فهرست مطالب

پژوهش آب ایران - پیاپی 31 (زمستان 1397)
  • پیاپی 31 (زمستان 1397)
  • 160 صفحه،
  • تاریخ انتشار: 1397/12/18
  • تعداد عناوین: 13
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  • حسن ترابی پوده *، فرهاد ایزدجو، پرستو همه زاده صفحات 1-10
    روند تغییرات بارش کل و بارش موثر در کل ایران در مقیاس های سالانه، فصلی و ماهیانه با استفاده از آزمون های آماری مورد بررسی قرار گرفت. داده های مورد استفاده، شامل داده های 33 ایستگاه هواشناسی منتخب در دوره 50 ساله آماری (2010-1961) در محدوده مورد مطالعه بود. در این تحقیق، روند تغییرات بارش و بارش موثر در 2 دوره زمانی 40 ساله (1971-2010 و 2000-1961) و یک دوره 50 ساله (2010-1961) مورد بررسی قرار گرفت. در این بررسی ها، ابتدا شیب خطی روند در داده های نمونه با استفاده از روش TSA تخمین زده شد و سپس، در صورت وجود خود همبستگی با استفاده از روش TFPW اثر ضریب خودهمبستگی از داده ها حذف شد و سری های زمانی آبدهی اصطلاحا پیش سفید و در نهایت روند تغییرات بارش کل و بارش موثر در سری های زمانی با استفاده از آزمون من کندال (MK) مورد بررسی قرار گرفت. نتایج نشان داد که میانه بارش موثر ایستگاه های منتخب در ایران منفی است و به همین دلیل، بارش موثر با کاهش همراه بوده است. همچنین، میانه بارش کل ایستگاه های منتخب برای دوره زمانی 40 ساله (2000-1961) نزدیک صفر و در دوره زمانی 40 ساله (2010-1971) منفی و در سطح 10 درصد معنی دار و برای دوره 50 ساله (2010-1961) منفی است؛ ولی معنی دار نیست
    کلیدواژگان: آزمون MK، بارش موثر، پیش سفید کردن، خودهمبستگی
  • فاطمه مهرشاد، داریوش رحیمی، مجید اسماعیلیان* صفحات 11-24
    در حوضه های رودخانه، زیرسیستم های اجتماعی، اقتصادی و طبیعی گوناگونی با هم در ارتباط هستند و بر یکدیگر اثر می گذارند. اطلاع از برهم کنش های این زیرسیستم ها و در نظر داشتن سناریوهای آینده آنها در اتخاذ تصمیم های کارآمدتر سیاست گذاران موثر است. در این پژوهش، با در نظر گرفتن شرایط توسعه، نیازهای آینده و پارامترهای هیدرولوژیکی در افق آینده حوضه بهشت آباد، چشم انداز منابع و مصارف آب این حوضه تخمین زده شد. برای این منظور، ابتدا با مرور ادبیات و مصاحبه با متخصصان و کارشناسان، اطلاعات مورد نیاز جمع آوری و به روش دلفی تلفیق، سپس با بهره گیری از تکنیک مدل سازی پویایی سیستم، مدلی از منابع و مصارف آبی آن حوضه طراحی شد. شبیه سازی های مدل برای سناریوهای گوناگون توسعه ای و اقلیمی، برای بررسی گزینه های مختلف سیاست گذاری و اثرهای آن، اجرا شد. نتایج نشان داد که روند توسعه باعث افت سطح آبخوان های حوضه در طول دوره شبیه سازی و قرارگیری دشت ها در وضعیت بحرانی شد که این امر، در شرایط تغییرات اقلیمی با سرعت و شتاب بیشتری رخ می دهد.
    کلیدواژگان: پویایی سیستم، حوضه بهشت آباد، رویکرد دلفی، سناریو، منابع آب، مدیریت منابع آب، مصارف آب
  • مجتبی احمدی زاده، صفر معروفی * صفحات 25-33
    استفاده از مدل های هیدرولوژیکی در مطالعات مختلف منابع آب یک ضرورت می باشد. با توجه به کمبود داده های مشاهداتی و نبود مقادیر متغیرهای حالت نظیر رطوبت خاک، در به کارگیری مدل های مفهومی بارش- رواناب، باید تخمین این متغیرها، با هدف کاربرد مناسب مدل و دستیابی به پیش بینی های بسیار دقیق انجام شود. یکی از روش های تخمین، استفاده از شیوه به روزسانی داده ها و یا تلفیق مقادیر مشاهداتی و پیش بینی های اولیه می باشد. این شیوه، شامل روش های مختلف، مانند فیلترکالمن و الگو های توسعه داده آن، مانند فیلتر کالمن دسته ای می باشد. در این تحقیق با استفاده از روش فیلتر کالمن دسته ای بر مبنای روش مونت کارلو، میزان رطوبت خاک در مدل HyMod در حوضه کسیلیان برآورد گردید. محاسبه پیش بینی ها در گام های زمانی روزانه و تصحیح آنها با تلفیق با جریان مشاهداتی انجام شد. برای شناسایی پارامترهای بهینه مدل از روش بهینه سازی سراسری به نام مجموعه های تکاملی ترکیبی (SCE-UA) استفاده شد. نتایج نشان داد که این شیوه می تواند به بهبود تخمین روزانه رطوبت خاک و به هنگام سازی جریان کمک نماید. شاخص نش- ساتکلیف برای روش پیشنهادی فیلتر کالمن دسته ای و روش بهینه سازی سراسری به ترتیب مقادیر 72/0 و 55/0را کسب کردند. استفاده از روش به روزرسانی سبب شد این شاخص در مقیاس روزانه به مقدار 31 درصد افزایش داشته باشد.
    کلیدواژگان: به هنگام سازی جریان، فیلتر کالمن، فیلتر کالمن دسته ای، مدل HyMod، مونت کارلو
  • ناصر گنجی خرم دل *، معصومه شمس، امیر پور حقی صفحات 35-50
    ارزیابی آسیب پذیری آبخوان برای توسعه و مدیریت منابع آب زیرزمینی، تصمیم های کاربری زمین و نحوه برنامه ریزی و مدیریت منابع آب خصوصا بهره برداری و حفاظت کیفی آب زیرزمینی بسیار مفید و پراهمیت است. در این تحقیق، هفت لایه از پارامترهای تشکیل دهنده مدل استاندارد دراستیک (DRASTIC) تهیه شد. سپس، میزان تاثیرگذاری هر یک از پارامترهای مدل بر وضعیت آبخوان بررسی و بعد از به کارگیری وزن پارامترهای مدل دراستیک، نقشه هم پوشانی هفت لایه تشکیل دهنده مدل که نقشه پهنه بندی شاخص آسیب پذیری مدل دراستیک بود، تهیه گردید. بر اساس این طبقه بندی 4/3، 2/42، 4/41، 24 و 7 درصد آبخوان به ترتیب دارای میزان آسیب پذیری قابل اغماض، خیلی کم، کم، متوسط و متوسط تا زیاد بودند. به منظور اعتبارسنجی مدل، از مقادیر آلاینده نیترات موجود در آب زیرزمینی آبخوان مورد مطالعه استفاده شد که بر اساس نتایج حاصل، میزان ضریب همبستگی پیرسون برابر 67/0 محاسبه شد. با توجه به شرایط هیدروژئولوژیکی منطقه، از روش تحلیل حساسیت تک پارامتری استفاده شد که بر اساس آن، مقدار ضریب همبستگی پیرسون برای پارامتر عمق سطح ایستابی، بالاترین و برای پارامترهای تغذیه خالص و محیط خاک کمترین بود. به دلیل تطابق نداشتن وزن پارامترهای اختصاص یافته به پارامترها در مدل با نتایج تحلیل حساسیت از روش رتبه بندی AHP استفاده شد. مدل اصلاح شده (DATIC)، منطقه را به سه دسته مختلف آسیب پذیری تقسیم بندی کرد. بر اساس نتایج حاصل، مقدار ضریب همبستگی پیرسون در مدل اصلاح شده از 67 به 79 درصد ارتقا یافت که می تواند تاییدی بر تعریف مدل اصلاح شده دراستیک در منطقه مورد مطالعه باشد.
    کلیدواژگان: آب زیرزمینی، پارامترهای هیدروژئولوژیکی، پتانسیل آسیب پذیری، کاربری اراضی، مواد آلاینده
  • اکبر هاشمی فرد *، پرویز کردوانی، فریده اسدیان صفحات 51-59
    دانش اکوژئومورفولوژی از تلفیق دو دانش اکولوژی و ژئومورفولوژی منشا می گیرد که به بررسی موجودات زنده و محل زندگی آنها، با توجه به تاثیرات محیطی زیستگاه ها، می پردازد. در این تحقیق، هدف اصلی بررسی نقش عوامل مذکور بر کیفیت آب رودخانه کارون در پایین دست سد گتوند تا اهواز می باشد. داده های تحقیق، شامل داده های کیفیت آب رودخانه کارون در چهار ایستگاه پایین دست سد گتوند، و همچنین داده های اکوژئومورفولوژی و آنتروپوژنیک محدوده مورد مطالعه است. با توجه به نقش پارامترهای مورد نظر ابتدا در ایستگاه های مورد مطالعه نمونه برداری از آب انجام شد و سپس با استفاده از نرم افزار های اکسل و Chemistry شاخص های کیفیت آب در قالب اشکال و نمودارها مورد بررسی و تجزیه و تحلیل قرار گرفتند. سپس، با استفاده از نرم افزار ARC GIS10.2 و Expert choice11 نقش عوامل موثر در کیفیت آب رودخانه کارون تحلیل فضایی شد و در نهایت، مکان های آسیب پذیر بر اساس مدل Fuzzy AHP مورد شناسایی قرار گرفتند. نتایج تحقیق نشان داد که علت نامطلوب شدن آب رودخانه کارون از محل تقاطع رودخانه گرگر و شطیط به بعد، روستاهای اطراف و پساب کارخانه ها و صنایع نزدیک رودخانه، کشاورزی و همچنین ورود رودخانه دز می باشد.
    کلیدواژگان: رودخانه کارون، سد، گتوند علیا، سازند گچساران
  • فاطمه کریمی صحنه سرایی*، علی محمد آخوند علی صفحات 61-73
    با توجه به اینکه در اغلب حوضه های آبریز کشور، وقوع سیل و خسارت های ناشی از آن روند افزایشی دارد، تعیین مناطق مولد سیل و اولویت بندی زیرحوضه ها برای اجرای پروژه های کنترل سیلاب از اهمیت بسزایی برخوردار است. در این پژوهش، با تلفیق ArcGIS و HEC-HMS، پتانسیل سیل خیزی و تولید رواناب زیرحوضه های حوضه آبریز امامه بررسی شده است. این حوضه در شمال شرق تهران و در دامنه های جنوبی البرز مرکزی واقع شده است. برای رسیدن به اهداف پژوهش، از روش تکرار حذف انفرادی زیرحوضه ها از مدل بارش- رواناب استفاده شد. نتایج نشان داد که میزان مشارکت زیرحوضه ها در دبی خروجی کل حوضه تنها تحت تاثیر مساحت و دبی اوج زیرحوضه نیست و اثر متقابل عواملی همچون موقعیت مکانی زیرحوضه ها، فاصله تا خروجی، شکل حوضه، پروفیل طولی آبراهه، CN که خود تابعی از شیب، کاربری اراضی، نوع خاک، پوشش گیاهی و... است، هم زمانی دبی اوج زیرحوضه ها و نقش روندیابی در رودخانه اصلی تاثیر بسزایی در تولید رواناب و سیل خیز بودن زیرحوضه ها دارند. در مجموع، زیرحوضه های واقع در بالادست و میانه حوضه بیشترین سهم را در دبی اوج خروجی به خود اختصاص داده اند. بنابراین، توصیه می شود عملیات اصلاحی و کنترل سیلاب در این مناطق متمرکز شود.
    کلیدواژگان: پتانسیل یابی، حوضه امامه، سیل خیزی، HMS، HEC، ArcGIS
  • سمیه صالحی*، محمد جواد خانجانی صفحات 75-83
    بحران آب آشامیدنی در بسیاری از نقاط جهان وجود دارد. تکنولوژی های نمک زدایی تا حد زیادی مشکلات کمبود آب را کاهش می دهند و کیفیت زندگی و وضعیت اقتصادی را بهبود می بخشند. با توجه به اینکه فرایندهای نمک زدایی مختلفی وجود دارد؛ اما اسمز معکوس از فرایندهای غشایی است که اخیرا پیشرفت ها و کاربردهای زیادی داشته است. همواره فاکتورهای زیادی بر عملکرد یک سیستم نمک زدایی تاثیر دارد؛ از جمله این موارد، می توان به تغییرات دما، فشار، غلظت آب ورودی، میزان آب ورودی، نحوه طراحی و چیدمان ممبرین ها اشاره کرد. در این پژوهش، تغییرات هر یک از این پارامترها و تاثیرش بر عملکرد سیستم با معادلات ریاضی، پکیج نرم افزاری و تجربیات میدانی به دست آمد. طبق یافته ها، فشار و دما همواره به عنوان فاکتوری با کارکرد متناقص در حفظ کیفیت و کمیت آب تصفیه شده عمل می کنند. افزایش غلظت و میزان آب ورودی باعث کاهش کیفیت آب تصفیه شده می شود. برای افزایش 10% راندمان می توان سیستم دو مرحله ای یا سیستم با بازگشت آب را طراحی کرد. همچنین، آرایش سری ممبرین ها، عملکرد بهتری نسبت به آرایش موازی آنها داشت؛ به طوری که باعث بهبود 12% در راندمان شد.
    کلیدواژگان: آرایش ممبرین ها، اسمز معکوس، پارامترهای طراحی، نمک زدایی
  • حسن اوجاقلو *، مهران رستملو، مسعود کرباسی صفحات 85-94
    یکی از مهم ترین معیارهای ارزیابی عملکرد در طراحی سامانه های آبیاری تحت فشار و به خصوص سامانه های آبیاری بارانی کلاسیک، شاخص یکنواختی پخش آب می باشد. در این تحقیق، عملکرد سامانه استنتاج فازی- عصبی و برنامه ریزی بیان ژن به منظور تخمین ضریب یکنواختی پخش آب در سامانه آبیاری بارانی کلاسیک ثابت در شرایط مختلف از نظر سرعت باد، آرایش آبپاش ها، دبی و نوع آبپاش ها مورد ارزیابی و مقایسه قرار گرفت. به همین منظور، یک سامانه آبیاری بارانی کلاسیک ثابت با در نظر گرفتن آرایش های مختلف لوله ها و آبپاش ها طراحی و اجرا شد. تعداد 54 آزمایش مزرعه ای برای ارزیابی عملکرد یک سامانه آبیاری بارانی کلاسیک ثابت انجام شد. کمترین مقدار میانگین خطای مطلق برای روش های استنتاج فازی و بیان ژن به ترتیب برابر با 2/6 و 1/5 درصد و بیشترین مقادیر ضریب همبستگی برای روش های مذکور به ترتیب 77/0 و 72/0 به دست آمد. به طور کلی، اختلاف بین عملکرد دو روش برنامه ریزی بیان ژن و سامانه استنتاج فازی ناچیز بود و حساسیت سنجی مدل ها نشان داد، عامل دما و سرعت باد به ترتیب کمترین و بیشترین اثر را بر تغییرات ضریب یکنواختی پخش آب داشتند. همچنین بررسی مقادیر تخمین یافته ضریب یکنواختی پخش آب نشان داد، مدل های هوشمند به خوبی توانسته اند اثر عواملی همچون سرعت باد و فواصل آبپاش ها را بر کاهش مقدار یکنواختی پخش آب شبیه سازی کنند.
    کلیدواژگان: آرایش آبپاش، پیش بینی، سرعت باد، مدل های هوشمند
  • عطا الله ندیری*، مرضیه داداش بابا، اصغر اصغری مقدم صفحات 95-102
    دشت تبریز، در شمال غرب استان آذربایجان شرقی مانند دیگر دشت های اطراف دریاچه با بحران کاهش سطح آب زیرزمینی ارومیه روبرو است؛ بنابراین برای مدیریت صحیح و موثر این منابع، مطالعه و بررسی تغییرات تراز آب زیرزمینی در دشت ها ضروری به نظر می رسد. در این پژوهش، از روش ترکیبی مدل شبکه عصبی پیش رو (ANN) با دسته بندی هوشمند نقشه خودسازمان ده (SOM) برای مدل سازی تراز آب در 10 چاه مشاهده ای آبخوان آزاد دشت تبریز استفاده شده است. ابتدا پنج پارامتر ورودی موثر بر تراز آب زیرزمینی شامل بارش (P)، دما (T)، تبخیر (E)، دبی خروجی (Q) و تراز آب زیرزمینی (GWL) در یک زمان قبل (t0-1) برای 10 چاه مشاهده ای آماده شدند. سپس این چاه های مشاهده ای، بر اساس تغییرات تراز آب 14 ساله در چهار کلاس دسته بندی و با استفاده از مدل ANN، پیش بینی تراز آب در تمام چاه های مشاهده ای برای دسته ها انجام شد. طبق نتایج، برای کلاس های یک، دو و چهار، میانگین خطای مرحله آموزش و آزمایش به ترتیب 10/0، 20/0 و 22/0 متر و برای کلاس سه که در مرکز دشت موقعیت یافته است، میانگین خطا 23/0 متر حاصل شد.
    کلیدواژگان: آبخوان آزاد دشت تبریز، تراز آب زیرزمینی، چاه های مشاهده ای، مدل SOM -ANN
  • محمدرضا امداد*، محسن دهقانی، هرمزد نقوی صفحات 103-111
    نفوذ، از مشکل ترین و زمان برترین اندازه گیری پارامترهای فیزیکی خاک بوده است که بایستی برای برنامه ریزی صحیح آبیاری تعیین شود. برای ارزیابی روش شاخص مقیاس در برآورد نفوذ آب در خاک، این پژوهش در سه بافت مختلف رس سیلتی، لومی و لوم شنی انجام شد. مقدار نفوذ آب در آبیاری جویچه ای با استفاده از اطلاعات پیشروی آب در کل جویچه و با استفاده از مدل بیلان حجمی (روش دو نقطه ای) در 9 جویچه اندازه گیری (در هر بافت خاک) تعیین شد. همچنین با استفاده از روش شاخص مقیاس و اطلاعات پیشروی آب در نصف طول جویچه، مقادیر نفوذ آب در خاک در هر یک از بافت ها تعیین گردید. نتایج نشان داد که مقادیر متوسط قدرمطلق خطا (مقایسه نتایج استفاده از روش شاخص مقیاس و مقادیر اندازه گیری شده نفوذ در 9 جویچه در هر بافت خاک) در بافت لوم شنی، لومی و رس سیلتی به ترتیب 00556/0، 00215/0 و 00449/0 است. همچنین متوسط شاخص توافق در هر سه بافت حدود 95/0 محاسبه شد. ضریب همبستگی بالا (90/0 = R2) و نزدیک بودن نتایج رگرسیونی مقادیر نفوذ اندازه گیری شده با مقادیر تعیین شده با روش شاخص مقیاس و خط یک به یک، بیان کننده مناسب بودن روش شاخص مقیاس در تعیین نفوذ آب به خاک در وضعیت های مختلف بافت خاک است
    کلیدواژگان: آبیاری جویچه ای، بیلان حجمی، فیزیک خاک، نفوذپذیری
  • احمدرضا قاسمی *، ژاله نوروزی، مهدی قبادی نیا، عبدالرزاق دانش شهرکی صفحات 113-122
    امروزه توسعه کشت گیاهان دارویی به دلیل ارزش افزوده بالایی که دارند، از اهمیت ویژه ای برخوردار است. کمبود اطلاعات مختلف، مانند نیاز آبی می تواند یکی از موانع توسعه کشت این گیاهان باشد. پژوهش حاضر با هدف تعیین ضرایب گیاهی یگانه و دوگانه کتان روغنی به وسیله لایسی متر در مراحل مختلف رشد در منطقه شهرکرد انجام شد. نتایج محاسبات ضریب گیاهی یگانه با لایسی متر نشان داد که مقدار میانگین ضریب گیاهی یگانه کتان روغنی در مرحله اول رشد برابر با 74/0، در مرحله میانی 23/1 و در انتهای مرحله پایانی برابر با 61/0 می باشد. نتایج مقایسه ضریب گیاهی یگانه با روش فائو 56 با نتایج لایسی متر حاکی از آن بود که تفاوت مقدار ضریب گیاهی یگانه با استفاده از این دو روش، در مرحله اولیه و میانی بسیار کم، ولی در مرحله پایانی زیاد می باشد. همچنین، نتایج ضریب گیاهی دوگانه نشان داد که ضریب گیاهی پایه برای کتان روغنی در مراحل مختلف رشد به ترتیب 15/0، 15/1 و 2/0 می باشد. تبخیر تعرق واقعی کتان روغنی با استفاده از ضرایب گیاهی یگانه، دوگانه و لایسی متر به ترتیب برابر 391، 445 و 444 میلی متر به دست آمد که به خوبی دقت روش ضریب گیاهی دوگانه را برای محاسبه تبخیر- تعرق واقعی گیاه نشان می دهد.
    کلیدواژگان: چمن، درجه روز رشد، شهرکرد، فائو 56، مدیریت آب
  • محمد مهدی معیری *، محمدعلی قربانی، یعقوب دین پژوه صفحات 123-130
    تصمیم گیری های دقیق با در نظر گرفتن عدم قطعیت ها در برنامه ریزی مدرن منابع آب منجر به حصول نتایج واقع بینانه تری شده که تاکید بر اهمیت برآورد عدم قطعیت مدل ها در مطالعات مربوطه نیز می باشد. در این تحقیق، از فیلتر کالمن همادی توام (JEnKF) برای برآورد و کاهش عدم قطعیت در یک مدل مفهومی هیدرولوژیکی بارش رواناب جهت مدل سازی حوضه بهشت آباد در استان چهارمحال و بختیاری برای سال های 1385-1380 استفاده شد. مدل مفهومی مورد استفاده، مدل HyMod بوده که با توجه به خصوصیات حوضه، زیرمدل ذوب برف نیز به آن اضافه شد. کارایی این روش در پیش بینی جریان، توسط معیار RMSE در مقادیر دبی طبقه بندی شده در چهار دسته متمایز با نتایج روش جستجوی بهینه سراسری SCE ارزیابی شد. نتایج نشان داد که به روزرسانی متغیرهای حالت، خطای پایین تری را در هر یک از دسته های مختلف جریان و به خصوص جریان های پایه ارائه می دهد. مقدار کاهش خطای روش JEnKF در مقایسه با روش SCE در دوره واسنجی 1383-1380 از حداقل 18 درصد تا حداکثر 63 درصد تغییر کرد؛ این رقم برای دوره صحت سنجی بین 7 تا حداکثر 73 درصد بود. در پایان، عدم قطعیت پیش بینی مدل در دو شرایط مختلف، یکی شرایط عدم قطعیت ناشی از (فقط) پارامترها و دیگری، شرایط عدم قطعیت ناشی از اجزای مختلف مدل، شامل پارامترها، متغیرهای حالت و خروجی ها با هم مقایسه شد. نتایج این بررسی، حاکی از پوشش بهتر داده های مشاهداتی در شرایط دوم توسط عدم قطعیت پیش بینی مدل بود.
    کلیدواژگان: ذخیره برف، عدم قطعیت، فیلتر کالمن همادی توام، مدل بارش رواناب HyMod
  • حسین خزیمه نژاد*، مهدی قمشی صفحات 131-136
    تاکنون مطالعات زیادی در خصوص شناخت مکانیزم آبشستگی اطراف سازه های هیدرولیکی به خصوص پل ها انجام شده و روش هایی هم برای کنترل یا کاهش آبشستگی در اطراف آن ها مورد بررسی و ارزیابی قرار گرفته اند. در زمینه آبشستگی اطراف پل ها، تمرکز تحقیقات بیشتر بر روی پایه بوده است تا تکیه گاه؛ در حالی که بررسی آمار موجود بر روی شکست پل ها نشان می دهد که بیشتر مشکلات، مربوط به تکیه گاه بوده و بالطبع هزینه های بیشتری نیز در این بخش صرف شده است. یکی از روش های کاهش آبشستگی اطراف تکیه گاه، استفاده از طوقه است. در تحقیق حاضر، تاثیر ابعاد و تراز نصب طوقه بر کاهش آبشستگی پیرامون تکیه گاه مستطیلی مورد بررسی قرار گرفت. هم چنین، مولفه های سه بعدی سرعت جریان پیرامون تکیه گاه مجهز به طوقه با استفاده از سرعت سنج الکترومغناطیس تعیین شدند و برای الگوی جریان مورد استفاده قرار گرفتند.نتایج نشان داد که با افزایش ابعاد طوقه عملکرد آن بهبود می یابد؛ همچنین، نتایج حاکی از عملکرد بهتر طوقه های زیر بستر نسبت به طوقه های روی بستر و بالاتر از بستر است. بر اساس نتایج تحقیق حاضر جریان رو به پایین و گرداب های ایجاد شده از عوامل اصلی آبشستگی پیرامون تکیه گاه بوده و طوقه با مهار جریان رو به پایین و مقاوم کردن بستر در مقابل گرداب های ایجادشده، نقش موثری در کاهش آبشستگی پیرامون تکیه گاه دارد.
    کلیدواژگان: الگوی جریان، آبشستگی، طوقه، تکیه گاه پل، مقطع مستطیلی
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  • Hasan Torabi Poudeh *, Farhad Izadjoo, Parastoo Hamezade Pages 1-10
    For the past several years, the severity and frequency of extreme events like flooding or prolonged droughts seem to be on the rise, globally. Precipitation is the most vital element of climate which almost influences many aspects. The effect of precipitation on different human activities including farming, industry and services is obvious (directly, indirectly, or with intermediate). In this regard, the relation between precipitation and farming, especially dry farming, is considerable and somehow distinct from other activities. It is clear that the most natural kind of using precipitation at farming section is dry farming. Identification of rainfall events are important in designing the related water structures, farming, weather modifying, policy making and planning and also in monitoring climate change. Methodology identification of trend or persistence in the rainfall series is essential to present the hydrological information in a condensed form for decision making and planning in water resources of any region. Effective rainfall (ER) is defined as that portion of rainfall which is useful directly and/or indirectly for crop production at the site where it falls. Effective rainfall is influenced by the factors such as quantity and intensity of rainfall, evapotranspiration (ET) and deep percolation losses, and irrigation management practices. Estimating the effective rainfall is extremely useful for operational planning and management issues. This paper exemplifies a study involving non-parametric statistical method of Mann-Kendall test for identification of trends in annual rainfall series in Iran. The nonparametric Kendall test was applied to find trends in a number of climatic and hydrologic variables. This test was selected because it can handle non-normality, censoring, or data reported as values "less than", missing values or seasonality and because it has a high asymptotic efficiency. Mann Kendall nonparametric test is widely used for the analysis of trends in meteorological and hydrological series. One of the advantages of this method is its applicability for a time series distribution, which does not follow a typical statistical distribution. This method of analysis adopts two parameters such as the Kendall statistic, S and the normalized test statistic Zs, which are used to determine the nature and level of the significance of trends exhibited by the variables. Generally, a positive value of S is an indication of an upward trend, while a negative value indicates a downward trend. Also, the value of Zs -greater than 1.96 at a selected confidence limit of 95%- shows that the trends can be interpreted as statistically significant or otherwise. The data must be serially independent in the case of the non-parametric tests. Based on the performed studies, the existence of serial correlation will increase the probability for significant trend detection. This leads to a disproportionate rejection of the null hypothesis of non-trend, whereas the null hypothesis is actually true. Therefore, the influence of serial correlation must be eliminated. In this regard, different methods such as pre-whitening, variance correction, and TFPW have been proposed. The TFPW procedure presented here provides a better assessment of the significance of the trends for serially correlated data than the other approaches and several researchers have used this procedure. The trend changing of total and effective rainfall of the entire country of Iran on three scales (annual, monthly and seasonally) was analyzed using statistical tests. The data of 33 stations was used in the study area. In this analysis, the trend changes of total and effective precipitation in the period of 40 years (1971-2010) and (1961-2000) and a 50-year period (1961-2010) were studied. The slope of the linear trend of data was estimated by TSA and then, if there was a correlation between data, the autocorrelation coefficient between data removed using TFPW method, and the time series of precipitation pre-whited. Then, the trend channeling of total and effective rainfall time series was analyzed, using the Mann-Kendall test. The results showed that the median of effective rainfall in the selected stations were negative and therefore they had decreasing trend. Also, the median of total rainfall in the selected stations for a period of 40 years (1961-2000) was approximately equal to zero and for the 40-year period (1971-2010) the trend was significant at the level of 10%. While, for the period of 50 years (1961-2010) the median was negative, but not significant.
    Keywords: Autocorrelation, Effective rainfall, MK test, Pre whited
  • fatemeh mehrshad, Dariush Rahimi, majid esmaelian* Pages 11-24
    Due to complexity in water resources management problems and its direct relation with other sciences, it is impossible for only one decision-maker to consider all of the necessary aspects in integrated managing and planning of water resources. Various sub-systems of social, economic, and natural diversity communicate and affect each other in river basins. Understanding the interactions among subsystems, feedbacks and their side effects and also knowing the developmental and climatic scenarios of the future are important for making decisions by politicians, more efficiently. With a partial view to the water resources management, traditional approaches do not consider the complexity of water management. But, a growing understanding in this regard that the water crisis is originally a management crisis has emerged, recently. It is necessary to consider proper methods for coordinating policy-making, planning and implementing in a consolidated and cross-sectional way. In this study, considering the development conditions and needs of the future of Behesht-Abad basin, as well as the prediction of climatic parameters (such as precipitation), we estimated the future vision of water resources and water uses in this basin. Therefore, a wide range of information in various specialized areas related to water resources was needed to design a comprehensive model. First, through interview with relevant experts, the required information was collected and integrated with Delphi method. Then, a comprehensive model of water resources for the basin was designed, using system dynamic techniques. The model simulations, for different developmental and climatic scenarios, were implemented in order to investigate various alternatives of policy-making and their effects. The boundaries of the model was determined through interview with experts of related fields, using Delphi method to incorporate the comments about the effective parameters on water resources and uses in Behesht-Abad basin and their relations with each other . Interviews were performed in several meetings to reach a consensus among the experts. Then, the water resources and uses model of Behesht-Abad basin was designed, based on the obtained results. The model's simulations for various scenarios were performed by considering the development conditions and needs in the future of the basin, as well as the prediction of climatic parameters, in order to investigate various alternatives of policy-making and their effects. The results showed that the current development trend will lead to a sharp drop in groundwater resources levels and a critical condition in plains after the year 2015. Also, water tension index showed a severe water tension in the basin after the year 2033 and the output runoff of Behesht-Abad basin do not provide the minimum need of downstream river in some years. However, by comparing the results of model simulation in scenarios 1 and 2, it was observed that the modification of growth rate of water needs- only in the industry sector- has a significant effect on groundwater resources and aquifer sustainability index. Therefore, the volume of groundwater resources in the final year of the simulation in Scenario 2 is about three times more than its value in Scenario 1. Also, the comparison of the value of water tension index in scenarios 1 and 2 showed that reducing the rate of growth of water demand in the industrial sector prevents the basin from severe water tension in the final onward years of the simulation. So, it seems that by applying the procedures of water saving in the industry sector such as using high-tech industries that require less water and also reusing wastewater in industry sector can prevent severe water tension in the basin and plains, in the critical condition. In addition, according to the simulation results for climate change scenarios and due to a significant decrease in precipitation and increase in evaporation rate in the basin, the volume of water in the basin will drop significantly. Also, the amount of water tension index, especially in the final years of the simulation period, indicated that the water tension is more severe, comparing with the scenario of continuing developmental and climatic trend. Finally as a suggestion, the developmental policies in the industry and agriculture sectors of the basin should be adopted by examining of all aspects and considering the consequences expressed in this research for the water resources and environmental needs, to improve the aquifers sustainability in Behesht-Abad basin
    Keywords: Behesht, abad Basin, Delphi approach, System dynamics, Scenario, Water resources, Water resources management, Water consumptions
  • Mojtaba Ahmadizadeh, Safar Marofi * Pages 25-33
    Conceptual Soil moisture rainfall runoff models (RRM) can be applied for simulation and forecasting daily stream flow based on their developed relations. There is an inherent uncertainty in the outputs of RRM. Data assimilation (DA) is an approach that can help to not only estimate the state variable, but also to calculate the uncertainty of outputs. DA can be used in order to reduce the state uncertainty via updating the model states by fusing observations and model outputs to obtain an estimate of the model states. Sequential DA techniques provide a general framework for explicitly taking into account input uncertainty, model uncertainty, and output uncertainty. DA approach is the process through which the available information is used to estimate the state of the conceptual hydrologic model, as accurate as possible. There are several different DA methods available. State-space filtering methods based on variations of the kalman filter (KF) approach have been proposed and implemented because of their potential ability to explicitly handle uncertainties in hydrologic predictions. Kalman filtering is a popular tool in the research community for estimating non-stationary processes when it is possible to model the system dynamics by linear behavior and Gaussian statistics. The first sequential DA method called Kalman filter that was employed for optimizing control of linear developed systems. KF has not used in hydrologic investigations because of its limitation to linear models. In hydrologic studies the Ensemble Kalman filter (EnKf) has been developed in order to estimate state variables, as well as parameters. DA is useful in state estimation and making the forecasts more accurate. In EnKf, the hydrologic model being run and gone forward temporally with a specified number of state variables. HyMod was used in this research. Hymod is a non-linear RRM. It relates the mean areal precipitation and the potential evapotranspiration, for a certain catchment, to the discharge. The model consists of a slow flow and quick flow components. The slow flow component consists of one linear tank. It represents the water that flows through the ground and eventually empty to the river. While the quick flow component consists of three identical quick flow tanks, representing the portion of water that flows directly into the river. It is a parsimonious model, which consists of five parameters. By applying EnKf method, the amounts of soil moisture in rapid and slow tanks of HyMod model are estimated by updating the forecasted steamflow based on the observations. Hence, the forecasted flow will be corrected with updated soil moisture in daily step. In the present study, parameters were estimated by applying the shuffled complex evolution method (SCE-UA). This method was applied in many studies and has been highly recommended by multiple scholars. As the procedure needs that the equations to be written in state space format, therefore the HyMod equations changed to matrix form to be calculated. The equations have written down in a matrix form and the state and measurement equations have been related. Different ensemble members also assessed in order to check the capability of the EnKf based on Nash-Sutcliffe measure in kassilian river basin. Kassilian watershed is located in the northern part of Iran. Its discharge area covers a surface of 67.2 km2 and its average slope is 16.4%. It is a mountainous watershed with 65% of its total area covered with forests. A gauging station, operated since 1970, is located at the outlet of the basin. An Ensemble with 25 members was selected as the elite results. To show the merits of the proposed method; first, the model was used in an open loop way without data assimilation and updating. Afterwards, the EnKf has been implemented. The Nash-Suttclife measure has been employed to show, which method performs better.The results revealed that by using EnKf and updating the soil moisture of the Hymod model the accuracy of forecasted streamflow improves and the Nash-Suttclife criteria increases by 31%. It reaches 0.72. This study has introduced the theory and concepts of EnKf as a DA methodology for inference of state variables in a RRM. As models besides the parameters have state variables, therefore, they can simultaneously be estimated with EnKf. So, we suggest that the dual combination of state and parameters can be explored in a complementary study.
    Keywords: Ensemble Kalman filter, HyMod model, Kalman filter, Monte Carlo, Streamflow updating
  • Naser Ganji Khorramdel*, masoomeh Shams, Amir Poor haghi Pages 35-50
    Water resources management comprises directives to protect both surface and groundwater. Agricultural activity is the most significant factor and the main cause of the prominent increase in chemical pollutant (e.g. nitrates or pesticides) in many aquifers. The other source of pollution (organic) can be attributed to agriculture, generating a local increase in the concentration of nitrate levels from farming activities and waste water. A long-term intake of water with a high nitrate concentration is harmful to human health. Groundwater as a source of water supply, ecological environment factor and geological has become increasingly prominent. However, groundwater has confronted with gradually serious pollution. Nowadays, groundwater vulnerability assessment has become a useful tool for groundwater pollution prevention and control. Groundwater vulnerability mapping can indicate regions which are more vulnerable to contamination in the planning stage of socio-economic activities. In this study, intrinsic vulnerability mapping was evaluated. Nitrate has been often selected as an indicator for the assessment of groundwater vulnerability and pollution risks. Existing methods to assess groundwater specific vulnerability include: overlay index method, process simulation method and statistical models. Overlay index method, based on superimposing the selected sub-indexes to calculate a composite index reflecting vulnerability extent, has four major factors which are indexes, weights, ranges and classification. The most widely used method of vulnerability evaluation is DRASTIC model, due to its ease to use, minimum data requirement, and clear explanation of groundwater vulnerability. In addition, DRASTIC model gives relatively accurate results for extensive regions with complex geological structure in absence of measured data of specialized indexes. DRASTIC model has been transformed by the modification of its indexes and applied to assess the vulnerability of unconfined and confined groundwater Aquifers. However, its results may be inaccurate due to high obvious subjectivity. The most critical challenge of groundwater vulnerability is achieving the optimal balance among the complexity of method, cost and uncertainty of assessment results. While it is important to check the accuracy of the vulnerability mapping, previous researches have neglected to discuss the validation method for vulnerability mapping, integrally. The choice of an appropriate validation criterion is still disputed in the research. Plain Aleshtar in Lorestan province, Iran, is located in the longitudes of 48° 02' and 48° 31' E and the latitudes of 33° 43' and 34° 05'N. DRASTIC term is Based on seven parameters include: depth of water table, net recharge, aquifer media, soil media, topography, impact of vadose zone and hydraulic conductivity. One of the most important factors is the water table depth in DRASTIC Model. In order to provide the data layer of this factor, 21 observation wells in the plain Aleshtar were used. By interpolating these point data, DRASTIC model was evaluated according to the criteria. In this study, maps of slope, rainfall plains and net recharge criteria were classified and the overlapping layers were prepared. The top layer of soil environment and vadose zone is unsaturated area. To prepare this parameter layer, logging of 21 operating wells in plain Aleshtar was done. Then, the wells were ranked according to DRASTIC model criteria. The prepared maps of classification and valuation were based on the results of Aller and colleagues (1987). In this research, in order to validate the potential areas of vulnerability, results were compared with maps of the distribution of nitrate. Single-parametric sensitivity assesses the impact of each of the model parameters sensitivity on the vulnerability index. In this analysis, "effective" or "real" weight of each parameter is compared with the "theoretical" weight assigned through the analytical model. In this study, seven layers of reference parameters required for the Standard Model Drastic were prepared according to Aller and colleagues (1987). Then, the effect of each of the aquifer parameters was investigated. After weighting DRASTIC parameters and overlaying the seven layers vulnerability index zoning maps were prepared. Based on this classification 3.4, 24.2, 41.4, 24 and 7 percent of the aquifer, respectively had the vulnerability of negligible, very low, low, medium and medium to high. In order to validate the model, its results compared with the measured nitrate pollution in groundwater aquifer and the Pearson correlation coefficient was 0.67. For the purpose of this study that was to try to increase the correlation coefficient based on existing methods and that model modified according to hydrogeological conditions, the model was developed and offered. Therefore, single parameter sensitivity analysis was done, based on the Pearson correlation coefficient. By the results, water table depth had the highest correlation while the net recharge parameters and soil environment had the lowest. Inconsistency due to the assigned weights of the parameters by the model and the results of sensitivity analysis method, AHP method was used. Results showed that the weight of topography parameter varied from 1 to 2 and weight of unsaturated zone was changed from 5 to 2.8. Also, net recharge parameters and soil environment were omitted due to negative correlation with the nitrate zoning map. By the Modified (DATIC) Model, the region was divided into three different classes of vulnerability, in which 67% was negligible, 24% too low and 9% in the classification of low vulnerability. Based on the results, the Pearson correlation coefficient was improved from 68 to 79 percent by the revised version.
    Keywords: Groundwater, Hydrogeologic parameters, Land use, Vulnerability potential materials
  • akbar hashemifard *, parviz kardavani, farideh asadian Pages 51-59
    The knowledge of eco-geomorphology is adapted from both ecology and geomorphology that investigates the living organisms and their locations due to the effects of habitat geo morphological features (moghimi, 1391). Anthropogenic impacts or Human Effects on the environment include impacts on the biophysical environment, biodiversity and other resources (Shaney& et al., 2010). These variables (often based on some factors such as geological formations and geomorphology of basin, river discharge regime, waste water from human activities and etc,) are used in order to evaluate the water resources status as well as development projects of utilization and allocation of water to different uses. Also, studies on eco-geomorphology and anthropogenic factors in river basin show the natural and unnatural effects on these resources. Arian et al. (2015), using multi-variety statistical techniques on water quality of the Bano River in Pakistan, showed that the water in some regions of this area was not suitable for drinking and irrigation, due to increased alkalinity. The main aim of this study was evaluating the role of eco-geomorphology and anthropogenic factors on water quality of the Karun River and management options, from Gotvand to Abadan. The research method was analytical. The data were collected from library and field methods. In this study, at first, indicators of water quality were analyzed by using the Excel and Chemistry software. Then, ARC GIS10.2 and Expert choice11 software was specially used to analyze the role of effective factors in the Karun River water quality and finally vulnerable areas were assessed. Then, the effect of eco-geomorphology and anthropogenic factors on the physical and chemical properties of the river water was investigated and results were analyzed. The next step for determining the vulnerable areas of the Karun River, affected from eco-geomorphology and anthropogenic factors, was performed by using Fuzzy-AHP model. After filling of Gotvand dam reservoir and increasing the contact of surface water with layers of water-soluble salts, especially in Gachsaran formation, million tons of salt dissolved in the reservoir. Due to the increasing density, saltier water placed in the bottom levelsand the water of the better quality in the upper layers.Eventually, the layer formation stated due to the quality of in the reservoir . So, in lower levels, water salinity is 3 to 4 times more than the seawater, while in the high levels, the water quality is suitable and salinity degree is less than allowed limit for variety of purposes including drinking water. In terms of geomorphology, sedimentation and any factor that exacerbates the issue should be considered for sensitively in this area. The increase in agricultural land has been associated with increased use of chemical fertilizers and pesticides that are transported to the river by drainage and cause the undesirable water of Karun River. Modern irrigation networks of Dez and Gotvand damscontain irrigated lands in Karun and Dez basins, mainly located in the southern region of Dezful and between Gotvand and the south of Shushtar. This area enters annually 152 million cubic meters of drainage water into the river. Also opening some units of sugarcane development project such as Imam Khomeini unit (Shoeybyeh) and part of the projects in Ahvaz, the amount of agricultural water withdrawals was increased significantly. Therefore, the waste water of these lands, which is generally saline with high Ec (Electrical Conductivity), increased sharply in this region and caused reducing the quantity and quality of the Karun River. Other factors such as sewage and urban wastes, dam construction and withdrawals of sand from the riverbed, themselves have caused pollution and changes in water quality. Finally, according to the investigations of eco-geomorphology and anthropogenic functions on the quality of Karun, the rate of these effects in different parts were zoned and then analyzed, that indicated the rate of the effects on the quality of water is very high at the confluence of Dez River, Gargar and Shoteyt to the down part of Ahwaz. The impact of these factors is relatively low in the upstream areas, comparing to the downstream; in other parts also, as the distance to Karun increases, the rate of impact of those factors lessens. According to taken investigations, maps and field observations, the causes of the unpleasant Karun water from Gotvand dam to Shushtar are as the following: The entrance of salty river to Aghili plain; drainage of extensive fish ponds (17,000 hectares) into the Gargar River; and the sewage from Shushtar town and surrounding villages. Also, in a branch of Shoteyt, part of the wastewater from Shushtar town entering the river as well as about 30 percent of wastewater from the sugarcane industry has increased 600 EC in the Karun River at the interval of regulatory dam of Gotvand to Bandeghir, on Shoteyt branch. Increase of EC of the Karun river from the junction of the Gargar and Shoteyt to the downstream is due to the surrounding villages, factories and industries near the river, agricultural areas and entrance of the Dez River (which contains sewage of surrounding towns, and drainage of sugarcane agro-industry of Imam Khomeini, Haft-tappeh, Mianab, and 70% of Karun agro-industry). Moreover, the eco-geomorphological and anthropogenic effects on water quality of the Karun River were assessed very high, from the junction of Dez- Gargar -Shoteyt down to Ahwaz. But, at the upstream areas, the impact of the factors is less.
    Keywords: Dam, Gotvandolya, Gachsaran, Karun River
  • Fatemeh Karimi sahnehsaraee *, Ali Mohammad Akhond, Ali Pages 61-73
    Introduction and methods
    Although floods are natural phenomena, human activities and interventions into the processes of nature, such as alterations in the drainage patterns from urbanization, agricultural practices and deforestation, have considerably changed the situation in all rivers' basins. As the result of these changes, exposition to risk and vulnerability in flood-prone area have been growing constantly. Understanding of this damaging phenomenon and adapting human activities based on legality of volatility are among the most important and fundamental scientific and practical methods to deal with the flood damages to life and property. It is necessary to promote and harmonize changes in water policies and land use, as well as environmental protection and nature conservation, in order to improve flood management in the frame of integrated river basin management. Due to large extent of basins, and economic and administrative constraints, reclamation of basins not only is impossible from point of view of the flood control in an individual project, but may have inverse effects. As regards that flooding and its damages is increasing in the most basins of Iran, determining flood productive areas and prioritizing sub-basins for comprehensive management of basins and flood control projects is very important. Therefore, assessing influence of different return periods on the intensity of flooding and run-off producing, and also determining of areas with maximum role on flood production in Amameh Basin has been done, in this study. Although the runoff resulting from rainfall is a complex and non-linear process, its modeling which is not too easy to run was performed in this research. One of the most important aims in this study was checking an applied and systematic method for identifying and prioritizing regions, regarding flood controlling operations and determining its function for other sub-basins in a system of actions and reactions.
    Discussion
    In the current research, ArcGIS software and HEC-HMS model were combined and the influence of different return periods on the intensity of flooding and run-off producing were considered. The contribution rate of different sub-basins in outlet flood of Amameh basin has been determined based on 2, 5, 10, 20, 25, 50 and 100-year return periods. The study area is located in northeast of Tehran City and southern hillside of Central Alborz Mountains. Among six main basins of Iran, this area sits in The Central Basin. To achieve the objectives of this study that is Sub-basins flooding priority, the Single Successive Sub-watershed Elimination (SSSE) method from rainfall-runoff model on HEC-HMS model has been used. A digital elevation model (DEM) for study area was also prepared and used to estimate the region’s hydrologic and geomorphic properties (including: basin shape factor, circular rate, main stream length, mean slope of basin and sub-basins, equivalent rectangle length and width, area, and so on). Furthermore, extracting main drainage network and dividing Amameh basin into five sub-basins was done by using this DEM. Finally, Sub-basins flooding priority map was extracted based on the (f) factor. The results of this study showed that the contribution rate of sub-basins in total basin’s output flow was not only affected by area and peak flow of sub-basins, but the interaction of many different factors such as location of sub-basins, distance from outlet, curve number (CN), and flood routing role in main river, also had significant impact on the sub-basins flooding.
    Conclusion
    This research indicated that it is possible to study the interaction of climatic conditions and physiographic factors on flooding potential of basins and sub-basins, by combining ArcGIS software and hydrological models. Moreover, influence of time changes and different return periods on various sub-basins’ run-off potential can be studied desirably. The results of this investigation illustrated that the contribution rate of different sub-basins in total basin’s output flow varied in different return periods. Therefore, to reduce the impact of sub-basins flooding in the basin’s outlet, a reasonable return period should be considered to carry out the basin management practices for flood mitigation with a higher certainty. In addition, flooding potential and run-off producing had an ascending trend with increasing of return period duration. Also, upstream sub-basins were more important in the output peak flow and run-off producing. So, it is recommended that corrective and flood controlling operations perform on the upstream instead of the downstream.
    Keywords: ArcGIS, Amameh Basin, Controlling flood, HEC, HMS, Sub basins priority
  • somaye salehi*, mohammad javad khanjani Pages 75-83
    Reverse osmosis (RO) is a type of pressurized filtration in which the filter is a semi-permeable membrane. The system is a complete technology and commonly uses as a practical desalination method. Nowadays, RO is a developing technology with53% world share in fresh water production. In previous studies parametric analysis was carried out based on mathematical or software modeling. In this study, field data was used to determine the impact of each of the parameters, considering environmental factors and operating conditions. In this model, according to the widely used solution-diffusion model, the water flux through the membrane is given by: (1) Where C1 is a conversion factor, Kw the water permeability, A the membrane area, ∆P the difference between the feed and permeate sides of the membrane pressure and ∆π the osmotic pressure difference across the membrane. By extending the proposed equation, mathematical modeling of reverse osmosis desalination system was developed. In this modeling, the permeate flux was assigned as the dependent variable and other parameters (such as temperature, pressure and feed concentration) as the independent variable. Finally diagrams of pressure, temperature and feed concentration in relationship with permeate flux were drawn using MATLAB 2012. The Reverse Osmosis Systems Analysis (ROSA) was supplied by Dow-Filmtec Company. This software was designed to evaluate the efficacy of RO system with RO membranes and Nanofilteration. So, after mathematical modeling, software modeling with ROSA was performed with the same conditions and assumptions. According to the modeling, results were more consistent in temperature of 15 to 30 degrees. Raising and decreasing the temperature increased the difference between the results. These differences may be due to the distance from the standard conditions and low impact of raising and decreasing the temperature in mathematical equations. Because in software modeling assigning the pressure as constant was not possible, the influence of pressure on other parameters was unknown. The empirical and field studies have shown that inlet pressure increased by increasing the rate of efficiency and leads to a linear increase of permeate flux and specific energy rate. With increasing the temperature, permeate flux had a non-linear increase. However, with constant flux, increase in temperature caused a decrease in brine. While, the lower feed water temperature resulted in the better quality of permeate. In addition, the operation of reverse osmosis systems requires large amounts of energy at low temperatures to reduce water permeability. Quality of feed water has a direct impact on the permeate quality. As the amount of dissolved solids in the feed water is higher, the amount of salt in the permeate water will increase. The arrangement of membranes was also evaluated. Water quality in series was better than parallel mode; however, more pressure was needed. Finally, as a case study, the desalination system with 20 cubic meters per hour capacity in Nina oil plan was intended. According to the desired permeate water quality and to achieve maximum efficiency, the single-stage device was designed with four parallel pressure vessels. Six membranes were placed in a pressure vessel. Life of each membrane according to feed pressure and recovery was assumed as 5 years, approximately. Also to the design, the efficiency of 65% was expected for this system. One of the main challenges for desalination system is the brine which has a high volume and concentration. Due to the analysis of the brine, it can be used for green space of factory. The pre-treatment system included different filters such as sand, carbon, 20 micron and 5 micron filters as well as UV lamp and antiscalant injection. Also, caustic soda in the post-treatment was used to adjust the pH. The results of this study are extracted as fallowing: (1) The pressure and temperature are always inconsistent factors in maintaining water quality and quantity of permeate. Rising feed pressure increases permeate quality, but on the other hand, needs stronger pump and increases costs. Increasing temperature increases the efficiency while reduces the quality of permeate. Hence, the pressure and temperature should be optimized. (2) Feed concentrate has a direct impact on permeate quality. The important factor in reducing the salt in the feed water, and eventually increasing water quality, is using a suitable pretreatment system. (3) Designing as an important factor in the efficiency, cost and water consumption, requires engineering experience and vision. To increase the efficiency, two-stage or water-returning system can be designed. Also, the membrane arrangement affects the efficiency and quality of permeate water.
    Keywords: Arrangement of membranes, Desalination, Design parameters, Reverse osmosis
  • Ataallhah Nadiri *, Marzieh Dadashbaba, Asghar Asghari Moghaddam Pages 95-102
    Increasing agricultural, industrial, and domestic demands as well as over abstraction of groundwater especially in semiarid areas like Iran is very important. Groundwater modeling in aquifers like Tabriz aquifer is vital for achieving the correct understanding of groundwater resources and also managing demands (agriculture, domestic and industrial) and engineering projects, as well as avoiding of groundwater declination. This research presents a hybrid model compose of self-organizing map (SOM) and artificial neural network (ANN) (SOM-ANN), for predicting groundwater level in the 10 observation wells which are located in unconfined Tabriz aquifer. The prevailing climate over Tabriz plain is semi-arid and cold, according to Emberger classification (Emberger, 1930). The average annual temperature is 13 °C (based on data from meteorological stations in Tabriz, 1986-2015) and the annual average rainfall is 251 mm as per data for the years of 1986-2015, recorded by the East Azerbaijan Regional Water Authority. Tabriz plain aquifer is composed of unconfined and confined aquifers with high heterogeneity and complexity. The unconfined aquifers overlay the confined aquifer and their composition comprises silt, clay, sand and gravel, which is repeated frequently, with varying thicknesses and grain size in different places. The bedrock of the confined aquifers is marl composed of clay and salt form Pliocene and Miocene. The unconfined aquifer in south of Tabriz is flanked to the hillside of Sahand mountains and the groundwater within this aquifer is freshwater; but the unconfined aquifer at the northern and western part of the plain is shallow (5 up to 58 m) and suffers from varying degree of salinity due to sedimentation originating from the Miocene Formation. The plain is drained by the Aji Chay River (the Aji River). The confined aquifer (58-120 m) has better quality (Nadiri, 2008) and is confined by marl. This study has focused on the unconfined aquifer component, which serves as the supply source of a significant proportion of drinking water in Tabriz. Based on data of 22 logs of drilled piezometers in the unconfined aquifer (prepared by East Azerbaijan Regional Water Authority, 2016), the saturation thickness in the central part of the plain is thicker than its margins. Unconfined aquifer of the plain has 42 piezometers and the general direction of flow is from the Northeast to the Southwest. In order to examine the effectiveness of the models in predicting groundwater levels, the performance measures were quantified for all models using Root Mean Squared Error (RMSE), Pearson correlation coefficient (R), Coefficient of determination (R^2). RMSE values range from 0 (the ‘perfect model’) to higher real numbers and measure global goodness-of-fit between the observed values and modelled value. The closer the value of RMSE to 0, the more accurate the prediction is. Pearson correlation coefficient and Coefficient of determination (0≤r^2≤1) describes the proportion of the total variance in the observed data that can be explained by the model. The amount of r^2 and r, with higher values, indicates better agreement between observed and predicted values. The SOM method was adopted to classify aquifer to homogeneous area, the ANN model utilized to predict groundwater level in each cluster. The 10 observation wells with monthly groundwater level data during 14 years were selected for this research. The observation wells were classified by SOM method into 4 classes. Effective parameters on groundwater variation were select as input data sets. The normalized five input parameters with one-month lag (t0-1) including precipitation (P), temperature (T), evaporation (E), withdrawal (Q) and the groundwater level (GWL) were applied to run the hybrid model. The SOM-ANN model is implemented for each class. According to the results of the models for Classes 1, 2 and 4, the average RMSE of the training and testing stages were obtained 0.10, 0.20, and 0.22 meters respectively, and for observation wells in Class 3 that are located in the center of the plain the average error was equal to 0.23 meter. The Higher error in model 3 or class 3 could be originated from increasing saturated thickness and complexity of hydrogeological in this area. The hybrid model error was acceptable to prediction of groundwater level variation. The aquifers are often complex like Tabriz aquifer, so, the SOM-ANN model is suggested as an applicable method to simplify other aquifers to decrease the errors of model.
    Keywords: Ground water level, Observation wells, SOM ANN hybrid model, Tabriz plain unconfined aquifer
  • MohammadReza Emdad *, Mohsen Dehghani, Hormozd Naghavi Pages 103-111
    About 80% of agricultural lands are irrigated with surface irrigation practices. In order to achieve proper irrigation management and taking into account the exact amount of infiltration, high efficiency irrigation has been considered. One of the physical characteristics of the soil that play an important role in the management and design of irrigation systems is infiltration. However, infiltration is of one of the most difficult and time consuming of soil physical parameters. Surface irrigation, especially furrow irrigation, is one of the most commonly used methods for irrigating crops around the word due to the low cost, low energy requirements and improved aeration of the root zone. The efficiency of surface irrigation is a function of the field design, infiltration characteristics of the soil and the irrigation management practices. However, the complexity of the interactions makes it difficult for irrigators to identify optimal design or management practices. The infiltration characteristic of the soil is one of the dominant factors in determining the performance of surface irrigation applications, and both spatial and temporal variations in the infiltration characteristic are a major physical constraint for achieving higher irrigation application efficiencies. There are some potential ways to reduce the amount of data required to determine the specific infiltration characteristic and characterize the general infiltration equation, using process of scaling. This approach formulates the relevant equation with the smallest possible number of variables and generalizes an infiltration equation for a broad range of applications. A real time control method can overcome these spatial and temporal variations. Also, a significant improvement in performance is achievable with real time optimization of individual irrigation events. The scaling process proposed for reducing the amount of data required to predict the infiltration characteristics for each furrow and each irrigation event and even for a whole field, with the purpose of real time irrigation management and control. The aim of this study is to determine infiltration in furrow irrigation using real-time method of water in the furrows (with advance information) and the scaling factor. For determining infiltration variability in furrow irrigation, 3 different of soil textures was selected including: heavy texture (Isfahan Site with silty clay soil), Loam Texture (Karaj Site) and Sandy soil (Kerman Site). The infiltration rate of water in furrow irrigation, using scaling factor (dynamic) was estimated and applied for determining infiltration of advance data in the half of the furrow length. Finding a generalized solution for two dimensional infiltrations in furrow irrigation by scaling is a very useful way of reducing field data measurements required for prediction of the infiltration from irrigation advance. The proposed method was evaluated using data from 3 fields having different irrigation characteristics and for which extensive advance data were available. Scaling factor is convenient and easy way for determining infiltration in furrow irrigation with advance data for proper irrigation management. The results showed, the average absolute error values (comparison scaling factor and measurement method) were 0.00556, 0.00215 and 0.00449), respectively in light texture (sandy loam), medium (loamy) and heavy (silty clay. Also root mean square error in all different soil types had low values and the agreement index of soil textures showed high values. The agreement index of sandy loam, loam and silty clay were 095, 0.96 and 0.94, respectively. High correlation (R2=0.90) and the proximity of the measured and obtained values of scaling factor with 1:1 line, indicating that the scaling factor is proper method for determining infiltration in furrow irrigation in different soil textures. Also, the strong correlations between the scaled and actual infiltrations clearly demonstrate the suitability of the scaling process for predicting the infiltration characteristics, while using only the minimum of field data. The statistical analyzed mentioned the scaling gives acceptable reproduction of the infiltration curves for the most furrows. The scaling will be successful (for the purpose of inclusion in a real time control system) if the mean and variability of the cumulative infiltration over the fields with different soil textures and/or over time is predicted successfully, i.e. if the statistical properties are predicted successfully. This implies that the irrigation performance for that field will also be predicted successfully, the confirmation of which is the subject of this paper. Consequently, this method could give good estimates of irrigation performance for the three fields so the proposed method could be suitable for use in real time control on different soil textures.
    Keywords: Furrow irrigation, Infiltration, Scaling factor, Soil texture
  • Ahmad Ghasemi *, zhaleh Norouzi, Mahdi Ghobadinia, Abdolrazagh Danesh Shahraki Pages 113-122
    amount of water that use by evapotranspiration. Estimation of evapotranspiration (crop water requirement) is also one the most significant stages for designing different irrigation systems, programming and correction of the water resources management. Determining crop coefficient is a necessary part of estimating evapotranspiration. Crop coefficients (Kc) are properties of plants which vary in different growth stages. Potential evapotranspiration occurs if a field of the crop had an ideal unlimited water supply. The effect of both crop transpiration and soil evaporation are integrated into a single crop coefficient. The Kc coefficient incorporates crop characteristics and averaged effects of evaporation from the soil; while in dual crop coefficient two sub-coefficients (basic crop and evaporation coefficient) are considered separately. Therefore, the dual crop coefficient approach is more complicated and computationally intensive than the single approach. Due to the importance of accurate determining of crop water requirement many researches have been done for measuring single and dual crop coefficient. The aim of this research is to determine the actual evapotranspiration and single and dual crop coefficients of linseed by lysimeter, during various stages of growth in the Shahrekord area. This research was conducted in Shahrekord University. Shahrekord is located 97 kilometers southwest of Isfahan with the geographical coordinates from 32°18'22'' to 32°21'50'' N and 50°49'22'' to 50°53'44'' E. It is topographically situated in the north of the Zagros Mountains. The annual average temperature and precipitation in Shahrekord is 11.5°C and 320 mm, respectively. This study was done in the crop year of 2014-2015. Four lysimeters were used with the length, width and depth of 190, 65 and 140 cm. respectively. After filling lysimeters with soil and before planting, samples were taken for determining the soil characteristics, in depth of 0-30 cm. One of the lysimeters was allocated to grass, for measuring the reference evapotranspiration, and three other lysimeters to the linseed. After each irrigating the drainage water was collected and then its quality and quantity was measured. The crop evapotranspiration (ETc) and crop reference evapotranspiration (ETo) were calculated by using of water balance equation. Single crop coefficient was calculated from ratio of the measured crop evapotranspiration (ETc) and measured reference evapotranspiration (ETo) and dual crop coefficient was determined using the FAO 56 method. The results showed that the initial, development, middle, late and total growing periods of linseed are 20, 14, 22, 24 and 80 days. The total values of growing degree days (GDD) for these stages are 226.5, 226.7, 379.1, 420.7and 1253, respectively. The average value of the single crop coefficient in the initial stage is equal to 0.74, in the middle stage is 1.23 and at the end of the final stage is 0.61. The single crop coefficient was also calculated using the FAO 56 method. The results indicated that the difference of single crop coefficients in these two methods was very little in the initial and middle stages, but it increased in the final stage. The basal crop coefficient, soil evaporation coefficient and dual crop coefficients were calculated using the FAO56 method. The basal crop coefficient for linseed at different growth stages of initial growth stage, middle and end final are 0.15, 1.15 and 0.2, respectively. During the initial stage, because of low green cover, the soil evaporations is the highest and it became decrease by increasing the green cover in the next growth stages. The actual evapotranspiration value of linseed that obtained from three lysimeters was equal to 444 mm during the growing season. The evapotranspiration value of linseed that calculated by dual crop coefficient (using FAO56 method) was 445.5 mm, while this value was equal to about 391 mm for the single crop coefficient (using FAO56 method). The comparison of these values clearly indicated that the dual crop coefficient can estimate the evapotranspiration more accurate than the single crop coefficient. The results showed that evapotranspiration of linseed and grass are 444 and 429 mm, respectively and it daily variations for linseed are 1 to 10 mm and for the grass are 4.3 to 8.5 mm. The main conclusion that can be extracting from this research is that the calculating of dual crop coefficient is necessary for estimating the accurate crop water requirements.
    Keywords: FAO 56, Grass, Growth degree days, Shahrekord, Water Management
  • Mohammad Mehdi moayeri *, Mohammad Ali Ghorbani, Yaghob Dinpashoh Pages 123-130
    Estimation of uncertainty is an important basis of decision-making in modern water resources management. There is no absolutely accurate model that could predict every component of hydrologic cycle, due to the high complexity in the nature. Because of this relative failure, hydrological modeling is always subject to uncertainty. The subjects that are well-known produce certainty; while, those are not known to us make uncertainty. Probabilistic framework can be applied for representing uncertainty in a mathematical formal fashion. There are two classes of approaches for coping with uncertainty. The first class, considers uncertainty as lumped, such as Generalized Likelihood Uncertainty Estimation (GLUE) method. The second class considers uncertainty in different parts of a model such as inputs, states, parameters and outputs. Data assimilation can be classified as the second approach, allowing the estimation of different uncertainty sources. Kalman Filter (KF), a state-estimation method, is one of the efficient data assimilation techniques that provide a probabilistic framework of assessing uncertainty in separate model elements. The original KF was designed for linear models, whereas most hydrological models are nonlinear. Extended Kalman Filter (EKF) was developed for nonlinear models by using Taylor series of a model. It was not efficient because of approximation and heavy computation cost. Ensemble Kalman Filter (ENKF) is an alternative method for nonlinear models by generating ensemble of states. Joint Ensemble Kalman Filter (JEnKF), is a modified version of ENKF for simultaneous parameter and state estimation that we applied in this study. In the current study, JEnKF has been implemented for estimating of uncertainty in a conceptual rainfall-runoff model of Behesht-Abad catchment in Chaharmahal and Bakhtiari Province, during 2001-2006. The catchment area was 3860 km2 on the upstream of Karun River. One advantage of this implementation, in addition to its probabilistic nature for considering uncertainty, is its ability of simultaneous state parameter estimation without need of an extra global optimization algorithm for parameter calibration. The JEnKF has been applied on a modified version of HYMOD rainfall-runoff model. HYMOD has five reservoirs including: soil moisture reservoir; three linear reservoirs in series representing the fast runoff component; and one slow reservoir. Due to the mountainous landscape of the catchment, we added an extra reservoir for considering snow. The dimension of parameter space increased from five to seven due to this modification. It has five parameters representing the maximum storage capacity of watershed, the spatial variability of soil moisture capacity, the partitioning between fast reservoirs and slow reservoir, as well as the residence time of the fast and slow reservoirs. The two parameters of the snow reservoir are threshold temperature and the degree-day factor, which defines the melted water per day per Celsius degree above threshold temperature. The key point of ENKF is the application of Monte Carlo to generate ensemble of state variable of the model and sequentially propagate ensembles in time as a filter, by updating the ensembles whenever a new observation is provided. JEnKF has two major steps: first, forecast step that the parameters are kept invariant, while the states are integrated in time through the dynamical model; Second, analysis step in which once a new observation is available, both states and parameters are updated according to Kalman Filter equation. Parameter uncertainty has been indicated in probability density function forms. After sampling the prior distribution of parameters from a uniform distribution, the posterior marginal probability density was obtained by applying the filter. The dispersion of the distribution around Maximum a Priori (MAP) of the parameter was relatively narrow which showed the parameter identifiability achieved well-defined parameters. The efficiency of the method in prediction of runoff in the catchment was also investigated by comparing its results with SCE global optimization algorithm by RMSE statistic in four discharge classes. It showed state updating decreased the errors in different discharge classes, especially base flows. Comparing JEnKF with SCE showed 18 to 63 percent error reduction in calibration period, while 7 to 73 percent in validation period. Finally, predictive uncertainty was presented for both three-year calibration and two-year validation periods, which confirmed the importance of considering other sources of uncertainty rather than just parameter uncertainty. The predictive uncertainty caused by parameter uncertainty covered 32% of the discharge, while total uncertainty, the mixture of all uncertainty sources, covered 95% of the measured discharge.
    Keywords: HyMod rainfall, runoff model, Joint ensemble Kalman filter, Snow reservoir, Uncertainty
  • hossein Khozeyme nezhad*, Mehdi Ghomeshi Pages 131-136
    Various studies have been done recently on the mechanism of scour around hydraulic structures, especially bridges. In the case of scour around bridges, researches have had more focus on scour of piers in compare with abutment. While, the review of available information on bridges break indicated the major problems were related to abutment. Therefore, most costs have been spent in this part. One of the methods of scour reduction around the bridge abutment is using collar. In this research the effect of dimensions and position of collar installation were investigated on abutment scour reduction. Results showed that increasing dimensions of collars increased the efficiency of performance. Also, results revealed that the collars located under the bed had better performance than the other collars located on the bed and above it. Following this research, three-dimensional components of velocity were determined with electromagnetic velocimeter around abutment with collar and used for drawing flow pattern. Result showed that down flow and generated vortex were effective parameters on abutment bridge scour and collar had effective role on reduction of scour abutment with controlling down flow and causing resistance in bed against generated vortex.
    Keywords: Bridge abutment, Collar, Flow pattern, Rectangular section, Scour