31 Iranian synoptic meteorological stations over a 25-year common statistical period were used to estimate the trend of heat units during the growing season for 1985-1986 and 2009-2010 periods.
    To calculate heat units, first the length of growth season was extracted for temperature thresholds of 5 °C and 10 °C using Julian coding (January 21st with code 1 and January 20th with code 365) and then heat units of the length of growth season were calculated by subtracting average day temperature from base temperature. Maps of heat units in GIS was prepared. The statistical defects were reconstructed using autocorrelation method, and the randomization of the data was tested by the Mann-Kendall test. The series that had specific changes or trends at the confidence level of α=0.05 were identified. Then, using Mann-Kendall test, it was determined how and when these trends were started and variations in heat units were estimated.
    To calculate the base heat units at 5 °C, the start and end dates of 5 °C and the length of growing season were first extracted and then based on the length of growing season, the number of heat units during each season was calculated for stations. The average length of the growing season at a temperature of 5 °C varied in different stations ranging from 147 days at Shahrekord station to 365 days at Bandar Abbas and Bushehr stations. The heat units during the growing season also varied from 2218 to 4174 degree-days at stations under study, with the lowest number belonging to Shahr-e-Kord Station and the highest to Gorgan Station. The length of growing season at 10 °C was variable from 67 days at Shahrekord Station to 348 days at Bandar Abbas Station. The number of heat units during the growing season for this base was 861 degree-days for Shahrekord station and 5664 degree-days of the Bandar Abbas station. The results of the Mann-Kundal test indicated that the average heat units in most stations under study over the past 25 years followed a specific trend throughout the growing season. That is, for a temperature threshold of 5 °C, changes in most stations had an increasing trend, with the exception Sanandaj and Shahrekord stations, which pursued a negative or decreasing trend. For a temperature threshold of 10 °C, most stations displayed a positive and incremental trend, except for Abadan and Ahwaz stations that had a negative and declining trend. The results of Mann-Kundal's graphic test on heat unit data with a temperature threshold of 5° C revealed that changes in all stations followed an incremental trend, except for Abadan and Bandar Abbas stations that had a dramatic and decreasing trend. Among the series of heat units at 10 °C, unlike Abadan, Ahwaz and Bam stations, which have a dramatic and declining, the rest of the stations followed an incremental trend.
    Conclusion
    The analysis of the change trends of heat units during the growing season for temperature thresholds of 5 °C and 10 °C indicated that most of these changes were dramatic with few of them following a progressive and steady trend. For a 5 °C temperature threshold, changes in all stations had an incremental trend with the exception of Bandar Abbas station, which demonstrated a sudden and declining change. Considering the temperature threshold of 10 °C for the analysis of heat unit series, it was observed that Abadan and Ahwaz stations had a sudden and decreasing trend whereas other stations such as Gorgan, Arak, Zahedan, Ramsar, Mashhad, Qom, Sanandaj, Anzali and Tehran followed a steady and incremental trend. Among the series of heat units for 10 °C, unlike the Bam station, which displayed a sudden declining trend, Urmia, Bushehr, Birjand, Khoy and Sabzevar stations followed a sudden and incremental event. The results of the research exhibited more significant changes in the series of heat units at a threshold of 10 °C in comparison to heat units at a threshold of 5 °C. At the base temperature of 5 °C, the number of heat units for the length of growing season increased from south to north and from west to east, and at the base temperature of 10 °C, it revealed an increasing trend from south to north and from west to east of the country. According to the results, it can be suggested that in areas where the length of the growing season declines, given that farmers struggle with low yields and crops that are not grown adequately
    Keywords: Growth Season Length, Growing Degree Day Trend during the Growing Season, Mann-Kendall Test, Iran
  • hamid babolimoakher, Kourosh Shirani, alireza taghian* Pages 747-773

    Application of morphometric indices in optimization of landslide susceptibility zonation maps using probabilistic
    methods
    Introduction
    As a geomorphic hazard, landslide incurs great deals of financial damages and casualties every year, and directly and/or indirectly contributes to large economic costs in different areas. Given that numerous factors contribute to the occurrence of a landslide, in order to prepare more accurate zonation maps, it is necessary to use more information layers and evaluate various factors that can possibly contribute to the occurrence of the event before adopting the existing models to zonation the susceptibility map. This phenomenon is a natural hazard which is affected by the land surface shape (morphology). As such, when it comes to susceptibility analysis of landslides in a particular area, not only common factors in zonation, but also morphometric features of ground surface are important and should be evaluated. Geomorphometric indices, which together comprise the so-called morphotectonic framework, can be used in studies on many geomorphologic events and natural hazards. These indices express quantitatively characteristics of hillsides which are susceptible to landslide.
    Materials and methods
    In this research, a total of 18 factors contributing to the occurrence of landslides in Fahlian watershed were identified and evaluated; these included slope, slope aspect, slope length, altitude, distance to fault, distance to river, precipitation, litology, landuse, general curvature, Plan curvature, profile curvature, Normalized Difference Vegetation Index (NVDI), topographic position index (TPI), Length and Slope Factor (LSF), Terrain Ruggedness Index (TRI), Stream Power Index(SPI), and topographic wetness index (TWI). In order to prepare layers of the effective factors, in addition to 1:100,000 geological maps, 1:50,000 topographic maps, digital elevation model (DEM: ASTER), satellite images, and aerial photographs, ArcGIS, Global Mapper, Surfer, and ENVI 4.5 software packages were utilized. Given the focus of this research on the application of morphometric indices to optimize zonation map of susceptibility to landslide, the indices were extracted. Land surface characteristics (i.e. morphometric, hydrologic, and climatic properties, etc.) and land features (watersheds, stream networks, landforms, etc.) were extracted using digital models of ground surface (DEM) and parameterization software. Subsequently, using Dempster-Shafer probabilistic models, evidence of weight, and the morphometric indices, zonation map of susceptibility to landslide was prepared for Fahlian River watershed. Finally, using receiver operating characteristics(ROC), both models were validated.
    Results and discussion
    Based on the weights related to the role of each unit of factor layers and their order of priority and importance in the occurrence of landslide, and upon combining factor maps and landslide distribution maps and calculating the weight of each level based on the relationships related to the Dempster-Shafer model in GIS environment, it was found that, with a belief function weight of 0.87 and minimum disbelief weight, slope > 40% imposes the largest contributions into the occurrence of landslide across the watershed. At lower slopes, other forces such as the friction between soil particles and other hillside material usually dominate over driving forces such as gravity. In contrast, on highly sloping hillsides, due to the dominance of shear stress over resisting force, one may end up with increased probability of the occurrence of a landslide. Moreover, based on the obtained results, with a belief weight of 0.77, TRI > 14 was the second most effective factor on the occurrence of landslides across the studied watershed. It was further found that, Stream Power Index < 1.2, concave curvatures, precipitation < 750 mm/year, TPI < -4.2, profile curvature of 0.3 – 4.2, TWI of -1.5 to 2.5, forest lands, surface curvature of -5 to -2.99, distance to fault of 0 to 500 and Pabdeh – Gurpi and formation (with belief function values of 0.68, 0.63, 0.60, 0.57, 0.49, 0.49, 0.47, 0.46, 0.38, and 0.37, respectively) imposed large contributions into regional landslides.
    According to the evidence of weight model, the class of TRI >14 (final weight: 2939.32) was found to the most effective factor on the occurrence of landslide across the region. Following a similar trend of reasoning, the class of slopes higher than 40% (final weight: 2611.21) was the second most important factor, which are in agreement with the results of Javadi et al. (2014) and Teymoori-Yanseri et al. (2017). Moreover, in their research, Pourghasemi et al. (2011) referred to the slope as the second most important factor contributing to the occurrence of landslide. In this model, NVDI > 0.6 (final weight: 400.60) is identified as the third most important factor. Following the land use, Stream Power Index > 1.2, TPI < -4.2, TRI of 7 – 14, profile curvature of 0.1 – 0.3, NVDI of 04 – 0.6, precipitation > 750 mm, and Pabdeh-Gurpi Formation imposed the largest impacts (sorted in the order of effectiveness, with final weights of 2037.60, 1925.99, 1803.48, 1793.34, 1722.40, 1494.60, and 1340.28, respectively).
    Conclusion
    Final results of the present research showed that, in both of the models, slopes higher than 40% and TRI > 14 exhibited the highest weights and played the most significant roles in the occurrence of landslide across the region. Moreover, based on the obtained results, 82.59% of the landslides across the watershed in an area of 547.82 hectare had occurred in postures. Based on the results of Dempster-Shafer model, very low, low, intermediate, high, and very high susceptibility classes covered 23.85% (961.34 km2), 31.82% (1282.49 km2), 21.72% (875.63 km2), 16.41% (661.45 km2), and 6.20% (249.97 km2) of the entire region, respectively.
    Moreover, the results obtained from the evidence of wight model model shows that 25.29% (1019.59 km2), 30.98% (1248.82 km2), 21.28% (857.64 km2), 15.68% (631.93 km2), and 6.77% (272.90 km2) of the entire susceptibility zonation map are composed of zones of very low, low, intermediate, high, and very high susceptibility, respectively. Results of evaluating the models using ROC showed that, the Dempster-Shafer model provides higher prediction accuracy (0.79) than the evidence of weight model (0.76). Considering quantitative results of validation, the combination of Dempster-Shafer model with morphometric indices is herein introduced as an appropriate model for zonation susceptibility to landslide.
    Keywords: landslide, Dempster-Shafer model, evidence of wight model, morphometry, Fahlian Watershed.
    Keywords: landslide, Dempster-Shafer model, evidence of wight model, morphometry, Fahlian Watershed
  • Hamid Nouri*, Alireza Ildoromi, Mahin Naderi, Soheila Aghabeigi, Hossein Zeinivand Pages 775-790
     
    Introduction
    Our Earth’s surface is warming rapidly and we can see social, economic and environmental impacts in the world. Failing to take sufficient action today entails potentially huge risks to our environment, economy, society and way of life into the future. This is the critical decade for action. Climate change and global warming will have direct and indirect impacts on water resources by accelerating the hydrological cycle and runoff. Hydrological simulation is an important approach to studying climate change impacts. With decreasing snowfall under climate change conditions, modeling of land use change in mountainous regions is an inherently difficult task Prediction of future changes in land use and climate change and its probability impacts on hydrological processes of watershed can be helpful for challenges of water resource manager and planners in the coming period that it is an important step in the correct planning and integrated management of watersheds. In this study, it has been coupled climate change scenarios, and land use change models with runoff models.
    Data and
    Methodology
    In the present research,Future land use scenarios were modeled by initially calculating the rate of current land use changes between three times snapshots (1986, 2000 and 2014) on Garin dam watershed using Land Sat satellite images, and based on transition probabilities markov-chain and CA markov-chain were used to generate future land use changes for 2042. Markov chain models are essentially projection models that describe the probabilistic movements an individual in a system comprised of discrete states. When applied to land use and many other applications, Markov chains often specify both time and a finite set of states as discrete values. Transitions between the states of the system are recorded in the form of a transition matrix that records the probability of moving
    from one state to another. The definition of a system as a finite Markov Chain requires a certain set of properties to hold (Stokey and Zeckhauser, 1978).
    SDSM Model used for down scaling of rain and temperature data and Hadcm3 output used for prediction of Garin future climate. Also, in order to study land use change and climate change impacts on runoff SWAT model was used.
    Results and discussion
    The simulation coefficients for calibration and validation (table1 and 2) was reasonable and well thus, performance of the model is acceptable. The results show that the forest area will be increased and rangeland will be decreased until 2042 (table3). The Result of Markov -chain and CA Markov-Chain analysis indicate that landuse change will decrease run off rate under A2 and B2 scenarios in 2042. The results reveal that climate change impacts on reducing of runoff is more than land use change during 2042 to 2050 compared 2000 to 2010. Table1. the coefficients for Calibration for discharge simulation
    br2 MSE P_factor R-factor R2 NS
    0.36 0.39 0.47 0.03 0.60 0.59
    Table2. the coefficients for Validation for discharge simulation
    bR2 MSE P_factor R-factor R2 NS
    0.51 0.16 0.39 0.04 0.67 0.66
    Table3. Comparison of the landuses area in 2014(at the present time) and 2042(in the future) Year Natural
    Forest Cultivated
    Forest Rangeland Rockland
    2014 2.35 0.82 14.63 3.24
    2042 2.59 1.05 14.19 3.20  
    Conclusions
    The NC,〖 br〗^2, R^2, MSE, P-factor and R-factor coefficients show that validation was better than calibration and both them reveals that performance of the model is reasonable and well. The results show that if trend be stable duration 1986 to 2014, the forest area will be increased by 2.28 percent and rangeland will be decreased by 2.07 percent until 2042 and also, mean precipitation will be reduced but mean temperature will has increased. The results indicate that rangland and rockland area decraesing and forest area increasing area cause to reduce runoff under A2 and B2 scenarios in the future time. Finally, the results show that influence of climate change on runoff reducing is more than effect of land use change from 2014 to 2042. The results can be used to improve management of Garin watershed and to focus on landuses damages and changes. The watershed studied has witnessed landuse change less than climate change effects on runoff rate. Without strong and rapid action there is a significant risk that climate change will undermine our society’s prosperity, health, stability and way of life. To minimize this risk, we must decarbonizes our economy and move to clean energy sources by 2050. That means carbon emissions must peak within the next few years and then strongly decline.
    Keywords: Climate change, Garin catchment, Runoff, Landuse, SWAT model
  • Sedighe Kiani Salmi*, seyyed hojat mousavi, parisa yeganeh Pages 791-811

    Skiing is one of the branches of sport tourism in winter sports sector. This kind of tourism today has become a special trend in the mountainous regions of developed countries and is known as the "white gold", which has a great contribution to the economy of the local communities of these countries. From a global point of view, ski tourism has become an industry, but the industry is now threatened by changes in climate change. The results of general atmospheric circulation models indicate a rise in temperature and a decrease in summer rainfall in Europe (Kaviani et al., 1995: 41). As global warming continues, some of the tourist destinations of skiing will be faced with the risk of decreasing in amount of snow and consequently loss of tourist's numbers. Therefore in such a situation, planning should be aimed at selecting the most suitable places for the construction of ski resorts with the least problem in terms of snowfall and other required parameters and the choice is made in principle and accurately. One of the problems that ski tourism in Iran faces is the installation of ski facilities and ski resorts in unsuitable places. specifying proper location for the construction of sports places and facilities in order to exploiting them optimally and efficiently in the present and future, is important that not paying attention to this issue in many cases leads to a lack of proper use of those places as well as spending too many to build them. One of the useful solutions in selecting and determining suitable sites for the construction of winter sports facilities and ski resorts is the using GIS.
    Therefore, in this study, the software was used to locate proper areas for construction of ski resorts.
    Materials & Methods
    This is an applied research. The research tool was a researcher-made questionnaire in which reliability was confirmed by calculating the incompatibility rate. The sample population of the study is 20 experts from the physical education and cultural heritage organizations of Chaharmahal and Bakhtiari province who respond to the questionnaire and have performed paired comparisons. In this research, the identification of suitable areas for the construction of a ski resort was carried out by weighting the criteria using the network analysis process and Super decision software. The network analysis process considers each issue and problem as a network of criteria, sub-criteria, and options. All elements in a network can, in any case, be linked together. In other words, in a network, feedback and interconnection between clusters are possible. Mapping is done by the ARC GIS software. In this regard, the most important measures affecting the locating of the ski resort were studied, which combination of these standards with the experimental knowledge of experts in the field of sports, identifies the proper locations for skiing.
    Results & Discussion
    Sports tourism in our country is not well- developed and there is no systematic program for sport tourism marketing and despite the huge costs of the physical education organization, the National Olympic Committee, federations and other relevant institutions for conducting national and international sporting events, the great benefits of tourism development resulting from these events cannot be used, and there is always a loss of opportunities in this area. Assessing the environmental capability and determining the potential power and allocating appropriate proportions to it is a method that can provide a logical and sustainable adaptation between the natural power of the environment, the needs of communities and human activities in space. In this way, while protecting biodiversity, sustainable productivity of the land can be achieved. Optimal locating attempts to help decision-makers and planners by regulating indicators and factors influencing decision making and finding logical solutions in order to choose appropriate places to carry out activities. In locating, it is trying to set various parameters in relation to each other. In the present study, in order to identify suitable areas for the construction of a ski resort using the history of the research, interviews which have been made with the experts, three main criteria and eight sub-criteria have been obtained. It should be noted that due to the lack of snowflake network density in the country, the number of snow and frost days and the amount of precipitation have been used. . After obtaining criteria and sub-criteria, the indices were weighed using ANP technique and by combining the results with the layers generated in ArcGIS software, the final map of the suitable areas for skiing in Chaharmahal and Bakhtiari province was produced.
    Conclusion
    In the study, after compiling the indices, the final score of each element was calculated using the ANP technique. In the next step, drawings were drawn and, by combining the weights obtained in the layers, the areas susceptible to the construction of the ski resort were located. In the study, after obtaining the indices, the final score of each element was calculated using the ANP technique. In the next step, needed maps were drawn and, by combining the weights obtained in the layers, the suitable areas for the construction of the ski resort were located. . According to the findings, about 12.9 percent of the province's area has the necessary conditions for the construction of a ski resort with an area of 1632.5 square kilometers, the main part of which is located in Koohrang city, the current most famous resort of Chahar Mahal and Bakhtiari province; Chelgaird, is also located in this area. The specified level is considered appropriate in terms of technical conditions, which are considered as necessary indicators. If the research findings are combined with empirical knowledge of experts, the best places in the province for the construction of ski resorts will be located
    Keywords: Zoning, ski resort, susceptible areas, sport tourism, Chaharmahal, Bakhtiari province
  • fateme jahani shakib, ali nakhaee, elham yusefi* Pages 813-827

    Efficiency of Gravitational Search Algorithm on Land Multi-Objectives Allocation in optimal selection of Agricultural Land use in Birjand Basin
    Introduction
    The background of spatial sustainable land planning is based on the position and establishment suitability of the land use activities and the interaction of judgments should be rooted in the three main elements of sustainable development, namely economic, social, and environmental. To the best of our knowledge, over the past 20 years, many significant the developments have been invented in the field of artificial intelligence techniques and tools that can be used to solve many practical geographic problems. The present research aims to introduce a new and effective searching method in order to solve complex, multiple, and non-obvious problems existing in the evolution of land suitability using optimization algorithms.
    Materials and methods
    The Birjand basin with 3435km2 area located in longitude from 88º, 41´ to 59º,44´ E and attitude from 32º, 44´ to 33º, 8´ N in the northern part of Bagheran mountains.
    Method
    Employing GSA
    This algorithm is designed to simulate the laws of gravity and Newton's motion in a discrete-time environment in search space. The positive features of GSA, including fast convergence, non-stop in local optimizations and computational volume reduction compared to Evolutionary Algorithms (EA) and no need for memory in comparison with other collective intelligence algorithms has created a new research field for researchers. Therefore, in the present study, by considering the advantages of GSA, its capability in optimizing the multi-objective land suitability problems was used.
    The objective functions of optimization model
    1- Maximize the environmental suitability: Compatibility of land for objective use based on physical, environmental and infrastructure factors requires the mapping of effective factors and their integration.
    2- Minimize the Land-use conversion: it results in a decrease in social capital costs and increase in economic benefit of society.
    3- Maximize the ecological suitability: it means as the preservation of natural features and environmental structures by maximizing the green lands, which can be evaluated using the Ecosystem Service Values (ESV).
    4- Maximize the stability of landscapes: in concepts of landscape, compressed forms close to the circle have more stability than shredded structures. This goal is achieved by maximizing compression function.
    5- Maximizing the compression function: In the present study, in order to create an integrated and compact surface a circle form was used around the image gravity centers. Besides, the noise and single cells were removed using the image-processing algorithm.
    Optimization model constraints:Setting constraint functions were applied in optimization model by considering the flood-protected areas, areas with a slope over than 70%, amount of demand for agricultural areas, placing a user per pixel, and the total area of the region.
    Measuring the efficiency of GSA
    In order to evaluate the efficiency of GSA, its results were compared with those of MOLA. At the end, three following approaches were used to compare and measure the efficiency of the algorithm.
    First approach: visual evaluation and studying the coherence of allocated spots
    Second approach: the use of statistical parameter such as mean and standard deviation of agricultural use suitability
    Third approach: Calculating and analyzing the landscape measures such as a number of plots (NP), plot density (PD), mean of shape index (SHAPE_MN), mean of plot area (PARA_MN), proximity index (PROX_MN) and cohesion of spot (COHESION) using FRAGSTATS software.
    Findings
    All objectives and constraints of optimization model were mapped. Therefore, amount of agriculture use suitability was applied using ANP Fuzzy technique of weight, fuzzier, and constraints (Fig. 1). Fig. 1: Agriculture use suitability using ANP fuzzy and WLC
    In Birjand basin, the ease of change from land covers to agricultural use was mapped (Fig. 2). Fig. 2: the ease of change from land covers to agricultural use
    The results from maximizing the ecological suitability were modeled using the difference between the present and future ESV (Fig. 3).
    Fig. 3: the difference between the present and future ESV
    After fitting all considered objectives and constraints by GSA, the allocation of agricultural use was provided (Fig. 4).   Fig. 4: Allocated agricultural use through GSA
    Relative efficiency of GSA
    The results of GSA were compared with those of MOLA. The results of allocating agricultural use by MOLA were presented in Fig. 5. Fig. 5: Allocated agricultural use through MOLA
    According to the comparison of statistical parameters, mean of agricultural suitability in MOLA had better performance, but in terms of SD, GSA showed better performance. Besides, analyzing all landscape measures demonstrated the efficiency and relative advantage of GSA compared to MOLA.
    Discussion and
    conclusion
    In the present research, optimal allocation of agricultural use was carried out using GSA. Besides, in order to measure the efficiency, its results were compared with those of MOLA. The results showed higher allocated spot for agriculture in MOLA as a disadvantage and higher suitability average was an advantage. On the other hand, since in the GSA, the number of allocated spots was less than MOLA, their suitability was not that much high. GSA showed the maximum sum of suitability with less spot on the map, which depended on the amount of demand. Therefore, it was a great advantage for GSA. Moreover, analyzing the landscape measures demonstrated the efficiency and priority of GSA compared to MOLA. Finally, it can result that the GSA have higher capacity in solving problems with complex and large space in short time and higher objectives and constraints.  
    Keywords: optimal selection of agricultural land, Gravitational Search Algorithm (GSA), Meta-heuristic algorithms, Multi-Objective Land Algorithm