فهرست مطالب

پژوهش آب ایران - پیاپی 35 (زمستان 1398)

مجله پژوهش آب ایران
پیاپی 35 (زمستان 1398)

  • 204 صفحه،
  • تاریخ انتشار: 1398/11/23
  • تعداد عناوین: 15
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  • امیر حمزه حقی آبی*، بهزاد جوادی علمی، الهه حسینیان صفحات 1-10

    با توجه به رشد روزافزون پروژه های عمرانی در سالهای اخیر، نیاز به استفاده از مصالح شن و ماسه جهت احداث ابنیه و راه ها بیشتر شده است. همچنین در دسترس بودن و سهولت برداشت و استحصال مصالح رودخانه ای به نسبت مصالح کوهی منتج به برداشت بی رویه شن و ماسه از بستر رودخانه ها شده است. که منجر به مشکلات متعددی از قبیل فرسایش بستر و کناره-های رودخانه را ایجاد نموده و پایداری سازه های طولی و متقاطع در رودخانه ها را تهدید می نماید و منجر به افت کیفیت آب رودخانه ها و تاثیرات مخرب بر اکوسیستم حاکم بر آنها می شود. در این تحقیق، با استفاده از نرم افزارهای HEC-RAS و FLUVIAL-12 و براساس روابط مختلف انتقال رسوب، تغییرات هیدرولیکی و مورفولوژیکی رودخانه خرم آباد بر اثر برداشت مصالح رودخانه ای بررسی شده است. نتایج این بررسی نشان می دهد در تغییر شکل بستر بیشترین تغییرات نسبت به بستر موجود از معادلات انتقال رسوب میر- پیتر-مولر (1948) و گراف (1970) و کمترین تغییرات مربوط به معادلات یانگ (1973و1984) و انگلند و هانسون (1967) می باشد. همچنین مشخص گردید که در بازه هایی که مصالح بستر به علت تخلیه نخاله های ساختمانی و کارگاهی از نوع درشت دانه باشد، رودخانه تمامی انرژی خود را صرف فرسایش کناره ها نموده و باعث تعریض بیش از پیش رودخانه می گردد.

    کلیدواژگان: فرسایش کناری، برداشت مصالح رودخانه ای، لایه محافظ، HEC RAS، FLUVIAL
  • لمیا نیسی*، محمد الباجی، سعید برومند نسب صفحات 17-25

    بحران کمبود آب موضوعی است که باعث ایجاد چالش در مصرف درست و بهینه منابع آب شده است. در این تحقیق تصمیم گیری چند معیاره (MCDM) جهت استفاده درست از منابع آب بکار گرفته شد. یکی از روش های رایج در تصمیم گیری چندمعیاره استفاده از روش تصمیم گیری تحلیل سلسله مراتبی است. این روش با درنظرگرفتن معیارها و زیرمعیارهایی و باتوجه به اولویت بندی معیارها به روش ساعتی (Saaty) و محاسبه وزن معیارها و زیرمعیارهای انتخابی به روش میانگین هندسی به سیستم آبیاری امتیاز می دهد. در این تحقیق دو معیار اقتصادی-اجتماعی و فیزیک مزرعه برای سیستم های آبیاری سطحی و تحت فشار در منطقه ی دشت ایذه درنظرگرفته شد. معیار اقتصادی-اجتماعی به 4 زیرمعیار تجهیزات موجود در منطقه، هزینه، مهارت کارگران و فرهنگ و معیار فیزیک مزرعه به 5 زیرمعیار آب، اقلیم منطقه، خاک، توپوگرافی و محصول تقسیم بندی شدند. در ابتدا معیارها و زیرمعیارها با توجه به جدول امتیازبندی سلسله مراتبی از 1 تا 9 امتیازدهی شدند و پس از محاسبه ی میانگین هندسی وزن نهایی معیارها و زیرمعیارها برای هر گزینه محاسبه شد و سپس درنهایت امتیازها وارد سیستم اطلاعات جغرافیایی می شوند و نقشه های خروجی برای هر سیستم بدست می آیند. درنهایت سیستم آبیاری سطحی بعنوان سیستم مناسب دشت ایذه انتخاب شد.

    کلیدواژگان: GIS، AHP، اولویت بندی، تصمیم گیری، آبیاری
  • مریم میربیک سبزواری*، حسن ترابی پوده، حجت الله یونسی صفحات 27-37

    بهره برداری بهینه از مخازن یکی از موضوعات مهم در مدیریت منابع آب سطحی بوده و روش های بهینه سازی مختلفی در این زمینه استفاده شده اندکه پرکاربردترین آنها الگوریتم های فراکاوشی می باشند. در تحقیق حاضر الگوریتم جستجوی هارمونی (HSA) برای تعیین بهره برداری بهینه از سیستم های چندمخزنه مورد ارزیابی قرار گرفت. مقدار بهینه مطلق با استفاده از یک مدل برنامه ریزی خطی (لینگو) به دست آمد. HSA ابتدا برای بهینه سازی یک سیستم چهار مخزنه به کار گرفته شد. مقدار تابع هدف با استفاده از لینگو برابر 308.2915 و با استفاده از HSA برابر 308.2900 محاسبه شد که 0.0005 درصد با بهینه مطلق اختلاف داشت. پس از موفقیت الگوریتم HS در حل سیستم چهار مخزنه، یک سیستم ده مخزنه در نظر گرفته شد. مقدار تابع هدف با استفاده از لینگو برابر 1194.4 و با استفاده از HSA برابر 1193.1 محاسبه شد که 0.1 درصد با بهینه مطلق اختلاف داشت. پس از موفقیت الگوریتم در حل مسائل چندمخزنه بهره برداری از مخزن سد دز برای یک دوره میان مدت (10 سال آماری) مدنظر قرار گرفت که جواب الگوریتم %1.31 با جواب بهینه مطلق اختلاف داشت. بنابراین می توان نتیجه گرفت که این الگوریتم توانایی حل مسائل بهینه سازی سیستم های واقعی را نیز دارد.

    کلیدواژگان: الگوریتم جستجوی هارمونی، الگوریتم فراکاوشی، برنامه ریزی خطی، بهره برداری چند مخزنه، بهینه سازی
  • فرشته اسدی*، علیرضا عمادی، رامین فضل اولی صفحات 39-49

    پرش هیدرولیکی یکی از پدیده‏های مهم جریان آب در کانال‏ها بوده که به تناسب شدت پرش، با استهلاک انرژی محسوسی روبرو خواهد شد. استفاده از بسترهای زبر، عامل موثری در کاهش هزینه‏ های حوضچه‏ های استهلاک انرژی می‏باشد. بنابراین هدف محققین، به‏ کارگیری بسترهای زبر در کف حوضچه ‏های آرامش و بررسی تاثیر آن بر ‏مشخصات پرش هیدرولیکی بوده است. در این پژوهش، به بررسی آزمایشگاهی اثر زبری بستر بر مشخصات پرش هیدرولیکی در فلومی به طول 12، عرض 0.5 و ارتفاع 0.7 متر در محدوده اعداد فرود 5/5 تا 9 پرداخته شد و از 24 بستر زبر مکعبی با آرایش زیگزاگی و ردیفی، ردیف ‏ها و زاویه ‏های مختلف استفاده گردید. نتایج نشان داد که عمق و طول نسبی (نسبت عمق ثانویه به اولیه و نسبت طول به عمق اولیه پرش) در آرایش زیگزاگی در مقایسه با ردیفی نسبت به بستر صاف کاهش بیش‏تری دارد. ضریب نیروی برشی که عامل اصلی کاهش عمق و طول نسبی پرش می‏باشد در هر دو آرایش 6 درصد بیش‏تر از بستر صاف محاسبه شد. در نهایت روابطی برای برآورد عمق نسبی و طول نسبی به ازای اعداد فرود، استخراج گردید. هم‏چنین اثر آرایش‏ ها در سطح معنی‏ داری 5 درصد برای همه بسترها بر عمق و طول نسبی به اثبات رسید.

    کلیدواژگان: استهلاک انرژی، اعداد فرود، بسترهای زبر، طول نسبی
  • مرضیه محسنی*، جمال محمد ولی سامانی، سید علی ایوب زاده صفحات 51-61

    توجه روزافزون به مسائل زیست محیطی در مدیریت رودخانه ها، موجب گسترش تحقیقات در زمینه بررسی پارامترهای موثر بر هیدرولیک جریان و انتقال- انتشار آلودگی و رسوب در رودخانه ها شده است. وجود پوشش گیاهی در بسیاری از رودخانه ها، تاثیر قابل توجهی بر هیدرولیک جریان، مورفولوژی و فرآیندهای انتقال و انتشار رسوب و آلودگی دارد، با این وجود مطالعه کمی در زمینه تاثیر پوشش گیاهی بر ضرایب انتشار و نرخ رسوبگذاری انجام شده است. هدف از تحقیق حاضر، برآرود ضرایب انتشار و نرخ رسوبگذاری در کانال مرکب با وجود پوشش گیاهی صلب غیرمستغرق در سیلابدشت است، بدین منظور توسعه مدل دوبعدی جریان و انتقال رسوب در کانال مرکب با وجود پوشش گیاهی در سیلاب دشت، مورد توجه قرار گرفته است. به منظور برآورد توزیع سرعت متوسط عمقی از مدل دوبعدی شیونو و نایت؛ که با افزودن نیروی کشانه به معادله مومنتم اصلاح شده، استفاده گردیده است. برای حل این مدل بایستی 4 پارامتر ضریب کشانه، فاکتور اصطکاکی، ضریب لزجت گردابه ای، پارامتر جریان ثانویه در کانال اصلی و سیلاب دشت محاسبه شود. معادله انتقال انتشار دوبعدی به روش حجم محدود حل شده است. ضرایب انتشار و نرخ رسوبگذاری بر اساس کمترین خطای مشاهداتی میان داده های آزمایشگاهی و نتایج مدل عددی توسعه داده شده در این مطالعه، برآورد شده اند. مدل دو بعدی توسعه داده شده برای مطالعه زانگ (2011) اجرا و مقدار نرخ رسوب گذاری را با اختلافی حدود 22% بیشتر از مقدار آزمایشگاهی برآورد نمود.

    کلیدواژگان: پوشش گیاهی، معادله انتقال، انتشار، کانال مرکب، ضرایب انتشار، مدل دوبعدی سرعت متوسط عمقی، نرخ رسوب گذاری
  • یعقوب دین پژوه*، رعنا صدیق پور صفحات 63-72

    هدف این مطالعه، بررسی روند تغییرات زمانی و مکانی مشخصه های تعداد روزهای با بارش در پنج دسته متمایز شامل کمتر از 1 میلیمتر، 1 تا 5 ، 5 تا 10 ، 10 تا 15 و بیش از 15 میلیمتر در روز در حوضه ی دریاچه ارومیه می باشد. برای ای منظور، از اطلاعات 25 ایستگاه با حداقل 10 سال آمار منتهی به 2015 و از روش های مان -کندال (MK) و تخمین گر سن (β) استفاده شد. برای تفسیر مکانی روند هر یک از مشخصه ها نقشه هایی تهیه شد. نتایج نشان داد که مقدار β در 84% ایستگاه ها، برای مشخصه اول مثبت بوده و شیب روند در پنج ایستگاه در جنوب حوضه، دارای روند صعودی معنی دار (05/0>α) بود. روند دسته دوم، در 15 ایستگاه نزولی و در پنج ایستگاه معنی دار بود. β برای مشخصه ی سوم در 44% ایستگاه ها منفی و در 4 ایستگاه معنی دار (10/0>α) بود. در 32% ایستگاه ها روند نزولی برای دسته 10 تا 15 میلیمتر مشاهده شد که در سه ایستگاه معنی دار (10/0>α) بود. مقدار β برای تعداد روزهای با بارش بیش از 15 میلیمتر در 52% ایستگاه ها مثبت بود.

    کلیدواژگان: تخمین گر سن، حوضه ی دریاچه ارومیه، روند، مان کندال
  • محمد هادی راد*، مهدیه تجملیان، مهدی سلطانی صفحات 73-81

    تاثیر آبیاری با پساب بر عملکرد و برخی شاخص های عملکردی سه گونه اکالیپتوس شاملEucalyptus microtheca Eucalyptus camaldulensis و Eucalyptus rubidaدر شرایط لایسیمتری مورد بررسی قرار گرفت. آزمایش به صورت فاکتوریل و در قالب طرح کاملا تصادفی با سه تکرار اجرا گردید. تیمارهای آبیاری در سه سطح شاهد یا آب معمولی،50 درصد آب معمولی و 50 درصد پساب و آبیاری کامل با پساب اعمال گردید. نتایج نشان داد که تیمارهای مختلف آبیاری تاثیر معنی داری (p<0.001) بر ارتفاع، رشد قطری، طول، عرض و سطح برگ، سطح برگ ویژه، گنجایش نسبی آب برگ، وزن خشک اندام هوایی، محتوی نسبی کلروفیل و کارایی مصرف آب، داشتند. با افزایش میزان پساب مصرف شده، ویژگی های ذکر شده در هر سه گونه بهبود یافت. بیشترین قطر تنه و طول و عرض برگ در تیمار 100 درصد پساب به ترتیب 47/8 ، 15/12 و 38/2 میلی متر بود. همچنین بیشترین محتوی کلروفیل برگ با 42/55 درصد مربوط به تیمار 100 درصد پساب و کمترین مقدار با 12/18 درصد مربوط به تیمار شاهد بود. بیشترین کارایی مصرف آب در تیمار 100 درصد پساب اتفاق افتاد و بالغ بر 4 برابر تیمار شاهد بود. همچنین از بین سه گونه مورد بررسی گونه E. camaldulensis از رشد بیشتر و کارایی مصرف آب بالاتری برخوردار بود.

    کلیدواژگان: Eucalyptus microtheca، camaldulensis Eucalyptus، Eucalyptus rubida، شاخص های فیزیولوژی، شاخص های مورفولوژی
  • سید نعیم امامی*، اعظم مومزایی صفحات 83-92

    در این تحقیق، برای مکانیابی بندزیرزمینی در حوزه آبخیز مرغملک - شهرکرد، رویکرد تصمیم گیری چند معیاره استفاده شد. ابتدا، محدوده های مناسب برای بند زیرزمینی با معیارهای حذفی و با استفاده از منطق بولین، مشخص شد. محورهایی که از نظر طول و سطح مخزن برای ایجاد بند زیرزمینی مناسب بود و کوره قنات را قطع نمی کنند، شناسایی شد. در مرحله بعد، این تعداد نقاط پیشنهادی با کمک فرآیند تحلیل سلسله مراتبی اولویت بندی شدند. برای این منظور، از چهار معیار وضعیت آب، مخزن بند، محور بند و عوامل اقتصادی- اجتماعی استفاده شد. با استفاده از جدول تعیین ارزش نظری و بر مبنای مقایسه جفتی و با توجه به نظرات کارشناسی، اهمیت و ارزش شاخص تعیین شد. پنج سناریو در ارتباط با اولویت بندی محورها در نظر گرفته شد. نتایج نشان داد که معیار هیدرولوژی با وزن51/0مهمترین معیار و بعد از آن معیار عوامل اقتصادی-اجتماعی با وزن 30/0 دومین معیارمهم در مکانیابی بند زیر زمینی است. بهترین محورها برای احداث بند زیرزمینی، در بستر آبرفتی رودخانه های با جریان زیرسطحی بالا، حجم مخزن زیاد، همچنین حجم رواناب بالا و شیب پایین و نفوذپذیری بالا بوده است. 15 محور مناسب برای احداث بندزیرزمینی در حوزه آبخیز مرغملک - شهرکرد شناسایی شد. روش ارائه شده در این تحقیق قادر است با دقت بالایی و از طریق بررسی های تفصیلی و دقیق و در نظر گرفتن عوامل موثر بر بندهای زیرزمینی، مکان های مناسب برای احداث بندهای زیرزمینی را تعیین کند.

    کلیدواژگان: مدل تصمیم گیری چند شاخصه، منطق بولین، مکان یابی، بندهای زیرزمینی، شهرکرد
  • نیازعلی ابراهیمی پاک*، عبدالمجید لیاقت، اصلان اگدرنژاد، محسن احمدی صفحات 93-102

    وجود سطح ایستابی نزدیک زمین یکی از مشکلات مناطق خشک و نیمه خشک است. این امر بر تولید محصولات کشاورزی اثر می گذارد؛ بنابراین پایش نوسانات آن بر اثر آبیاری و زهکشی اهمیت می یابد. تحقیق حاضر با هدف ارزیابی سه مدل ENDRAIN، DRAINMOD و SWAP در تخمین سطح ایستابی در مزارع نیشکر کشت و صنعت امیرکبیر واقع در استان خوزستان انجام شد. بدین منظور داده های سطح ایستابی در یک واحد زراعی با وسعت 25 هکتار مورد استفاده قرار گرفت. نتایج نشان داد که آماره های RMSE، EF، CRM و R2 برای مدل DRAINMOD در مرحله صحت سنجی به ترتیب برابر 19/13 (سانتی متر)، 84/0، 008/0- و 85/0 بود. این آماره ها برای مدل SWAP در مرحله صحت سنجی به ترتیب برابر 00/17 (سانتی متر)، 75/0، 020/0 و 82/0 به دست آمدند. آماره های مذکور برای مدل ENDRAIN نیز به ترتیب برابر با 10/28 (سانتی متر)، 80/2-، 603/0 و 91/0 تعیین شد. بنابراین مدل DRAINMOD با توجه به ضریب تبیین بالاتر و خطای کمتر به عنوان مدل مناسب تری برای پیش بینی سطح ایستابی در این منطقه معرفی می شود. بنابراین مدل DRAINMOD با توجه به ضریب تبیین بالاتر و خطای کمتر به عنوان مدل مناسب تری برای پیش بینی سطح ایستابی در این منطقه معرفی می شود. بنابراین مدل DRAINMOD با توجه به ضریب تبیین بالاتر و خطای کمتر به عنوان مدل مناسب تری برای پیش بینی سطح ایستابی در این منطقه معرفی می شود.

    کلیدواژگان: پایش آب زیرزمینی، سطح ایستابی کم عمق، نوسان سطح ایستابی، مزارع نیشکر
  • هومن حاجی کندی*، صابر ابراهیمیان، محمود شفاعی بجستان، سعید جمالی، ابراهیم اسدی صفحات 103-112

    در تحقیق حاضر تاثیر شیب جانبی کانال بر تنش برشی بستر و مشخصات پرش هیدرولیکی از جمله استهلاک انرژی، طول پرش و نسبت اعماق مزدوج مورد بررسی قرار گرفته است. بدین منظور ابتدا مدل عددی فلو تری دی به کمک نتایج آزمایشگاهی منتشر شده برای کانال ذوزنقه ای با شیب بدنه 45 درجه واسنجی شده، مدل آر ان جی از بین مدلهای آشفتگی انتخاب گردید و سپس مدل برای شرایط هیدرولیکی متفاوت (عدد فرود بین 5/1 تا 12) و دو شیب 60 و 75 درجه بدنه کانال اجرا و نتایج بدست آمد. نظر به اهمیت تنش برشی، که معمولا در مطالعات آزمایشگاهی بررسی نمی شود، در این مطالعه علاوه بر مشخصات پرش، توزیع تنش بستر در هر سه کانال محاسبه گردید. نتایج حاصل رفتار متفاوت پرش و تنش برشی در فلوم ذوزنقه ای با شیب 45 درجه را نشان میدهد بطوریکه عدم تقارن پرش در آن بسیار ملموس بوده و تمرکز تنش برشی در سمت چپ فلوم مشاهده می شود. مقایسه نمودارهای تنش برشی حاکی از کاهش چشمگیری مقادیر تنش برشی بعد از پرش بوده که بیشترین آن مربوط به فلوم با شیب جانبی 45 درجه است. همچنین مشخص گردید که با افزایش شیب جانبی میزان تنش برشی و نسبت اعماق مزدوج افزایش و میزان افت انرژی و طول پرش کاهش می یابد.

    کلیدواژگان: افت انرژی نسبی، پرش هیدرولیکی، دینامیک سیالات محاسباتی، تنش برشی، کانال ذوزنقه ای، مدل Flow3D، مدل آشفتگی RNG
  • زهره ابراهیمی خوسفی*، عباسعلی ولی، رضا قضاوی، محمد خسروشاهی صفحات 113-123

    در پژوهش حاضر میزان تغییرات سطح آب زیرزمینی و حجم ذخایر آبی آبخوان های کوهپایه سگزی و مهیار جنوبی طی سال های 71-1370 تا 92-1391 مورد بررسی قرار گرفت. بدین منظور متوسط سطح تراز ایستابی آبخوان ها با استفاده از روش تیسن محاسبه گردید. از مقادیر به دست آمده، جهت محاسبه ی میانگین سطح تراز ایستابی در محدوده ی غربی تالاب گاوخونی استفاده گردید. سپس تغییرات سطح ایستابی ، تغییرات حجم ذخیره ی آبخوان ها و همچنین متوسط تغییرات پارامترهای مذکور برای نواحی غربی محدوده تالاب محاسبه گردید. روند تغییرات سطح ایستابی با استفاده از آزمون من کندال مورد بررسی قرار گرفت. در نهایت، به منظور تعیین اثرپذیری تالاب از آبخوان های اطراف و یا اثرگذار بودن آن بر آبخوان ها، اقدام به انجام عملیات میدانی و تهیه نقشه سطح تراز ایستابی گردید. نتایج نشان داد که سطح ایستابی آبخوان کوهپایه سگزی و مهیار جنوبی تا پایان دوره آماری مورد مطالعه به ترتیب 75/2 و 83/12 متر و حجم ذخایر آبی آبخوان های مذکور حدود 160 و 300 میلیون متر مکعب کاهش یافته است. به طور کلی متوسط سطح تراز ایستابی محدوده تالاب گاوخونی در این مدت به اندازه 8/7 متر و متوسط حجم ذخایر آبخوان ها 229 میلیون مترمکعب کاهش داشته است. نتایج حاصل از بررسی آزمون من کندال نیز کاهش معنی دار سطح تراز آب زیرزمینی آبخوان های محدوده مطالعاتی را در این بازه ی زمانی نشان داد. همچنین نتایج نشان داد که تالاب گاوخونی نقش تغذیه کنندگی برای آبخوان های اطراف خود داشته است.

    کلیدواژگان: من کندال، تیسن، کوهپایه سگزی، مهیارجنوبی، اصفهان
  • سید سجاد رضوی کهنموئی*، کامران داوری، مهری شاهدی، فاطمه طالبی، عطا جودوی صفحات 125-136

    مطالعات بیلان آب یکی از ارکان مدیریت و سیاست‏گذاری در مدیریت منابع آب و ابزاری برای ارزیابی کمی ذخایر منابع آب در حوضه و تغییرات این منابع در اثر فعالیت‏های انسانی است. در حال حاضر برای محاسبه بیلان در ایران مشکلاتی وجود دارد. پرهزینه و زمان‏بر بودن تامین داده ‏های موثق برای برآورد بسیاری از مولفه‏ های بیلان (در سطح حوضه) و اتکا به روش ‏های تجربی (تخمینی) برای برآورد این مولفه ‏ها، و از طرفی نبود روش‏ های تجربی واسنجی شده و بومی برای برآورد دقیق ‏تر عوامل بیلان برخی از این مشکلات است. در بسیاری از کشورها از مدل ‏هایی در برنامه‏ ریزی منابع آب استفاده می‏شود که در کشورهای دیگر با شرایط اقلیمی متفاوت تولید شده‏اند. بنابراین قبل از استفاده از این مدل‏ها باید به ساختار مدل توجه شود. هدف از این مطالعه بررسی مدل ها و روش هایی است که در دنیا برای محاسبات بیلان آب، به کار گرفته می شود. با توجه به مزیت مدل های مفهومی در مقایسه با مدل های فرایند- محور و مدل های داده-محور در مدل سازی بیلان آب و همچنین با توجه به ضعف مدل‏ های یکپارچه در شبیه‎سازی تغییرات پارامترها در سطح حوضه آبریز، تمرکز اصلی مقاله بر روی مدل های مفهومی در حالت های توزیعی و نیمه توزیعی است. این مدل ها متفاوت از مدل های کاملا توزیعی فرایند محور بوده و قابلیت کاربرد بیشتری را در حوضه های متوسط و بزرگ مقیاس (که داده های هیدروژئولوژیکی کافی وجود ندارد) دارند. سعی شده است با بررسی مدل های مختلف بیلان بتوان یک مدل اجرایی برای مناطق خشک و نیمه خشک ایران انتخاب کرد. با توجه به شرایط موجود، در مناطقی که هنوز اطلاعات دقیق و موثق هیدرولوژیکی برای واسنجی مدل ها وجود ندارد (مانند اکثر حوضه های آبریز در ایران) برای تولید، توسعه، واسنجی و بومی سازی یک مدل بیلان که هدف آن تخمین موجودیت آب در یک حوضه است، می بایست ابتدا مدل های ساده تر مد نظر قرار گیرد و نه مدل هایی که تحت عنوان مدل شبیه سازی هیدرولوژیکی شناخته می شوند. در این مطالعه تعدادی از مدل ها، براساس برخی از معیارها از جمله عدم پیچیدگی، دسترسی به داده ها و کد، دسته بندی و از نظر خروجی ها، مقیاس زمانی و مکانی و ساختار مدل بیلان مقایسه شده اند.

    کلیدواژگان: بیلان آب، خشک و نیمه خشک، مدل های توزیعی، شبه توزیعی و نیمه توزیعی، مدل های ریاضی، مفهومی
  • سمیرا رضاپوریان*، محمد مهدی احمدی، کوروش قادری صفحات 137-147

    هندسه هیدرولیکی پایین دست کانال های آبرفتی در شرایط دبی لبریز توسط پارامترهای عرض کانال، عمق متوسط جریان، شیب کانال و سرعت متوسط جریان تعریف می شود. این متغیرها توسط پارامترهای مستقل دبی جریان، قطر متوسط ذرات بستر و پارامتر شیلدز قابل تعریف هستند. در این تحقیق عملکرد مدل هوشمند داده محور GMDH و مدل هوشمند مختلط GMDH-HS برای بیان بهترین رابطه بین متغیرهای هندسه هیدرولیکی پایین دست کانال های آبرفتی بر حسب پارامترهای مستقل مورد بررسی قرارگرفته است. 880 سری داده اندازه گیری شده از رودخانه ها و کانال های آزمایشگاهی تحت شرایط جریان و بسترهای متفاوت جمع آوری شد، که 498 سری داده برای آموزش و مابقی برای ارزیابی مدل ها استفاده گردید. صحت سنجی مدل های توسعه داده شده با استفاده از سری زمانی مکی-گلاس انجام گرفت. ارزیابی عملکرد مدل های توسعه داده شده با استفاده از شاخص های آماری CE، MSRE، MAPE، RMSE، RB و R2 حاکی از عملکرد رضایت بخش هر دو مدل در پیش بینی هندسه هیدرولیکی پایین دست کانال های آبرفتی است. بررسی دقیق تر و مقایسه نتایج دو مدل برای هر چهار متغیر نشان داد که مدل GMDH-HS در پیش بینی هندسه هیدرولیکی پایین دست کانال های آبرفتی عملکرد بسیار بالاتری داشته است.

    کلیدواژگان: جستجوی هارمونی، دسته بندی گروهی داده ها، مدل هوشمند مختلط، مورفولوژی رودخانه های آبرفتی هیدرولیک
  • موسی محمدپور*، علی افروس، حسین بابازاده، ابراهیم پذیرا صفحات 147-155

    فلزات سنگین جزء آلوده کننده های خطرناک برای سلامتی انسان بوده که معمولا توسط پسابهای صنعتی وارد محیط آبی می شوند. در این آزمایش، از سه دوز جاذب، پوسته شلتوک برنج و کربن فعال، نه غلظت اولیه فلز سرب، سه pH متفاوت و در چهار زمان تماس برای حذف یون سرب از محیط آبی استفاده شد. بررسی زمان تعادل در غلظتهای مختلف نشان داد که با کاهش غلظت اولیه ی محلول، زمان تعادل برای هر دو جاذب کاهش یافت. زمان تعادل برای هر دو جاذب با هم برابر و مقدار آن 30دقیقه به دست آمد. بررسی کارایی جذب در غلظتهای مختلف نشان داد که با کاهش غلظت اولیه ی محلول، کارایی جذب برای هر دو جاذب افزایش و به هم نزدیک می شوند. بهترین وضعیت حذف سرب از دو جاذب پوسته برنج و کربن فعال در 6=pH به ترتیب 77/4و 94/4 درصد در جرم جاذب 1گرم بر لیتر به دست آمد. کربن فعال، توانایی حذف سرب بالاتری از محیط آبی را نشان داد. برازش پارامترهای همدمای جذب لانگمویر و فرونیدلیچ بر داده های جذب نشان داد که فرآیند جذب سطحی از هر دو ایزوترم فروندلیچ و لانگمویر تبعیت کرد، اما مدل فرونیدلیچ داده های آزمایش را بهتر توصیف کرد.

    کلیدواژگان: شلتوک برنج، کربن فعال، زمان تماس، تصفیه فاضلاب صنعتی
  • مریم یعقوبی*، سید حسن طباطبایی، طاهره ریسی، رسول شادنیا صفحات 159-169

    فرآیند های زیادی موجب تشدید آلودگی مربوط به نیترات در آب های زیرزمینی می شوند. آبشویی نیترات از زمین های کشاورزی علاوه بر زیان های اقتصادی ناشی از استفاده بیشتر از کود های نیتراته، لطمات جبران ناپذیری به محیط زیست وارد می کند. کاربرد بایوچار در خاک به عنوان یک روش مطلوب برای کاهش آبشویی عناصر غذایی خاک مطرح شده است. بدین منظور، این پژوهش با هدف کاربرد بایوچار برگ درخت خرما بر کاهش آبشویی نیترات از خاک و بررسی تاثیر تغییرات افزایشی وکاهشی ضریب انتشار و ضریب ایزوترم جذب بر منحنی رخنه و پروفیل توزیع نیترات انجام شد. در این پژوهش از مدل HYDRUS- 1D برای مقایسه تغییرات منحنی رخنه و پروفیل توزیع نیترات در نقاط مختلف نمونه خاک استفاده شد. پارامترهای هیدرولیکی بایوچار از طریق اندازه گیری به دست آمدند. نتایج نشان داد که افزایش مقدار عددی ایزوترم جذب بایوچار باعث می شود منحنی رخنه نیترات به سمت راست کشیده شده و غلظت نیترات خروجی کاهش یابد؛ در حالی که با افزایش ضریب انتشار طولی بایوچار، کاهش غلظت نیترات خروجی کاهش یافته و منحنی رخنه به سمت چپ کشیده می شود. . وجود لایه بایوچار، مقدار نیترات توزیع شده در انتهای ستون را حدود 61 درصدکاهش داد. با افزایش مقدار عددی ایزوترم جذب و کاهش ضریب انتشار بایوچار، سرعت انتقال آلاینده به اعماق خاک کاهش می یابد که این به معنای خروج دیرتر و کمتر املاح از ستون خاک با لایه بایوچار می باشد. نتایج آنالیزمومنتم نشان داد که میزان جرم آلاینده ی خروجی از ستون در حالت بدون بایوچار 36/15 میلی گرم بر سانتی متر مکعب بر ساعت و در حالت استفاده از بایوچار برابر 78/13 میلی گرم بر سانتی متر مکعب بر ساعت است که بیانگر کاهش 3/10 درصدی در خروج آلاینده از ستون می باشد. این مقدار در تمامی تیمارهای پژوهش کمتر از شاهد بود و نشان می دهد که بایوچار تحت هر شرایطی باعث جذب آلاینده از محیط آبی و کاهش میزان فرونشت آن به اعماق خاک خواهد گردید.

    کلیدواژگان: ضریب انتشار طولی، ضریب ایزوترم جذب، نیترات، HYDRUS، 1D
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  • elahe hosseinian Pages 1-10

    Sand and gravel mining from the riverbed causes many environmental and social problems in the rivers because of disturbing the natural conditions of the bed and also, its changes. Some of these problems are subsidence of riverbeds and erosion of hydraulic structures its path, bank erosion and damage to land placed in riverbank, the destruction of dewatering openings, drainage of agricultural land placed in riverbank and also, the change of plant and animal environment. In studying the morphological changes of the rivers’ cross-sections, it is often assumed that the riverbanks are non-erodible or the erosion of river banks is less than the erosion of bed, so, river width is considered constant. A closer study of the changes in river alluvial, particularly, with the erodible banks shows that the river width will be faced with significant changes because of material mining.In this study, it has been tried to study the changes in the bed, bank erosion of the river and its causes and also to identify the vulnerable intervals by simulating hydraulic conditions of sediment flow in Khorramabad River with the use of model Fluvial-12. Khorramabad River is located in 36.48-45.47 east latitude and 10.33 to 50.33 North longitude and of the important branches of Kashkan River. The case study includes an interval of Khorramabad River with the length of about 7 kilometers before the inset of Kakasharaf River. IN this interval, Khorramabad River is a mature river in the plains with the average slope about 1.6%, and a flow with u-shaped cross-section. In mentioned interval, there a map with the scale of 1:1000 that includes about 9 kilometers of the river and the hydraulic studies were performed on this interval. In this study, 1372 cross-sections surveyed in 2003 were used. According to the changes in the sections along the way due to the construction of the bridge, the protection wall of the bank, river materials mining and encroaching the bed of Moradabad River, firstly the required sections were extracted from the topographic map in the GIS environment using HECGeo-RAS interface and then, these sections were modified in model HEC-RAS and inappropriate sections were removed. With this approach, totally, 51 cross-sections were entered in model HEC-RAS to introduce a geometry of the river in the studied interval. For hydraulic modelling of the sediments of Khorramabad River in the studied interval, the model FLUVIAL-12 was used. The model FLUVIAL-12 was provided in 1972 by Cheng.it a mathematical one-dimension model is used to rout the flow and sediment in the natural and built waterways (Journal of 383, Ian Management and Planning Organization, 2007). This model cannot model the unsteady flow. In model FLUVIAL-12, digital techniques and physical relations are used to analyze the momentum, flow resistance and sediment transport. The main parameters required for calibration of the model, are roughness coefficient, Sediment transport equation, coastal erosion factor, bed erosion factor and the factors such as these. Model FLUVIAL-12 has been tested with data from many different rivers in the world that most of the data was used to test and calibrate other models. Roughness coefficient of Khorramabad River in the suited area was estimated by field survey and engineering judgment and completing the checklist of SCS method. To calculate the Manning roughness coefficient which is used in hydraulic model HEC-RAS, the values of vegetation, artificial irregularity and additional roughness of barriers created in the river by the people were considered in the calculation of river roughness coefficient. To calculate and estimate the Manning roughness coefficient in floodplains and main section, US Soil Conservation Service (SCS) and also, field survey were used. The sediment transport was simulated by using the functions of the model, the Graph’s (1970) sediment transport equation, Yang’s (1972-1986) flow power unit, the equation of Engelund & Hansen (1976), the equation of Parker et al.(1982) for sand, the sediment equation of Akers and White, the equation of Meyer-peter & Muller for bed load (Shafaei Bejestan, 2005). Result revealed in the v-shaped sections and the channels with small sections, the bank erosion is developed after armoring the bed materials. Also, In the U-shaped sections and the channels with larger sections, the bed erosion is reduced and the development of bank erosion is inconsiderable after armoring the bed materials. Furthermore, In the sections that the section shape and slope make the stable section, no significant difference will be observed in terms of erosion and sedimentation after armoring the bed materials. As it is mentioned before, importance of studying and discussing the river mining becomes clear. Each river has the sediment transport capacity depending on its discharge. There is a reverse relationship between the transport capacity and the size of the constituent grains, so that the coarse grains have the less transport capacity than the smaller grains. So, determining the river transport capacity, the proper points to mine the materials according to the deposition intervals and the appropriate volumes of material mining according to the bed load requires the comprehensive studies on the potential of material mining in different parts of the country. Also due to illegal river mining activities in recent years, the need for the studies on improving the rivers based on the modelling the current situation and providing the protection plans are essential.

    Keywords: bank erosion, river mining, armored layer, FLUVIAL, 12, HEC, RAS
  • lamia neissi*, mohammad Albaji, saeed boroomand nasab Pages 17-25
    Introduction

    Multi-criteria decision making (MCDM) and Geographic Information System (GIS) for accurate decision making about the evaluation parameters used in natural sciences. This selection is influenced by different factors such as production and irrigation system expenses, water availability and quality, soil characteristics, climate conditions, labor skills, and cultural acceptability. The present study was conducted over an area of approximately 11081 ha in the Izeh plain Khuzestan province, south west Iran during 2015-2016. Results of the comparison (for each factors pair) were described in term of integer values from 1 (equal value) to 9 (extreme different) where higher number means the chosen factor is considered more important in greater degree than other factor being compared with. Analytic Hierarchy Process (AHP) is one of Multi Criteria decision making method that was originally developed by Prof. Thomas L. Saaty. In short, it is a method to derive ratio scales from paired comparisons.. The AHP was used for optimization.Spatial analysis to identify susceptible regions for pressurized irrigation systems starts with representing each selected physical sub-criterion by a thematic layer in which each point takes a value (1 to 9) which the samples have been gathered in a laboratory or a qualification according to that criterion. In order to layer all the criteria, data are gathered from satellite images and official sources at different available forms (digital and hard copy maps, tables and charts). Then, they are analyzed and treated using GIS and geostatistical tools. Each layer is obtained in raster data model. Spatial data on water characteristics, topography and climate (temperature map) are obtained from “water and power authority’’ of Khuzestan district, which is the Iranian official source of agricultural spatial database. Data are already available in digital format with 1/150,000 scale.

    Methods

    Major advantage of AHP is to formalize and renders systematic what is largely a subjective decision process and as a result facilitates ‘accurate’ judgments, that weights of criteria are also provided to decision maker, and that sensitivity analysis is easy to conduct by using computer. The weights of each criterion were computed by using the geometric mean to obtain the weight values. After that the weights should be aggregated and each weight divides on aggregated weights in order to normalize the weights. The normalized weights determine the priority of criteria. The sum of all normalized weights in each Table is equal to unity. The AHP methodology says that prioritizing and weighting the criterions should be done firstly. According to fundamental Saaty 's scale for the comparative judgments and by performing pair - wise comparisons of criteria with respect to the object, here the comparison and calculation of criteria in 1st , 2nd and 3rd levels in general for Localize irrigation system as an example. Most large drip irrigation systems employ some type of filter to prevent clogging of the small emitter flow path by small waterborne particles. New technologies are now being offered that minimize clogging. Considering conditions of water used for irrigation in the study region, suspended materials (W sm) and biological materials (W bm) were seen in the water according to laboratory experiments. Filters were employed in the farm and the water is available in the farm by pumping it from wells, but filters need to be changed after a while so possibility of clogging in the drippers still exists, therefore, these two alternatives have higher weight than available water. The amount of Sodium concentration (W na) was low and has less importance than other criteria except available water. Localized irrigation systems designed for no leaching fraction. High electrical conductivity (EC) and salts applied with the irrigation water may build up in the root zone but EC of the study region is almost low. Alkaline water (refers to pH) could make sediments in the drippers

    Results

    In this study surface irrigation system found to be the best systems for this region. The comparisons expose that the results from the proposed model are in good agreements with results from the field investigations. An additional benefit of the model is that the decision-maker can perform a more exhaustive conceptual comparison of the different decision components. Causing that an extensive set of factors involved in selecting an irrigation system has been included in the proposed model, it can be claimed to be a comprehensive and practical model that can be used in selecting the irrigation methods for various agricultural sites, thereby improving soil and water resources exploitation and productivity.

    Keywords: Priority, GIS, AHP, Irrigation, Decision making
  • Maryam Mirbeyk Sabzevari*, H. Torabi, Hojjat Allah yonesi Pages 27-37

    Existence periods of drought in the past decade, increasing growth of population, limitation surface water resources, cause the proper management of the reservoirs of dams. Operation of reservoirs is influenced by a lot of goals and generally many of these goals are incompatible with each other. The inflows to the reservoir and the storage volumes are uncertain which increases the operation of the complexity of the reservoir. The main challenge is to find the best release of the reservoir and hydrosystems optimization. Various optimization methods have been introduced for the operation of the reservoir. But some of these methods have disadvantages that use of them are not possible for all issues. Bozorg Haddad (2005) used Honey Bees Mating optimization for solving design problems and o The ant colony algorithm was also used to exploit a four-reservoir system in a discrete space that was able to optimize the problem with greater accuracy and less computing time than the genetic algorithm (Jalali et al 2007). Mousavi et al (2017) used the Harmony Search Algorithm to the optimization of water powerhouse storage projects and reported satisfactory results. Harmony search algorithm was presented by Geem et al for the first time in 2000. In this research Harmony Search Algorithm (HSA) is evaluated to determine the optimal operation of multi-reservoir systems. Then in order to evaluate the ability of the algorithm to solve real problems, the optimal operation of Dez Dam reservoir in Khuzestan province has been considered for a period of 10 years (1990-1992) with 120 months. In the single- reservoir issue of Dez Dam, the goal is to provide of agricultural demand of downstream or to determine the optimal monthly release for 10 years operation. The optimum value was obtained by using a linear programming model (Lingo). Lingo model has the ability to solve nonlinear models and provides the global optimum in some cases such as the intended problem where the objective function is convex. Therefore, the solutions obtained from the HSA model were compared with the solutions obtained from Lingo software program. A new heuristic algorithm derived from an artificial phenomenon found in musical performance namely the process of searching for better harmony can be introduced. Music harmony is a combination of sounds considered pleasing from an aesthetic point of view. Harmony in nature is a special relationship between several sound waves that have different frequencies. Musical performances seek the best state (fantastic harmony) determined by aesthetic estimation, as the optimization algorithms seek the best state (global optimum-minimum cost or maximum benefit or efficiency) determined by objective function evaluation. Aesthetic estimation find by the set of the sounds played by joined instruments, just as objective function evaluation find by the set of the values produced by component variables; the sounds for better aesthetic estimation can be improved through practice after practice, just as the values for better objective function evaluation can be improved iteration by iteration. The new algorithm is named Harmony Search (HS) and the steps in the procedure of HS are as follows: Step 1) Initialize a Harmony Memory (HM). Step 2) Improvise a new harmony from HM. Step 3) If the new harmony is better than least harmony in HM, include the new harmony in HM, and exclude the minimum harmony from HM. Step 4) If stopping criteria are not satisfied, go to Step 2. Harmony Memory Considering Rate (HMCR), which ranges from 0 to 1. If a uniformly generated value between 0 -1 occurs above the current value of the HMCR, then HS finds notes randomly within the possible playable range without considering HM. An HMCR of 0.85 means that at the next step, the algorithm chooses a variable value from HM with an 85% probability. For improving solutions and escaping local optima, yet another option may be introduced. This option mimics the pitch adjustment of each instrument for tuning the ensemble. For computation, the pitch adjustment mechanism is devised as shifting to neighboring values within a range of possible values. A Pitch Adjusting Rate (PAR) of 0.10 means that the algorithm chooses a neighboring value with 10% probability (an upper value with 5% or lower value with 5%. In the present study, first HSA was used to the optimization of a four-reservoir system. The objective function was calculated to equal to 308.2915 by using Lingo software, and this amount was calculated to equal to 308.2900 by using HSA that had a different of 0.0005 percent with the global optimum. After the success of HSA in solving the four-reservoir system, a ten-reservoir system was considered. The Objective function was calculated to equal to 1194.4 by using Lingo software, and this value was calculated to equal to 1193.1 by using HSA that had a different of 0.1 percent with the global optimum. In the single- reservoir issue of Dez Dam, the value of global optimum of the objective function was calculated by using software Lingo 1.9188 and by using HSA 1.944 that had a different of 1.31% with the global optimum. So it can be concluded that this algorithm has the ability to solve optimization problems of the real system

    Keywords: Harmony Search Algorithm, Linear programming, Meta, heuristic algorithm, Multi dam operation, Optimization
  • Fereshte Asadi*, Alireza Emadi, Ramin Fazloula Pages 39-49

    The hydraulic jump is one of the important phenomenon of water flow in channels that in proportion to the intensity of jump, will face a significant energy dissipation. True hydraulic jump form for Froude numbers greater than 4.5. Position of steady jump is the least sensitive type to fluctuations in the tail water elevation and forms steadily at the same location. The change of flow state from supercritical to a subcritical state is accompanied by discontinuity in depth of flow, formation of a surface roller, visible air entrainment and two phase flow, significant turbulence, kinetic energy dissipation, generation of spray and sound. The basic characteristics of a hydraulic jump, such as conjugate depth, location of jump, the energy loss in the jump, efficiency of jump, the length of the jump. From the designer's standpoint, hydraulic jump is a powerful energy dissipation mechanism and due to its erosive potential, is the centroid of scour. In order to take full advantage of the hydraulic jump in apron design, the erosive effect of jump should be confined to the limits of the heavily protected bed surface, hence intensive scour energy would not cause any harm to apron. This is why; hydraulic jump should be in a stilling basin with a fixed location. Turbulent flow over a rough surface is an important problem and it has been subject of diverse fields. Using roughness elements at the bottom of the flow causes increase in resistance to the flow hence accelerate the upstream flow development and increase in amount of kinetic energy, converted into the turbulent energy. Using of rough beds are effective factor in reducing costs on energy dissipation basins. So researchers’ next purpose have been the use of roughness beds in the stilling basins bed and investigation the effect it on hydraulic jump characteristics. In this research, experimental investigation effect of bed roughness on hydraulic jump characteristics in a flume with length of 12 meters, width of 0.5 meters and height of 0.7 meters was done in range of Froude numbers 5.5 to 9 and used 24 cubic rough beds with staggered and strip arrangement, different rows and angles. Discharge was measured by a triangular weir with a 90° angle, placed at the end of channel and size of cubic blocks was 0.05 meters. Point gauges with a sensitivity of ±0.1 mm used to measure the depths of flow. To evaluate the effect of roughness, both staggered and strip arrangement were used in the experiments. For creating a hydraulic jump, sharp sluice gate has been used in a condition which places the rough beds in downstream. Relative depth and relative length was obtained as a function of Froude number. The relative depth values on smooth beds obtained in the present study are in good agreement with the data of Belanger classic jump. Relative depth, relative length and shear force coefficient increase for staggered arrangement, strip arrangement and smooth bed with increasing Froude number. The value of relative depth, relative length in compare to smooth bed in the same Froude number on rough beds is less and shear force coefficient is greater than smooth bed. Equations obtained with SPSS software for jump relative depth. Result shows that relative depth and length for staggered arrangement in compare strip have more reducing ratio smooth bed. Also showed staggered arrangement produced better performance compare to strip arrangement in ratio secondary to primary depth and ratio length to jump primary depth. Both types arrangement a better performance compared to jumps formed on smooth beds. For staggered and strip arrangement the average of length ratio to jump primary depth was obtained 1.9 and 1.6 times less than smooth bed respectively. In the experiments the ranges of relative for the staggered and strip arrangement were 20.47 to 39.04 and 46.66 to 24.28, respectively. Shear force coefficient that main factor is in reducing of depth and jump length calculated 6 percent more of smooth bed in both arrangement. On the other hand, comparing of this experimental results with the other similar researches on different types of rough beds expresses match results. Finally, equation for estimate of relative depth and relative length for Froude numbers extracted. Also the effect of arrangements in the level of 5 percent were proofed for all beds on relative depth and relative length.

    Keywords: Energy Dissipation, Froude Numbers, Relative Length, Rough Beds
  • marzieh mohseni*, Jamal Mohamad Vali Samani, Seyed Ali Ayyoubzadeh Pages 51-61

    Increasing attention to environmental issues in the management of rivers, causese the development of research in the field of hydraulic parameters and sediment transport in the rivers. Vegetation in many rivers, has a significant impact on the flow hydraulic, morphology and sediment transport processes. Understanding the hydraulics of flow in a compound channel with vegetated floodplains is very important for determining the stage-discharge curve and for supporting the management of fluvial processes. There are few models within CFD codes that conceptually or physically represent the hydrodynamic impact of a vegetation canopy on the velocity field and conveyance characteristics within an estuarine or riverine system. The present research investigates the numerical and experimental modelling aspects of flow in compound channels with vegetated floodplain, emphasis to the suspended sediment transport. This study, has proposed a method for predicting the depth-averaged velocity in compound channels with vegetated floodplains, based on an analytical solution to the depth-integrated Reynolds-Averaged Navier-Stokes equation (RANS) with a term included to account the effects of vegetation. Two dimensional advection-diffusion equation were used to calculate the dispersion coefficients and sedimentation rate, this equation were solved by using a finite volume method. The vegetation is modeled via an additional term in the momentum equation to account for the additional drag force. The method includes the effects of bed friction, drag force, lateral turbulence and secondary flows, via four coefficients f, CD, λ & Γ respectively. This model is able to estimate the velocity distribution in channels with different dimensions, different vegetation densities. This model is able to estimate the velocity distribution in channels with different dimensions, different vegetation densities. The wake interference model given by Nepf (1999) is used to estimate the bulk drag coefficient. Modified forms of the Colebrook–White equation can be used to calculate a local friction factor in compound channels with vegetated floodplains. Several eddy viscosity models have been used in the literature to predict transverse momentum exchange in the mixing layer. Once velocity profile is obtained, the dispersion coefficient is evaluated and the remarkable role of vegetation is shown. Both the velocity profile and the dispersion coefficient have been validated using our new experimental results. The model was applied in inverse mode to estimate the model parameters that quantified eddy viscosity coefficient, secondary flow, longitudinal dispersion, transverse dispersion and filtration in the experiments. In addition, the Elder’s and Neph’s relationships also calibrated to calculate the Longitudinal and transverse dispersion coefficients. A Levenberg-Marquardt algorithm was used to find the values of the model parameters that minimized the sum-of-squared differences between measured and modeled velocities and particle concentrations. Experiments performed in a flume of the Hydraulic laboratory. The experimental channel is employed in this investigation was 10 m long × 0.3 m wide and 0.6 m deep. The channel has a simple rectangular cross section; however, this was modified by using Plexiglas sheeting to produce an asymmetrical compound shape. The artificial stems were PVC rods of 5 mm outside diameter, arranged in staggered grid. The model substance used as suspended load was silica of mean particle diameter around 7µm and density 2143 kg/m3. Silica suspensions were injected to produce fully mixed inflow concentrations of about 6 g/l. In general, two series of experiments have been done in this study. In The first series of experiments the depth averaged velocity were measured, the second series have been conducted to estimate the rate of sedimentation. Depth averaged velocity measured by using micro-propeller and pitot tubes. Results showed that the use of constant coefficient of 0.0683 for eddy viscosity coefficient have not a significant impact on depth averaged velocity. The error about 1% have been observed between results of numerical modeling and experimental data, when the relationships 0.417δρgS0 HDr and 0.62δρgS0HDr have been used for secondary flow coefficients, to the main channel and floodplain, respectively. Results showed that dispersion coefficient in vegetated channels increased cross the main channel compared to no vegetated case, due to the gradient of velocity. Sedimentation rate coefficients calibrated by comparing the experimental and numerical sedimentation rate. The numerical model underestimates the experimental data about 8%. Experimental data of Zong(2011) were used to verification of numerical model, the results showed that the modified model overestimates the data with 22% difference. The results show that the quasi 2D model reproduces a reasonable simulation of the flow field and sediment transport in compound channels with vegetated floodplains.

    Keywords: depth averaged velocity model, Vegetation, sedimentation, compound channel, advection, dispersion equation, dispersion coefficients
  • yaghob dinpashoh*, rana sedighpour Pages 63-72

    Urmia Lake is one of the largest hypersaline Lake in Iran which its capacity is about 32 MCM in its normal condition. In recent years, climate change and decreasing rainfall led to falling water level in the Lake. Although, due to its high salt concentration this fall in water level led to extending areas of saline lands around the Lake. Furthermore, drought occurrence and rainfall decreasing trend cause solute concentration to be increase in the Urmia Lake water. For logical and scientific management of fresh water in Urmia Lake Basin it is necessary to investigate the trends of different characteristics of daily rainfall. The aim of this study is to detect trends in the number of days with different rain depths in five distinct classes in Urmia Lake basin. In order to detect trends the information of the twenty five stations having at least 10 years consecutive daily rainfall data were used. Trends of time series detected using the non-parametric Mann-Kendall method. Moreover, slope of trend lines estimated by using the Sen's estimator approach. In order to analyze the spatial trends for each of the time series some relevant maps prepared in which, the stations having significant trends were shown by markers. This facilitate the interpretation of trends in the area under study. The results showed that the slope of trend lines for days having rainfall less than 1 mm is often positive. About 84% of the stations had upward trend line. The five stations located in the southern part of the basin experienced (in level of 10% or less) significant upward trend in the number of days with precipitation less than 1 mm. The slope of trend lines in the case of the days having rainfall depth between 1 and 5 mm were almost negative. In the case of days with rain between 1 and 5 mm, the 15 stations had downward trend lines, which five of them showed significant trend, whereas the remaining stations had upward trend line slops (insignificant at 10% level). On the other hand, the slope of trend lines for the number of days with rainfall between 5 to 10 (mm) in 44% of the stations were negative in which, only four of them were significant (in 10% level). Trend line slopes in 40% of the station were positive, in which only one station experienced significant trend at ten percent level. The steepest positive trend magnitude belonged to the station namely Herris with β = 1. 633 (day/year). For the number of days with precipitation between 10 and 15 mm about 32% of the stations had negative trend line slopes, in which only three stations experienced negative significant trend. About 26% of stations had positive trend line, in which only one section (namely Maraghe) exhibited significant trend in 1% level. The steepest slope of the trend lines was related to station Shahindezh with β = 0.585 (days/year). The slope of trend lines for the number of days with rainfall more than 15 mm were positive for 52% of the stations, in which only one of them experienced significant trend (in 10% level). Moreover, 24% of the stations had negative trend in the mentioned class. Out of the total 25 selected stations only one section (namely Maraghe) had significant negative trend. The steepest slope of the trend lines belonged to the station Herris with β = 0.464 (days/year). In general trends of the number of days having rain depth less equal one mm in Urmia Lake basin was upward. But trends for the time series of the number of days having rainfall in the classes of 1-5, 5-10 and 10 -15 mm were downward. This means that light (shower) storms events in the study area is going to be occur frequently but heavy rains is going to be rare. It can be concluded that the number of light raining days had increasing trend. This implies that such light rains can not to be used for crops and trees. Because such rains immediately lost by evaporation proses after ceasing the rain. On the other hand, heavy rains which showed increasing trends for most of the selected station might be crate huge floods in the rivers flowing into the Urmia Lake Basin.

    Keywords: Sen’s estimator, Urmia Lake Basin, Trend, Mann, Kendall
  • mohammad hadi Rad*, Mahdiyeh Tajamolian, mahdi soltani Pages 73-81

    Sewage and wastewater are extensive sources of water in the suburbs of many cities of the country. In many parts of the world, treated sewage and wastewater have been successfully used for the irrigation, and many researchers have recognized its benefits. In arid and semi-arid regions have provided good conditions for planting of susceptible species by irrigation with sewage or wastewater for development of green cover and economic exploitation such as wood production. Different eucalyptus species are prepared for planting by irrigation with industrial and household sewage and wastewater, because they have high growth rate and high resistance to biotic and non-biotic stresses and they have high product of wood too. In this regard, a study was conducted by measurements of yield, water use efficiency and some performance indicators in three eucalyptus species that they were planted in drainage lysimeters and they were irrigated with wastewater. This experimental was carried out in Yazd city and greenhouse condition. The research was conducted by factorial experiment in completely randomized design and three replications. Two main treatments were applied: Irrigation with wastewater in three levels (control or without wastewater, 50% water and 50% wastewater, 100% wastewater) and eucalyptus species in three levels (Eucalyptus microtheca, Eucalyptus camaldulensis and Eucalyptus rubida). Each treatment was applied to tow eucalyptus trees or two pot. Annual seedlings planted in drainage lysimeters or pot with 7 liters capacity and they were kept for four months. The soil of the experimental pot was a soil field, with loamy sand texture (76% sand, 20% silt and 4% clay). Wastewater that was used from the wastewater treatment plant of Yazd city was prepared. Wastewater samples were taken during the irrigation period and examined for mineral, bio materials and biological. The chemical and biological analyses of the wastewater were according to standard methods. We studied the influence of irrigation with wastewater on high and diameter of trees, length and wide of leaves, leaf surface, dry mass of leaves, stem and root, specific leaf area, shoot and root dry mass, chlorophyll content and water use efficiency (WUE). The significance of differences between mean values was determined by one-way analysis of variance. Duncan’s multiple range test was used to compare the means. The use of tree plantations for the renovation of wastewater and the simultaneous production of forest produce is now being widely studied. In the condition of wastewater use, the presence of nutrients and organic matter in the wastewater will help to growth and water use efficiency in some plant species. However, reclaimed sewage or wastewater application may create undesirable effects in soils and plants with direct effects on soil suitability for cultivation and water resources availability. The use of wastewater for irrigation of fast growing trees it can be useful. They can use to excessive fertility elements in the wastewater. Irrigation with wastewater can cause increase of number of leaves, length and width of leaves in plants. Increase of leaves number and leaves area will make the absorption of solar energy better and enhance the efficiency of photosynthesis. Irrigation with wastewater can accelerate the flowering of plants and the seeds produced are also healthier. All of this factors can improve water use efficiency in plant. The results show that the potential for utilizing tree plantations in wastewater management. The results showed that there was a significant difference between irrigation treatments at 1% level (p <0.001) on morphological characters such as height and diameter of trees, length, width and leaf area. Specific leaf area, leaf water content, chlorophyll content also increased with increasing of wastewater concentration and we absorbed significant different at 1% level (p <0.001) between of different irrigation treatments. In 100% treatment wastewater, chlorophyll content increased up to three times than control treatment. Shoot dry weight and water use efficiency were increased with increasing of wastewater concentration that in subject can be due to the high levels of fertilizer elements in the wastewater. The results showed that there was significant difference between trees species in a number of morphological and physiological characteristics. By increasing the amount of wastewater concentration, these characteristics improved in three species experimented. The E. camaldulensis had higher growth and water use efficiency than other species. This species has a high growth rate and therefore its can use good wastewater conditions. We suggested that for economic use of wastewater for wood producing, E. camaldulensis than other species in this experiment is suitable and its can be used.

    Keywords: Eucalyptus microtheca, Eucalyptus camaldulensis, Eucalyptus rubida, morphological characteristics, physiological characteristics
  • Azam Mumzai Pages 83-92

    Most part of Iran including Chaharmahal and Bakhtiari province is arid and semi-arid; thus in most parts of the region, groundwater is the only source of water. Thus, in the most parts of the region, groundwater is the only water resource, and is a major constraint on economic and social development. In arid regions, the underground dam is a new industrial site for supplying water for farming, especially in summer. An underground dam is a sub-surface barrier across the stream which retards the natural ground water flow of the system and stores water below ground surface to meet the demands during the period of need. The aim of this study was to prioritize the effective factors in the construction of underground dams and to develop and evaluate a multi-criteria decision making system based on GIS techniques in order to identify and prioritize potential areas for building underground dams in the watershed of Shahrekord. Marghmalek-Shahrekord watershed is located in north east of Chaharmahal and Bakhtiari province. This watershed is located in Sanandaj-Sirjan zone based on structural divisions and the atmospheric rainfall in the basin is mainly influenced by low-pressure Mediterranean systems. In order to accelerate the decision-making process, as well as avoiding the accumulation of excessive information for a surveyed problem, it is first necessary to eliminate inappropriate points by considering a number of key criteria and factors. At the first, suitable areas for establishing underground dams were determined with ommisive criteria and using Boolean logic and suitable areas for establishing underground dams were determined. The axes that do not cut the Qanat's gallery and are suitable from the aspect of length and area of the reservoir were identified. In the next stage, the proposed locations were prioritized using the analytic hierarchy process. Therefore, the indices that are more fit, matches the more suitable axes for the construction of underground dams in the study area. Five scenarios were considered for the prioritization. Quaternary formations are suitable for the construction of underground dam. Poor, medium and good rangelands and garden lands are suitable for underground dam. According to the first, second, third and fourth scenarios, axis number 46 and according to the five scenarios, axis number 41 have the first priority for groundwater dam construction. The results showed that the hydrologic factors and the socioeconomic factors were chosen as the most important factors with weights of 0.51 and 0.30, respectively. In determining the value of the indicators, the water quantity (runoff height) with a weight of 0.833 and also the depth of alluvium with a weight of 0.743 are more important than other indicators that this indicates the importance of the hydrologic criterion for experts. The best axes for the construction of an underground dam are in the alluvial river bed with high subsurface flow, the large reservoir capacity, high runoff volume and areas with high permeability and low slope. By integrating the maps of the Qanats axis of the study area and the map of possible gaps of underground dam construction, 15 axes were identified for the construction of underground dam in Marghmalek-Shahrekord watershed. The results of the reservoir analysis indicated that suitable subsurface reservoirs in these areas are matched with this fact that with decreasing slope, the length of the reservoir increase, that ultimately causes increases the volume of the reservoir. The large area of the watershed upstream of the dam has a higher priority and value because the high amount of runoff passes through the construction site. The depth of the alluvium has the most relative importance among the axis indices, because in the economy of an underground dam, length and depth of axis are most important. By investigating the results of the reservoir depth, it was found that the best region are alluvial bed with a depth of less than 10 meters, that is consistent with the results of Chezgi (2015). The water of these tables is very good in terms of quality because they are naturally refined by constituent lands. Also, they have a high subsurface discharge. These valleys are the best and most suitable place for underground water extraction. According to the obtained results about the slope, the relative importance of the slope increases with its lowering. The results of this study showed that most of waterways 3 and 4 were located at slopes less than 5 percent, which are suitable areas for building underground dam because the gradient factor has inverse relationship with reservoir volume and permeability and is consistent with results of Nilsson (1988); Rezaei et al. (2013) and Chezgi (2015). The proposed method can accurately be used to select the suitable sites for construction of underground dams through detailed and accurate surveys and by considering the effective factors.

    Keywords: Multi criteria decision making, Boolean logic, Site selection Underground dam, Shahrekord
  • Niyaz Ali Ebrahimipak*, Abdol Majid Liaghat, aslan egdernezhad, Mohsen Ahmadi Pages 93-102

    Shallow water table is an important problem in arid and semi-arid regions. Since it causes reduction of agricultural yield; therefore, water table fluctuation is necessary to be monitored in irrigation and drainage fields. These conditions are intensified for arid and semi-arid countries, such as Iran, which saline groundwater are main water resources. These problems increased in sugarcane industrial farm that covered large area in Khuzistan province, Iran. Therefor, it is necessary to determine water table in sugarcane field during growing season. Regarding the purpose, it is important to evaluate water table fluctuations in each farm continuously. There are some problems to achieve this purpose like spending time and financial supports. So, computer models are developed to solve the problems. Water table can be simulated in different farm conditions, even before designing an agricultural unit, using the models. This research was conducted to evaluate two models: DRAINMOD and SWAP in order to estimate water table levels in Amirkabir Agro-industry farms located at latitude between 31˚ 15’ to 31˚ 40’ and longitude between 48˚ 12’ to 48˚ 30’, Khuzistan. Regarding the aim, water table data were collected from a 25 ha-farm. In order to evaluate the results, four statistics criteria root mean square error (RMSE), modeling efficiency (EF), coefficient of residual mass (CRM) and coefficient of determination (R2) were used. The calibration results of soil physics parameters for SWAP and DRAINMOD revealed that in both models, the parameters n and Alpha had the most variations compared to other parameters. In calibration stage, the amount of R2 for DRAINMOD model was 87. This result showed that there was a good correlation between field and simulated data. The result of R2 for SWAP and ENDRAIN models were 83 and 93, respectively. RMSE values for DRAINMOD, SWAP and ENDRAIN were 12.42, 10.46 and 11.63 cm, respectively. So, in calibration stage, SWAP had more accuracy compared to other models to determine water table. The CRM values were obtained as -0.028, -0.022 and -0.061 cm for DRAIMOD, SWAP and ENDRAIN, respectively. Then, all three models lead to overestimate of water table. The results of EF were 0.83, 0.85 and 0.88 for mentioned models, respectively. Validation results of DRAINMOD model revealed that RMSE, CRM and R2 were 13.19 (cm), -0.008 and 0.85, respectively. These statistical criteria were found to be 17.00 (cm), 0.020 and 0.82 for SWAP. These parameters were obtained as 28.10 (cm), 0.603 and 0.82 for ENDRAIN model. The results of EF were 0.84, 0.75 and -2.80 for DRAINMOD, SWAP and ENDRAIN models, respectively. These results showed that ENDRAIN had no efficiency to determine water table. SWAP and DRAINMOD had good efficiency to simulate water table. Thus, DRAINMOD had overestimate error and SWAP and ENDRAIN had underestimate error. DRAINMOD is recommended as a better model according to higher coefficient of determination and lower error value.

    Keywords: Water Table Monitoring, Shallow Water Table, Water Table Fluctuation, Sugar fields
  • Hooman Hajikandi*, Saber Ebrahimiyan, Mahmood Shafai Bajestan, Saeed Jamali Pages 103-112

    One of the most important issues to be considered in trapezoidal channels is the effect of side slope effects on the shear stress and jump characteristics including energy loss, jump length and conjugate depths ratio which have been studied in this study. For this purpose, at first, model has been calibrated by using an experimental results published for trapezoidal channel of 45 degree side slope, the RGN model was selected from the turbulent models, and then the model for different hydraulic conditions (Froude number between 1.5 to 12) and two slopes of 60 and 75 degrees has been performed and the results have been obtained. Due to the shear stress importance, which is usually not investigated in experimental researches, in this study the distribution of bed shear stress has been calculated in all three channels side slopes, and also the hydraulic jump characteristics. The results of this study on the three side slopes show different behavior of hydraulic jumps and shear stress in trapezoidal channel of 45 degree side slope, in which the asymmetry of jump is very tangible and the shear stress concentration is observed on the left side of the channel wall. Comparison of the shear stress results show a significant reduction in shear stress after jump which the maximum amount of this reduction is related to the trapezoidal channel of 45 degree side slope. It was also found that by increasing the side slope the amounts of shear stress and the sequent depths ratio increase, and the amounts of energy loss and length of jump decrease.

    Keywords: Computational Fluid Dynamics, Hydraulic Jump, Relative Energy Loss, Shear Stress, Trapezoidal Channel, Turbulence RNG Model
  • zohre ebrahimi khusfi*, abbas ali vali, reza ghazavi, mohammad khosroshahi Pages 113-123

    In this research, the changes in groundwater table and the volume of water reservoirs of the Kuhpayeh Segzi and southern Mahyar aquifers during the years 1981-1982 to 2012-2013 were investigated. For this purpose, the average level of aquifers' water table was calculated using the Thiessen method. The mean values of the groundwater table obtained from the Kuhpayeh Segzi and southern Mahyar aquifers were recorded as the average level of groundwater table in the Gavkhouni wetland during a 22-years statistical period. Then, changes in the groundwater table and the water volume of Kuhpayeh Segzi and southern Mahyar aquifers, as well as the average changes of the above mentioned parameters were calculated for the wetland area. The trend of groundwater table changes was examined using the Mann-Kendall method. Finally, a hydrodynamic gradient map and field observations were applied to analyze the the interaction of the wetland and its leading aquifers. The results showed that the groundwater table in the Kuhpayeh Segzi and the southern Mahyar aquifers has decreased 2.75m and 12.83 m, respectively and the water volume of the aquifers was reduced by 160 m3 and 300 m3 per year, respectively, until the end of the statistical period studied. The results of Mann-Kendall test also showed a significant decrease in the level of groundwater table in the studied aquifers during the study period. In general, the level of groundwater and the volume of water resources in the wetland area has declined were 7.8 m and 229 million m3, respectively. Also, the results indicated that the Gavkhoni wetland had a nutritional role for the aquifers surrounding during 22 years.

    Keywords: Mann Kendall, Thiessen, Kuhpayeh Segzi, Southern Mahyar, Isfahan
  • sajjad razavi*, kamran davary, fatemeh talebi, Ata Joodavi Pages 125-136
    Introduction

    Water consumption has been rising during the last five decades across the globe because of population growth, higher standard of living, and economic development. Water resources limitations in Iran has led to the emergence of sustainable water resource management. To deal with the complex and interlinked water challenges, we need knowledge about the quantity and quality of water in the watersheds through water balance investigation. Evaluating available water resources is a prerequisite step in the water resources management to avoid adverse environmental impacts. Water balance investigations, as a tool for quantitative evaluation of water resources, is a prerequisite step in water resources management process. However, we have faced to some problems with water balance calculations such as: it is costly and time-consuming to provide reliable data for a large area and the estimation methods of water balance components rely on the methods that would not be appropriate for Iran's meteorological, hydrological and hydrogeological conditions. For example, in many cases, the empirical methods and mathematical models used in Iran were developed in other countries with different climates.

    Methods

    Water balance models have been developed over multiple timescales (hourly, daily, monthly and yearly) and different spatial resolutions and varying degrees of complexity. Water balance models were first developed in the 1940s by Thornthwaite. With the increasing use of water balance models to address hydrological problems, a considerable amount of efforts has been devoted to the development of such models and techniques. A variety of models have been considered, ranging from relatively complex conceptual models to complex physical based models. Previous studies showed that using conceptual water balance models rather than process-based models or data-driven models have some advantages. Process-based models require high resolution, in both space and time, data and data-driven models may not remain valid in changed climatic conditions. Therefore, we focus on distributed and semi-distributed mathematical conceptual models. After evaluation different models, we introduce and classify some models that have relative advantages for being applied in Iran. These models have at least one of the following properties: they are conceptual models, some of them have been used for different regions, and some of them have been used for dry and semi-arid areas, and they use a simple method for water balance calculation, or their code, software or graphical interface are available freely.

    Results

    To choose and modify an appropriate water balance model for Iran's watersheds, we should consider a simpler one especially when there are usually uncertainties about the model parameters and input data due to sparse data and lack of knowledge about the natural systems. We investigated different models especially models that have a fewer number of parameters for calibration and consider hydrological spatial variability in a water basin. Considering these facts, it seems the model developed by Portoghese et al. could be a good choice for the most arid and semiarid regions in Iran, after necessary corrections and modifications. The modified model was successfully implemented in different watersheds in Razavi Khorasan province. The model results, such as runoff, actual evapotranspiration, and deep percolation were in agreement with other studies, and consistent with the basin hydrological process.

    Keywords: mathematical, conceptual hydrological models, distributed semi, distributed models, water balance, arid semi, arid areas
  • Samira Rezapourian*, Mohammad Mehdi Ahmadi, Kourosh Qaderi Pages 137-147
    Introduction

    Alluvial rivers always change their hydraulic geometry to achieve a balance between water discharge, input and output sediment. Hydraulic geometry focuses specifically on the evolution of the river form and how the bed and channel influence this evolution. The morphology of alluvial rivers has led to the creation of two concepts: (1) at-a-station hydraulic geometry and (2) downstream hydraulic geometry (Julien, 2015). Downstream hydraulic geometry is defined by the top channel width (W), average flow depth (h), mean flow velocity (V), and slope of the flow energy (S) under bankfull conditions. Downstream hydraulic geometry as a function of hydraulic parameters and bed conditions, including flow rate, median size of bed particles and the Shields parameter is paramount to determine the state of a river. Therefore, various relationships have been derived based on various methods to estimate the channel hydraulic geometry, include: empirical relationships based on collected fields observation and theoretical relationships based on governing equations such as flow rate, resistance to flow, secondary flow and sediment transport in alluvial river. Result of theoretical derivations indicated reasonable agreement with field observations and regime equations. In recent years, intelligent data driven methods is used as new methods for predicting and estimating the parameters of complex hydraulic models. One of the common methods is the Group Method of Data Handling (GMDH) with self-organization approach, which has the ability to solve complex non-linear problems with higher accuracy and simpler structure. In GMDH method the coefficients of the polynomial are found by a Least Square Estimation (LSE) method. It is possible that combined the GMDH methods and optimization algorithms. By doing this, a hybrid method will be created. In this method an optimization algorithm used to calibrate the weights of each neuron in GMDH rather than LSE method and so the hybrid methods may have better performance. The GMDH method is combined with artificial intelligence and optimization techniques such as harmony search (HS) optimization method. Harmony search algorithm (HS) is one of the optimization methods that used to solve nonlinear problems, which was introduced in 2001 by Geem et al. based on a metaheuristic technique. The advantages of this algorithm are less computations to find a solution, fast convergence and significant ability to achieve the optimal solution due to the appropriate structure. HS algorithm has become one of the most used optimization algorithms because can be used for both continuous and discrete problems. Since the GMDH algorithm has a self-organizing approach and its structure is initially unclear, the Harmony search algorithm is used to train and optimize the weights in the structure of each neuron in the GMDH network. In fact, the objective of HS sub model is to determine the optimal weights in short time to achieve the optimal GMDH structure and minimize the cumulative error between the measured and computed data sets.

    Methods

    In this study, to predict and improve the accuracy of the relations of the downstream hydraulic geometry in alluvial channels the GMDH model and a hybrid intelligent model based on the combination of GMDH and HS optimization algorithm that called GMDH-HS developed in the MATLAB software. Before using the developed models to predict and improve the accuracy of downstream hydraulic geometry in alluvial channels, it is necessary to check the accuracy of their results. Typically, researchers use the Mackey and Glass standard time series to verify the accuracy of developed models. Therefore, the validation of the developed models was done using the Mackey-Glass time series and calculated the verification results of the models for the two prediction methods by the CE, RMSE, MSRE, MPAE and RB criteria. To evaluate the developed models, 880 data series were collected from previous research. This data set include a wide range of field and laboratory measurement data. From this collection, 498 series were used to train and 382 remaining data series employed to test models. The results of GMDH and GMDH-HS are compared with observed data. Also, the intelligent models results are compared with theoretical equations proposed by Lee and Julian (2006).

    Results

    Evaluate the performance of developed models using statistical indices CE, MSRE, MAPE, RMSE, RB and R2 indicate satisfactory performance of both models in predicting the downstream hydraulic geometry alluvial channels. A closer examination and comparison of the results of the two models showed that the hybrid GMDH-HS model had a much higher performance in predicting hydraulic geometry. Also, the comparison of the statistical indices obtained from the results of both developed models with the theoretical relationships presented by Lee and Julein (2006) suggests the very satisfactory performance of the hybrid intelligent model GMDH-HS in predicting the downstream hydraulic channel geometry in alluvial channels.

    Keywords: Alluvial river morphology, Group Method of Data Handling, Harmony search, Hydraulic, Intelligent hybrid model
  • Ali Afrous, Ebrahim Pazira Pages 147-155

    Heavy metals are hazardous pollutants that are usually produced by industrial waste water and enter the aqueous environment. In this experiment, three doses of adsorbent, rice husk and Activated carbon, nine Initial concentrations of lead metal, three different pH and four contact times were used to remove lead ions from the aqueous environment. Investigation of the equilibrium time at different concentrations showed that with decreasing initial concentration of the solution, the time of equilibrium for both adsorbents decreased. The time of equilibrium for both adsorbents was equal and its value was 30 minutes. Investigation of adsorption efficiency at different concentrations showed that by decreasing the initial concentration of the solution, the adsorption efficiency increased for both adsorbents and get close together. The best removal of lead by two adsorbents of rice husk and activated carbon was obtained at 77.4 and 94.4%, respectively, at pH=6 and adsorbent mass=1 g/L. Activated carbon had the higher ability to lead remove from the aqueous environment. The fitting of Langmuir and Freundlich adsorption isotherm models showed that the adsorption process followed both the Freundlich and Langmuir isotherms, but the Freundlich isotherm is fitted better than the Langmuir isotherm.

    Keywords: Rice Husk, Activated Carbon, Contact Time, Industrial Wastewater Purification
  • Pages 159-169

    Many processes amplify the nitrate contamination in the groundwater. In addition to economic losses caused by further utilization of nitrate fertilizers, nitrate leaching from agricultural lands imposes irreparable damages to the environment .Biochar has been recently used as an optimal method to decrease the leaching of soil nutrients. To meet this purpose, the present study was carried out to investigate the effect of using Biochar on the decrease of nitrate leaching from soil as well as the effect of changes (including increase and decrease) of dispersivity coefficient and absorption isotherm coefficient on the break through curve and nitrate distribution profile. The HYDRUS-1D model was used to simulate the variations of the break through curve (BTC) and nitrate distribution profile in different points of the soil depth Biochar hydraulic parameters were measured in the lab. The results showed that increasing the value of Biochar adsorption isotherm decreases the output nitrate concentration and causes the nitrate BTC moves to the right side (Retardation). The results also showed that the increase of the Biochar dispersivity coefficient decreases the reduction rate of output nitrate concentration and causes nitrate BTC moves to the left side. The results also showed that the presence of the Biochar layer can decrease the content of nitrate distributed at the end of the column by about 61%. The transfer velocity of pollutants into the soil depth also decreased with the increase of the Biochar adsorption and decrease of dispersivity coefficient meaning that the solutes exit later and less from the soil column when the biochar layer is used. The results of momentum analysis showed that the value of output pollutant mass from the column in the case of non-Biochar is 15.36 (mg/cm3×h) while in the case of using Biochar is 13.78 (mg/cm3×h) indicating a 10.3% reduction of output pollutant from the column. In all treatments, this value was lower than the control treatment meaning that the Biochar, can absorb contaminants in all conditions from the aquatic environment and reduce the contaminant percolation to the soil depths.

    Keywords: Biochar, dispersivity coefficient, Biochar absorption isotherm coefficient, Nitrate, HYDRUS, 1D