فهرست مطالب

نشریه مهندسی اکوسیستم بیابان
پیاپی 28 (پاییز 1399)

  • تاریخ انتشار: 1399/12/10
  • تعداد عناوین: 8
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  • زهرا جعفری*، سید حمید متین خواه صفحات 1-12

    در تحقیق حاضر، توانایی مخازن سفالی در روش آبیاری زیرسطحی به منظور استفاده از آب های نامتعارف مورد بررسی قرار گرفت. بدین منظور، مخازن سفالی به ابعاد 7/4 لیتر ساخته و محلول هایی با غلظت های مختلف شوری، 4، 8 و 32 دسی زیمنس/متر و غلظت های مختلف نیترات و فسفات، به ترتیب 5، 50 و 100 و 5، 30 و 60 میلی گرم/لیتر تهیه شدند. سیستم آزمایشی به صورت کاملا تصادفی با سه تکرار اجرا شد. مقدار نیترات و فسفات خروجی به روش اسپکتروفتومتری جذب فرابنفش و هدایت الکتریکی خروجی با استفاده از هدایت الکتریکی سنج اندازه گیری شد. درصد تخلیه آب متعارف، آب با غلظت های مختلف سدیم کلرید، نیترات و فسفات در طول زمان اندازه گیری شد. نتایج نشان داد که اختلاف غلظت نیترات و فسفات آب خروجی قبل و بعد از آبیاری معادل 1/1، 8/0 و 2 میلی گرم/ لیتر و 1، 8/0 و 1/1 میلی گرم/ لیتر به ترتیب در غلظت های 5، 10 و 50 میلی گرم/ لیتر بود. همچنین، اختلاف غلظت سدیم کلرید آب خروجی قبل و بعد از آبیاری در غلظت های 4، 8 و 32 دسی زیمنس/متر به ترتیب برابر 7/0، 7/0 و 4/1 دسی زیمنس/متر بود که از نظر آماری این اختلاف معنی دار نبود (P>0.05). درصد تخلیه مخزن شاهد نسبت به مخازن دارای آب شور و نیترات و فسفات بیشتر بود.

    کلیدواژگان: آبدهی، آب های نامتعارف، فسفات و نیترات، آلودگی آب، مخازن سفالی، مناطق خشک
  • حامد اسکندری دامنه، غلامرضا زهتابیان، حسن خسروی*، حسین آذرنیوند، علی اکبر براتی صفحات 13-28

    در این پژوهش به ارزیابی روند خشکسالی هواشناسی، تبخیر و تعرق پتانسیل استانداردشده، شاخص پوشش گیاهی (NDVI) و بررسی رابطه آن ها با یکدیگر با استفاده از ضریب همبستگی پیرسون در استان هرمزگان پرداخته شده است. بر اساس شاخص های خشکسالی SPI و SPEI بیشترین مقادیر شاخص های خشکسالی به ترتیب مربوط به سال های 1388، 1393، 1391 و 1390 می باشد. بررسی روند تغییرات شاخص NDVI و بارندگی سالیانه نشان داد که روند این شاخص ها در طول بازه زمانی (1395-1379) در سطح اطمینان 95% معنی دار بوده و افزایشی می باشد. روند تغییرات پارامتر دما و شاخص های خشکسالی SPEI و SPI طی این بازه زمانی کاهشی است. همچنین پیک شاخص پوشش گیاهی مطابق با بیشترین بارندگی رخ داده در این بازه زمانی در سال 1384 بوده است که بیانگر متاثر بودن پوشش گیاهی از نوسانات بارندگی می باشد. نتایج حاصل از ضریب همبستگی پیرسون در مقیاس زمانی 12 ماهه بین شاخص های خشکسالی هواشناسی، تبخیر و تعرق پتانسیل شده، شاخص پوشش گیاهی NDVI، پارامتر بارش و دما نشان داد که بیشترین میزان همبستگی بین شاخص SPI و بارش (99/0) و کمترین میزان همبستگی بین دو شاخص دما و خشکسالی تبخیر و تعرق پتانسیل (48/0-) وجود دارد.

    کلیدواژگان: استان هرمزگان، NDVI، SPI، SPEI، ضریب همبستگی پیرسون، مناطق خشک و نیمه خشک
  • امیرحسین حلبیان*، مهران شبانکاری، مریم امینی صفحات 29-46

    هدف این پژوهش کشف رابطه میان الگوهای گردشی پدیدآورنده گرد و غبارهای شدید اهواز با رویکرد محیطی به گردشی است. بدین منظور، داده های شبکه ای روزانه ارتفاع ژیوپتانسیل تراز 500 هکتوپاسکال، فشار تراز دریا و مولفه های باد مداری و نصف النهاری به صورت متناظر با 229 روز گرد و غباری شدید دوره گرم از پایگاه داده (NCEP/NCAR) دریافت شد. با انجام تحلیل خوشه ای پایگانی انباشتی بر روی نقشه های ارتفاع ژیوپتانسیل و فشار تراز دریا با آرایه ای به ابعاد 1617×229 و ادغام روزها به روش وارد 3 الگوی گردشی برای تراز 500 هکتوپاسکال و 3 الگوی گردشی برای فشار تراز دریا شناسایی و برای هر الگو، یک روز به عنوان نماینده بر اساس ضریب همبستگی با آستانه 95% تعیین و نقشه های ترکیبی فشار تراز دریا و الگوهای ارتفاع ژیوپتانسیل تراز 500 هکتوپاسکال، بردارهای سرعت و جریان های هوا در این روزها ترسیم و تحلیل شد. نتایج این پژوهش نشان می دهد که بر اساس الگوهای 1 و 2 در ترازهای 500 هکتوپاسکال و فشار تراز دریا رخداد گرد و غبارهای شدید اهواز متاثر از استقرار فرودی در شرق مدیترانه و کم فشارهای حرارتی سطح زمین به ویژه کم فشار خلیج فارس است. در الگوی 3 دو تراز مزبور نیز همگرایی مداری سامانه چرخندی خلیج فارس و پرفشار آزور و در نتیجه افزایش شیو فشار روی منطقه موجب انتشار و انتقال پدیده گرد و غبار در خوزستان و شهر اهواز می شود. بر اساس این پژوهش، مهم ترین منابع گسترش گرد و غبار به قلمرو مطالعاتی بیابان های عراق، عربستان و سوریه است.

    کلیدواژگان: تحلیل همدید، گرد و غبار، دوره گرم، تحلیل خوشه ای، سامانه های فشار، اهواز
  • وحید سرافرازی، لیلا کاشی زنوزی، محمد خسروشاهی* صفحات 47-60

    پدیده فرسایش بادی و حرکت ماسه های روان از چالش های جدی سرزمین های خشک محسوب می شود. در پژوهش حاضر برای کنترل طوفان های ماسه و تثبیت گرد و غبار، پوشش سنگ ریزه پیشنهاد شده است. برای این کار با انتقال ماسه از منطقه بیابانی بلاک ریلی منتظر قایم- تل حمید تاثیر پوشش سنگ ریزه با تراکم 30، 50 و 75% در میزان باد بردگی ذرات شن و ماسه به کمک تست تجربی تونل باد و در سرعت های متفاوت مورد بررسی قرار گرفت. نتایج نشان داد که برای سرعت های باد تا 10 متر بر ثانیه نیازی به پوشش دهی سنگ ریزه نیست ولی در سرعت های بیشتر از 20 متر بر ثانیه با افزایش درصد پوشش سنگ ریزه میزان فرسایش بادی به صورت توانی کاهش می یابد در سرعت های باد حدود 16 متر بر ثانیه کارایی پوشش 50 و 75% به هم نزدیک بوده و تقریبا نتیجه یکسانی در بر داشت. ازاین رو در این گونه مناطق پوشش بیشتر از 50%، فقط هزینه کار را بیشتر کرده ولی در نتیجه کار تاثیر قابل توجهی نخواهد داشت؛ بنابراین در مناطقی که امکان استفاده از سایر روش ها به دلایل مختلف ادافیکی یا اقلیمی وجود نداشته باشد می توان از پوشش دهی مواد غیر فرساینده مانند ریگ یا پوشش های سنگ ریزه ای به عنوان یک راهکار عملی برای جلوگیری از فرسایش بادی و گرد و غبار استفاده کرد.

    کلیدواژگان: سنگ ریزه، تثبیت، گرد و غبار، تونل باد
  • آزاده سلطانی، حمیدرضا عسگری*، حسین یوسفی صفحات 61-72

    شوری خاک یکی از مهم ترین عوامل تخریب اراضی در مناطق بیابانی است. امروزه روش های مختلفی به منظور اصلاح خاک های شور مورد استفاده قرار می گیرند. در این پژوهش سعی شده است علاوه بر مواد شیمیایی و بیولوژیکی در اصلاح خاک های شور، تاثیر نانو کود دامی بر اصلاح خاک های شور نیز مورد بررسی و مقایسه قرارگیرد. این تحقیق در قالب طرح فاکتوریل کاملا تصادفی و با به کارگیری 8 تیمار شامل تیمار شاهد، گچ، گچ و کود دامی، کود دامی، نانوکود 03/0 درصد از 250 گرم خاک سطحی هر گلدان، نانوکود 06/0 درصد، نانوکود 06/0 درصد و گچ، و نانوکود 03/0 درصد و گچ هرکدام با سه تکرار انجام شد. تجزیه و تحلیل آماری داده ها توسط آنالیز واریانس یک طرفه و آزمون چنددامنه دانکن توسط نرم افزار SPSS انجام گردید. نتایج نشان داد که تیمارهای نانوکود 06/0 درصد+گچ و نانوکود 03/0 درصد گچ در سطح 1 درصد بیشترین تاثیر را در کاهش سدیم قابل تبادل و تیمارهای کود دامی و نانوکود 03/0 درصد بیشترین تاثیر را در کاهش هدایت الکتریکی عصاره اشباع خاک داشتند. اسیدیته خاک نیز تحت تاثیر تیمارهای گچ و کود دامی+گچ بیشترین کاهش را داشته است. درمجموع، یافته های این تحقیق اهمیت نانومواد در بهبود عملیات اصلاح خاک های شور-سدیمی را نشان می دهد.

    کلیدواژگان: خاک های شور، نانو کود، مواد اصلاح کننده شیمیایی و بیولوژیکی، استان گلستان، دشت صوفیکم
  • افشین یوسف گمرکچی*، علیرضا حسن اقلی، مهدی اکبری، مهرزاد مستشاری محصص، دانیال امینی صفحات 73-88

    وسعت بالای بیابان های ایران و شرایط نامناسب اقلیمی حاکم بر آن ها، اندازه گیری میدانی شوری خاک را در برخی موارد غیرعملی کرده است. در تحقیق حاضر از قابلیت های شبکه عصبی و مدل های رگرسیونی برای تهیه نقشه شوری خاک در محدوده زهکش حایل شوره زار دشت قزوین استفاده شده است. به منظور تحلیل شوری خاک، شاخص شوری خاک و پوشش گیاهی با استفاده از قابلیت تصاویر ماهواره ای استخراج شد. نتایج تحلیل همبستگی میانگین داده های زمانی نشان داد شاخص GVI دارای همبستگی منفی بالایی با همه شاخص های شوری داشته و بر اساس یک رابطه رگرسیون مرتبه 3 و با ضریب تبیین 79/0 با شاخص شوری خاک (SI) همبستگی داشته و بر اساس نتایج آزمون من-کندال، تغییرات سری زمانی دو شاخص، در بازه زمانی 15 ساله معنی دار بوده است. به منظور پیش بینی شوری خاک دو مدل شبکه عصبی و رگرسیون با متغیرهای کمکی شامل شاخص های شوری خاک و پوشش گیاهی (مستخرج از تصاویر ماهواره ای)، داده های میدانی اندازه گیری شده شوری خاک و تراز آب زیرزمینی به کار گرفته شد. نتایج تحقیق نشان داد مدل شبکه عصبی مصنوعی با ضریب تبیین 69/0، دارای دقت بیشتری نسبت به مدل رگرسیون برای پیش بینی شوری خاک بوده همچنین در فرایند مدل سازی، دقت پیش بینی هدایت الکتریکی خاک (EC) بیشتر از شاخص SAR خاک بوده است.

    کلیدواژگان: سطح ایستابی، شبکه عصبی، شوری خاک، قزوین، زهکش حائل، مدل سازی
  • محمدامین اسدی*، فاطمه جم نژاد، محمدرضا اختصاصی، سید زین العابدین حسینی صفحات 89-102

    برداشت بخش قابل توجهی از آب شرب و کشاورزی از منابع آب زیرزمینی، باعث کاهش شدید ذخایر آب زیرزمینی در کشور شده است. با توجه به وقوع خشکسالی در مناطق مختلف کشور، پیش بینی می شود که این پدیده روی تغذیه آب های زیرزمینی تاثیر چشمگیری داشته باشد. از طرف دیگر، تغییرات کاربری اراضی و توسعه شهری و کشاورزی نیز به شدت منابع آب زیرزمینی را تهدید می کند. هدف از این تحقیق، بررسی تاثیر خشکسالی هواشناسی و تغییرات کاربری اراضی بر کمیت و کیفیت آب های زیرزمینی دشت داراب در دوره آماری 13721396 است. در این تحقیق با استفاده از داده های بارش، سطح ایستابی و شوری آب های زیرزمینی، شاخص های SECI،  GRIو  SPIمحاسبه شد. نقشه کاربری اراضی حوزه برای سال های 1380، 1388 و 1396 با استفاده از تصاویر ماهواره ای تهیه شد. طبقه بندی کاربری اراضی به صورت نظارت شده (Supervised Classification) و با روش حداکثر احتمال (Maximum likelihood) انجام شد. هرکدام از تصاویر به 5 نوع کاربری شامل مناطق مسکونی، اراضی زراعی، باغات، مرتع و اراضی بایر طبقه بندی شد. مقایسه کاربری اراضی در طی سه سال مذکور نشان داد که تغییرات کاربری زراعی و باغی در سال 1388 نسبت به 1380 حدود 53/0% افزایش داشته، ولی در سال 1396 نسبت به سال 1388، 82/1% کاهش یافته است. در مرحله بعد، رابطه بین شاخص SPI و تغییرات کاربری اراضی با شاخص های GRI و SECI بررسی شد. نتایج نشان داد که خشکسالی های اقلیمی و تغییرات کاربری اراضی اخیر بر روی کمیت و کیفیت آب زیرزمینی دشت داراب اثر مستقیم داشته است؛ به طوری که در طی دوره آماری مذکور به طور متوسط حدود 36 متر افت سطح آب در کل دشت اتفاق افتاده است. همچنین شوری آب زیرزمینی در حدود 293 میکروموس بر سانتی متر افزایش یافته است. برای مقایسه بهتر نتایج، داده های آماری به سه دوره هشت ساله (13721380، 13811388، 13891396) تقسیم شد و میانگین شاخص های SPI، GRI، SECI و کاربری اراضی برای هر سه دوره به دست آمد. نتایج نشان داد افزایش شدت خشکسالی و افزایش کاربری اراضی زراعی و باغی در دوره دوم نسبت به اول باعث افت کمی و کیفی آب در این دوره نسبت به دوره قبل شده است (میانگین شاخص GRI از 03/1 در دوره اول به 08/0- در دوره دوم رسیده است که بیانگر کاهشی برابر 11/1- می باشد)، اما کاهش شدت خشکسالی و کاهش کاربری زراعی و باغی در دوره سوم نسبت به دوم باعث کاهش شدت افت آب زیرزمینی در این دوره نسبت به دوره قبل شده است (میانگین شاخص GRI در دوره سوم به 93/0- رسیده است که نسبت به دوره دوم، کاهشی برابر 85/0- را نشان می دهد).

    کلیدواژگان: خشکسالی، دشت داراب، کاربری اراضی، کمیت و کیفیت، منابع آب زیرزمینی
  • حامد خیراندیش، احمد صادقی پور*، حنانه محمدی کنگرانی صفحات 103-117

    توسعه پایدار در صورتی تحقق می یابد که همپوشانی بین لایه های اکولوژیکی، اقتصادی و اجتماعی ایجاد گردد. هدف از این پژوهش، مقایسه دو روش HLEP و سازمان جنگل ها، مراتع و آبخیزداری در ارزیابی پایداری حوزه آبخیز بختگان است. روش اول، حوزه آبخیز به 5 بوم سازگان تقسیم شد و برای هر بوم سازگان معیارها و شاخص های مختلفی، تعریف و تعیین و اندازه گیری شد که امتیاز نهایی برای بوم سازگان مرتع و بیابان 45 شد که آن را در طبقه متوسط قرار می دهد و امتیاز نهایی برای بخش مسایل اقتصادی و اجتماعی 32 شد که آن را در طبقه متوسط قرار می دهد و با استفاده از ماتریس برآورد امتیازات و جدول ارزشیابی حوزه آبخیز، وضعیت پایداری مشخص شد. با توجه به جمع کل امتیازات، حوزه آبخیز بختگان به لحاظ پایداری وضعیت ضعیفی دارد. روش دوم مدل HELP بود که بر اساس چهار مقوله هیدرولوژی، محیط زیست، حیات آبخیزنشینان، سیاست گذاری و سه پارامتر فشار، وضعیت و واکنش و تحت عنوان شاخص پایداری حوزه (WSI) به بررسی پایداری حوضه در سه سطح پایین، متوسط و بالا می پردازد. نتایج نهایی نشان داد سطح پایداری حوضه با امتیاز 61/0 متوسط رو به پایین در دوره مورد مطالعه ارزیابی شد که توجه بیشتری را برای ارتقای سطح پایداری منطقه طلب می کند.

    کلیدواژگان: بوم سازگان، توسعه پایدار، سطح پایداری، برنامه ریزی سرزمین، سرانه آب
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  • Zahra Jafari*, Sayed Hamid Matinkhah Pages 1-12
    Introduction

    As Iran faces limited water resources, it should take the use of unconventional waters into account in its drought management. In many countries, including Iran, conventional water is relatively scarce. However, should water, soil, and plants be appropriately managed, there would be significant saline water sources for irrigation purposes. Together with reducing salinity and refining polluted waters, subsurface irrigation is now considered as an increasingly important tool in improving the quality of unconventional waters. In this system, besides the application of subsurface irrigation, water is used at lower volumes and pressures, and soil and plant contamination are minimized, and thus, concerns regarding the use of wastewater in specific plant irrigation are reduced to some extent. This study, therefore, sought to investigate the efficiency of clay reservoirs in subsurface irrigation as a way to manage unconventional waters properly. It should be noted that such reservoirs are formed when saline and polluted waters with different concentrations are used

    Material and Method

    having been conducted at the lands of Isfahan University of Technology, Iran, this study investigated the possibility of making use of unconventional waters for subsurface irrigation through clay reservoirs. To this end, an experiment was performed with three replications, using random sampling. Some 50 cm×50 cm (width and depth) planting pits were drilled with a 2 m distance from each other. The clay reservoirs were made in 4.7-liter size, and solutions were prepared with their salinity concentrations being 4, 8, and 32 ds/m, and nitrate and phosphate concentrations being 5, 50, and 100 mg/L and 5, 30, 60 mg/L, respectively. The output of nitrate and phosphate was measured by UV spectrophotometry, and the electrical conductivity output was measured by an electrical conductivity meter. The depletion percentage of conventional water, saline water with different concentrations, and water with varying nitrate and phosphate concentrations were also measured over time. Moreover, the data analysis was performed in SPSS 22.0 Software.

    Result

    The results of the study showed that the difference between nitrate and phosphate concentration of clay reservoirs before and after the irrigation was 1.1, 0.8, and 2 mg/l and 1, 0.8, and 1.1 mg/l at concentrations of 5, 10, and 50 mg/l, respectively. The difference in sodium chloride concentration before and after the irrigation was 0.7, 0.7, and 1.4 ds/m at concentrations of 4, 8, and 32 dS/m, respectively, so the difference was not significant statistically (P>0.05). The depletion percentage in the control reservoir was higher than water polluted with nitrate and phosphate and the reservoirs filled with saline water.

    Discussion and conclusion

    The advancement of the wetting front increased with decreasing salinity levels of the pitcherschr('39') water. Salt concentration in the soil with pitcher irrigated by saline water was found to be minimum near the pitcher and maximum at the periphery of the wetted zone around the pitcher. One reason for a decrease in the flow rate with an increase in salt concentration could be the increase in the aqueous viscosity with concentration. It could, thus, be concluded that the rate of depletion partly decreases with increasing salinity and the amount of nitrate and phosphate in irrigation water over time, which was not noticeable and was attributed to the higher viscosity of saline water and the water contaminated with nitrate and phosphate. Should those responsible for developing water resources in Iran do not seek logical solutions for using other water resources, such as using low-quality water, the country would face serious problems. As water resources are limited, using unconventional waters would be very useful in drought management. Therefore, it seems that changing the policies regarding water management and arranging for the application of this irrigation method could help relevant Iranian officials manage the countrychr('39')s water crisis efficiently. In the last two decades, subsurface clay irrigation has been implemented in parts of the country. The use of saltwater and wastewater in this method would open new windows for the use of unconventional waters. As a result, pottery depletion is a suitable way to meet the plantschr('39') water needs, provided that proper filtration and acceptable irrigation water quality are used

    Keywords: Depletion percentage, Unconventional waters, Nitrate, Phosphate, Water pollution, Clay reservoirs, Arid areas
  • Hamed Eskandari Damaneh, Gholamreza Zehtabian, Hassan Khosravi*, Hossein Azarnivan, Aliakbar Barati Pages 13-28
    Introduction

    As a hazardous complex climate condition, drought has affected many parts of the world, and in times when its duration is prolonged, its damage would be tremendous, affecting various sectors such as agriculture, environment, economic, social, etc. Due to the wide range of this phenomenonchr('39')s effects on all ecosystems, especially in arid and semiarid regions, continuous monitoring of drought is particularly important. Vegetation and its products are among the most significant parameters affected by this destructive phenomenon. Observation of such harmful effects can be done using remote sensing science. In recent years, this science has played a significant role in managing and monitoring drought, vegetation, and their interactions by increasing sampling points, widening the coverage area, improving temporal resolution, lowering costs, and applying regular and higher spatial resolution. Considering the importance and necessity of this issue, this study set out to investigate and monitor drought indices (SPEI, SPI), vegetation index (NDVI), and these indiceschr('39') interactions from 2000 to 2016 in Hormozgan province, Iran.

    Materials and Methods

    To study meteorological drought and potential evapotranspiration, the required data concerning the monthly rainfall and temperature of 164 rain-gauge stations in the region were collected. Then, the homogeneity test was applied to all stations. Statistical deficiencies were reconstructed for the data, and finally, the annual SPI values were calculated using MATLAB software. Kriging geostatistics was used to map the SPI drought. Due to the availability of satellite images for 2000-2016, a drought map was prepared for this period. The NDVI index obtained from the Modis satellite images (MOD13A2) was also used to study the vegetation. Finally, to investigate the effects of meteorological drought and potential evapotranspiration on vegetation, the average NDVI and drought index was calculated for each year, and the severe effects of drought on vegetation were examined. Moreover, the correlation between vegetation and drought was studied through the Pearson correlation coefficient.

    Results

    According to the results of the study, the highest values of SPI and SPEI were found in the years 2009, 2014, 2012, and 2011, respectively. NDVI and annual rainfallchr('39')s changing trend indicated that these indiceschr('39') mean values were significant at 95 levels over the 17 years, showing an increasing trend. The trend of temperature, SPEI, and SPI changes was decreasing during this time interval. Also, the vegetation index peak was in accordance with the highest rainfall value in this time period. In other words, the highest rainfall occurred in 2005 in this region. The vegetation index showed the highest increase this year, suggesting that vegetation was affected by rainfall fluctuations in the region. Based on the results of the Pearson correlation coefficient between meteorological drought, evapotranspiration potential, NDVI vegetation index, precipitation parameter, and temperature at a 12-month time-scale, the highest correlation was reported between SPI index and precipitation, which was equal to 0.99, and the lowest correlation was found between temperature and SPEI, being 0.48. Moreover, this correlation coefficient analysis showed a high correlation between the meteorological drought index and NDVI vegetation index at 95% level in the study area. This correlation was reported as 0.792. The correlation between SPEI and NDVI was also reported as 0.797, indicating that with an increase in precipitation rate, the NDVI increased.

    Discussion and Conclusion

    It could be concluded that, depending on the prevailing conditions of the area, the extent, time, and type of rainfall affect the amount of vegetation. Therefore, studying and identifying vegetation in each area could lead to the discovery of each regionchr('39')s conditions and the vulnerability status of the area. Any reduction in the effects of drought on these fragile and sensitive ecosystems requires careful planning according to each regionchr('39')s conditions. Planners and relevant authorities should take appropriate measures to improve the irrigation system, reduce evaporation, enhance the crop system, mitigate the damages caused by drought, and get the ecosystem adapted to climate conditions. Moreover, this study used Modis images with a kilometerchr('39')s pixel size. For a closer look at the vegetation index, satellite images with smaller pixel sizes, such as Landsat ones, could also be used to increase spatial accuracy. Finally, a more detailed study is recommended to investigate the effects of drought on vegetation in different land-uses.

    Keywords: Hormozgan Province, NDVI, SPI, SPEI, Pearson Correlation Coefficient, Arid, Semi-Arid Lands
  • Amirhossein Halabian*, Mehran Shabankari, Maryam Amini Pages 29-46
    Introduction

    increasing dusty storms has been one of the most important consequences of climate change in recent years that directly or indirectly affected human society. Countries located in the arid and semiarid regions of the world, including Iran, have been affected more than other parts of the globe by this natural disaster and its harmful consequences, especially the atmospheric dust, which could bring about a wide variety of detrimental effects such as the reduction in growth and yield of crops, the occurrence of plant plagues and diseases, an increase in road accidents due to the decrease in the vision field, cancellation of flights, and rising health costs. These facts, along with repeated droughts in recent years and the potential consequences of climate change as a result of desertification, have brought the issue of dust storms and their relevant side effects, including increasing respiratory and pulmonary diseases, a disorder in the ground and air transportation, environmental destruction, and pollution of agricultural products to the attention of many researchers. Therefore, numerous researches have been carried out on the increase of global and regional dust and the identification and analysis of dust-generating regionschr('39') circulation patterns. These include Romanof (1951), Goudie and Midelton (2001), Kutiel (2003), Barkan et al. (2005), Dayan et al. (2008), Barkan (2008), Calastrini et al. (2012), Awad and Mashat (2014), Kang et al. (2016), Beegum et al. (2018), Hemmati( 1995), Dehghanpour (2005), Zoualfaghari and Abedzadeh (2006), Heidari (2007), Raeispour (2008), Karami (2009), Tavousi et al. (2011), Movahedi et al. (2012) Tavousi and Zahraei (2013), Zangeneh (2014), Khorshiddoust, et al. (2014), Omidvar and Sepandar (2018) to mention a few.

    Materials and methods

    as located near deserts, Ahwaz city is directly exposed to dusty storms. This study, therefore, set out to investigate the relationship between circulation patterns that cause severe specks of dust in Ahwaz and the environment-circulation approach. To this end, the required data were collected from the environmental database of 390 sever dusty days of the region during 14 years (2001-2014), and the severity of dusty days was determined according to the allowance limit index AQI (150 μg/m3) for two cold (161 days) and hot (229 days) periods. The data were then evaluated based on the frequency of severe dusty days throughout the hot period. For this reason, daily network data regarding the geopotential height in 500 hPa, sea level pressure, and the zonal and meridional wind were obtained from the database (NCEP/NCAR). Conducting an accumulation hierarchical cluster analysis for sea level pressure and geopotential height map with matrix in 229×1617 dimension and linkage days using Ward method, three circulation patterns were identified for level 500 hPa, and three circulation patterns were found for sea level pressure. Moreover, for every pattern, one day has been determined as an indicator based on the correlation coefficient of 95% threshold, and the composite maps of sea level pressure and height patterns of geopotential in level 500 hPa, the speed vectors, and streamlines in these days have been drawn and analyzed.

    Results & Discussion

    The results of the study indicated that according to patterns 1 and 2 in level 500 hPa and at sea level pressure, severe dusty storms in Ahwaz were influenced by the eastern Mediterranean currents and low thermal pressures of the earth surface, especially the Persian Gulf low pressure. In pattern 3, the two levels mentioned above, cyclonic system zonal convergence of the Persian Gulf, Azores high pressure, and enhancement of gradient pressure on the region, resulted in the distribution and transfer of the dust phenomenon in Khuzestan province and Ahwaz city.

    Conclusion

    According to the findings of this study, the most important sources of dust distribution in the study area are the deserts of Iraq, Saudi Arabia, and Syria. This studychr('39')s results could be useful for preventing and controlling dust storms via the identification of dust-generating regions. To reduce the damages caused by the study regionchr('39')s dust phenomenon, an international agreement with the adjacent countries needs to be made. Moreover, the issue requires inter-organizational cooperation of relevant entities at the domestic scale.

    Keywords: Synoptic analysis, Dust, Warm period, Cluster analysis, Pressure systems, Ahwaz
  • Vahid Sarafrazi, Leyla Kashi Zenouzi, Mohammad Khosroshahi* Pages 47-60
    Introduction

     Due to the detrimental consequences of the application of stabilizers such as mulch and other protectives on the soil surface, including the wafting of bad smell, blackening of the ground, increasing thermal coefficient, warming of the whole area, and even destruction of plants and their unsustainability in nature, wide use of such stabilizers could not be considered as a useful solution to control wind erosion. Therefore, to solve the problem of sandstorms in Iran and get the desertschr('39') soil stabilized, this study proposes that deserts be coated with non-erodible materials (e.g., gravel, sandblasting, etc.)

    Materials & Methods

    Based on the purpose of this study, the effect of gravel cover with 30%, 50%, and 75% coverage on the sandblasting rate of MontazerQaem -TaleHamid desert was investigated using the wind tunnel. To investigate the effect of different gravel coatings on the sand particle transport rate, first, a sand sample was gathered from the Talle-Hamid area in Tabas, located 209 km off the Bafgh Railway, at 55/89 latitude and 32/93 longitude degrees, respectively, and the particle density of sand particles size was measured using standard ASTM D854-02. Its amount was found to be 2724 kg/m3. In the next stages, dry aggregation of sand particle size was first extracted from different parts of the MontazerQaem-Talle-Hamid track. According to the ASHTO T27 standard, at least 500 gr random fine sample particles should be collected from each site to sieve. Four samples were collected from sites that were 209, 213, 217, 222, and 222.7 km off Tabas. Having enumerated Standard-sized sieved particles, we used a vibrating machine to shake different particle diameters for at least 15 minutes. Furthermore, scales with a minimum accuracy of 0.01gr were used to weigh particles of different diameters. According to the standard of reconstitution for fine particles such as sand, the minimum sample size for sieving is 300gr, and the sample should be dried at 110 ° C in a three-stage oven. Then, these particleschr('39') transportation rate was measured at different wind speeds for uncovered gravel samples.

    Results & Discussion

    Initially, by increasing the wind speed from 1 m/s to 8 m/s, it was found that the particlechr('39')s creeping movement started at 6.9 m/s and its creeping speed was 6.9 m/s. The index sample was then placed in the wind tunnel for 5 minutes at different speeds of 9.9, 12.4, 17.2, and 22 m/s, and sand particle transportation was determined. It was also found that wind erosion increased by increasing wind speed polynomials. Subsequently, sands with 30-50% and 75% gravel cover were inserted into the wind tunnel for 5 minutes at wind speeds of 10.5, 15.7, and 22.9 m/s. Having determined the rate of wind erosion, we observed that the wind erosion rate decreased with an increasing percentage of gravel cover at a certain speed. We also found that the greatest effect on decreasing wind erosion rate occurred at wind speed 22.9 m/s, with the reduction percentage of erosion being 67.5%. The study results showed that the wind erosion rate decreased with an increasing rate of gravel cover at a certain speed, and the highest effect of graved on reducing wind erosion was reported for gravel cover of 75%. Therefore, covering the surface of a sandy desert with non-corrosive materials such as sand or gravel could be a practical solution for preventing wind erosion.

    Conclusion

    The effects of non-erodible coating or gravel on the rate of sand particle erosion were investigated via the wind tunnel, the results of which showed that the samples with gravel cover were effective in reducing wind erosion of sand particles. The greatest reduction in wind erosion rate was reported for the sites covered by 75% gravel. According to research conducted in the Chinese deserts, gravel cover with eroding sand particles and reducing wind velocity at the sand surface could well improve erosive sand levels. The present study also showed that at 22.9 m/s wind speed and 75% gravel cover, the erosion rate decreased by 67.5%. Therefore, to reduce the effects of sandstorms in Iran and stabilize the sandy desert area, non-erodible coating such as gravel would be recommended instead of mulch.

    Keywords: non-erodible materials, stabilization, dust, wind tunnel
  • Azadeh Soltani, HamidReza Asgari*, Hosein Yousefi Pages 61-72
    Introduction

    Saline soil contains large amounts of soluble salts. In addition to natural factors affecting soil salinization such as climate, topography, and abundance of evaporative formations in the region, the human factors that result from incorrect management of the agricultural system (such as using low-quality water for irrigation, overuse of chemical fertilizers, the frequency of irrigation, the type of irrigation system, poor soil drainage, etc.), are considered as the main causes of soil salinization (secondary salinity). According to the FAO report (2002), these regionschr('39') area is estimated to be approximately 831 million hectares, out of which 397 million hectares are saline soils, and 434 million hectares are sodic soils. As found by recent researches, the area of saline soils is estimated as 44.5 million hectares in Iran, constituting 27% of the total area of the country. Different methods including the selection of salinity-resistant plants, application of special methods of bed preparing and seed planting that minimize the accumulation of salts around the seeds, the use of larger amounts of irrigation water to leaching salts from the depth of plant roots penetration, and the use of chemical amendments such as sulfur, sulfuric acid, iron sulfate, gypsum, ammonium polyphosphate, calcium polyphosphate, etc., have already been used for reclamation of saline soils. Studies on this issue have often focused on the use of various amendments (chemical and organic matters). However, saline-sodic soils have not been studied based on nanoscale organic modifiers. Having various usages in natural resources and agriculture, including the remediation of soils contaminated with different contaminants such as saline-sodic soils, nanomaterials have found much application in industrial and semi-industrial laboratory scales in recent decades. Therefore, this study sought to investigate the effects of chemical, biological, and Nano-particle solutions on the modification of these soils.

    Materials and Methods

    The purpose of this study was the reclamation of saline and sodic soils using chemical, biological, and nanotechnology methods. The study region with an area of ​​about 100 hectares was located in the northwest of Golestan province, between 37° 09chr('39') 18" to 37° 10chr('39') 15" Northern latitude and 54° 25chr('39') 15" to 54° 25chr('39') 30" Eastern longitude. The study was arranged in a completely randomized factorial design by using eight treatments, including 1) control, 2) gypsum, 3) gypsum and livestock manure, 4) livestock manure, 5) nano- livestock manure of 0.03%, 6) nano-livestock manure of 0.06%, 7) nano- livestock manure of 0.06% and gypsum, 8) nano- livestock manure of 0.03% and gypsum. Each treatment was repeated three times. Statistical analysis of the data was performed by one-way analysis of variance and Duncanchr('39')s multi-domain test in the SPSS software.

    Results

    Prior to the experiment, soil samples were examined in the laboratory, and some soil parameters such as exchange sodium percentage (ESP), acidity (pH), and soil electrical conductivity (EC) were measured. After adding the amendments to the pots, they were leached for 30 days so that this amount of water was added to the soil four times (once every seven days). After leaching, each potchr('39')s ESP, EC, and pH values ​​were measured. The results showed that nano-manure treatments of 0.06% + gypsum and nano-manure of 0.03% + gypsum (at the level of 1%) had the greatest effect on reducing the ESP, and treatments of manure and nano-manure of 0.03% had the greatest effect on reducing EC. It was also found that soil acidity had the greatest decrease under the influence of gypsum and animal manure + gypsum treatments.

    Results and discussion

    The results of the study indicated that the gypsum amendment, along with animal manure, had significant effects on reducing ESP, EC, and pH in micro and nanoscales. Livestock manure was also found to positively reduce ESP, EC, and pH in both nano and micro scales. The applied nano-manure at both levels of 0.06% and 0.03% had a significant effect on improving the soil condition, especially on reducing soil acidity. In general, it could be concluded that the application of organic matter (animal manure) on a nanoscale exerts a greater influence on improving the condition of saline and sodic soils in comparison to that caused via micro-scale, which will be more effective if used in conjunction with gypsum.

    Keywords: Saline soils, Nano-fertilizers, Chemical, biological amendments, Golestan province, Sufikem plain
  • Afshin Uossef Gomrokchi*, Alireza Hassanoghli, Mehdi Akbari, Merzad Mostashari Mohasses, Danial Amini Pages 73-88
    Introduction

    The spatial and temporal distribution of salts in the soil, the great extent of the Iranian deserts, and the adverse climatic conditions prevailing over them make it difficult to accurately determine the parameters and field measurements in some cases. In the last two decades, the use of field techniques and their combination with remote sensing data has contributed significantly to preparing baseline maps on saline soils. Accordingly, recent advances in the application of remote sensing technology in salt-affected mapping and management have also reduced the costs of large-scale land monitoring. Many researchers worldwide have been preparing soil salinity maps using satellite imagery, aerial photographs, terrestrial and radiometric techniques based on correlations between salt reflection and soil salinity indices. One of the significant problems in Qazvin Plain is the drainage of the area, which may affect the control of the process of salinization and improvement of its soils and rangelands. Thus, to prevent the progress of the salt area in Qazvin plain, the drainage project had started in 2008. The aim of this study, therefore, was to predict soil salinity in the central drainage basin of Qazvin plain using remote sensing capabilities and an artificial neural network.

    Materials and methods

    The study area was part of Qazvin province 150 km northwest of Tehran that included the saline margin of Qazvin with a longitude of 380000 to 420000 and north latitude of 3920000 to 3980000 (according to UTM). The height of the area was 1135 to 1145 meters above sea level. The major cities adjacent to the area were northwest of Qazvin, vineyards in the west, Abyek in the north, and Dansfahan in the southwest. The central salinity area of the Qazvin plain was about 65,000 hectares. The core area was about 20,000 hectares, and the salinity of these lands was very high. The measurements showed a salinity of 280 dS/m (7 to 8 times the Persian Gulf salinity). About 95% of the lands in this area had an electrical conductivity of more than 20 dS/m, and 65% of the lands had an electrical conductivity of more than 100 dS/m. As for the purposes of this study, soil salinity and vegetation status of the study area were analyzed using satellite imagery and remote sensing indices. Mann-Kendall test was also used to study the time series trends (salinity and vegetation indices derived from satellite images). In order to take advantage of the neural network capabilities and based on the type of data monitored in the design area, the soil salinity prediction process was performed in three cases. In the first case, the soil salinity prediction model was based solely on salinity and vegetation indices monitored in the saline area because the reference land data were only recorded for a few years in the region. However, remote sensing capabilities enabled us to study the process of soil salinity changes over a broad period of time. In the second case, soil salinity was predicted according to the reference land data (groundwater level and SAR and EC indices) of the drainage area. In the third case, considering the timeframe of recording groundwater level data in the observed wells, the process of soil salinity modeling was performed by deleting groundwater level data to keep the model applicable even if the groundwater level was not recorded.

    Result

    the results of correlation analysis of mean temporal data showed that GVI had a high negative correlation with all salinity indices, but there was a lower correlation between salinity and other vegetation indices. The results also suggested that the training error was less than the test error in both modeling modes, and the neural network model error was 60% lower than the cubic regression model. The R software showed that the corresponding correlation coefficient was τ =- 0.63 and the p-value = 2*10-12, indicating a significant trend. It was found that using multivariate regression modeling had acceptable accuracy in predicting soil salinity in the study area. In the second modeling, EC and SAR indices in the catchment drainage area, vegetation indices, soil salinity indices derived from satellite images, and groundwater level values ​​in the observed wells were used. According to the results, the neural network model had a higher accuracy than the regression model, but its test error was higher than the regression model, and in this case, the results of the neural network model were proved to be of higher accuracy. In the third modeling case, soil salinity was predicted regardless of groundwater levels. In this case, the neural network accuracy was only better in the training mode, and no difference was found in the test mode. Also, by eliminating groundwater level data, the modelchr('39')s prediction accuracy was considerably reduced.

    Discussion and Conclusion

    In this study, soil salinity was simulated and predicted using the neural network model and regression model in the drainage area of ​​the central saline delta of Qazvin plain. To this end, reference land data and the indices derived from satellite images were used, and a soil salinity prediction model was presented. The results showed that the neural network models could simulate soil salinity with acceptable accuracy, requiring fewer factors than the computer model. Poor results for some models and states also indicated that any structurechr('39')s neural network models would not principally yield good results, but they require careful selection of the constituent factors. Performing many repetitions and selecting the appropriate factors constitute the network.

    Keywords: Drainage, Modeling, Neural network, Qazvin, Soil salinity, Water level
  • MohammadAmin Asadi*, Fateme Jamnezhad, MohammadReza Ekhtesasi, Seyed Zeynalabedin Hosseini Pages 89-102
    Introduction

    Drought is a natural hazardous phenomenon occurring in all climate types. However, it affects arid and semiarid regions more intensely than other areas. It also severely affects both the quantity and quality of water resources in arid zones. Moreover, land-use changes and urban and agricultural development also adversely influence water resources in these regions, especially groundwater resources.The extraction of a significant portion of drinking and agricultural water from groundwater resources has led to a sharp decline in groundwater storage in Iranchr('39')s arid and semiarid regions. Furthermore, as mentioned before, frequent droughts and land-use changes have affected these resources. This study, therefore, sought to investigate the effects of meteorological drought and land-use changes on groundwater quantity and quality in Darab plain, Fars Province, Iran.

    Materials and Methods

    Darab Plain is located in the south of Iran. The water supply in this plain is highly dependent on groundwater. The mean annual rainfall is 275 mm, and the mean annual temperature is 22 0C. In this study, data regarding precipitation, groundwater level, and salinity were used to estimate SPI (Standardize Precipitation Index), GRI (Groundwater Resources Index), and SECI (Standardized Electrical Conductivity Index). SPI is considered as the indicator of meteorological droughts. GRI quantifies changes in groundwater levels as a standardized index. SECI is applied to estimate any potential shifts in groundwater quality. Land-use maps of the basin for 2001, 2009, and 2017 were prepared using satellite imagery. Moreover, Landsat TM, ETM+, and OLI sensors were used. It should also be noted that land-use maps were created using the Supervised Classification method (Maximum likelihood algorithm). The produced maps included five classes: urban area, farmlands, gardens, rangelands, and bare lands.

    Results

    SPI results showed normal classes for most of the years throughout the study period (-0/99 to +0/99). However, the trend line indicated an apparent decreasing trend for SPI during the period. Therefore, it could be concluded that the region is experiencing more droughts. A study of groundwater level changes suggested a continuous reduction of 36 m for the entire study period. While the comparison of SPI and GRI showed a general decreasing trend for GRI, it could be seen clearly that SPI changes caused GRI shifts. Moreover, droughts accelerate GRI reduction, and SPI growth either reduces GRI decreases or increases it slightly.On the other hand, SECI results indicated the salinity growth and quality reduction in the region. During the study period, the plain experienced a 293.6 µmho/cm increase in salinity. Furthermore, the comparison of GRI and SECI showed that any reduction in groundwater level would result in more saline. The comparison of land-use maps during the three years (2001, 2009, and 2017) also proved that agricultural uses increased by only 0.26% in 2009 compared with 2001. However, in 2017 compared with 2009, such uses decreased by 1.62%.The relationships between SPI and land-use changes with GRI and SECI were also investigated, indicating that droughts and land-use changes directly affect the quantity and quality of groundwater in Darab Plain.

    Discussion and Conclusion

    Climate change has affected many parts of the world, changing drought characteristics in many regions. Therefore, the subsequent changes in water resources could be considerable. Furthermore, water resources are under pressure for population growth and land-use change. In this study, the collected data was divided into three 8-years periods (1993-2001, 2002-2009, 2010-2017), and the averages of SPI, GRI, SECI, and land-use were calculated for the three periods. The results showed that the increase in the severity of drought and the rise of the agricultural lands in the second period compared to the first one caused a decrease in water quantity (GRI decrease) and quality (SECI increase). However, a decrease in the severity of drought and the fall of the agricultural land-use in the third period compared to the second one lowered the rate of groundwater level decline (compared to the rate of GRI decreasing in the second period). In the third period, SECI increased (less quality) in response to the GRI decrease. The results showed that groundwater resources in Darab Plain were strongly dependent on both drought and land-use changes. The groundwater quality in the region was also directly affected by changes in groundwater level.

    Keywords: Meteorological Dought, Darab Plain, Land Use, Quantity, Quality, Groundwater Resources
  • Hamed Khayrandish, Ahmad Sadeghipour*, Hananeh Mohammadi Kangarani Pages 103-117
    Introduction

    as healthy watersheds provide many ecosystem services in various fields such as social and economic welfare, some methods need to be developed for measuring the extent of watershedschr('39') health and sustainability. Sustainable development is a comprehensive approach to improving human life quality by providing the economic, social, and environmental well-being of human settlements. Therefore, it is achieved if there is an overlap between the ecological, economic, and social layers. The purpose of this study was to compare two methods of HLEP and the organization of forests, rangelands, and watershed management in assessing the sustainability of the Bakhtegan watershed in Fars province.

    Materials and methods

    The first Method used the guidelines for monitoring and evaluating natural resource management and watershed management plans prepared by the Vice President for Strategic Planning and the Organization of Forests, Rangelands, and Watershed Management for Iran. In this method, the watershed was divided into five ecosystems: forest, desert, rangeland, aquatic environment, and economic and social issues. Different criteria and indicators were defined, determined, and measured for each of these ecosystems. Each variable was divided into different classes numerically, and each class was given a score (from high to low). The second method for analyzing and measuring stability in the field was the HELP that was based on four categories of hydrology (quantitative and qualitative), environment, watershed life, and policy-making. Moreover, three parameters of pressure, status, and reaction were used under the title of Basin Stability Index (WSI) to study basin stability at three levels: low, medium, and high.

    Result

    as for the first method, the scores were added up to create a class, and according to the study area, three criteria, nine indicators, and 14 variables were selected and measured based on the rangeland and desert ecologistschr('39') section. In the ecologistschr('39') section, five criteria and 16 indicators (the indicators themselves act as variables) were selected and measured. The final scores for rangeland and desert ecologists and the economic and social issues were reported as 45 and 32, respectively, putting both in the middle class. The watershedchr('39')s sustainability status was also determined using the score estimation matrix and watershed assessment table. Taking the Bakhtegan watershedchr('39')s total points into account, it could be said that it is in a weak position in terms of stability. The results of the application of the HELP method showed that the pressure parameter with a score of 0.75 and the response parameter with a score of 0.45 had the highest and lowest scores for assessing the sustainability of the Bakhtegan watershed, respectively, indicating an appropriate response to reduce the pressure on the ecosystem. The results also suggested that quantitative hydrological sub-indices with a score of 0.25 and environment with a score of one had the highest and lowest priority for watershed management (especially management and protection of existing water resources), respectively. The level of watershed stability was assessed with a mean downward score of 0.61 in the study period, indicating that improving the regionchr('39')s level of sustainability requires more attention.

    Discussion and Conclusion

    This studychr('39')s results in terms of selected criteria and indicators concerning the quality and quantity of information and accuracy of the data could be generalized to other parts of Iran (although similar to the field). To achieve acceptable sustainability, the area must be developed in terms of ecosystem, economic, and social issues and surpass the current equilibrium state. These conditions are made possible by protecting the ecosystem and providing a decent life for watershed dwellers. Considering the watershed management operations carried out in the basin, it is expected that the ecosystem sector will reach the desired level of stability. Moreover, for the basin to be sustainable, the economic and social sectors must get involved, conducting some measures to improve peoplechr('39')s living standards. Naturally, ecosystemschr('39') substantive and functional value in the formation and sustainability of watersheds are not the same; Therefore, according to the consensus of experts, aquatic ecosystems have the highest value, and desert ecosystems have the lowest value in the evaluation of a watershed. Thus, in the process of determining the sustainability of the watershed, the essential value of the composition of the ecosystems and the surface of the watershed that are covered must be taken into consideration.

    Keywords: Bakhtegan Watershed, Ecosystems, HELP, Sustainability Assessment, Sustainable Development