فهرست مطالب

مهندسی اکوسیستم بیابان - پیاپی 21 (زمستان 1397)
  • پیاپی 21 (زمستان 1397)
  • تاریخ انتشار: 1397/12/23
  • تعداد عناوین: 7
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  • رضا دهقانی بیدگلی* صفحات 1-12
    درمنه دشتی یکی از گونه های مهم بوته ای اسانس دار در ترکیب گیاهی مراتع استپی است که به علت دارا بودن اسانس، معمولا در اواخر فصل تابستان و فصل پاییز، مورد چرای دام قرار می گیرد. از آنجایی که علاوه بر عوامل ژنتیکی، عوامل محیطی نیز بر نوع و میزان اسانس این گونه گیاهی اثر می گذارند، و چرای دام تا حد زیادی متاثر از تغییرات اسانس این گونه است، هدف این پژوهش بررسی تغییرات فصلی اسانس گیاه درمنه دشتی در مراتع استپی منطقه گلچکان کاشان طی فصل های سال 1396 بود. نمونه برداری به صورت تصادفی انجام شد. نمونه های گیاهی پس از جمع آوری از رویشگاه های طبیعی، خشک شده و با روش تقطیر با آب توسط کلونجر به مدت 60 دقیقه اسانس گیری شدند. اسانس حاصل از هر گیاه توسط دستگاه GC-MS آنالیز شد. نتایج حاصل نشان داد درمجموع 43 ترکیب در اسانس درمنه دشتی وجود دارد که 35 ترکیب بین فصول مختلف مشترک اند. اجزای اصلی اسانس را alpha-thujene، alpha-pinene، Camphene، 1,8cineol و alpha-phelandrene تشکیل می دادند. بیشترین میزان alpha-pinene در فصل تابستان (50/32درصد) و بیشترین میزان Camphene در فصل بهار مشاهده شد (7/23درصد). بیشترین میزان alpha-thujene و 1,8cineol در فصل بهار و تابستان، به ترتیب به میزان 50/26 و50/ 24درصد مشاهده شد. به جز برخی ترکیب ها از جمله alpha-thujene، alpha-pinene، Camphene، سایر ترکیب های سازنده اسانس به طور محسوس، تحت تاثیر تغییرات فصلی قرار نگرفتند. بعضی از آن ها به مواد دیگر تبدیل شدند؛ ازاین رو غلظت آن ها در فصل پاییز و زمستان کاهش و در فصل بهار و تابستان افزایش یافت که بر میزان چرای دام از این گونه گیاهی تاثیر قابل ملاحظه ای داشتند.
    کلیدواژگان: آلفا- پینن، باران، چرای دام، درمنه، GC-MS
  • شهاب عراقی نژاد*، محمد انصاری قوجقار، مسعود پورغلام آمیجی، عبدالمجید لیاقت، جواد بذر افشان صفحات 13-32
    مناطق مختلف، استعدادهای متفاوتی در تولید گردوغبار دارند و افزایش طوفان های گردوغبار نشان دهنده حاکمیت اکوسیستم بیابانی در هر منطقه است. بدین منظور، داده های ساعتی گردوغبار و داده های ماهانه هواشناسی و اقلیمی شامل دمای بیشینه، دمای کمینه، دمای متوسط، سرعت بیشینه باد، مجموع بارش و دمای خاک در اعماق مختلف (5، 10، 20، 30 و 50 سانتی متر) در 37 ایستگاه سینوپتیک کشور با طول دوره آماری 25ساله (19902014) گردآوری، و روند آن ها توسط آماره های ناپارامتری من-کندال و سنس استیمیتور محاسبه شد. همچنین برای بررسی تاثیرپذیری طوفان های گردوغبار از نوسانات اقلیمی علاوه بر متغیرهای مذکور، شاخص خشکسالی بارش-تبخیر و تعرق پتانسیل استاندارد (SPEI) نیز در بازه زمانی فصلی محاسبه و سپس برای تحلیل همبستگی عناصر اقلیمی و طوفان های گردوغبار، از روش اسپیرمن استفاده شد. نتایج فراوانی روزهای گردوغباری در این بازه 25ساله نشان می دهد که زابل، آبادان و اهواز رکورددار بیشترین روزهای همراه با طوفان های گردوغباری، به ترتیب با 711، 401 و 321 روز بوده اند. نتایج آزمون من-کندال نشان داد که از 37 ایستگاه هواشناسی مورد بررسی، 6 ایستگاه اردبیل، بیرجند، مشهد، سبزوار، یزد و سمنان دارای روند نزولی، 5 ایستگاه دارای روند افزایشی معنی دار در سطح اطمینان 95% و 21 ایستگاه دارای روند افزایشی معنی دار در سطح اطمینان 99% بوده اند. نتیجه آزمون سنس استیمیتور نشان داد که 6 ایستگاهی که در روش من-کندال دارای روند نزولی بودند، در این روش بدون روند هستند و به ترتیب 11، 10 و 10 ایستگاه دارای روند افزایشی، افزایشی معنی دار در سطح اطمینان 95% و افزایشی معنی دار در سطح اطمینان 99% هستند؛ به طور کلی در اکثر موارد نتایج دو آزمون در سطوح اطمینان مورد نظر مشابهت دارد. نتایج همبستگی اسپیرمن در کشور نشان می دهد که فراوانی روزهای گردوغباری با سرعت بیشینه باد، شاخص SPEI و دمای بیشینه از بین پارامترهای اقلیمی گفته شده، به ترتیب با ضرایب 74/0، 57/0- و 48/0 بیشترین همبستگی را داشته و همگی در سطح اطمینان 99% معنی دار شده اند. ضمن اینکه دمای عمق 5 سانتی متر خاک نسبت به دیگر اعماق، بیشترین همبستگی را با طوفان گردوغبار داشته و با ضریب 39/0 در سطح 95% معنی دار شده است. به طور کلی، نتایج آزمون های انجام شده بیانگر افزایش روند طوفان های گردوغبار در غرب و جنوب غرب، قسمت هایی از شمال غرب و جنوب شرق کشور است. نتایج این مطالعه می تواند در شناخت اثرات نوسانات اقلیمی بر فراوانی طوفان گردوغبار و مهار بیابان زایی ایران مفید باشد.
    کلیدواژگان: آزمون من-کندال، پارامترهای اقلیمی، طوفان های گردوغبار، شاخص خشکسالی SPEI، همبستگی اسپیرمن
  • فاطمه قیطاسی، علی محمدیان بهبهانی*، محسن حسینعلی زاده، حمیدرضا عسگری صفحات 33-44
    در طول دو دهه گذشته، توجه فراوانی به نقش پوسته های بیولوژیک در اکوسیستم های خشک و نیمه خشک شده است. با توجه به نقش پوسته های زیستی سطحی خاک در بهبود خصوصیات فیزیکی و شیمیایی، و نبود اطلاعات کافی در خصوص ویژگی های ذاتی آن ها، این پژوهش می تواند در راستای درک مکانیسم موثر این پوسته ها مفید باشد. هدف از این پژوهش، بررسی خصوصیات فیزیکوشیمیایی، در خاک های دارای پوسته های فیزیکی و بیولوژیکی (گلسنگ و خزه)، همچنین مطالعه ویژگی های شاخص فرسایش پذیری خاک و ارتباط متقابل آن ها، در منطقه تپه ماهورهای حاشیه دریاچه آجی گل در استان گلستان است. در این تحقیق، پس از انجام عملیات آزمایشگاهی و تعیین پارامترهای فیزیکو شیمیایی نمونه ها، همچنین تعیین شاخص فرسایش پذیری خاک با استفاده از روابط تجربی، به منظور بررسی و مقایسه میانگین خصوصیات فیزیکوشیمیایی پوسته های فیزیکی و بیولوژیکی (گلسنگ و خزه) در نمونه های سطحی خاک، در سطوح معنی داری مختلف در محیط نرم افزار R استفاده شد. با انجام آزمون آماری ANOVA تفاوت بین متغیرهای مورد نظر در سه پوسته مطالعه شده (فیزیکی، گلسنگ و خزه) بررسی شد. نتایج آزمون های آماری انجام شده برای خصوصیات شاخص فرسایش پذیری ذرات خاک تشکیل دهنده رسوبات پوسته های فیزیکی، گلسنگ و خزه نشان داد که بین پوسته های فیزیکی- گلسنگ تفاوت معنی داری وجود ندارد، ولی این شاخص بین پوسته های فیزیکی- خزه و خزه- گلسنگ اختلاف معنی دار دارد. همچنین در بین خصوصیات فیزیکوشیمیایی مقدار کربن آلی، هدایت الکتریکی(EC)، پایداری خاک دانه، جورشدگی و میانگین قطر ذرات در پوسته های خزه- گلسنگ اختلاف معنی داری وجود نداشت. با توجه به مقدار p-value در خصوص اندازه ذرات تشکیل دهنده بافت خاک، بین تمامی ذرات رس، سیلت و شن برای 3 نوع پوسته به استثنای خزه و گلسنگ از نظر درصد رس، اختلاف معنی داری در سطح 05/0 وجود داشت.
    کلیدواژگان: پوسته های بیابانی، فرسایش پذیری خاک، استان گلستان
  • محسن نوروززاده، محمد جواد قانعی بافقی*، مهدی تازه صفحات 45-58
    کمبود آب در کشور ایران، به خصوص در مناطق خشک و نیمه خشک، همواره مشکل ساز بوده است. در این تحقیق، به منظور مکان یابی سازه های استحصال آب در شهرستان راور، از ترکیب روش های تصمیم گیری چندمعیاره و سیستم اطلاعات جغرافیایی استفاده شد. نتایج این تحقیق نشان داد که از معیارهای مورد استفاده در این تحقیق، به ترتیب بر اساس وزن به دست آمده از پرسش نامه های تکمیل شده توسط خبرگان، شامل معیارهای بارندگی، شیب، شوری، پوشش گیاهی، بافت، ژئومورفولوژی با وزن های 362/0، 298/0، 151/0، 82/0، 53/0، 51/0 است. پس از تلفیق لایه های اطلاعاتی مربوط به هر معیار، نقشه های نرمال شده، در وزن هر لایه ضرب و نقشه تجمیع شده، طبقه بندی شد. بر این اساس، منطقه مطالعاتی به چهار دسته کاملا مناسب، مناسب، تناسب کم و بسیار نامناسب تقسیم بندی شد. مناطقی که بر اساس هریک از معیارها امکان اجرای پروژه مذکور را نداشتند، با استفاده از روش بولین به دو کلاس صفر و یک طبقه بندی و مناطق نامربوط از نقشه تناسب حذف شد. نتایج به دست آمده با واقعیت زمینی که همان پروژه های اجراشده در منطقه است، مقایسه و صحت کار ارزیابی شد. نتایج نشان داد که نقشه های به دست آمده با میزان صحت 8/65درصد با واقعیت زمینی مطابقت دارد.
    کلیدواژگان: مکان یابی، جمع آوری آب، تصمیم گیری چندمعیاره، استحصال آب
  • مهدی زارعی*، مجتبی سلیمانی ساردو صفحات 59-74
    خشکسالی پدیده ای آرام و خزنده محسوب می شود که با تاثیر در بخش های کشاورزی، منابع آب و پوشش گیاهی در نواحی مختلف، به خصوص مناطق خشک و نیمه خشک، می تواند گسترش مناطق بیابانی را تسریع کند. یکی از روش های بررسی وضعیت خشکسالی در هر منطقه، پایش و پهنه بندی خشکسالی با استفاده از شاخص های هواشناسی و سیستم اطلاعات جغرافیایی (GIS) است. در تحقیق حاضر به منظور بررسی و پایش خشکسالی در منطقه مطالعاتی قم-کهک طی دوره آماری 29ساله (13671368 تا 13951396)، شاخص های خشکسالی مانند شاخص بارش استانداردشده (SPI) ، درصد نرمال (PNI)، شاخص دهک (DI)، شاخص Z چینی (CZI) و شاخص نمره Z (ZSI) بررسی شدند. سپس با هدف پهنه بندی خشکسالی، روش های مختلف درون یابی در تمامی سال های دوره آماری مورد مطالعه در محیط نرم افزار ArcGIS ارزیابی گردیدند. نتایج شاخص های مختلف نشان داد که حالت نزدیک به نرمال در همه ایستگاه ها، طی دوره آماری مورد مطالعه، دارای بیشترین فراوانی است. بر اساس نتایج شاخص های SPI و CZI، بیشترین (7 سال) و کمترین (3 سال) تعداد خشکسالی به ترتیب در ایستگاه های کهک و جنت آباد اتفاق افتاده است؛ درحالی که بر اساس شاخص PN بیشترین و کمترین تعداد خشکسالی به ترتیب در ایستگاه های قم (9 سال) و جنت آباد (3 سال) مشاهده شد. همچنین نتایج شاخص PN حاکی از عدم وجود دوره ترسالی طی دوره آماری مورد مطالعه بوده است. بر اساس شاخص ZSI خشکسالی بسیار شدید در منطقه رخ نداده و نتایج ZSI در خصوص فراوانی طبقه ترسالی بسیار شدید، مشابه نتاج شاخص SPI است. در بین شاخص های مورد مطالعه، شاخص SPI مقارن با سال وقوع کمینه بارندگی در طول دوره آماری رخداد خشکسالی شدید و بسیار شدید را در تمام ایستگاه ها نشان داده، لذا به عنوان مناسب ترین شاخص برای پهنه بندی خشکسالی انتخاب شد. نتایج پهنه بندی نشان داد که در سال های آبی 13681369، 13731374 و 13751376 بیشتر منطقه در وضعیت خشکسالی بسیار شدید تا خفیف قرار داشته است. در سال های آبی 13881389 و 13951396 نیز در بیشتر سطح منطقه مورد مطالعه، خشکسالی خفیف تا شدید رخ داده و تنها در قسمت شرقی منطقه، ترسالی خفیف مشاهده شد؛ درحالی که طی سال های آبی 13701371، 13741375 و 13871388 منطقه مورد مطالعه، ترسالی متوسط تا شدید را تجربه کرده است. در سال آبی 13891390 نیمه شرقی منطقه، ترسالی متوسط و نیمه غربی منطقه، ترسالی خفیف را نشان می دهد.
    کلیدواژگان: پایش خشکسالی، درون یابی، پهنه بندی، شاخص های هواشناسی، خشک و نیمه خشک، قم-کهک
  • آذین نصریان، مرتضی اکبری*، علیرضا فریدحسینی، احسان نعمت الهی صفحات 75-90
    این تحقیق با هدف بررسی تغییرات کمی و کیفی آب زیرزمینی ناشی از توسعه کشاورزی در شدت بیابان زایی دشت درگز در شمال خراسان رضوی انجام شد. برای آنالیز کمی، از شاخص افت سطح تراز آب و برای بررسی کیفی، از شاخص های هدایت الکتریکی آب، نسبت جذب سدیم و کلر استفاده شد. مبنای اطلاعات آماری، داده های بیش از 124 حلقه چاه پیزومتر بود که برای مدت زمانی 20ساله از 1375 تا 1395 و در چهار دوره 5 ساله، به روش زمین آمار کریجیگ در محیط نرم افزاری GIS پهنه بندی و طبق مدل ایرانی ارزیابی پتانسیل بیابان زایی (IMDPA) طبقه بندی شدند. نتایج نشان داد میزان افت سطح آب در بخش های غربی و شمال غربی منطقه، بیشترین مقدار بوده که علت آن حفر چاه های عمیق غیرمجاز و برداشت بیش از حد آب است. از بعد تغییرات کیفی هدایت الکتریکی، بخش های شرقی در کلاس شدید و گاه خیلی شدید بیابان زایی قرار دارد؛ به طوری که در مدت 20 سال گذشته، از 14 به 23درصد رسیده و این نشان دهنده وضعیت هشدار در مقدار شوری آب آبیاری و به تبع آن، افزایش شدت بیابان زایی است. به نظر می رسد در شرایط فعلی، مدیریت منابع آب زیرزمینی دشت درگز باید به عنوان یک اولویت مدیریتی مورد توجه قرار گیرد.
    کلیدواژگان: آبیاری، بیابان زایی، درون یابی، شوری، مدیریت منابع آب
  • ساناز پورفلاح، محمدرضا اختصاصی*، محسن صادقیان صفحات 91-105
    پدیده فروچاله‏ ها و نشست زمین در دشت‏ ها از خطرات طبیعی تشدیدشونده هستند که امروزه به ‏دلیل سرعت و تراکم شکل‏ گیری مورد توجه قرار گرفته ‏اند. از دیدگاه ژئومورفولوژی، می‏ توان فروچاله‏ های اطراف شهر ابرکوه را به دو دسته فروچاله‏ های کوهستانی و دشتی تقسیم ‏بندی کرد. هدف از این پژوهش، شناخت عوامل موثر در شکل‏ گیری فروچاله ‏ها در دشت ابرکوه است. در گام اول با استفاده از روش‏ سلسله مراتبی، مهم‏ترین معیارهای تاثیرگذار طراحی شد و در نهایت، ارزش وزنی آن ها با استفاده از پرسش‏نامه در محیط نرم‏ افزار اکسپرت چویس تعیین شد. معیارهای تاثیرگذار به‏ ترتیب اولویت عبارت اند از: وجود لایه‏ های انحلال‏ پذیر در اعماق (30 درصد)، بافت رسوبات و سازندهای آهکی (4/20 درصد)، افت سفره ‏های زیرزمینی (4/17 درصد)، سیستم آبیاری غرقابی (6/12 درصد)، نوع کاربری (1/7 درصد)، فاصله از چاه ‏های بهره ‏برداری (8/5 درصد)، فاصله از آبراهه ‏های قدیمی (6/3 درصد) و فاصله از گسل (1/3 درصد). در گام دوم، برای صحت ‏سنجی نتایج، از اطلاعات میدانی و آزمایش‏ های پارامترهای مهم خاک‏شناسی استفاده شد. لوگ‏های حفاری پیزومترهای اطراف فروچاله ‏ها و سنگ کف آبخوان دشت ابرکوه، وجود لایه ‏های انحلال‏ پذیر در اعماق را تایید کرد. از طرفی آزمایش‏ ها نشان داد که بافت رسوبات فروچاله ‏های دشتی بسیار ریزدانه و با درصد بالای مقادیر رس و آهک و املاح است. پمپاژ آب از اعماق در جهت مصرف کشاورزی، منجر به ایجاد حفره‏ های انحلالی و در نتیجه فروچاله‏ های دشتی می ‏شود. همچنین موقعیت فروچاله ‏های کوهستانی در بالادست آبخوان دشت ابرکوه است که در دهه ‏های اخیر با افت شدید آبخوان روبه ‏رو شده، بحران افت سفره به ‏همراه سازندهای آهکی، پدیده فروچاله ‏های کوهستانی را به وجود آورده است.
    کلیدواژگان: سازندهای آهکی، مدل تحلیلی سلسله مراتبی، آب زیرزمینی، AHP
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  • Reza Dehghani Bidgoli * Pages 1-12
    Introduction
    Artemisia is a large and diverse genus from the Asteraceae family, that with Astragalus genus constitute the 60% of Iran’s rangeland vegetation. This plant species has been used since ancient times as a medicinal plant. One of the most important species of this genus is the Artemisia sieberi Besser, which is feed by livestock in some season. Since, in addition to genetic factors, environmental factors affect the quantity and quality of essential oil of this plant. Also, the grazing of livestock is largely affected by changes of essential oil of this plant species. The aim of this study is the investigation of the seasonal changes in the essential oil of Artemisia sieberi Besser.
    Material and Methods
    This research was conducted in a randomized sampling with 3 replications from the Artemisia sieberi in 2017. Artemisia species were taken from step rangeland of Kashan province. In this study, 3 plant bases were selected randomly and dried at room temperature and shadow and prepared for essential oil operation, in this regard plant samples (100g) were dried and extracted by Clevenger distillation method for 60 minutes. The essential oil analyzed by GC/MS. GC analysis was performed by using a thermoset gas chromatograph with a flame ionization detector (FID). The analysis was carried out using the fused silica capillary Innowax column (60 m × 0.25 mm i.d.; film thickness 0.25 µm). The operating conditions were as follows: injector and detector temperatures were 230˚C and 250˚C, respectively. Nitrogen was used as carrier gas at a flow rate of 4 ml/min; oven temperature programme, 80˚C–230˚C at the rate of 3˚C/min, and finally held isothermally for 10 min. The constituents of the essential oil were identified by calculation of their retention indices under temperature-programmed conditions for n-alkanes (C5–C10) and the oil on an Innowax column under the same chromatographic conditions. In order to Identification of individual compounds was made by comparison of their mass spectra with those of the internal reference mass spectral library or with authentic compounds and confirmed by comparison of their retention indices with authentic compounds. In order to more accurately identify the compounds, relative area percentages obtained by FID were used without the use of correction factors.
    Results and Discussion
    The results showed that there are 43 compounds in Artemisia essential oil which 35 compounds are common between different seasons. The main components of the essential oil were alpha-thujene, alpha-pinene, Camphene, 1.8cineol, and alpha-phellandrene. The highest amount of alpha-pinene was observed in summer (32.50%) and the highest amount of Camphene was observed in spring (23.7%). The highest levels of alpha-thujene and 1.8cineol were observed in the spring and summer, in the amount of 50.56 and 24.5%, respectively. Except for some compounds such as alpha-thujene, alpha-pinene, and Camphene, other essential oil composition, not affected by seasonal changes. The evaluation of essential oil of this plant in different stages in this region indicated that the amount of this composition in the essential oil before the flowering stage was 87.9% and after the flowering stage was 91.33%. The studied plant was collected from the natural habitats of Kashan, which is considered being hot and dry regions, and in general, the plants that have been grown in these areas are alpha-tense. In contrast, there are more common parts of the essential oils of cold weather. The changes in Camphor from December to September were 45.2%, 37.5%, 14.1%, and 10.5% respectively, and the highest rate of camphor was observed in January. In the populations of Artemisia, Khorasan was 20% to 24.5% of Camphen, which is consistent with the results of this research. In Kerman, it was reported as 23%. 8 and 1, cineole was identified as one of the main components of essential oil in Artemisia populations of Turkey in plains. The amount of this substance in Kerman was 34.8%, which is more than the samples studied in this study. Some essential oil composition was converted to other compounds, and their concentration decreased in fall and winter and increased in the spring and summer which had a significant impact on livestock’s grazing.
    Conclusion
    This appears that drought stress has been effective in producing more alpha-pinene. On the other hand, in winter, several compounds are produced in the essence of this plant species, and the reason for the decrease of alpha-pinene in fall and winter may be its conversion to other components in the essential oil. It seems that this compound is high in the essential oil of the plants grown in Iran. Because the amount of this compound has increased after autogenous grazing in fall, this may be due to the biochemical defense of the plant against grazing of the livestock, which needs to be more investigated. The observed differences are mainly related to environmental conditions, and each plant grown in one region is richer in one of the essential oil components. Different components of the essential oil of Artemisia plain have different applications, for example, alpha-pinene in perfumes and insecticides, cineol in perfumes, and pharmaceuticals are used as the suppository, anesthetizing and reducing blood pressure and amphetamine in perfume. Therefore, finding plants that are rich from the essential oil components is important in this regard.
    Keywords: alpha-pinne, Rain, Grazing livestock, Artemisia, GC-MS
  • Shahab Araghinejad *, Mohammad Ansari Ghojghar, Masoud PourGholam Amigi, Abdolmajid Liaghat, Javad Bazrafshan Pages 13-32
    Introduction
    Different regions have various dust production; and the increase of dust storms illustrates the arid ecosystem dominance in each region. Analyzing and identifying of dust storms and its association with climatic parameters is one of the crucial approaches to reduce the caused damage of this phenomenon. Since besides determining the portion of each climate variables in intensifying the circumstances, it also can play a fundamental role in priorities, macro management policies, and upstream rules in order to control and prevent dust particles.
    Methods and Materials
     In order to carry out this study hourly horizontal visibility data, World Meteorological Organization codes, hourly dust data, and also monthly meteorological and climatic data including maximum temperature, minimum temperature, average temperature, maximum wind speed, total rain, and soil temperature of different depth (5, 10, 20, 30, 50 cm) in 37 synoptic stations of the country were gathered through a longitudinal statistics of 25 years (1990-2014) and its trend was calculated by non-parametric statistics of Mann-Kendall and Sen’s Estimator tests. After the qualitative analysis of the stations’ statistics and elimination of defects, all the data were assessed via Run Test at the coefficient level of 95%. In order to analyze the effect of climate fluctuations on dust storms, beside the mentioned variables, draught variable of evaporation-rain index and standardized precipitation evapotranspiration index (SPEI) in seasonal period calculated and then Spearman test was applied for correlational analysis of climate elements and dust storms.
    Results
    The frequency outcomes of dusty days during a long-term study of 25 years indicates that Zabol, Abadan and Ahvaz orderly with 711, 401, and 321 days have the most dust storms. The results of Mann-Kendall show out of 37 under study weather stations, six stations of Ardebil, Birjand, Mashhad, Sabzevar, Yazd, and Semnan reported a descending trend. Five stations reported a meaningful growing trend with coefficient of 95% and 21 stations out of the 37 present stations have a growing coefficient of 99%. The result of Sen’s Estimator test shows the six stations which based on Mann-Kendall test had a descending trend, they don’t follow a trend in this method and orderly 11, 10, and 10 stations had a rising trend, significant rise at 95% coefficient level also at 99% coefficient level. Generally, in most cases the results of the two tests had the same coefficient level. The results of Spearman coefficient across the country shows that the frequency of dusty days with the maximum wind speed, SPEI scale, and maximum temperature among the mentioned climatic parameters in order 0.74, -0.57, and 0.48 had the highest coefficient and were all significantly coefficient at the 99% level. Among the rest temperature of different soil depths (5, 10, 30, 50 cm) in all 37 under study stations there is a direct relation with dust storms and were significant with 0.39 at the level of 95%. So, we can conclude the surface levels of soil (5 and 10 cm) have a crucial role in dust storms in different soil depths.
    Discussion and Conclusion
    The results of this study show, applying two methods of Mann-Kendall and Sen’s Estimator tests are effective for analyzing the long-term changes of dust storms. Generally, the results of Mann-Kendall tests show a rising trend of dust storms in west and south west and some parts of north west and south east of the country. The result of the Sen’s Estimator test says that Ardebil, Birjand, Mashhad, Sabzevar, Yazd, and Semnan don’t follow a trend. As far as the mentioned stations do not have regular dusty days, thus we can consider Mann-Kendall is not a very strong test because of presenting integer results in the stations which contain data of many zeros. The results of correlation between climate elements and the frequency of the dust storm days showed that the highest correlation is related to the maximum wind speed variable with 0.74 as a strong lever for picking up the dust. There is a negative correlation between rain and evaporation-rain index and potential standardized precipitation evapotranspiration with dust phenomenon. This negative correlation is more tangible in SPEI and in most of the stations at the coefficient level of 95% and 99% significant. Thus, as there is more rain in the specified station, there are less dust days. All in all, after maximum wind speed, the SPEI index receives the highest correlation that justifies dust storms. The results also show as we go deeper to the soil layers, the correlation between soil temperature and dust storms declines. The highest and lowest correlation exists in depth of 5.50 cm of soil with the registered numbers of 0.39 and 0.017. The results of this study are useful for recognizing the effect of climate years on the frequency of dust storm and restraining deserts.
    Keywords: Mann-Kendall test, Climate Parameters, Dust Storms, SPEI, Spearman Coefficient
  • Fatemeh Gheytasi, Ali Mohammadian Behbahani *, Mohsen Hosseinalizadeh, Hamid Reza Asgari Pages 33-44
    Introduction
    During the past two decades, the attention has been paid to the role of biological crusts in dry and semi-arid ecosystems. According to the roles of soil surface crusts in improving physical and chemical characteristics, and lack of sufficient information on their inherent characteristics, this research can be useful in understanding the mechanism of these crusts.
    Materials and methods
    The purposes of this study were investigating the physicochemical characteristics, methods of measuring and computing of these characteristics for physical and biological soils crusts (lichens and moss), studying the characteristics of soil erodibility index and their mutual relationship in the around Aji-Gol lake located in Golestan province. In this study, after laboratory operations for determination of physicochemical parameters, the soil erosion index using empirical relationships was considered. In order to compare the physicochemical characteristics of physical and biological crusts (lichens and moss) in surface soil samples, different levels of significance were investigated using environment package of R software. Based on ANOVA, the differences between variables were considered in the three studied crusts (physical, lichen, and moss).
    Results
    The results of statistical tests for the soil particle erodibility index showed that there was no significant difference between physical crusts–lichens (P≥0.05), but there were significant differences between the physical crusts-moss and moss-lichens (P≤0.05).
    Discussion and Conclusion
    There were no significant differences among physicochemical characteristics of organic carbon content, EC, aggregate stability, sorption and average particle diameter, and moss-lichen crusts (P≥0.05). With regards to the size particles of the soil texture, there were significant differences among all the particles of clay, silt, and sand belonged to 3 types of crusts (with the exception of moss and lichen in the clay( (P≤0.05).
    Keywords: Desert crusts, Soil erodibility, Golestan province
  • Mohsen Nowruzzadeh, Mohammad, Javad Ghanwi, Bafghi *, Mahdi Tazeh Pages 45-58
    Introduction
    Deficit of rainfall and consequently, water scarcity is one of the most important problems in arid and semi-arid areas. Water collecting structures have a positive effect on light textured lands due to deposition of clay and organic matter, as well as controlling the floods will enhance the vegetation (Abdollahi et al., 2015). Water Collection in order to store surface water runoff, especially during periods where water availability is limited, is an appropriate option in dry areas (Nazarian and Najafinejad, 2015). Due to the numerous criteria and indicators (such as geomorphology, climate, soil, vegetation etc.) in choosing the type of efficient operation and the most suitable areas for their design and implementation, it is practically difficult to select the correct operation with the expected accuracy (Mia and Skumann 2007); Therefore, one of the most important and essential steps in the application of rainwater collection systems is to identify suitable sites for the implementation of these projects.
    A general overview of resources shows that collecting and storing rain water in arid areas is one of the best techniques for managing and using rainwater and it is a suitable method to provide the required water in arid and semi-arid areas. Rain water collection requires a spatial assessment and hydrological studies of surface and ground water (Nazarian et al. 2015). The main purpose of this research is to determine the most important criteria for locating suitable areas for rainwater harvesting as well as mapping these locations.
    Materials and methods
    In this research, based on the results of completed questionnaires from experts, as well as by referring to the research background in this field, to select appropriate areas for collecting water, slope criteria, rainfall, vegetation, salinity, soil texture and Geomorphology were considered as main criterias. Layers were classified in the ArcGIS software. For weighting the criteria, using the AHP technique, matrixes of paired comparisons were created and using the expert opinion, the value of each criterion was determined and the results were entered into the Super Decision software. Land suitability map was made by combining layers. and the map was compared with the Boolean map. In order to verify the accuracy of the results, Land suitability map was compared with a map of successful and unsuccessful executives' work in the.
    Results
    The final suitability map was obtained as follows. The map is divided into four classes, perfectly suitable, appropriate, slightly suitable and very inappropriate. the area of each of these categories listed in Table 1.
    تناسب نهایی
    Figure (1): Final suitability map

    Tabel (1): Area of each category of suitability
    Area (ha) Present area
    inappropriate 53154 31
    very inappropriate 18288 10.7
    slightly suitable 47474 27.7
    appropriate 38144 22.3
    perfectly suitable 14324 8.3
    Comparison of implemented projects in the region with modeling shows that 67.5% of the successful structures are in perfectly suitable range, while unsuccessful structures do not have any overlaps with a perfectly suitable range.
    Discussion and conclusion
    In this research, using AHP, areas were zoned for the implementation of rainwater harvesting projects. The results showed that among the used criteria, the highest score was attributed to rainfall. While this criterion had the lowest value in the study conducted by Yousefi et al. (2015). The reason for this difference can be due to experts' experience of unsuccessful structures in the region. Nevertheless, the results of Ali Kasi (2010) and Al-Adamat (2010) regarding the rainfall criterion are consistent with the present research. After rainfall, the criteria for gradient and salinity were the highest scores respectively. The results showed that slopes of 3 to 8 percent achieved the highest score. The results of this study are consistent with the results of Bulcock et al. (2013) and Akbarpour et al. (2015).
    Vegetation, soil texture and geomorphology criteria were ranked in subsequent grades, respectively. Places with less vegetation require more attention in terms of providing moisture and increasing coverage. This is in line with the results of Zarrin Abadi and Vaezi (2016). Medium to semi-heavy soil texture has a better suitability for rain water collection. Results showed that, sandy clay loam texture had had the highest score among the sub-criteria. This texture appears mainly in the northern parts of the region, and the results of Akbarpour et al. (2015) confirmed this result.
    Between geomorphology criteria Epandage pediments had the highest score due to suitable slope and grading.
    The important point is that overlapping information in the GIS without analyzing and performing multi-criteria evaluation operations cannot provide the right planning and decision. Also, when different factors interfere in decision making, their priorities and weights should be determined. Results of modeling in this research is consistent with the results of Ali Khasi (2010), Yousefi et al. (2015), Gohari (2015), Ketsela (2009) and Singh et al. (2017).
    Keywords: Locating, Collecting water, Multi-criteria decision making, Water harvesting
  • Mahdi Zarei *, Mojtaba Solaimani Sardo Pages 59-74
    Introduction
    Drought is recognized as a slow, creeping phenomenon that can accelerates the expansion of desertification in different regions especially in arid and semi-arid area with its effect on the agricultural sectors, water resources and vegetation cover. Positioning of Iran in the world arid and semi-arid belt is exposed to drought and water crisis and desertification. Drought monitoring and zoning with the goal of planning and water resources management are very important in different area especially in arid and semi-arid regions. One of the methods for drought study is monitoring and mapping of drought using meteorological indices and Geographic Information System techniques.
    Materials and Methods
    In order to investigate and drought monitoring in present research during the period of 29 years (1989 to 2017) in Qoum-Kahak study region we used annual rainfall data from four stations (i.e. Qoume, Kahak, Koohsefid and Janatabad) which are located inside and around the Qoume-Kahak catchment. Then we applied meteorological indices such as Standard of Precipitation Index (SPI), Percent of Normal Index (PNi), Deciles Index (DI), Chinese Z Index (CZI) and Z-Score Index (ZSI) for drought monitoring during the study period. Afterward for drought mapping, four interpolation methods included Simple Kriging (SK), Ordinary Kriging (OK), Inverse Distance Weighting (IDW) and Radial Basis Functions (RBF) were used and compared. After determination of best method in each year, yearly drought map were produced based on the best interpolation methods in ArcGIS software environment.
    Results
    According to the result of meteorological indices the near-normal class occurred more than other classes in study stations. SPI results indicated that Jannatabad and Kahak stations have the highest and lowest frequency of extremely dry class during the study period, respectively. The most extremely dry class with the SPI of -2.35 was occurred in Janatabad station in the year of 1997-98. Based on the results of PNI and ZSI indexes there was no occurred extremely dry class in all stations. The result of PNI index indicated that Koohsefid station has the highest frequency of very dry class between all stations. According to the result of CZI index the extremely dry class was occurred only for Kahak and Janatabad stations in the water years of 2016-2017 and 1997-98 respectively. Extremely wet class was occurred also for Kahak and Janatabad stations during the water years of 2009-2010 and 1992-1993 respectively. The results of DI index illustrated that the class of very much below normal was occurred in Qoume and Koohsefid stations 4 times and in Kahak and Janatabad stations 3 times during the study period. We applied geostatistical analyst tools in ArcGIS software to produce zoning maps for rainfall and drought. Its result showed that ordinary kriging with RMSE of 28 mm is the best method to create rainfall map. Accordingly mean annual rainfall was 136 mm/year during the study period. We selected SPI index for drought monitoring and zoning because of according to the results of all meteorological indices,only for this index the extremely and severely drought classes for all stations have occurred Simultaneous with the minimal rainfall during the study period. Afterward we compared different interpolation methods to produce drought zoning maps for each year during the study period. Based on the results of RMSE ordinary kriging and simple kriging were the best methods for most years.
    Discussion and Conclusion
    The results of all meteorological indices suggested that in all stations the near-normal class has the most frequency during the study period. According to the results of SPI and CZI indices, the highest (7 years) and lowest (3 years) number of drought were occurred in Kahak and Jannatabad stations, respectively. While according to PN index the highest (9 years) and lowest (3 years) number of drought were observed in Qoum and Jannatabad stations, respectively. Also the results of PN index illustrated that there was no wet period during the study period. According to the ZSI Index, the extremely dry class did not occurred in the region and the ZSI results about the frequency of extremely wet class was similar to the SPI results. The results of drought zoning indicated that in the years of 1990, 1995 and 1997, most of the region has been in a state of extremely to slightly drought. In the years 2010 and 2017, slight to sever drought classes were occurred in most parts of the study area and the slight wet class was observed in the eastern part of region. While during the years of 1992, 1996 and 2009 whole of the study area has experienced moderate and severe wet conditions. In the year of 2011, half of the study area which is located in the eastern part of the region has been in a state of moderate wet condition.
    Keywords: Drought Monitoring, Interpolation Methods, Zoning, Meteorological Indices, Arid, Semi-Arid, Qoum-Kahak
  • Azin Nasrian, Morteza Akbari *, Alireza Faridhosseini, Ehsan Neamatollahi Pages 75-90
    Introduction
    A lot of part of Iran is covered by dry and semi-arid climate. In these regions, due to the lack of rainfall, agriculture is heavily dependent on groundwater resources. The continuing drought in recent decades and the excessive withdrawal of groundwater aquifers for agricultural development, has led to more land degradation and desertification. Understanding the quality and quantity of groundwater as one of the most important and most vulnerable sources of water supply in recent decades which is so necessary. For optimal groundwater management, it is necessary to collect sufficient information from a set of quantitative and qualitative characteristics of aquifers in different regions and to be evaluated in appropriate ways. Therefore, due to the importance of this issue (non-systematic use of water resources for agricultural activities), the present study aims to assess the process of ground water changes due to the agricultural activities in Dargaz county of Khorasan Razavi province along with the presentation and proposal of management plans for risk reduction Desertification was carried out. Demir et al. (2009) investigated the spatial variation of depth and salinity of groundwater in agricultural areas in northern Turkey using the statistical method of the earthquake. The results of their research showed that the eastern part of agricultural lands in the middle parts of the Black Sea, which has poor drainage, has the highest salinity risk. Akbari et al. (2009), using the Geographic Information System, studied the groundwater level in Mashhad Plain during the twenty years and estimated the average annual loss of 60 centimeters. Their results indicated that the increase in the number of wells in the area and drought, were the main causes of groundwater subsidence decline.
    Methodology
    The study area is located in northeastern part of Iran and in the north of Khorasan Razavi province. Dargaz County has an area of about 376459 ha. Dargaz Plain is considered as one of the agricultural poles in Khorasan Razavi province. In order to study the process of water change, two sub-criteria of groundwater quantity such as the groundwater table index, and quality indices were used such as water conductivity, sodium adsorption ratio, and chlorine index. For evaluation and zonation of quantitative indices of groundwater level, 124 wells and 111 aqueducts were used and the analyzed using geo-statistical interpolation such as Kriging method in GIS software environment. In addition, groundwater quality criteria has evaluated during the 20 years period of 1996-2016 and in the 5 years’ time period.

    Validation and verification of the model
     The non-parametric Mann-Whitney Test (Mann and Whitney, 1947) in the Minitab environment was employed to test the model validity. The non-parametric Mann-Whitney test is used to compare two independent categorical groups. The Mann-Whitney test relies on these null and alternative hypotheses: H0: There is no difference between the two groups, H1: There is a difference between the two groups. In the Mann-Whitney test, N is the number of samples randomly selected from the map and sampled in the field. The Mann-Whitney value is compared with the value identified by consulting the significance table
    Results
    The results showed that the highest rate of groundwater was in the northwestern part of this region. The research area was not badly affected by changes in chlorine concentration and sodium absorption ratio in groundwater, and classified into very low and low. Finally, two quantitative and qualitative indicators of groundwater in the severity of the risk of desertification, the region is located in three low, moderate and severe risk classes, respectively.
    Discussion and Conclusions
    At present, uncontrolled management of underground water utilization, the development of agricultural land in the traditional way, and the release of lands, have made these areas one of the centers of the erosion crisis. The amounts of changes in the electrical conductivity index in the eastern parts of this region fluctuated from extreme to very intense. It has risen from 14 percent in 1996 to 32 percent in 2011 and finally reaches 23 percent at the end of the year (2016). This condition indicates an early warning stage for the salinity of irrigation water in this area. The results indicate that the rate of groundwater loss in the western and northwest parts of the study region is the highest, mostly, due to the deep and unannounced drilling of wells and the excessive removal of groundwater. Given the current situation and recent droughts, Dargaz Plain Underground Water Management should be considered as a priority for crisis management by officials and experts in executive agencies.
    Keywords: Irrigation, Desertification, Interpolation, Salinity, Water Resources Management
  • Sanaz Pourfallah, Mohammad Reza Ekhtesasi *, Mohsen Sadeghi Pages 91-105
    Introduction
    One of the most important evidence of karst development is the existence of Devlin or sinkholes. Devlin is a natural depression in the karstic areas with internal or subcutaneous drainage. In recent years several genetic classifications have been published for sinkholes sink holes in these categories into two main groups sinkholes of "liquidation" and "depression" are segregated. The sinkholes are closed pits that form holes in the surface of calcareous and other soluble or alluvial soils, and generally runoff from the hole in the floor to groundwater Joins.
    materials and methods
    The study area with an area of 3714.43 km2 is part of the Abarkuh-Sirjan desert catchment area. Karsts of the region play a major role in the hydrology of the region, but because of the karst cavities in the area adjacent to alluvium, and with the maturation of the karsts, as well as the decrease of the surface area of the area, the internal pressure of the cavities was reduced and the gradual subsidence Alluvial layers are provided. Several cases of sinkholes and longitudinal gaps have also been observed in this area. The areas of occurrence of these hazards can be summarized as follows.
    30 sinkholes in the study area. Abarkuh sinkholes on the plains can be divided into sinkholes and sinkhole mountainous desert divided. These halls are different in terms of shape, dimensions, structure, geomorphology
    Result
    AHP model proposed measures are incompatible with a rate of 09/0 for the presence of soluble layers deep with standard weight of 30%, sediment texture (the sinkhole plain) and limestone formations (sinkholes mountain in ) with a weight of 4.20 percent, down from 4.17 percent weight aquifers, irrigation system with a weight of 12.6% and standard user type, distance from the well of operation, distance from the old stream and fault by weight, respectively, 1/7, 8/5, 6/3, 1/3 were prioritized. Abarkuh plain is based on hydrograph of the underground water unit during the long period of 35 years, during the years 1360 to 1395, equal to 19.64 m (0.56 m per year), Investigation of the drilling log of some piezometers around plain sinkholes showed that the major part of the thickness of the saturated layers of these piezometers was micro-clay and silty granular materials, which in different horizons and limited thicknesses, granular materials Along with sand and The sand is also of different proportions and the stone floor is from calcareous marl .The amounts of chlorine, calcium and magnesium, carbonate and bicarbonate, lime, EC, TDS, PH, volumetric elastic modulus were measured in both fossils. The reason for these experiments is to determine the degree of solubility of the soil and sediments within the hollows. High amounts of lime percent, TDS and carbonates in the soil indicate relatively high solubility in the soils of the study area.
    Discussion and Conclusion
    The texture is very fine-grained sediments sinkhole plain and with a high percentage of clay content, lime and minerals to pump water from depths to agricultural use leads to dissolution and the resulting sinkhole plain holes as well as the location of sinkholes Abarkuh upstream mountain aquifer, which in recent decades has faced with a sharp drop in the aquifer, the crisis of falling into sinkholes and limestone formations mountainous phenomenon has created.
    Keywords: Calcareous Formations, Analytical Hierarchy Model, Groundwater, AHP