فهرست مطالب

  • پیاپی 34 (پاییز 1398)
  • تاریخ انتشار: 1398/07/09
  • تعداد عناوین: 16
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  • مطالعه آزمایشگاهی ساختار جریان آشفته در یک کانال مستقیم با بستر زبر
    سید حسین مهاجری *، اکبر صفرزاده، سید علی اکبر صالحی نیشابوری، مسعود قدسیان صفحات 1-8
  • امکان سنجی الگوریتم بهینه سازی غذایابی باکتری(BFO) جهت تخمین ضرایب یکنواختی توزیع آب درسیستم آبیاری بارانی
    الهه حسینیان، حسن ترابی* صفحه 1

    یکی از پارامترهای مهم در کشاورزی، ضریب یکنواختی توزیع آب (CU) در آبیاری بارانی می باشد. مقدار CU حاصل از هر آب پاش در مقادیر مختلف فشار کارکرد آب پاش، ارتفاع پایه آب پاش ، فاصله آب پاش ها روی لوله های جانبی و فاصله لوله های جانبی از یکدیگر تغییر می یابد. تعیین بهترین ترکیب از پارامترهای فوق که بالاترین ضریب CUرا حاصل نماید، همواره سئوالی بی جواب برای کاربران بوده است. در این پژوهش، مقادیر ضریب CU آب پاش مدل zb ساخت ایران در 3 تیمار مختلف فشار کارکرد آبپاش ، 2 تیمار ارتفاع پایه آب پاش و 7 تیمار آرایش شبکه آبپاش ها که در ایستگاه تحقیقات پنبه هاشم آباد گرگان اندازه گیری شده است، با استفاده از الگوریتم غذایابی باکتری بهینه گردید و رابطه ای با بهینه ترین ضرایب برای تخمین مقدار CU با استفاده از پارامترهای ذکر شده توسط این الگوریتم بدست آمد. در این الگوریتم پارامترهای Nc، Nre، Ned و C(i) به ترتیب برابر 500، 8،8 و 01/0 بهترین جواب را ارائه می کنند. نتایج نشان داد این الگوریتم دارای خطای مطلق 2 درصد می باشد. همچنین مقدار پارامتر ریشه ی دوم میانگین مربع خطا برابر 13/2 بدست آمد که نشان دهنده دقت بالای این مدل برای برآورد ضریب یکنواختی پخش می باشد.

    کلیدواژگان: الگوریتم غذایابی باکتری، ضریب یکنواختی، توزیع آب، آبیاری بارانی
  • تاثیر روش های مختلف مدیریتی بر عملکرد، اجزا عملکرد و کارایی مصرف آب گوجه فرنگی در کشت هیدروپونیک
    محمد هوشمند*، سعید برومند نسب، محمد الباجی، ناصر عالم زاده انصاری صفحه 2

    کم آبیاری از مدیریت های به کار رفته برای کسب محصول با درآمد و سود بیشینه در سال های اخیر به دلیل تشدید بحران آب مورد توجه قرار گرفته است. در این پژوهش اثر روش های آبیاری تنظیم شده (RDI) وخشکی موضعی ریشه (PRD) بر گوجه فرنگی در شرایط کشت هیدروپونیک بررسی گردید. تیمارهای آزمایش شامل تیمارهای آبیاری RDI در دو سطح 85 و 70 درصد نیاز آبی گیاه، آبیاری PRD در دو سطح 85 و 70 درصد نیاز آبی گیاه که به صورت متناوب آبیاری را انجام می دادند و شاهد در قالب طرح کاملا تصادفی با چهار تکرار اجرا گردید. نتایج نشان داد که شیوه ها و سطوح مختلف کم آبیاری بر وزن تر و خشک ریشه، وزن تر و خشک ساقه، وزن خشک بوته، وزن میوه و کارایی مصرف آب محصول و بخش هوایی تاثیر معنی دار دارد ولی بر وزن تر و خشک و میزان آب برگ، سطح برگ، شاخص سطح برگ، سطح برگ ویژه، نسبت سطح برگ، وزن بیوماس و شاخص برداشت تاثیر معنی داری نداشته است. بیشترین وزن میوه در بوته و کارایی مصرف آب در تیمار PRD85 به میزان به ترتیب 2572/5 گرم و 16/07 کیلوگرم بر متر مکعب و کمترین آن در تیمار PRD70 به میزان به ترتیب 1189/5 گرم و 9/02 کیلوگرم بر مترمکعب بدست آمد. همچنین کم آبیاری به صورت خشکی موضعی ریشه با سطح 85% نیاز آبی گیاه به عنوان بهترین روش برای کشت هیدروپونیک گوجه فرنگی انتخاب شد.

    کلیدواژگان: خشکی موضعی ریشه، کارایی مصرف آب، کشت بدون خاک، گوجه فرنگی، کم آبیاری
  • ارزیابی روش های مختلف SOM-AI برای پیش بینی سطح آب زیرزمینی (مطالعه موردی: آبخوان دشت سلماس)
    کیوان نادری، عطا الله ندیری*، اصغر اصغری مقدم، مهدی کرد صفحه 3
  • بررسی وضعیت سفره آب زیرزمینی دشت جیرفت و مقایسه هزینه پمپاژآب از چاه با پمپ های دیزلی و برقی
    ابراهیم محمدی سلیمانی*، مجید احمدیان، محسن شوکت فدایی، علی کرامت زاده، ابوالفضل محمودی صفحه 4
  • تحلیل اقتصادی پوشش در کانال های انتقال آب بروجن
    احسان توکلی*، بهزاد قربانی، علیرضا توکلی صفحه 5

    با توجه به اهمیت حیاتی آب در مناطق خشک و نیمه‌خشکی چون ایران، حفاظت و استفاده بهینه از منابع آب امری ضروری است. پژوهش حاضر با هدف تحلیل اقتصادی پوشش در کانال‌‌‌‌‌‌‌‌های انتقال آب انجام شد و در آن به بررسی اقتصادی نفوذ از کانال بدون پوشش به آب زیرزمینی و پمپاژ دوباره آب از طریق چاه، در مقایسه با نگهداشت آب در کانال‌‌‌‌‌‌‌‌ پوشش شده پرداخته شد. برای انجام این پژوهش، کانال بتنی شبکه آبیاری و زهکشی گندمان و بلداجی، در شهرستان بروجن استان چهارمحال و بختیاری، با مقطع ذوزنقه و عرض کف 3/1 متر، عمق 8/1 متر و عرض بالای 5/6 متر انتخاب و با کانال خاکی با ابعاد مشابه مقایسه گردید. داده‌‌‌‌‌‌‌‌های اولیه شامل الگوی کشت انتخابی و سطح زیر کشت، عملکرد و مصرف آب گیاهان در بازه زمانی پژوهش و هزینه کارگری قبل و بعد از پوشش کانال بود. برای محاسبه هزینه‌‌‌‌‌‌‌‌های پوشش کانال، با فرض عمر مفید 10، 20 و 40 ساله پوشش، هزینه عملیات خاکی، هزینه پوشش‌‌‌‌‌‌‌‌دهی کانال، ارزش آب صرفه‌‌‌‌‌‌‌‌جویی شده، کاهش هزینه تعمیر، لایروبی و نگهداری و امکان توسعه کمی و کیفی محصولات زراعی و باغی در سطح زیر پوشش کانال انتقال، درنظر گرفته شد. به منظور محاسبه هزینه‌‌‌‌‌‌‌‌های پمپاژ آب زیرزمینی از اعماق مختلف نیز، هزینه‌‌‌‌‌‌‌‌های انرژی، استهلاک سامانه پمپاژ لحاظ گردید. نتایج نشان داد در هر سه نرخ تنزیل 12، 15 و 18 درصد و با هر سه عمر مفید 10، 20 و 40 سال، همواره کانال خاکی توجیه اقتصادی بیشتری نسبت به کانال بتنی دارد. همچنین، با افزایش عمر مفید کانال بتنی از 10 به 40 سال (در نرخ تنزیل ثابت)، ارزش حال خالص و نسبت سود به هزینه ابتدا افزایش و سپس کاهش نشان داد. بررسی دقیق محاسبات نشانگر آنست که پس از 30 سال، با حداکثر شدن مخارج نگهداری کانال پوشش‌‌‌‌‌‌‌‌دار، هزینه‌‌‌‌‌‌‌‌های آن فراتر از درآمدهای حاصل خواهد شد، بنابراین پوشش با شرایط ذکر شده پس از 30 سال توجیه اقتصادی نداشته و شاخص‌‌‌‌‌‌‌‌های اقتصادی مورد بررسی نسبت به قبل کاهش می‌‌‌‌‌‌‌‌یابند. بنابراین، پوشش‌‌‌‌‌‌‌‌دار کردن کانال در منطقه بروجن استان چهارمحال و بختیاری در مقایسه با گزینه کانال خاکی و پمپاژ دوباره از چاه، توجیه اقتصادی ندارد. نتایج نشان داد در هر 3 نرخ تنزیل 12، 15 و 18 درصد و با هر 3 عمر مفید 10، 20 و 40 سال، همواره کانال خاکی توجیه اقتصادی بیشتری نسبت به کانال بتنی دارد. بنابراین، پوشش دار کردن کانال در منطقه بروجن استان چهارمحال و بختیاری در مقایسه با گزینه کانال خاکی و پمپاژ دوباره از چاه، توجیه اقتصادی ندارد

    کلیدواژگان: شبکه آبیاری و زهکشی گندمان و بلداجی، کانال پوشش دار، کانال خاکی، مدل سازی فیزیکی
  • ارزیابی تغییرات تبادل آب سطحی و آب زیرزمینی در زیرحوضه لنجانات
    علی اصغر هاشمی*، روح الله فتاحی، حسین صمدی صفحه 6

    در سال‏های اخیر استخراج بیش از حد آب از منابع آب آبخوان‏ها در سراسر کشور، پایداری منابع آب زیرزمینی را تهدید کرده است. لذا شناخت ارتباط بین آب سطحی و آب زیرزمینی و تبادلات حجمی بین آنها از اهمیت بالایی برخوردار است. در این مطالعه بر اساس بیلان آب سطحی و جریان ماهانه چهار ایستگاه آبسنجی، بازای هر ماه معادله‏ای برای خروجی هر بازه رودخانه استخراج شد. پارامترهای این معادله، بیانگر ارتباط خالص آب سطحی با جو و آب زیرزمینی می باشند. سری تاریخی داده‏ها به دو دوره بیست ساله تقسیم شد و تبادل آب در دو دوره مقایسه شدند. نتایج مطالعه بر روی سه بازه موجود نشان داد که در بازه اول طی دو دوره، آب زیرزمینی بطور خالص تغذیه کننده آب سطحی بوده است. آب سطحی بازه انتهایی، در دوره اول تغذیه کننده آب زیرزمینی بوده در حالیکه در دوره دوم در اکثر ماه‏ها بوسیله آب زیرزمینی تغذیه شده است. در خشکسالی شدید بجز بازه اول، دو بازه دیگر دچار کمبود آب شدند. یافته‎ها نشان داد که افزایش آب سطحی بوسیله آب زیرزمینی، اهمیت بالایی در تامین آب در شرایط خشکسالی دارد. بر اساس نتایج، روش ارائه شده ابزار مناسبی در بررسی تبادل آب سطحی با آب زیرزمینی می‏باشد.

    کلیدواژگان: تبادل، آب سطحی، آب زیرزمینی، جریان ورودی و خروجی، بیلان جرمی، بازه رودخانه
  • کارایی روش آبیاری قطره ای در مزارع گوجه فرنگی در شرایط شور بودن منابع آب
    مهرداد نوروزی *، مختار زلفی باوریانی صفحه 7

    در دهه‌های اخیر استفاده از آب‌های شور در تولید کشاورزی به دلیل کاهش منابع آب شیرین رشد چشمگیری داشته است. ولی استفاده بی خطر از آب شور مستلزم مدیریت صحیح آبیاری است. این پژوهش به منظور بررسی اثر شوری آب بر عملکرد، کارایی مصرف آب و کیفیت میوه گوجه‎فرنگی تحت روش آبیاری قطره‎ای نواری طی یک فصل زراعی (90-1389) در استان بوشهر با شرایط آب و هوایی خشک و نیمه خشک اجرا شد. آزمایش به صورت کرت‎های خرد شده در قالب طرح بلوک‌های کامل تصادفی با چهار سطح شوری آب آبیاری (شامل 1/1، 5/3، 5/5 و 5/7 دسی‌زیمنس بر متر) و سه سطح دور آبیاری (شامل 2، 4 و 7 روز) با سه تکرار انجام شد. طبق نتایج، با افزایش دور آبیاری از 2 روز به 7 روز مقادیر میانگین‎ عملکرد محصول(Y)، کارایی مصرف آب آبیاری (IWUE) و وزن میوه (FW) به ترتیب 20، 19 و 26 درصد کاهش داشتند. همچنین، با افزایش شوری آب آبیاری از dS.m-1 1/1 به dS.m-1 5/7 این مقادیر به ترتیب 33، 39 و 32 درصد کاهش داشتند. بطور کلی، تحت شرایط آب و هوایی و ویژگی‌های خاکی محل آزمایش کاهش عملکرد محصول در اثر شوری آب به مراتب کمتر از مقادیر گزارش شده در نشریه 29 فائو (آیرز و وستکات، 1985) بود. همچنین با افزایش دور آبیاری و شوری آب آبیاری کیفیت میوه به لحاظ میزان مواد جامد محلول (TSS) افزایش داشت.

    کلیدواژگان: آبشویی نمک، آبیاری تیپ، دور آبیاری، شوری آب آبیاری، کارایی مصرف آب
  • حذف نیترات از آبهای زیرزمینی بصورت درجا با منابع کربنی مایع
    فریده انصاری سامانی*، سید حسن طباطبائی، فریبرز عباسی، ابراهیم علایی صفحه 8

    نیترات در طبیعت به واسطه فعالیت‌های میکروبی می‌تواند به نیتروژن یا دیگر شکل‌ها تغییر یافته و حذف شود. روش‌های مختلفی برای حذف نیترات از آبها وجود دارند که رایج‌ترین آنها، استفاده از بسترهای نیترات زدایی است. در این پژوهش با طراحی بسترهای نیترات زدایی حاوی مخلوطی از خاک و چهار منبع کربنی مایع شامل گلوکز، استات، اتانول و متانول عملکرد آنها برای حذف نیترات آب زیرزمینی بررسی شد. به همین منظور از یک ستون پلکسی گلاس به عنوان ستون ماریوت (منبع آب) و یک ستون پلکسی گلاس دیگر به عنوان محیط متخلخل پر شده با خاک با بافت لوم رسی به طول 50 و قطر 10 سانتی متر استفاده شد. نمک نیترات پتاسیم برای ساختن غلظت 100 میلی‌گرم بر لیتر نیترات استفاده شد. این پژوهش در دو نسبت C/N 5/1و 5/3 انجام شد و اندازه گیری غلظت نیترات خروجی تا حجم منفذی10 ادامه داشت. نتایج نشان داد با گذشت زمان، میزان غلظت نیترات خروجی کاهش یافت به طوری که با گذشت 250 ساعت از شروع آزمایش مقدار غلظت خروجی به مقدار ثابتی رسید. راندمان حذف در گلوکز 83/97، استات 97، اتانول66/98 و متانول 99 درصد بدست آمد و بنابراین متانول بیشترین کارایی را در حذف نیترات داشته و توانسته است نیترات به غلظت 100 میلی‌گرم در لیتر را به 1/2میلی‌گرم بر لیتر برساند. متانول با تعداد 131000 باکتری، بیشترین میزان رشد باکتری را در نسبتC/N 5/3 داشت. در واقع با افزایش غلظت ماده کربنی میزان رشد باکتری‌ها افزایش و میزان غلظت نیترات کاهش یافت، در نتایج حاصل از آزمون همبستگی، تفاوت میانگین‌های دو جامعه از سطح اطمینان 5 درصد کوچکتر است که اختلاف معنی‌داری بین غلظت منابع کربنی وجود داشت.

    کلیدواژگان: آلودگی، باکتری، حذف بیولوژیکی، راندمان، نرخ حذف
  • اثرات بیوچار برگ خرما بر هدایت هیدرولیکی اشباع و ضرایب رطوبتی خاک لوم رسی شنی
    پریا نسیمی*، حمیدرضا متقیان، احمد کریمی صفحه 9

    ماده آلی خاک نقش مهمی در بهبود ویژگی های فیزیکی، شیمیایی و بیولوژیکی ایفا می کند. بیوچار سبب بهبود ویژگی های فیزیکی و شیمیایی خاک می شود. این پژوهش با هدف بررسی نقش زمان بر اثرات برگ خرما و بیوچار حاصل از آن بر هدایت هیدرولیکی و ضرایب رطوبتی خاک لوم شنی رسی انجام گرفت. برگ خرما و بیوچار به طور یکنواخت و به صورت پودری با خاک عبور داده شده از الک 4 میلی متری مخلوط شد و به صورت طرح فاکتوریل در قالب کاملا تصادفی با دو فاکتور زمان در چهار سطح و فاکتور برگ خرما و بیوچار هر کدام در چهار سطح در 3 تکرار انجام گرفت. هدایت هیدرولیکی اشباع (Ks)، رطوبت ظرفیت زراعی (θFC)، رطوبت نقطه پژمردگی دایم (θPWP)، آب قابل استفاده گیاه (PAWC) و ظرفیت زراعی نسبی (RFC) تعیین شدند. نتایج نشان داد تفاوت معنی داری (01/0>P) بین تیمارها وجود دارد. کاربرد 5/0، 1 و 2 درصد وزنی برگ خرما هدایت هیدرولیکی اشباع را به ترتیب 2/24، 7/17 و 3/74 درصد افزایش داد. کاربرد 5/0 درصد وزنی بیوچار 4/39 درصد کاهش و تیمار 1 و 2 درصد آن به ترتیب باعث افزایش 4/29 و 4/41 درصد در هدایت هیدرولیکی گردید. اثرات نوع ماده اصلاحی بر RFC ، θPWP و PAWC و اثر سطوح کاربرد بر همه ضرایب رطوبتی خاک افزایش معنی دار(01/0>P) بود. اثرات متقابل زمان، نوع ماده اصلاحی و سطوح کاربرد بر PAWC و θPWP در سطح آماری (01/0>P) و بر RFC در سطح آماری (05/0>P) تفاوت معنی داری دارند و این اثرات بر θFC معنی دار نبود.

    کلیدواژگان: بیوچار، هدایت هیدرولیکی اشباع، ظرفیت زراعی، نقطه پژمردگی دائم، آب قابل استفاده گیاه
  • پیش بینی سرعت جریان و بررسی تاثیر زبری کانال ها بر هیدرولیک جریان در آبگیرهای جانبی بوسیله ترکیب شبکه عصبی مصنوعی و مدل عددی CFX
    سهراب کریمی*، حسین بنکداری، آزاده غلامی صفحه 10
  • اندازه گیری غلظت برخی فلزات سنگین در نمونه های آب شرب در شبکه آبرسانی شهر زنجان
    مهدی امانلو*، محمدرضا یافتیان، عبدالحسین پری زنگنه، عباسعلی زمانی صفحات 19-26
  • مدلسازی عوامل اقلیمی موثر بر افت سطح آبهای زیرزمینی با رویکرد تغییر اقلیم (مطالعه موردی: دشت مشهد)
    الهام کدخدا، غلامعباس فلاح قالهری*، محمد باعقیده، سید علیرضا فرید حسینی صفحات 27-38
  • مدل سازی کمی آبخوان بجنورد با تاکید بر لایه بندی آن
    مینا تاج آبادی، علینقی ضیائی، کامران داوری*، عزیزالله ایزدی صفحات 39-50

    هدف از این پژوهش، مدل سازی کمی آبخوان بجنورد با تاکید بر لایه بندی آن می باشد. در این مطالعه مدل سه بعدی لیتولوژی آبخوان با استفاده از تکنیک های مدل سازی سه بعدی در نرم افزار Rockworks، با اطلاعاتی نظیر لاگ چاه های بهره برداری و مطالعات ژئوفیزیک بدست آمده است. مدل لیتولوژی بدست آمده آبخوان که شامل چهار گروه بافت خاک درشت دانه، متوسط دانه و ریزدانه و خیلی ریزدانه است، به صورت چهار لایه با ضخامت 30 متر به نرم افزار GMS وارد شد و در شرایط ماندگار اجرا شد که مجذور میانگین مربعات خطا بعد از کالیبراسیون به مقدار 794/0رسید به طوریکه مجذور میانگین مربعات خطا، نسبت به مدل تک لایه که دارای مقدار 0.852هست، بهبود یافته است. مقاطع عرضی بدست آمده بیانگر وجود عدسی ها و ناهمگنی رسوبات آبخوان بجنورد می باشد که در صحت تخمین هدایت هیدرولیکی بسیار تاثیرگزار هستند. مقادیر هدایت هیدرولیکی در شرایط ناهمگنی آبخوان به صورت موضعی و با توجه به جنس های مختلف موجود با مقادیر 1/8، 7/6، 9/1 و 4/0 متر بر روز به ترتیب برای بافت خاک درشت دانه، متوسط دانه، ریزدانه و خیلی ریزدانه بدست آمد. چکیده کامل نیست چکیده کامل نیست چکیده کامل نیست چکیده کامل نیست چکیده کامل نیست چکیده کامل نیست چکیده کامل نیست چکیده کامل نیست چکیده کامل نیست چکیده کامل نیست چکیده کامل نیست چکیده کامل نیست چکیده کامل نیست چکیده کامل نیست

    کلیدواژگان: هدایت هیدرولیکی، بجنورد، مدل لیتولوژی، GMS. Rockworks
  • بررسی و مقایسه مدل های تجربی برآورد نشت در کانال های آبیاری (بررسی موردی دشت داراب)
    محمد علی شاهرخ نیا*، لادن جوکار صفحات 51-62

    استفاده از فرمول های تجربی برآورد نشت آب در کانال ها در مقایسه با روش های عملی، باعث صرفه جویی در وقت و هزینه می گردد. با توجه به تجربی بودن، ارزیابی و واسنجی این فرمول ها ضروری است. در این پژوهش، نشت آب در سه کانال آبیاری دشت داراب فارس، با استفاده از 9 فرمول تجربی برآورد و با روش مستقیم دبی ورودی- خروجی مقایسه شد. روابط تجربی برای کانال های مذکور مورد واسنجی و صحت سنجی قرار گرفت. نتایج اولیه نشان داد فرمول موریتز و آفنگندن با داشتن خطای 49% و 1445% به ترتیب دارای کمترین و بیشترین تفاوت با روش دبی ورودی-خروجی و خطای بقیه فرمول ها حدود 125% است. نتایج حاصل از واسنجی نشان داد که فرمول های اینگهام، مولس ورث-ینی دومیا، دیویس ویلسون، موریتز و آفنگندن با داشتن خطای نسبی کمتر از 10%، مطابقت خوبی با روش دبی ورودی- خروجی دارند. پس از این فرمول ها، فرمول گارگ، آبیاری مصر، میسرا و پنجاب هند، بترتیب با داشتن خطای 16، 18، 20 و 20 درصد در رده های بعدی هستند. نتایج صحت سنجی نشان داد فرمول های موریتز و میسرا به ترتیب دارای بیشترین و کمترین مطابقت با روش مستقیم در شرایط مورد بررسی هستند.

    کلیدواژگان: کانال آبیاری، داراب، فرمول تجربی، نشت آب
  • ارزیابی اثر درصد تراکم و مقدار ریز دانه خاک بر ضریب نفوذپذیری و جریان نشت دائمی و غیر دائمی از گوره های مهارسیلاب
    فواد کیلانه ئی*، حمید رضا منعمی، امیر محجوب صفحات 63-74

    در این مقاله اثر درصد تراکم و مقدار ریزدانه خاک بر مقدار نفوذپذیری خاک SC و جریان نشت از گوره های مهارسیلاب در حالت دائمی و غیردائمی مورد بررسی قرار گرفته است. بدین منظور سه نمونه ی منتخب خاک که در این تحقیق با نام های A، B و C مشخص شده اند و به ترتیب دارای درصد ریزدانه 12، 8/20 و 4/28 می‌باشند، با درصد تراکم های 100، 85، 70 و 60 مورد آزمایش نفوذپذیری قرار گرفته اند. نتایج نشان داد با افزایش درصد تراکم در هر یک از نمونه های مورد بررسی از مقدار 60 به 100، 70 به 100 و 85 به 100 ضریب نفوذپذیری به ترتیب به مقدار متوسط 25، 3/14 و 91/8 برابر کاهش داشته است. در هر درصد تراکم نیز مقدار ضریب نفوذپذیری نمونه A به طور میانگین 2/1 برابر نمونه B و 69/1 برابر نمونه C و ضریب نفوذپذیری نمونه B به طور میانگین 41/1 برابر نمونه C تعیین گردیده است. در ادامه با مدلسازی عددی پدیده تراوش، دبی عبوری از گوره های مهار سیلاب با درصد تراکم‌‌های مختلف در حالت تراوش دائمی و سطح فریاتیک در حالت تراوش غیردائمی مورد بررسی قرار گرفته است.

    کلیدواژگان: گوره مهار سیلاب، جریان دائمی و غیردائمی، ضریب نفوذپذیری، درصد تراکم، درصد ریزدانه، مدل عددی
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  • Iranian Water Researches Journal Laboratory study of rough bed open channel turbulent flow
    Seyed Hossein Mohajeri*, Akbar Safarzadeh, Seyed Ali Akbar Salehi Neyshabouri, Masooud Qodsian Pages 1-8
  • using Bacterial Foraging Algorithm (BFO) to estimate the coefficients of uniformity of water distribution in sprinkler irrigation
    elahe hosseinian, hassan torabi* Page 1

    One of the important parameters in agriculture is water distribution uniformity coefficient (CU) in sprinkler irrigation. The first study of sprinkler irrigation uniformity has been executed by Christiansen (1942) in California that led to the Christiansen uniformity coefficient. Nowadays it is very common to use Christiansen uniformity coefficient in sprinkler irrigation systems. Many researchers have investigated water distribution uniformity coefficient in fixed sprinkler systems. Other researchers such as Hart and Reynolds (1965), Karmeli (1997), Vories and Bernuth (1986), Dabbous (1962), Heerman (1983), Keller and Bliesner (1990), Carrion et al. (2001), Montero et al. (2003) and Bavi et al. (2006) have investigated different aspects of water distribution uniformity coefficient. A sprinkler water distribution pattern depends on the system design parameters such as: the sprinkler spacing, operating pressure, nozzle diameter, and environmental variables such as: wind speed and direction. The sprinkler irrigation distribution patterns have been characterized by various statistical uni formity coefficients and various coefficients of uniformity (CUs) have been developed over the past decades. CU amount of water sprinkler operating depends on different pressure heads (P), riser height (RH), distance between sprinklers on lateral pipes (Sl) and the distance between lateral pipes (Sm). The best combination of the above parameters for maximum CU, is still unknown for applicators. Many researches has been done to the estimation of various relationships using different algorithms. Research such as Hezar Jaribi et al. (2009), Vasan and Raju (2007) and Janga Reddy and Nagesh Kumar (2007). Different researchers have used various concepts to express the coefficients of uniformity, hence the equations lead to different results in the expression of the distributed water uniformity in the same fields. This paper evaluates different uniformity coefficients using Bacterial Foraging Algorithm (BFO) to propose the best and optimized equation for CU. Generally, the task is to optimize certain properties of a system by pertinently choosing the system parameters. So in this study, CU has been estimated by Bacterial Foraging Algorithm, and funded the best and optimizes coefficients in CU equation. The field experiments were conducted on farmland located in Hashem Abad Agricultural Research Station of Gorgan Cotton Research Institute, about 11 kilometers northwest from Gorgan. The lands were irrigated by solid set sprinkler irrigation systems. The sprinkler uniformity tests were conducted using rain-gauge for uniform ity coefficients measuring. CU quantities of zb model sprinkler (made in Iran) were considered under 3 different pressure heads (2.5, 3 and 3.5 atm), 2 riser heads (60 and 100 cm) and 7 sprinkler (Sl×Sm including 9×12, 9×15, 12×12, 15×12, 12×18, 15×15, 15×18m) arrangements. In this study nonlinear equation uniformity coefficients in sprinkler irrigation has been optimized by using Bacterial Foraging Algorithm (BFO). Typically, the BFO consists of four main mechanisms including chemotaxis, swarming, reproduction, and elimination-dispersal event. Totally, the algorithm was run more than 70 times for various conditions and obtained the best case. While optimizing CU Equation by Bacterial Foraging Algorithm (BFO), The best results obtained in S, Nc, Nre, Ned, and C(i) are equal to 24, 500, 8, 8 and 0.01 respectively. The result of this optimization to estimate the Christiansen uniformity coefficient for the specified working pressure of the sprinkler, sprinkler height, distance between sprinklers on the pipes side and distance between side pipes was derived as shown in Equation 5. (5) To evaluate the goodness of the proposed optimal equation, the equation was used to estimate Christiansen uniformity coefficient distribution of the 70% of the experimental data. Then, the model obtained from 70% of the data was verified with remaining 30% of the experimental data. The estimated Christiansen uniformity coefficient distribution using Equation 5 has been compared with the 30% and 70% of the observed value and good agreement was observed. Result shows that the maximum absolute error between the results of this algorithm with the measured results is less than 3%, this error was for 30% data also the value of the root-mean square error (RMSE), is equal to 2.13. It is revealed that that this algorithm has high accuracy to estimate water distribution uniformity coefficient. Generally, can be said that Bacterial Foraging Algorithm for optimizing nonlinear functions is very good and acceptable, and compare to other algorithms it has a much higher rate of convergence, whereas does not make local optimal problems.

    Keywords: Uniformity Coefficient, Water Distribution, Sprinkler Irrigation, Bacterial Foraging Algorithm (BFO)
  • Effect of different management methods on yield, yield components and water use efficiency of tomato in hydroponic culture
    mohammad hooshmand*, Prof. Saeed Boroomand nasab, mohammad albaji, naser alam zadeh ansari Page 2
  • Evaluation of SOM-AI models for prediction groundwater level (Case study: The Salmas plain aquifer)
    Keiwan Naderi, Ataallhah Nadiri*, Asghar Asgari Moghaddam, Mehdi Kord Page 3
  • Investigating of Jiroft Plain Aquifer status and comparing the cost of water pumping from wells with diesel and electric pumps
    ebrahim mohammadi soleimani*, majied Ahmadian, mohsen shokat fadaeiali, ali Keramarzadeh, Abolfazl Mahmoodi Page 4
  • Economic Analysis of Lining in Water Conveyance Canals of Borujen
    Ehsan Tavakoli*, Behzad Ghorbani, Alireza Tavakoli Page 5

    Introduction Considering the vital importance of water in arid and semi-arid regions like Iran, conservation and optimal use of water resources is necessary. In this regard, increasing conveyance efficiency and reducing water losses in distribution canals are very imperative. Low water conveyance efficiency in distribution canals is mainly due to seepage losses in channels. However, since infiltration and seepage cause groundwater recharge, it is sometimes beneficial. Reviewing the literature revealed that some specialists believe lining channels is not justified, technically and economically. Other experts do not reject lining at all, however, suggested that since seepage could help groundwater recharge indirectly, in regions which there is no ponding problem, channel lining should justify from the economic point of view. Additionally, another group of researchers found that although construction costs of lining seems very high, considering its long term benefits for countries with vital need to water in future, such as Pakistan and Iran, is economic. Meanwhile, according to some studies, concrete lining is not economically justified. Based on numerous different and sometimes opposite opinions regarding economic justification of lining, it seems necessary to investigate this issue on regional scale. Thus, the current study aimed at economic analysis of infiltrating water from unlined canal to groundwater and pumping again through wells to surface, in comparison with lining canals and not allowing to seep. Method In order to do this research, the concrete canal of modern Irrigation and Drainage network of Gandoman and Boldaji, Borujen city, Chaharmahal and Bakhtiari province, with 1.3 m width, 1.8 m depth and 6.5 m top width, was chosen as prototype. In order to analyze the lining, this channel was compared with an earth canal, having the same dimensions. Soil texture was determined using hydrometer method, which was obtained as loam that was constant to the depth of water table (6.79 m from soil surface). In order to estimate the amount of seepage in the earth channel, using physical modelling and dimensional similitude relations and considering 0.13 as scale ratio, dimensions and discharges of lined canal have converted to laboratory dimensions at soil mechanics lab of Shahrekord University. Lining lifetime was selected10, 20 and 40 years, and the interest rates were 12, 15 and 18 percent. Results Based on the results, the measured seepage loss in experimental flume of laboratory for the unlined and lined canal was 26 and 11 %, respectively. According to calculations, the price of groundwater in the study region is nearly 0.24 cents per cubic meter. Bearing in mind the low depth of groundwater in the study area (6.79 m), this small value in comparison with the price of surface water (0.31 cents per cubic meter), will justify. According to ‘base unit price index for irrigation and drainage works’, the costs of earth and lined canal construction with length 30000, top width 6.5 and bottom width 1.3 m, was calculated and obtained as 10768 and 91060 M.Rials respectively. It has been noticeable that for construction of both type of canals, half of cutting practices have considered in stony lands and the remaining in earth lands. Furthermore, renovation and maintenance costs for unlined channel were taken into consideration, which have been applied from year 1 to 10, 20, and 40 years. These costs have increased by 15% increase per year (according to the inflation rate). Results showed that increasing the interest rate from 12 to 18% has been resulted in decreasing both NPV and B/C values (except for B/C in concrete-lined canal, 40 years). On the other hand, increasing the lifetime of lining from 10 to 40 (constant interest rate), the NPV and B/C values were increased at first and then were decreased. Investigating the calculations showed that after 30 years, with maximizing the maintenance costs of lined canal, its costs exceed its benefits. Therefore, lining canal with the mentioned properties will not be economical after 30 years. Consequently, with all lifetime values, the earth canal is more economic than the lined one, considering both economic indices and for all interest rates. Therefore, it could be concluded that when the water table depth is 6/79 m and it is possible to pumpage the infiltrated water from well (while the canal is unlined with a loam soil), which are the properties of Borujen region in the current study, lining with concrete is not justified economically.

    Keywords: earth canal, Gandoman, Boldaji irrigation, drainage network, lined canal, physical modelling
  • Efficiency of drip irrigation method in tomato fields under salinity conditions of water resources
    Mehrdad Nowroozi*, Mokhtar Zolfi Bavariani Page 7

    In recent decades, the use of saline water in agricultural production has increased dramatically due to the reduction of fresh water resources. But, safe use of saline water requires proper irrigation management. This experiment was carried out to study the effects of water salinity on yield, water use efficiency and fruit quality of drip irrigated tomatoes in southern Iran (Bushehr) with arid and semi-arid weather during one cropping season (2010-2011). The experiment was designed as split plot in a randomized complete block design (RCBD) with four levels of water salinity (1.1, 3.7, 5.5 and 7.5 dS.m-1) and three levels of irrigation intervals (2, 4 and 7 days) with three replications. According to the results, with increasing irrigation interval from 2 to 7 days, the mean values of crop yield (Y), irrigation water use efficiency (IWUE) and fruit weight (FW) decreased by 20, 19 and 26% respectively. Also, with increasing salinity of irrigation water from 1.1 dS.m-1 to 7.5 dS.m-1, these values decreased by 33, 39 and 32% respectively. In general, under climatic conditions and soil characteristics of the experiment site, yield loss due to water salinity was far lower than that reported in FAO No. 29 paper (Ayers and Westcott, 1985). Also, with increasing irrigation interval and salinity of water, fruit quality increased in terms of the amount of soluble solids (TSS).

    Keywords: Drip, Tape Irrigation, Irrigation interval, Irrigation water salinity, Salt leaching, Water use efficiency
  • Removal of nitrate from groundwater in situ with liquid carbon sources
    faride ansari samany*, seyed hasan Tabatabaei, fariborz abbasi, ebrahim alaiee Page 8

    Limited water resources will be available if the quality is desirable today, by entrance of extensive industrial activities and the use of fertilizers in agriculture, the most important source of human life is in dangerous. According to researchers result, groundwater contamination is often due to poisoning wastewater from industries or from wastewater reservoir resources, one of the most important pollutants is nitrate. Nitrate in nature can be exchange to nitrogen or other forms by microbial activity. There are various methods for removing nitrate from water those most commonly using denitrification substrates. It has been proposed to create a wall of denitrification as a buffer against nitrate contaminated streams as a suitable way to prevent the entering of nitrate into groundwater resources and then surface water resources. In this research, tried to study the effect of nitrification using denitrification substrates that containing a mixture of soil and four carbon sources of liquid including glucose, acetate, ethanol and methanol. In this research, a Plexiglas column was used as a pillar of Marriott and water source and a porous media column filled with soil with a loamy clay texture of 50 cm length and 10 cm in diameter. Potassium nitrate salt was used to make a concentration of 100 mg / L nitrate solution. This study was carried out in two ratios of 1.5 and 3.5 C / N, and the concentration of nitrate was measured until when the pore volume reach to 10 and also concentration of nitrate output was stabilized. This research was carried out at the research laboratory of the Water Engineering Department of Shahrekord University. After about 250 hours from the start of the biological removal process, it was observed that the concentration of output nitrate was almost constant and there is not much change. This phenomenon may be due to the growth of bacteria because of the favorable growth conditions at the beginning of the experiment and the optimal separation of nitrate in a process and, finally, the lack of one of the factors affecting growth due to the maximum growth of bacteria. It is clear that at the end of the experiments and after the concentration of nitrate output from the column was fixed, green algae were observed in parts of the absorption column due to bacterial growth and massification. The removal efficiency of nitrate by glucose, acetate, ethanol and methanol was 97.83%, 97%, 98.66% and 99% respectively, and so methanol had the most efficiency in nitrate removal. Methanol, with 99% removal efficiency, can easily remove nitrate to a concentration of 100 mg / L at groundwater reduce to 2.1 mg per liter. Methanol with 131,000 bacteria had the highest bacterial growth rate in the C / N ratio of 3.5. In fact, by increasing the concentration of carbon, the growth rate of the bacteria increased and the concentration of nitrate decreased. In statistical analysis, both carbon-to-nitrogen ratios showed significant differences in carbon-nitrogen ratios other than glucose-acetate, with a significant difference in the mean carbon concentration. Also a paired test between different concentrations of a carbon source showed that there is a significant correlation between concentrations of 1.5 and 3.5 for each carbon source.

    Keywords: Bacteria, Efficiency Nitrates, Biological, Pollution, Removal rate
  • Effects of Biochar produced from date palm’s leaves on saturated hydraulic conductivity and soil moisture coefficients of sandy clay loam soil
    Paria Nasimi *, Hamidreza Motaghian, Ahmad Karimi Page 9
    Introduction

    Soil organic matter plays an important role in improving physical, chemical, and biological properties of soil in agriculture. Biochar is a carbon-rich organic material that produced by pyrolysis of biomass under oxygen limited conditions and it improves the physical and chemical properties of soils. In recent years, biochar application in soil has been considered as a desirable way to improve physical conditions and increase soil moisture storage capacity. Achieving any of the above objectives depends on the physical and chemical structure of the biochar and its application to the soil.The main objective of this paper was to evaluate the effects of biochar, produced from date palm’s leaves, on the physical properties and hydrological behavior of a sandy clay loam soil by carrying out under greenhouse conditions.

    Methods

    For this aim, Pyrolysis at 400 degree of centigrade at 2 hour in an electric furnace biochars was obtained. Biochars were in powdered form and evenly added to soil (air-dried and passed through a 4 mm sieve) and incubated for 2 months. Therefor with determination of soil moisture content at field capacity, one, three, six and nine months after mixture soil and biochar, were measured hydraulic conductivity (kS) by taking soil samples from the pots. By measuring gravimetric water content at saturation percentage (SP), field capacity (FC) and permanent wilting point (PWP), plant available water content (PAWC) and relative field capacity (RFC) calculated. The Factorial experiment was conducted in a completely randomized design with two factors. The factors of this experiment was including amendment (palm’s leaves and biochar), application level (0, 0.5, 1, and 2% w/w), and time (1, 3, 6, and 9 month incubation).The treatments in this experiment were zero (B0), 0.5 (B1), 1 (B2) and 2% (B3) of biochar and zero (control) (D0), 0.5 (D1), 1 (D2) and 2% (D3) of palm leaves (zero, 18, 36 and 72 ton/ha, respectively) in three replications. Biochar were in powdered form and evenly added to soil (air-dried and passed through a 4 mm sieve) and incubated for 2 months.

    Results

    The results showed a significant difference (P <0.01) between treatments. The effects of soil conditioner on relative field capacity (RFC), permanent wilting point (θPWP) and plant available water content (PAWC) and the effect of application levels on all soil moisture coefficients were significant (P <0.01) and increased these coefficients. The results showed that with increasing palm’s leaves amount, saturation kS of soil is increasing and there is a significant difference (P <0.01) between treatments. The results showed that application of biochar and date palm’s leaves enhanced soil kS. Increasing palm’s leaves from 0.5, 1 and 2 percent w/w (18, 36 and 72 ton ha-1) compared to control increased kS by 24.2, 17.7, and 74.3% respectively. Increasing biochar from 18 to 72 ton ha-1 compared to control increased kS by 29.4 and 41.4 % respectively. The results indicate that date palm leaves have a higher effect on θFC than it is biochar. The results showed that adding of palm’s leaves from 0.5, 1 and 2 % w/w compared to control increased θFC by 12, 11.3 and 12.4 percent, and biochar application increased by 10.3, 9.2 and 8.4 percent in field capacity respectively. Also the results showed that the adding of palm’s leaves from 0.5, 1 and 2 % w/w compared to control increased θPWP by 15.7, 12 and 10 percent, and biochar application increased by 9, 5.6 and 12.6% θPWP respectively. The results showed that the addition of 1% w/w biochar after 9 months and adding 2% w/w of date palm leaves after 6 months produced the highest increase PAWC. The effect of biochar on PAWC indicates that there is a dramatic effect compared with the control, which can be attributed to the extracted surface and the increase of the micro porous pores, which increased water storage. Soil moisture behavior in the high matric suction is under the control of soil texture and its fine pores, but in the low suction it is under the control of the soil structure and its large porosity. There is a significant difference (P <0.01) between the short and long term effect of date palm leaves and biochar on hydraulic conductivity. The effect of biochar supplemental in long-term was more than the effect of palm leaves on increasing kS, while in the short term, the effect of date palm leaves was more than the effect of biochar on increasing kS. The interaction effects between time, type of soil conditioners (biochar and date palm’s leaves) and application levels on PAWC and θPWP were significant (P <0.01) and also (RFC were significant (P <0.05) but their effects on the θFC were not significant. The results revealed that biochar application is considered one of the best methods for soil management and improvement, which increased soil constant organic matter and improve soil physical properties. It is concluded that biochar can be used as a soil amendment in fine textured soil to increase water holding capacity and to improve the drainage and hydraulic conductivity. The results showed that the application of biochar in a sandy clay loam soil could be used as an effective modifier to improve the physical properties of the soil and increase the FC, PWP and PAWC. Increasing the time and amount of biochar in soil resulted in significant changes in physical properties and soil moisture behavior. Unconventional application in sandy clay loam soils, especially in arid and semi-arid regions, due to lack of water resources in these areas, will be a good solution.

    Keywords: biochar, saturated hydraulic conductivity, field capacity, permanent wilting point, plant available water
  • predicting the flow velocity and Examining the effect of the roughness of channels on the flow hydraulics in intakes through using a combination of Artificial Neural Network and Numerical model CFX
    sohrab karimi*, hossein bonakdari, azadeh gholami Page 10
  • Up to journal Iranian Water Researches Journal Determination of some heavy metal's concentration in drinking water distribution system in Zanjan city
    mehdi amanlou, mohammadreza yaftian, abdolhosein parizanganeh, abbasali zamani Pages 19-26
  • Modelling of climatic factors on the loss of groundwater resources with a view to climate change (Case Study: Mashhad plain)
    Elham Kadkhoda, Gholamabbas Fallah Ghalhari*, Mohammad Baaghideh, Seye Alireza Farid Hosseini Pages 27-38
  • Groundwater modeling in Bojnourd aquifer with emphasis on hydro-stratigraphy
    mina tajabadi, ali ziaei, kamran Davary*, azizallah izady Pages 39-50
    Introduction

    Groundwater is the most important water resources in Iran that provides majority of agricultural and urban demands. In recent years, recharge from natural and extended urban areas caused the water table in alluvial Bojnord aquifer to be increased. Transffering water from Karstic aquifers and Shirin Dareh dam intensified this problem specially in fine grain areas of the city. Supplying water from f alluvial aquifer from natural and urban areas, low thickness and discharge potential of alluvial and development of Bojnourd were caused enhancement in the absolute height of water table in the alluvial aquifer. Also in the plains such as Bojnourd plain that are urban uses, According to the mentioned problems, water supply is very important. Therefore, it is essential as much as possible, the current situation and future of Bojnourd alluvial aquifer are identified and management solutions are pursued to eliminate probable problem. The numerical model of groundwater flow can be used as a tool to test the effect of management decisions but usually lack or incomplete information of the hydraulic characteristics of the aquifer causes limitation of use of these models. Nowadays, in the all of the world many studies are ongoing about stratigraphy of aquifers in order to more understanding about the complicated condition in the water flow hydraulics. So it seems that understand of Bojnourd plain aquifer stratigraphy and a better estimation of the hydrodynamic coefficients can help to make decision appropriately to deal with the problems. The aim of this research was to make model of Bojnourd aquifer with emphasis on hydro-stratigraphy. Discuses: According to the variety of Bojnourd aquifer sediments, it cannot be assumed one-layer aquifer; so in order to reduce uncertainties, as well as developing, the conceptual model has been tried to identify natural effects that impact on groundwater system, especially stratigraphy of sediments are introduced to models. The effective factors include geological studies, geophysical sections, boundary of modeling, using of observational wells and determination of the recharge and discharge. In this study, to verify and judge models with different fifteen lithology cross section during aquifer using Rockworks software to obtain the appropriate layer of aquifer that eventually lead to more accurate estimation of three-dimensional lithology model. Rockworks software uses lateral Bending Horizontal method to interpolate lithology of wells log data. Then using three-dimensional model techniques in Rockworks16 software, the three-dimensional model of the aquifer lithology with all available data and information, i.e., logs and geophysical studies has been obtained. Three-dimensional models of geology are as subsurface three-dimensional representative that those can show spatial relations of logs lithology and lenses. Interpolation between the existing logs is not defined as the distance fillers and increase of boreholes in aquifer adds accuracy of these models. The results of three-dimensional models represent three-dimensional groundwater flow model of the aquifer system. The result of lithology modeling of aquifer is composed of four soil textures including of coarse grain, medium-grain, fine grain and very fine grain with four layers and with a thickness of 30m that was imported to version 1.7.10 of GMS software. Conclusion The model was run in steady state for October 1380. In the first step, the initial model coefficients were calculated. After running the model in steady state, the mean square error was 2.77 m. In the next step, the results were better with changes in the soil hydraulic conductivity values and the mean square error was 0.794m after calibration. Heterogeneity and lenses in the aquifer system caused changes in hydraulic conductivities of coarse to very fine-grained sediment, so the identification of aggregation and different genders, lithology of the aquifer with higher accuracy is achieved and consequently, the hydrodynamic coefficients (k,s) will be estimated more precisely. So considering that the aquifer materials are heterogeneity, the hydraulic conductivity values were obtained as 8.1, 6.7, 1.9 and 0.4 for soil textures of Coarse grain, medium grain, fine grain and very fine grain, respectively. Totally Changes of water level were between 1020 to 1080 meter and in the first layer; the northern and eastern parts of aquifer were dry. According to flow budget of the aquifer in one layer model was obtained with acceptable accuracy in multi-layer models, to establish flow budget in accordance with the single-layer model. The calculated flow budget by the model showed that the aquifer layer was in balance with the amount of input and output approximately.

    Keywords: Lithology modeling, Bojnourd, GMS, Hydrodynamiccoefficients, Rockworks
  • Evaluation and comparison of empirical seepage estimation models for irrigation canals (Case study Darab Plain)
    Dr M.A. Shahrokhnia*, Ladan Jokar Pages 51-62
    Introduction

    Water is a valuable asset for agriculture in arid and semi arid regions, worldwide. Reducing water leaks from the irrigation canals will save more water and leads to economic agriculture. Previous studies showed the importance of seepage assessmemt in irrigation canals. Assessment of seepage can be done by practical, theoritical and empirical methods. The review of literature reveals that the direct or practical methods can be more trustable comparing to theoretical or empirical methods or models. Ponding and inflow-outflow methods were widely used as direct or practical methods for seepage evaluation in irrigation canals. Use of empirical seepage formulas needs less cost and time comparing to other type of methods. However, the empirical models have different estimation accuracy and needs to be evaluated more. It is recommended in literature that the empirical models should be calibrated for a specific region before use. Simple empirical models have an estimation error about 15 percent due to direct measured values.

    Methods

    In present study, seepage was measured and compared in three irrigation earth canals in Darab plain using inflow-outflow method and various empirical formulas. These three canals named Hasanabad Canal, Mansuriyeh Canal, and Janatshahr Canal. The soil texture class of these three canals is Loam, Clay Loam and Sandy Loam, respectively. The canal flow velocity was measured using Valeport flow meter in the beginning and the end of three distances of 200 meters along each canal. The discharges were computed by multiplying the mean velocities and flow areas. Difference between the inflow and outflow discharge shows the canal seepage in the selected reaches. The Ingham, Davis-Wilson, Molesworth-Yennidumia, Affengendon, Moritz, Misra, Garg, Indian Punjab, Egyptian Irrigation Department empirical models were used for the study. Mean absolute error, root mean square error, normalized root mean square error, coefficient of variation of root mean square error, and χ2 test were used for the comparison of estimated and measured values. These empirical formulas were calibrated and validated due to the inflow-outflow method.

    Results

    Results showed that the Moritz and Affengendon formulas with mean absolute error of 49% and 1445% percent had the least and most difference with inflow-outflow method before calibration. The error of estimation of the other formulas was about 125%. The highest estimated seepage was in the Affengendon formula, while the lowest was in the Ingham and Indian Punjab formulas. Comparison of estimated seepage values using t-test shows that the difference between the empirical seepage formulas is significant at 95% confidence probability. However, the difference between Moritz and inflow-outflow methods, Ingham and Molesworth-Yennidumia, Ingham and Indian Punjab, Molesworth-Yennidumia and Indian Punjab formula, Garg and Davis-Wilson formula was not significant at 95% confidence probability. The seepage estimation error of uncalibrated Ingham formula was about 95%, while for calibrated formula was less than 11 percent. The error of seepage estimation using uncalibrated Moritz and Molesworth-Yennidumia formulas were about 52 and 96 percent. This error for the uncalibrated Indian Punjab, Affengendon, Egyptian irrigation department, Garg and Misra formulas were about 95, 1220, 90, 92 and 68 percent, respectively. Results also showed that the error of calibrated Ingham, Molesworth-Yenidumia, Moritz, Davis-Wilson and Affengendon models, was about 7, 8, 9, 10, 10 percent comparing to inflow-outflow method, respectively. After these five formulas, the error of estimation of Garg, Egyptian, Misra, and Indian formulas were 17, 18, 20 and 20 percent, respectively. In order to validate the evaluated empirical formulas, some statistical parameters such as root mean square error, normalized root mean square error, coefficient of variation of root mean square error, and χ2 test were used. Results shows that the evaluated empirical formulas can be sorted from the better validated to the worse validated as Ingham, Molesworth-Yennidumia, Davis-Wilson, Moritz, Affengendon, Garg, Egyptian Irrigation Department, Misra and Indian Punjab. The χ2 values of the evaluated empirical formulas were 0.077 for Ingham formula to 0.757 for Misra formula. It can be concluded from this research that the uncalibrated empirical seepage formulas had significant difference to the inflow-outflow direct method. However, all of the calibrated formulas had a mean relative error less than 20 percent comparing to inflow-outflow method. Ingham formula was the best formula due to less calibration error. Moritz and Misra formulas had the best and worst validation condition in the study, respectively.

    Keywords: Seepage, empirical formula, Darab, irrigation canal
  • ا Evaluation of the effect of compaction percent and the amount of fine aggregate of the soil on permeability coefficient and steady and unsteady seepage flow through the levee
    Fouad Kilanehei*, hamid reza monemi, amir mahjoob Pages 63-74

    Levees are man-made embankments built to prevent rivers from overflowing their banks. A levee is a naturally elongated ridge or artificially constructed fill or wall that regulates the water level. It is usually earthen and often parallel to the course of a river in its floodplain or along low-lying coastlines. The levee construction is a common and very old method of river flood control recently used considerably as an engineering operation to reduce or prevent the detrimental effects of floodwaters. It can be used either alone or together with other methods to minimize the floodwater damage. Engineered earthen levees are of three general types: compact, semi-compact, and uncompact; the former are usually and traditionally used in areas of high property values, high populations, high land use, or in controlled compaction, steep-sloped embankments utilized on good foundation conditions during construction. The semi-compact or uncompact levees are generally used in low value, poor foundation areas or those with high rainfall during the construction season. Compared to other floodwater control methods, levees are more efficient because they are not only quite cost-effective, but also provide more factor of safety for slope stability. Artificial levees are aimed at preventing the adjoining countryside flooding and slowing the waterways' natural course changes to provide reliable shipping lanes for maritime commerce over time; they also confine the river flow causing higher and faster water flow. Levee construction materials should be coarse enough to withstand the erosion caused by the flowing water, their shear strength should be enough to satisfy the levee's slope stability, and they should be adequately impermeable meaning that they should also contain fine aggregates to prevent the extra seepage that has undesirable effects on the levee's slope stability; therefore, making specific arrangements to reduce repercussions deems necessary. Massive constructions that require large amounts of materials need to use the available on-site materials to reduce the transportation distance and hence the project construction cost; using on-site materials is a significant advantage the levee construction enjoys. As mentioned before, since the levee construction needs both coarse- and fine-grained materials to reduce permeability, the best choice can be the coarse-grained soil containing clay; therefore, both GC (clayey gravel) and SC (clayey sand) soil types take priority over any other types. Hence, evaluating the amount of the soil fine aggregates and the effects of compaction percentage on the permeability coefficient and on other strength parameters to meet the economic, speed, and time requirements of the levee construction is quite important. This research studies the effects of compaction percentage and the amount of fine aggregates on the SC soil permeability and on the steady and unsteady seepage flow through levees. Accordingly, three levee samples A, B, and C (from Mehran River borrow area) with respectively 12.8, 20, and 28.4% fine aggregates and 60, 70, 85, and 100% compaction have been selected to carry out the permeability tests. Results of tests with different compaction and fine aggregate percentages showed that an increase in the percent compaction of each sample (from 60 to 100, 70 to 100, and 85 to 100) decreased the permeability coefficient 25, 14.3, and 8.91 times, respectively. At every compaction percentage, sample A's permeability coefficient was 1.2 times that of sample B and 1.69 times that of sample C and that of sample B was 1.41 times that of sample C. Next, using the numerical modeling, both the flow rate (in the steady state) and phreatic line (in the unsteady state) through the levee were studied with different compaction percentages and the results showed that in simulating the unsteady seepage through the levee the phreatic line did not intersect the downstream slope and was significantly far from it. The results of this research can be used to either design or construction of the levee; furthermore, it can used to analyze the effect of the soil compaction percent on permeability parameter during construction of levees.

    Keywords: levee, steady, unsteady flow, permeability coefficient, compaction percentage, fine grained percentage, numerical modeling