فهرست مطالب

  • پیاپی 23 (تابستان 1398)
  • تاریخ انتشار: 1398/04/22
  • تعداد عناوین: 7
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  • محمد حسین جهانگیر*، مهناز ابوالقاسمی صفحات 1-16

    طی دهه های اخیر در میان بلایای طبیعی که جوامع انسانی را تحت تاثیر قرار داده، تعداد و فراوانی خشکسالی بیشتر از سایر حوادث طبیعی بوده است. خشکسالی از جمله بلایای طبیعی است که در مقایسه با مخاطرات طبیعی نظیر بارش های سنگین و سیلاب ها، به طور خزنده شکل می گیرد و گسترش می یابد. برای بیان کمی خشکسالی، شاخص های متعدد و متفاوتی وجود دارد. شاخص تبخیر و تعرق استانداردشده SPEI از برازش توزیع لوگ- لوجیستیک بر دما، بارش و تبخیر و تعرق پتانسیل در هر بازه زمانی دلخواه به دست می آید. هدف از این تحقیق، بررسی وضعیت خشکسالی استان تهران و همچنین مطالعه تطبیقی شاخص خشکسالی SPI و SPEI در این استان است. با برازش توزیع های احتمالاتی مختلف بر مقادیر داده ها، مناسب ترین تابع توزیع سازگار با سری  Diبا استفاده از آزمون کولموگروف اسمیرنوف انتخاب شد و نتایج نشان داد توزیع کوماراسویمی برای دو ایستگاه مهرآباد و تهران و توزیع ویبول برای ایستگاه های شمیران و آبعلی، مناسب ترین توزیع برای تعیین مقدار شاخص  SPEIدر این منطقه است. سایر نتایج نشان داد که از آنجا که در شاخص SPEI در مقایسه با شاخص SPI پارامترهای اقلیمی بیشتر لحاظ می شود، می توان گفت نتایج شاخص SPEI در بازه زمانی کوتاه ماهانه، واقعی تر و منطقی تر است؛ به طوری که این شاخص، شرایط خشکسالی شدیدتری را نشان می دهد. همچنین با تغییر ماه های سال به علت تغییر در شرایط دمایی و بارش مناسب ترین تابع توزیع برای هر ماه تغییر می کند.

    کلیدواژگان: شاخص SPI و SPEI، تابع توزیع مناسب، استان تهران، تبخیر و تعرق
  • سید جواد ساداتی نژاد*، آرش ملکیان، هادی زارع پور، عاطفه محمدی صفحات 17-32
    برای بررسی خشکسالی ها چندین شاخص خشکسالی اقلیمی وجود دارد. در تحقیق حاضر، شش شاخص خشکسالی هواشناسی شامل شاخص دهک ها، شاخص درصد نرمال بارندگی، شاخص بارش استانداردشده، شاخص معیار استاندارد (ZSI)، شاخص Z چینی و شاخص Z چینی اصلاح شده مورد ارزیابی قرار گرفته است. این شاخص ها طی یک دوره آماری 27 ساله (19902017) بر روی 10 ایستگاه همدیدی استان اصفهان در مقیاس های زمانی 1، 3، 6، 12، 24 و 48 ماهه انجام شد. سپس شاخص ها از مقیاس ماهانه به واحد مشترک سالانه تبدیل شدند و به منظور انتخاب مناسب ترین شاخص از کمینه بارندگی در طول دوره آماری بارندگی سالانه استفاده شد. نتایج حاصل از آزمون فرضیه ها نشان داد شاخص دهک ها، شاخص بارش استاندارد شده و شاخص چینی مقارن با سال وقوع کمینه بارندگی، رخداد خشکسالی شدید و بسیار شدید را به ترتیب در تمام ایستگاه های و در چهار ایستگاه تحت مطالعه نشان دادند. این سه شاخص انحراف معیار کمتر و کارایی بیشتری به لحاظ نمایش خشکسالی بسیار شدید نسبت به سایر شاخص ها دارند. بر این اساس، مناسب ترین شاخص برای تحلیل و پهنه بندی وضعیت خشکسالی، شاخص های دهک ها و بارش استانداردشده در جایگاه نخست و شاخص Z چینی در جایگاه دوم است. از این سه شاخص به منظور پهنه بندی گستره های تحت تاثیر خشکسالی، با استفاده از روش میان یابی معکوس استفاده و انجام شد. نتایج حاصل از ارزیابی، نشان دهنده تاثیر حساسیت خشکسالی های اقلیمی بر عرصه مورد مطالعه است.
    کلیدواژگان: شاخص درصد نرمال، شاخص دهک، پهنه بندی خشکسالی، میانیابی معکوس، نمایه خشکسالی اقلیمی
  • محمد ساغری*، مسلم رستم پور، گلناز محمودی مقدم، بهاره چکشی صفحات 33-44
    ترکیب گونه ای و تنوع زیستی از سریع ترین و مهم ترین شاخص های تعیین وضعیت اکوسیستم های مرتعی است. این تحقیق به بررسی اثر احداث هلالی های آبگیر بر ترکیب پوشش گیاهی و تنوع زیستی در اکوسیستم های مناطق خشک و بیابانی استان خراسان جنوبی می پردازد. بدین منظور، نمونه برداری از پوشش گیاهی در بهار سال 1393، در مراتع منطقه مورد نظر در مرحله گلدهی گیاهان غالب به روش سیستماتیک - تصادفی و به صورت پلات گذاری انجام شد. سپس خصوصیات پوشش گیاهی از قبیل تراکم، ترکیب، درصد پوشش و شاخص های غنای گونه ای (مارگالف، منهینیک)، تنوع گونه ای (سیمپسون، شانون- وینر و آلفای فیشر) و یکنواختی گونه ای (پیلو) در دو منطقه اجرای طرح و منطقه شاهد بررسی گردید. نتایج آزمون تی تست مستقل نشان داد که اثر احداث سامانه هلالی آبگیر بر درصد پوشش گیاهی کل و تراکم گیاهان مرتعی معنی دار (01/0>p) است. بررسی ترکیب گونه ای نشان داد که منطقه اجرای طرح شامل 30 گونه گیاهی از 17 خانواده و منطقه شاهد شامل 9 گونه گیاهی از 8 خانواده بوده و شاخص های غنای گونه ای مارگالف، تنوع گونه ای سیمپسون و شانون وینر در منطقه اجرای طرح بیشتر از منطقه شاهد است. در نهایت می توان گفت که اثر هلالی های آبگیر بر خصوصیات اکولوژیکی پوشش گیاهی در مراتع تحت اجرای این طرح، مثبت بوده و لذا می توان از آن به عنوان یکی از روش های قوی و موثر احیای مراتع تخریب شده نام برد.
    کلیدواژگان: تراکم، درصد پوشش گیاهی، تنوع گونه ای، غنای گونه ای، هلالی آبگیر
  • اکبر شائمی برزکی*، نسرین نیک اندیش، ابوالقاسم مظفری صفحات 45-58
    الگوهای مکانی و زمانی شرایط آسایش اقلیمی متاثر از یکسری ویژگی های جغرافیایی است که آشکارسازی آن با استفاده از شاخص های بیوکلیماتیک میسر است. از سوی دیگر، خروجی های حاصل از به کارگیری شاخص های بیوکلیماتیک با ساختار های متفاوت و با پارامترهای خاص دارای نتایج مختلف بوده و بر یکدیگر منطبق نیستند. سنجش کارایی هریک از این شاخص ها و مقایسه نتایج حاصل از آن ها ما را در جهت استفاده بهینه از پتانسیل های محیطی، به ویژه در مقاصد گردشگری کاراتر می کند. در این پژوهش، برای ارزیابی و پهنه بندی شرایط اقلیم آسایش جنوب ایران و مقایسه عملکرد شاخص های مختلف مدل بیوکلیما همچون UTCI, HIS, PST, STI, SST, PhS از داده های اقلیمی میانگین دما، رطوبت نسبی، سرعت باد، فشار بخار آب و میزان ابرناکی 39 ایستگاه سینوپتیک جنوب ایران شامل استان های خوزستان، بوشهر، کهکیلویه و بویراحمد، هرمزگان، فارس، کرمان و سیستان و بلوچستان به تفکیک هر ایستگاه از سال 1988 تا سال 2017 استفاده شده است. نتیجه این بررسی نشان داده است که شاخص های PhS و STI در انعکاس احساس حرارتی از کارایی بیشتری برخوردار بوده و در اغلب روش ها ماه های بهمن و اسفند بهترین مقاطع زمانی سال از لحاظ شرایط آسایش اقلیمی هستند. همچنین خروجی حاصل از اجرای مدل بیوکلیما نشان می دهد که در ماه های فروردین، اردیبهشت، آذر و دی نیز به طور نسبی این شرایط برقرار است.
    کلیدواژگان: اقلیم آسایش، پهنه بندی، شاخص های بیوکلیما، ایران
  • محمود بهروزی، سعید بازگیر*، حمید نوری، محمدعلی نجاتیان، داود اخضری صفحات 59-72
    به منظور شناسایی کانون گردوغبار بیابانی و اثرات آن روی ویژگی های انگور در دشت ملایر، پدیده گردوغبار به صورت ماهانه و سالانه بررسی و الگوهای همدید مولد آن در تراز 500 هکتوپاسکال و سطح دریا با روش کاهش متغیرها استخراج شد. سپس سرچشمه گردوغبار با مدل HYSPLIT ردیابی و گل غبار آن نیز ترسیم شد. برای بررسی اثرات گردوغبار بر انگور رقم بی دانه سفید، مطالعات آزمایشی در تاکستان ایستگاه تحقیقات انگور شهرستان ملایر طی سال های 1394 تا 1396 با تیمارهای شست وشو و عدم شست وشو پس از رخداد طوفان گردوغبار انجام شد. نتایج این پژوهش نشان داد بیشینه طوفان های گردوغباری در ماه خرداد و فصل بهار بوده که با روند صعودی از سمت غرب و جنوب به دلیل استقرار سامانه کم فشار در عربستان به همراه ناوه کم ارتفاع تراز میانی جو از رسوبات آبرفتی دجله و فرات در عراق، حورالعظیم در استان خوزستان و ربع الخالی در عربستان وارد دشت ملایر می شود. همچنین نتایج آزمون تی- استیودنت بیانگر اثر معنی دار گردوغبار بر کلروفیل a و b، تشکیل میوه، تعداد حبه، وزن خوشه و عملکرد انگور بود. رشد رویشی بوته همچون طول شاخه، وزن و سطح برگ تحت تاثیر گردوغبار تغییری نکرد، اما تشکیل میوه حدود 12 درصد نسبت به تیمار شست وشو کاهش یافت که با کاهش تعداد حبه در خوشه، عملکرد بوته های گردوغبار را نسبت به شست وشو 13 درصد کاهش داد.
    کلیدواژگان: تجزیه به مولفه های اصلی، تشکیل میوه، رنگیزه های فتوسنتزی، گل غبار، مدل HYSPLIT
  • سعید نجفی* صفحات 73-84
    تنش آبی یکی از مهم ترین عوامل تنشی است که رشد گیاهی و تولیدات حاصل از آن را در سراسر جهان تحت تاثیر قرار می دهد. بر همین اساس در این مقاله، اثر سامانه های سطوح آبگیر باران تحت پنج تیمار شاهد و بدون تغییر در سامانه (A)، حذف پوشش گیاهی و سنگریزه همراه با فیلتر سنگریزه ای (B)، حذف پوشش گیاهی و سنگریزه بدون فیلتر سنگریزه ای (C)، عایق کردن بخشی از سامانه همراه با فیلتر سنگریزه ای (D) و عایق کردن بخشی از سامانه بدون فیلتر سنگریزه ای (E) بر عوامل فتوسنتزی نهال بادام مورد بررسی قرار گرفت. پژوهش در قالب طرح بلوک کامل تصادفی در 3 تکرار و در ابعاد 8، 5 و 5/0 متر به ترتیب برای طول، عرض و عمق در هر سامانه در ایستگاه پژوهشی قره چریان واقع در شهرستان زنجان طراحی شد. در سال 1390، پس از یک بارندگی 22 میلی متری با فاصله زمانی 10 و 22 روز از بارندگی، چهار عامل فتوسنتزی شامل میزان فتوسنتز در واحد سطح برگ، هدایت روزنه ای آب، میزان تعرق و جذب  CO2زیر روزنه ای اندازه گیری شد. نتایج نشان داد که درباره دو عامل فتوسنتز و تعرق اثر سامانه های مذکور معنی دار بوده است. هرچند نتایج نشان داد که اثر سامانه های سطوح مدیریت شده به ویژه تیمارهای عایق کردن بخشی از سامانه بدون فیلتر سنگریزه ای (E)، حذف پوشش گیاهی و سنگریزه همراه با فیلتر سنگریزه ای (B) و حذف پوشش گیاهی و سنگریزه بدون فیلتر سنگریزه ای (C) بیشترین و تیمار شاهد (A) کمترین عملکرد را داشته اند، به طور کلی برای دستیابی به جزئیات بیشتر و پاسخ به مواردی چون ارجحیت تیمارها، اثر فیلتر سنگریزه ای به کاررفته در سامانه ها، تاثیر بلندمدت سامانه ها بر رشد نهال های مثمر با گونه های مختلف، تاثیر سامانه ها در استقرار، تثبیت و تولید محصول، طراحی سامانه ها مبتنی بر فواصل بارندگی و حجم آب مورد نیاز برای جمع آوری در هر سامانه جهت عدم ایجاد تنش خشکی برای نهال ها نیاز به مطالعاتی جامع و حداقل با دوره زمانی 10 ساله است تا بتوان طبق آن برنامه ها و توصیه های مدیریتی لازم و ممکن برای غلبه بر مشکلات کم آبی و پاسخ به نیازهای جمعیت در حال رشد به محصولات کشاورزی را ارائه کرد.
    کلیدواژگان: ایستگاه پژوهشی قره چریان، تنش خشکی، حفاظت آب، درختان مثمر، شهرستان زنجان
  • عاطفه جبالی، محمد زارع*، محمدرضا اختصاصی، رضا جعفری صفحات 85-105
    فراوانی و شدت طوفان های گردوغبار تحت تاثیر فعالیت های مخرب انسانی در سال های اخیر روندی افزایشی به خود گرفته و موجب خسارت های فراوانی شده است. هدف از پژوهش حاضر، مقایسه عملکرد الگوریتم های آشکارکننده گردوغبار در محدوده استان یزد است. به این منظور، شش الگوریتم معرفی شده شامل الگوریتم های آکرمن، میلر، روسکونسکی و لیو، TDI، TIIDI و NDDI بر روی تصاویر سنجنده مودیس بررسی شد. بر اساس نتایج، در رخداد 04/11/1389، الگوریتم های TDI و TIIDI، به ترتیب با همبستگی 65/0 و 49/0 نسبت به عمق اپتیکی ذرات غبار و معنی داری در سطح 99% عملکرد بهتری را در آشکارسازی گردوغبار داشت. درحالی که رخداد 21/11/1393، الگوریتم روسکونسکی و لیو را با همبستگی 68/0 و 76/0 به ترتیب نسبت به عمق اپتیکی ذرات غبار و قدرت دید افق در سطح معنی دار 99% و 95% به عنوان الگوریتمی مناسب در آشکارسازی گردوغبار معرفی کرد. در رخدادهای 24/01/1394 و 29/04/1394 به ترتیب TIIDI و TDI با همبستگی های 81/0 و 71/0 نسبت به نقشه های عمق اپتیکی ذرات غبار و قدرت دید افق در سطح 95% و 99% معنی دار بود. بر اساس نتایج، هیچ یک از الگوریتم های مورد استفاده قادر به آشکارسازی تمامی رخدادهای گردوغبار نخواهد بود.  با وجود این، به کارگیری باندهای حرارتی و یا تلفیقی از باندهای حرارتی و انعکاسی در الگوریتم ها، کارایی بیشتری را در آشکارسازی گردوغبار نشان می دهد. به منظور آشکارسازی بهتر گردوغبار هر منطقه، استفاده از حدود آستانه ای متناسب با ویژگی های طیفی آن منطقه و حتی هر رخداد، در زمان به کارگیری الگوریتم های آشکارساز مورد نیاز است.
    کلیدواژگان: باند انعکاسی، باند حرارتی، سنجش از دور، عمق اپتیکی ذرات غبار، قدرت دید افق، یزد
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  • Mohammad Hossein Jahangir*, Mahnaz Abolghasemi Pages 1-16
    Introduction

    The study of drought as a natural phenomenon that affects the lives of most people is very important. According to researchers in the field of drought, rainfall, temperature, evaporation, wind and relative humidity have been shown to play an important role in drought. The low variety of data required and the simplicity of calculating the SPI index led to its widespread use. The effect of increasing temperature in drought intensification is far more than the decrease in rainfall, which can confirm the effective role of temperature in strengthening or weakening of drought. Based on this, the SPEI index can be used as the appropriate index for determining the drought. In our hydrological studies, we try to fit the empirically measured data into a proper fitting function. And the best function that matches the data is chosen as the probability distribution function to derive the value of the variable for each probability. This research seeks to find the best distribution function for the SPEI index at the stations studied in Tehran province and also compares the SPI and SPEI indices at different time intervals.

    Materials and methods

    In this research, monthly precipitation and temperature data were used for Shemiran, Abali, Mehrabad and Tehran stations in Tehran province in 2017-1987. After qualitative control and correction and completion of statistics, statistical analysis of precipitation, based on the standardized precipitation index (SPI) and statistical analysis and dispersion analysis, are based on the standardized precipitation evapotranspiration index (SPEI). The values of the SPEI index are calculated using four Fatigue life, Weibull (three parameters), Loglogestic and kumaraswamy functions. Relationships (1) and (2) and (3) and (4) are used to calculate various cumulative distribution functions in the SPEI of the index. Fatigue life Weibull Log logistic kumaraswamy In order to investigate the most suitable distribution function compatible with Di, P-value comparison was performed based on Kolmogorov –Smirnov test ،Also to check the compatibility of the two indexes, graphs were plotted 24,12,6,3,1 and 48 months. To find out the degree of compatibility, we used the absolute value graphs of Difference of Two Indices.

    Results

    The results of computing and comparing the SPI and SPEI index indicate that in general, all stations in a drought condition are largely consistent and only in short periods of this adaptation are confused. Also, in comparison to the severity of drought between the two indices, the SPI index shows a lower intensity of drought and it can generally be concluded that the SPEI index shows the dry weather in terms of severity. Also, this index shows the beginning of drought in shorter time intervals, which can be attributed to the sensitivity of the SPEI index to rainfall variations and to include the temperature parameter in this index. In the short intervals, two indicators have a better match, and in the long term (24-48 months), the two indicators do not fit well. Abali station displays the best fit with the least error in all time intervals. The reason for the suitability of the Abali standardized evapotranspiration index station to show the overlap between the two SPI and SPEI indicators is the maximum rainfall and the minimum temperature and minimum evapotranspiration between stations however, it can be concluded that the drought index is well-matched in wet weather conditions with low temperatures. The difference between the two indicators in the hardest case in 1997 was 0.63, which means that each year, when the standardized rainfall index is reduced, the Standardized Precipitation Evapotranspiration Index is also declining. It can be concluded that these two indicators are in good agreement at this time interval and one can estimate one with a mean error of ± 0.209on the other consequently, reducing or increasing rainfall can directly affect the reduction and increase of evapotranspiration and temperature.

    Discussion and Conclusion

    In this research, it is assumed that, in addition to the spatial variation that causes changes in the statistical distribution, the annual variations of Di also confirm this hypothesis So, in calculating droughts or other climate studies, this should be considered, since rainfall, evapotranspiration, and temperature vary in different seasons, and therefore, in terms of statistical distribution, they act differently, for example The stations under study in Tehran province in the middle of June till the end of summer are followed by logistical distribution and in the middle of the warm year to late spring, more diverse statistical distributions are followed. The results showed that the behavior of both SPI and SPEI indicators in the monthly time intervals, especially in wet areas (Abali station), and in the 12-month period are very similar. It was also found that the two indicators did not match the annual time interval and that the same behavior of the two indicators could not be expected in the study of drought with annual data. The severity of all drought events, especially the most severe droughts, has been higher by the SPEI index for all periods of time. This is due to the sensitivity of this index to precipitation variations. Although rain has a special role in the diversity of drought time, the effect of temperature is significant and increases the phenomenon of drought. Based on the results, standardized evapotranspiration index has high accuracy in addition to having the main advantages of the SIP index, such as multi-variability and the use of minimum parameters of meteorology.

    Keywords: SPI index, SPEI index, Probability distribution function, Tehran province, Evapotranspiration
  • Sayed Javad Sadatinejad*, Arash Malekian, Hadi Zarepour, Attefeh Mohamadi Pages 17-32
    Introduction
       Drought, as a natural disaster, has a major impact on agriculture and ecosystem of the affected region. Droughts occur mainly in areas like Iran being located in the world dry belt, with below normal levels of rainfall.  There is a need to study and predict the drought situation because, according to statistics, Iran is among the most water-stressed countries, with serious problems in occurring floods, supplying drinking water and generation of electricity, so assessing the drought situation in order to reduce damage, comprehensive drought plans are essential for the country and the studied province.In this study drought situation in Isfahan province, has been evaluated using a relatively long (> 27 years) monthly precipitation data, with simultaneous considering of six drought indies including MCZI, CZI, ZIS, SPI, DI and PNPI. 
    Materials and methods
    Study area and data:   Isfahan province has geographical coordinates of 30 degrees 43 minutes to 34 degrees and 27 minutes north latitude and 49 degrees and 38 minutes to 55 degrees 32 minutes east length and area of ​​107145 square kilometers (equivalent to 3.6 percent of the total area of ​​Iran). The annual rainfall in the study area is 130 mm which is less than half the country's average rainfall and one sixth of the global average.   In this study, in order to study the drought indices of Isfahan province, 27 year precipitation data of 12 stations in the province and neighboring areas were used with appropriate statistical quality. Case Study Indicators: In this study, six drought indexes based on rainfall were selected to evaluate drought indices of Isfahan province. The basis of drought indicators is often based on the estimation of precipitation deviation from the long-term average over a given period. General features and formulas used to calculate each of the drought indicators are: , , , , and each of the indicators has different classes of drought. Evaluating the Efficiency of Drought Indicators:  The meteorological drought is based on the assumption that the minimum rainfall during the long term of the weather represents a very severe or severe meteorological drought that occurred in the studied area. In order to investigate this hypothesis, rainfall at each station was determined using drought indices and the indicators that were most consistent with the climate conditions were identified.Finally, using inverse distance method in ArcGIS tools, the most accurate index maps were developed.Findings and
    Results
    In the first stage of this research, in order to better evaluate the spatial variations of rainfall in the selected stations, in addition to the quantity and quality of data, latitude and longitude, and altitude from the sea level, the 27-year time base (from 1990-2017) as the common statistical basis for the study of time variation Precipitation was taken into consideration. Then, the accuracy and homogeneity of the data and the incomplete statistics of precipitation of the stations were reconstructed using correlation method and normal ratio method.In the second stage, using the moving average method, dry and wet periods were measured by long-term rainfall data with continuity periods and drought severity using different drought indices. Then, to determine the hypothesis, the minimum rainfall was determined at each station and then evaluated using drought indices. Using inverse interpolation method and using the GIS and based on available spatial distribution data, an interpolation map was prepared and using the superior climatic index (CZI, DI, SPI and PNPI) during the 27 year statistical period (1990- 2017), drought zoning maps were prepared monthly, quarterly, and five-monthly and annual.Discussion and
    Conclusion
    The results showed that the ability of the SPI, DI, PNPI, ZSI, CZI and MCZI indices is based on the relationships defined in the climatic drought conditions. Drought indicators at different stations have different results that can be seen even at nearby stations. The reason for this is the high rainfall variation in the study area.Among the indices, the DI ranked first, the second highest SPI, the third highest CZI, and the PNPI index, the ZSI index, and the MCZI index in the next ranking. Therefore, in order to zoning the drought, the first three indicators are used.Although the results of the hypothesis test showed that the SPI index and Decile precipitation (DI) index were consistent with the minimum rainfall year, but showed a severe and severe drought occurrence in all stations, and, in terms of other indicators, had more performance. Display Severe drought, but the range of monthly and annual Deciles of Index (DI) is slightly higher than other indicators in the charts. Especially in the graphs shown by the decimal index (DI), it seems a small increase in the rate of drought and tropical manifestations. It can be said that according to this study, precipitation index fluctuations (DI), although according to other indicators, are more marked in monthly and annual rainfall graphs.Based on the calculations, six climatic indicators at annual time scale showed that SPI, ZSI and CZI indices are consistent with drought persistence and drought severity. The results of selected criteria show that in the years 1994 to 1995, 2001 to 2005 and 2008 severe drought occurred in most parts of the province.From the station's point of view, the highest drought frequency in the studied area for DI, SPI, ZSI and CZI indicators from Natanz and Kebootar Abad stations and the longest drought resistance in different time scales in the study area; DI: Kabottarabad station from 2007 to 2009 and Naine station from 1993 to 1995 on a seasonal scale is the longest drought. According to the SPI index, the Neen station spent the longest drought from late 1999 to the beginning of 2007 on a 24-month scale from 2001 to early 2007 at Reza Station.In the preparation of annual drought maps using the indicators, it was found that annual time indices cannot accurately represent drought zoning and estimate the severity of drought at the lower end. So, for these indicators, drought plans should be prepared monthly to month. This result shows that droughts are heavily dependent on the time of occurrence and vary locally and locally according to short-term time. Therefore, providing annual drought map using monthly indicators cannot provide a realistic picture of spatial development and drought severity.In the droughts map, the most severe droughts during the studied period show severe droughts in the center and south-east of the area around the stations of Naein, Kabootar Abad, KhoroBiabanak, Ardestan and Shah Reza compared to other areas of the area. From the point of view of the longest continuity in the region, the central and south-east and north parts of the area are more susceptible to potential, and the western and southwest sections are less susceptible. This feature is especially important in the southeast and the center of the area surrounding the Naein, Kabootar Abad, Shah Reza and Ardestan stations
    Keywords: Arc GIS, Drought zoning, IDW, Isfahan, Meteorological Index
  • Mohammad Saghari*, Moslem Rostampour, Golnaz Mahmoudi Moghaddam, Bahareh Chakoshi Pages 33-44
    Introduction
    One of the ways of restoration and reclamation of damaged rangeland is to use different methods of rain harvesting such as pitting, counter furrowing, flood spreading, small arc basins system and etc., along with the reduction of runoff, it increases the soil moisture content and thus increases vegetation cover. Biodiversity is most commonly used to describe the number of species. It is studied in 3 levels, including genes, species, and ecosystems. However, species diversity is a major issue of biodiversity on a local and regional scale. Species composition and biodiversity are among the fastest and most important indicators for determining rangeland ecosystems condition. Due to the new construction of this structure in the rangelands of Iran, so far, little research has been done on the effect of small arc basins system on vegetation and forage production. Particularly, there is limited research on the variation of richness and species diversity by Construction of this structure. Abdollahi et al. (2016) investigated the effects of crescent pond structure on vegetation and soil parameters in Saravan rangelands of Sistan and Baluchestan province. The results of their research showed that, significant differences were found for all vegetation parameters between the crescent structure and control treatment, indicating the positive effect of crescent structure on vegetation parameters. The purpose of this study was to investigate the effect of constructing small arc basins system has been investigated on the composition of vegetation and biodiversity in the rangelands of South Khorasan province.
    Materials and methods
    Sampling in the rangelands of Sarbisheh, South Khorasan Province, was carried out in small arc basins area. Vegetation sampling was carried out in the rangelands by systematic-random method at the flowering stage of the dominant plant species in the spring of 2014.vegetation characteristics such as density, composition, cover percentage, and species richness indices (Margalef and Menhinick), species diversity indices (Simpson, Shannon - Wiener and Fisher's alpha) and species evenness (Pielou) were investigated in two areas (small arc basins area and the control area).The all biodiversity indices were calculated using PAST software. To compare the vegetation characteristics including density, composition, vegetation percentage, species richness, diversity and evenness, independent samples t-test were used.
    Results
    In general, 30 plant species were identified in two areas (small arc basins area and the control area), which belong to 17 families and 27 genera. The results showed that the number of plant species in the control area is 9 and in the small arc basins area is 30 species. The results of comparing the total vegetation cover percentage in both areas showed that the percentage of total coverage is very significant (p <0.01). The effect of construction of the small arc basins area system on the density of rangeland plants was very significant (p <0.01) and this system has significantly increased the density of rangeland plants., there is a significant difference in species diversity between the two regions in terms of Simpson diversity index and Shannon-Wiener's diversity index, but this difference is not significant in the alpha-Fisher's index. The results of the data on the study of richness indices also show that the Margalaf's richness index shows a very significant difference in the comparison of species richness in the two study areas, but this difference was not significant in terms of the Menhinick's index. Discussion and
    Conclusion
    The results showed that the construction of small arc basins in the study area increased the number of plant species, species density and vegetation percentage compared to the control area, which indicates the positive effect of this structure on improving the ecosystem conditions. Research in this area also confirms this result. The results of this study indicate that the number of annual and perennial species in the control area (totally nine species) from 4 and 5 species in the control area has increased to 15 species for both species (a total of 30 species) in the small arc basins area. As well as, the results indicate that the vegetation cover percentage and frequency of perennial species is more than annual species. Several studies have indicated that species diversity has a significant relationship with soil texture and soil moisture. Since the construction of small arc basins leads to changes in soil moisture content and soil texture. Therefore, it has a significant effect on species diversity. Finally, according to the results of this research as well as previous researches, we can say that the effect of small arc basins system was positive on the ecological characteristics of vegetation in the study small arc basins treatment. Therefore, it can be considered as one of the most effective methods for the restoration of degraded rangelands.
    Keywords: Density, Vegetation Cover, Species Diversity, Species Richness, Small Arc Basin
  • Akbar Shaemi Barzoki*, Nasrin Nikandish, Abolghasem Mozaffari Pages 45-58
    Introduction
    Climate conditions are the most important factors affecting human activity on short- and long-term scales. The study of the effect of climate conditions on human life and behavior investigate in the branches of science called human bioclima. The condition of comfort is a set of conditions that, in terms of heat and humidity, at least 80% of the individuals randomly selected and placed in those conditions have mental judgment of comfort. Climate comfort models are considered as useful tools for illustrating the interactions of environmental stressors and human responses that are expressed in terms of empirical classification. In the present study, we try to determine the spatial and temporal patterns of climatic comfort in southern Iran and the ability of bioklima model indices to detect it. 
    Materials and Method
    In this research, the methods of analysis of bioclimatical indices have been used. Initially, monthly average temperature, relative humidity, wind speed, water vapor pressure and cloud cover data of 39 synoptic meteorological stations in southern Iran were collected from the Meteorological Organization during the period 1988 to 2017. In the next step, the above datas was arranged by using Excel software. Then with using of biklima software comfort indices (UTCI, PHS, SST PST, STI, and HIS indices) calculated and graphs are plotted by using Excel software. In order to zoning the studied area, we using the correlation between bioclimatic indices and height in ArcGIS software and in the Geostatical Analysis.The bioclima model was developed by Professor Christoph Blansky in 2003 that includes various indicators of human bioclimate. By using this model, we can calculate 60 variables related to biomclimate and thermal physiology. Its input data includes two groups of meteorological data and data related to human physiology conditions. 
    Results
    Analysis of the outputs from the implementation of the bioklima model shows how the heat sensation in different months at each station is based on the six indices of the bioklima model separately. Qualitative evaluation of the results of the bioclima indices in the South & southwest in spring shows that the output of the SST and PST indices are more consistent and the STI and HSI index have the least consistency with other indices and because their output reflects geographical realities, especially topographic diversity. On the contrary, PhS, SST and PST indices reflect the better picture of climatic comfort at this season. A qualitative assessment of the results of the benchmark indices in the study area in the fall season shows that the SST indices reflects a better picture of climate comfort. On the contrary, HIS, STI and PhS indices are not fully effective in reflecting climate realities. The results of this study indicate that HSI and STI indices are not suitable for reflection of climatic comfort conditions in winter. Conversely, the pattern of zoning from the SST index shows that this index is more effective in reflecting the regional climatic realities. Discussion and
    Conclusion
    In this study, by using the six bioclimatic indices of the bioklima model, the bioclimate condition of south & southwest of Iran was analyzed at monthly and seasonal in 7 southern provinces of Iran. The results of this study show that spatial and temporal patterns of thermal comfort do not correspond to each other. Increasing the time of climate unhealthy conditions in the warm season of the year and Low altitude areas & lower latitudes reveals the combined effect of these factors in creating the above conditions. Maximum annual thermal comfort conditions in southern Iran is during the cold period of the year. Also, seasonal patterns indicate that there is maximum comfort in the high areas and Zagros region at period of warm. This condition confirmed in southern coasts and the Khuzestan plain in cold period of the year. Seasonal evaluations of the thermal comfort by apply of six indices of the bioklima model are not match with together, therefore application of these indicators are requires localization and calibration.
    Keywords: Comfort climate, zoning, bioclimate indices, Iran
  • Mahmoud Behrouzi, Saeed Bazgeer*, Hamid Nouri, Mohammad Ali Nejatian, Davod Akhzari Pages 59-72
    Introduction
    Dust storm is one of the air pollutants in desert areas that have damaging effects on environmental ecosystems. This phenomenon usually happens when severe winds occur in arid areas which are accompanied by the ascent of dust particles to the upper layers of the atmosphere. HYSPLIT model can assist in detecting the path of dust entering the stations. In addition, synoptic patterns play an important role in the occurrence of dust storms; as the atmospheric low-pressure system with a pressure gradient causes dust storms in desert areas. Dust can cause physiological and morphological effects on the plant. The deposition of particles on the leaf surface reduces light and shades on the leaf, which reduces photosynthesis and chlorophyll and stomata conduction in the leaf which has a negative effect on plant growth. The purpose of this study was detection the origin of dust storms at Malayer Plain with the tracing and extraction of generation of synoptic patterns and its effects on vegetative and reproductive traits of grape varieties of white seedless variety. 
    Materials and Methods
    At first, the dust codes were extracted in a 24-year period (1992 to 2015) and were monthly and annually analyzed. Then the sand rose was plotted by wind rose plot software. In order to identify the synoptic patterns of dust storms in Malayer plain the PCA (Principal Component Analysis) method was used. The HYSPLIT model was used to detect atmospheric dust. In the second part of this study, the effects of dust storms on Malayer plain vineyards were studied during 2015 and 2016 years. The treatments were 1) washing and 2) non-washing grapevine after event of dust storm. Then, chlorophylls a and b, relative water content, leaf fresh and dry weights, length of shoot and internode were measured. Moreover, reproductive traits such as fruit set, number of berry per cluster, weight of cluster, sugar berry and yield were measured. 
    Result
    A total of 459 dusty days were observed during the study period with an annual mean of 19. The statistical analysis indicated a considerable increase in dust storm frequencies in the study area. The total number of dusty days in June accounts for 18.4% of each year, followed by April (15.8%), and May (12.4%). According to sand rose study of Malayer plain, prevailing dust storm blew from West (16% all dust storm) and South (15%) during the year. In the dominant patterns over 500 hPa and sea level pressure, the NCEP/NCAR reanalysis data show that an upper trough over the eastern Mediterranean is reflected in lower surface and accompany with a low-pressure center over Saudi Arabia which associated with the high pressure in Siberia and extending towards the south-east during warm times. This condition led to occurrence of dust storm in Malyer plain. There are two main paths to transfer the dust to the study area: (a) NW-SE which dust particles are transported from the northwestern region of Iraq and eastern Syria (60%) and (b) S-N where the dust particles are transported from central regions of Iraq and an internal source in southwestern of Iran, Khuzestan province (30%) to the Malayer station. Dust particles by deposition on the leaf of the grapevine reduced the chlorophyll a and b, fruit set, cluster weight and grape yield compared to plants washed with water; but dust particles did not impact on length of shoot, relative water content, leaf fresh and dry weight of grapevine. Discussion and
    conclusion
    The increasing trend of temperature and drought led to disruption of soil and vegetation cover. Additionally, desertification and drought resulted from mistreatment of water resources and climate change contributes to increasing of dust storm sources in the Iraq and West of Iran. The main cause of dust storm events in the spring is the formation of a low-pressure system in the lower atmosphere of the west of Iran with a divergence in upper level of atmosphere (500 hPa) over the deserts of Syria, Iraq and western Iran. Al-Hawizeh/Al-Azim marshes are covered by fine sand which is regarded as the extension of the dust storm source areas in Iraq border. In West Asia, most of dust storm events can be classified into Summer Shomal and Frontal dust storms. Shomal dust storm occurs across Iraq, Kuwait, western part of Khuzestan plain and some parts of Arabian Peninsula. Results of present study showed that main dust storm sources of western parts of Iran are central to northern parts of Iraq, and Eastern and central parts of Iraq and Syria, western parts of Baghdad and dry Al-Howizeh/ Al-Azim marshes. The results revealed that Chlorophylls measures are an important tool to evaluate the effect of air pollutants on plants. Chlorophyll plays an important role in plant metabolism and the reductions in chlorophyll concentration correspond directly to the reduction in plant growth. This study showed that the reduction of grape yield was 13 percent in dusty treatment as compared to control one. It can be concluded that increase of dust load resulted in lower stigma pollen loads. Moreover, dust can form a blockage layer on the stigma which could prevent the germination of pollen grains on the stigma and consequently reduction of fruit set.
    Keywords: PCA, Fruit set, Photosynthetic Pigments, Sand Rose, HYSPLIT Model
  • Saeed Najafi* Pages 73-84
    Introduction
    Water deficit is one of the most important stress factors affecting plant growth and production in the worldwide, as due to series drought stress photosynthetic activities are negatively affected. Subsequently, a reduction will happen in the growth of leaves and plants, stomatal conductance and agricultural products. Accordingly, major concern exists in countries like Iran where water scarcity and poor water management in combination with increased population and water consumption endanger food security. Therefore, exploring ways to increase agricultural and horticultural products along with optimizing the use of water is essential. The aim of this paper is a) to examine the effects of Rain Water Harvesting (RWH) systems on photosynthetic activities of Almond seedlings and b) determination of the most effective treatment of the RWHs which has the most positive effect on photosynthetic parameters. 
    Material and Methods
    The current research was conducted in a randomized complete block design with three replications to assess the impact of RWH systems under five treatments viz. control (A), eliminated of vegetation and pebble with a gravel filter (B), eliminated of vegetation and pebble without any gravel filter (C), insulated some portion by plastic with a gravel filter (D) and insulated some portion by plastic without any gravel filter (E) on activity of photosynthetic parameters in Almond seeding. RWH systems were designed in 8, 5, and 0.5 meters for the length, width, and depth respectively. The gravel filter with 10 and 30 cm in diameter and depth was devised to facilitate runoff infiltration in the root region. Four photosynthetic factors viz. Photosynthetic rate per unit leaf area, stomatal conductance, transpiration rate, and substomatal CO2 adsorption were measured after 9 and 22 days after a rainfall event in 2011. 
    Results
    The obtained results showed that the RWH systems had a positive effect on two photosynthetic parameters included photosynthesis and transpiration. In General, in addition of the positive effect of the RWH systems, the E, B and C treatments could increase the activity of photosynthetic parameters versus the A treatment which exhibited the least activity of the parameters in Almond seedlings. Discussion and
    Conclusion
    Nevertheless, for more details and answers to issues such as selecting the treatment with best efficiency, the effect of the gravel filter in RWH systems efficiency, the long-term effects of the RWH systems on the growing of fruit seedlings and their establishment, designing the RWH systems based on the rainfall intervals and the water use of the seedlings to collect enough water in each system to avoid drought stress for seedlings require comprehensive studies at least in a period of 10 years. Ultimately, the results of aforesaid comprehensive studies lead managerial and necessary plans to overcome the problems of water deficit and responding to the rapid growth of world population and consequently their agriculture production needs.
    Keywords: Drought Stress, Gharecharian Research Station, Productive Trees, Water Conservation, Zanjan City
  • Atefeh Jebali, Mohammad Zare*, Mohammad Reza Ekhtesasi, Reza Jafari Pages 85-105
    Introduction
    In recent years, frequency and intensity of dust storms have been increased because of human destructive activities and caused significant loss in different aspects of hygienic and health, environmental and socio-economic sections. Therefore, detection and trace of dust storms in shortest time is the first effective step in preparation and implementation of strategic and operational plans in regions where are affected by dust storms. Using of remote sensing techniques in running of detector algorithms of dust storm plumes via satellite images are efficient methods to detect dust storm events, especially in large areas presented by researchers who study in this field. In this research has been tried to compare the most important algorithms to detect dust plumes and introduce the most suitable algorithm for the Yazd province suffered dust storm events and their loss. 
    Materials and methods
    To detect dust storms, the events with wind speed of more than 10 m/s and horizontal visibility of less than 1000 m were identified using meteorological synoptic stations data in the study area during 2010-2015. In the following, six common algorithms for detection of dust plume including Ackerman, Miller, Roskovensky and Liou, Thermal Infrared dust index (TDI), Thermal Infrared Integrated Dust Index (TIIDI) and Normalized Difference Dust Index (NDDI) were examined via satellite data of MODIS sensor in four dust storm events. In order to evaluate the accuracy assessment of dust maps, relation between the produced maps and horizontal visibility records of the meteorological stations located in the study area, as well as, Aerosol Optical Depth (AOD) of dust based on deep blue algorithms were analyzed.  
    Results
    Results showed that Roskovensky and Liou, Thermal Infrared dust index (TDI) and Thermal Infrared Integrated Dust Index (TIIDI) had better accuracy and precision to detect dust storm events based on aerosol optical depth (AOD) maps and horizontal visibility records of the study area. According to the results, TDI and TIIDI algorithms had better performance to detect dust plume in 03/02/2011 event. Correlation of TDI and TIIDI maps with AOD were 0.65 and 0.49, respectively, which were significant at 1% level, while, Roskovenskey and Liou algorithm presented more suitable result to detect dust storm in 10/02/2015 event. Correlation of Roskovensky and Liou map with AOD and horizontal visibility records were 0.68 and 0.76, respectively, which were significantly at 1% and 5% levels, respectively. In 13/04/205 and 20/07/2015 events, TIIDI and TDI algorithms showed better performance to detect dust plumes. Correlation of TIIDI with AOD was 0.81 which was significant at 5% level. Also, the correlation between TDI and horizontal visibility records was 0.71 which was significant at 1% level.Discussion and
    Conclusion
    Some dust storm events are analyzed by remote sensing techniques via methods such as indices and algorithms related to dust detection, interpretation of false color composite and brightness temperature difference of features and phenomena in satellite images. These methods are very efficient to detect dust especially, the dust plumes which their visual detection are difficult because of low density. However, the results of indices of dust detection are different, because of various chemical composite of dust particles and resulted in different spectral and thermal properties in different regions. According to the results, none of the algorithms could detect dust plumes in all events. They were just able to detect dust plumes in one or two events. However, the algorithms that used thermal bands or combination of thermal and reflective bands in their equations had been more effective to detect dust storm. To have better dust storm detection, using threshold ranges according spectral and thermal properties are required in each region and even in each event. Using quantities data of aerosol optical depth of dust as well as horizontal visibility records of meteorological stations are suitable tools to adjust to the real situation and analyze accuracy assessment of dust maps made by different algorithms.
    Keywords: Reflective, Thermal, Remote sensing, Aerosol Optical Depth, Horizontal visibility, Yazd