فهرس المقالات Sediment Transport

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  1 - مدل‌سازی بار رسوب کل رودخانه‌ها با استفاده از شبکه‌های عصبی مصنوعی
  امین فلامکی مهناز اسکندری عبدالحسین بغلانی سید احمد احمدی
  برآورد بار رسوب کل رودخانه ها از مسائل مهم و کاربردی در مدیریت و برنامه ریزی منابع آب است. غلظت رسوب می تواند به روش های مستقیم و یا غیرمستقیم محاسبه شود که معمولاً روش های مستقیم پرهزینه و زمان بر هستند. همچنین بار رسوب کل می تواند به کمک روابط مختلف انتقال رسوب محاسبه أکثر

  برآورد بار رسوب کل رودخانه ها از مسائل مهم و کاربردی در مدیریت و برنامه ریزی منابع آب است. غلظت رسوب می تواند به روش های مستقیم و یا غیرمستقیم محاسبه شود که معمولاً روش های مستقیم پرهزینه و زمان بر هستند. همچنین بار رسوب کل می تواند به کمک روابط مختلف انتقال رسوب محاسبه شود، لیکن به طور معمول کاربرد این روابط نیاز به شرایط معینی داشته و به علاوه در بیشتر موارد نتایج حاصل از آن ها با یکدیگر و با مقادیر اندازه گیری شده متفاوت است. هدف از این پژوهش ارائه روشی بر پایه شبکه های عصبی مصنوعی (ANN) در تخمین بار رسوب کل بود. بدین منظور از دو نوع شبکه عصبی پرسپترون چند لایه (MLP) و توابع پایه شعاعی (RBF) و 200 نمونه، استفاده شد. 75 درصد از داده ها برای آموزش و 25 درصد برای آزمون شبکه ها در نظر گرفته شدند. متغیرهای ورودی مدل ها شامل سرعت متوسط جریان، شیب کف آبراهه، عمق متوسط، عرض آبراهه و قطر میانه ذرات رسوب و خروجی مدل، غلظت رسوب بود. متغیرهای ورودی مرحله به مرحله به شبکه ها اضافه شدند و هر بار نتایج ارزیابی شد تا مناسب ترین مدل تعیین شود. سپس نتایج حاصل از مدل های ANN با پنج معادله معروف انتقال رسوب مقایسه شدند. شاخص‌های آماری نشان داد که دقت شبکه های عصبی به ویژه مدل MLP در تخمین بار رسوب کل با ضریب همبستگی 96/0 بیش از سایر مدل هاست. همچنین مشخص شد که برای افزایش دقت مدل نیاز به آموزش آن با هر دو نوع داده های هیدرولوژیک و رسوب است. رابطه Ackersو White در برآورد مقدار بار رسوب کل بسیار بیش برآورد و سایر روابط، کم برآورد بودند. نتایج این پژوهش نشان داد که مدل های ارائه شده بر پایه شبکه های عصبی با مقادیر رسوب کل مشاهده شده هم خوانی بیشتری دارند و بویژه شبکه MLP می تواند مقدار رسوب را در نقاط پیک به خوبی برآورد نماید. تفاصيل المقالة
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  2 - Estimate particles and Investigation of Tank’s Sediment in Olya Gotvand Dam by Using of CCHE2D software
  محمد رضا فرشادی سعید حاجی علی گل جواد احدیان محمد جواد نصر اصفهانی
  Sedimentation in the Tank’s dam is complicated phenomenon and If we don’t have any information about sediment transport and control method, It cause decrease duration of use dam and waste of huge popular wealth. Thesis goal is study on Estimate particles and أکثر

  Sedimentation in the Tank’s dam is complicated phenomenon and If we don’t have any information about sediment transport and control method, It cause decrease duration of use dam and waste of huge popular wealth. Thesis goal is study on Estimate particles and Investigation and of tank`s sediment in olya Gotvand dam by using of CCHE2D software. To run this model use many base data like upstream river cross section specification, daily discharge statistics and air temperature, river discharge, varied reversion of flood water, river bed grain size and other need information’s. After insert all need data and run this model, the load sediment import in olia Gotvand dam`s tank is equal 89435 million cube meter per year and according to this result, after 100 year the sedimentation in order to trap coefficient 90 %, the whole sediment logs are jammed in the dam`s tank is equal 241 million cube meter and consequently this sediment to be formed 7.23% total volume of this dam`s tank. Most of Sediment Transport is kind of large silt with size 0.031-0.0625 mm and very small sand with size 0.0625-0.125. تفاصيل المقالة
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  3 - Qualitative monitoring of physical, chemical and microbial parameters along the water transfer channel of the southeast treatment plant
  سید محمد مهدی آیتی مهدی اسدی لور
  Rivers are more exposed to secondary pollutants than other water sources (groundwater) due to the entry of some pollutants from the activities of human communities. Investigating the quality of the water transfer canal of the southeast treatment plant is of special impo أکثر

  Rivers are more exposed to secondary pollutants than other water sources (groundwater) due to the entry of some pollutants from the activities of human communities. Investigating the quality of the water transfer canal of the southeast treatment plant is of special importance due to the supply of drinking water to the cities of Mahshahr, Bandar Imam and petrochemical industries, other administrative and commercial subscribers of Bandar Imam. In this study, physicochemical and microbial quality parameters including temperature (T), electrical conductivity (EC), total soluble solids (TDS), turbidity (TUR), acidity or alkalinity (pH), water hardness (TH), calcium ( Ca), magnesium(Mg), chloride (Cl-), carbonate (Co2-3), bicarbonate (Hco-3), sodium (Na), potassium (K), chemical oxygen demand (COD), sulfate (SO4 And fecal coliforms were applied along the southeastern water transfer canal from Kot Amir to Sarbandar. .Accordingly, during the period of November 1997 to May 1998, during field operations, quality samples were taken twice a month and each time two quality samples were taken from 5 points along the southeast water canal and a total of 60 quality samples. Water classification in terms of agriculture, drinking and industry was performed based on qualitative analysis through Wilcox, Schuler, and Piper diagrams, and finally, using NSFWQI index, water quality classification was performed. It was acceptable to review the test results and diagrams regarding water quality from the drinking water in the classroom. Also, using the NSFWQI index, water quality along the canal path is average. تفاصيل المقالة
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  4 - Influence of intake’s angel and location on sediment rate in bend of river using CCHE2D software
  رضوان زنگنه امیرعباس کمانبدست علیرضا مسجدی
  Investigating the features and flow behavior and related component is one of the complex phenomena that make using of software inevitable. The rivers carry sediment content along with water which is created by erosion of riverbed sediment and erosion caused by rainfall أکثر

  Investigating the features and flow behavior and related component is one of the complex phenomena that make using of software inevitable. The rivers carry sediment content along with water which is created by erosion of riverbed sediment and erosion caused by rainfall or surface runoff flowing over the catchment area. If the action of river dewatering occurs, the entry of sediment into the intake would make new challenges due to the sedimentation. In particular, these factors are valuable for Meander Rivers which have unsteady flow patterns. There are three general approaches to study this process. numerical model was used in this study due to the lower costs compared to existing methods and expediting the process of result obtaining, the model can also be applied to other similar cases to obtain feedbacks resulting from changes in different components that affect the phenomenon under study conditions and evaluate different functions. In this study, simulation of the discharge and sedimentation input into these intakes was investigated to evaluate the hydraulic conditions of flow and sedimentation in the intake with different angles of 30, 45, 60, 75 and 90 by different location (25, 40, 55 and 70) using CCHE2D numerical model that has a sinusoidal-like turn is analyzed. Besides, variation of parameters like velocity, Froude number, shear stress, river bed elevation and total sediment deposits of the river are calculated and discussed. The impact of these different angles on Hydraulic flow was studied. The results of these tests indicated that intake with 90-degree angle and 70 of arc can improve the flow patterns at the inlet. This can overcome sedimentation problems and water shortages in some seasons. تفاصيل المقالة
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  5 - Model study reservoir flushing
  S.H Ghoreishi M.R Majdzadeh Tabatabai
  Sediment flushing of reservoirs is an operational technique, whereby previously accumulated sediments in the reservoirs are hydraulically removed by accelerated flow when the bottom desiltingoutlets of the dam are opened. In this research, the process of sediment flushi أکثر

  Sediment flushing of reservoirs is an operational technique, whereby previously accumulated sediments in the reservoirs are hydraulically removed by accelerated flow when the bottom desiltingoutlets of the dam are opened. In this research, the process of sediment flushing is simulated by a three dimensional numerical model in which sediment and flow interaction are reflected in the reservoirs. Reynolds Averaged Navier-Stokes (RANS) equations are solved numericallyby Finite Volume on a three dimensional grid and a standard k −e turbulence model is used.The resulting flow analysis is used as an input data for the sediment model. The convection diffusion equation for the sediment concentration is solved. The concentration equation derived by Van-Rijn is adopted as a boundary condition, resulting in a calculation of bed material load.The depth integrated mass balance equation is applied to find the bed changes. The results from the numerical model are compared favorably with the data from physical model studies availablein the literature. تفاصيل المقالة
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  6 - Uncertainties in Evaluation of the Sediment Transport Rates in Typical Coarse-Bed Rivers in Iran
  M Yasi R Hamzepouri A.R Yasi
  Flow and sediment transport processes are different and more complex in coarse-bed rivers than in sand-bed rivers. The main goal of the present study is to evaluate different modes of sediment transport using different hydrometric and hydraulic methods, and to address t أکثر

  Flow and sediment transport processes are different and more complex in coarse-bed rivers than in sand-bed rivers. The main goal of the present study is to evaluate different modes of sediment transport using different hydrometric and hydraulic methods, and to address the major uncertainties. Four river reaches were selected as representatives of coarse-bed rivers in the Northwest of Iran. A sediment transport model (STM) has been developed to calculate the sediment loads from 5 hydrometric and about 60 hydraulic methods. The extent of the data and flow domain and also the effects of bed material characteristics were examined. The order of prediction intervals of 50%, 75% and 90% were determined. Results indicated that the order of 40% to 70% error is expected despite using the standard sediment measuring system and fitting the measured data to the best predictors. Predictions from the best-fitted hydraulic relationships indicated an order of error between 77% and 200%. This paper presents the prediction results and the order of errors for different modes of sediment loads applicable to similar coarse-bed river reaches. تفاصيل المقالة
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  7 - Effects of Upward Seepage on Depth of Scour Hole Downstream of Free Falling Jets Under Constant Tail Water Depth
  S.M Razavi Nabavi M Shafai Bejestan
  rade control structures are used to control bed erosion in steep small rivers mostly in the mountains. Scour downstream of this structure can lead to failure. Over the past years, the effect of different variables on this phenomena have been studied, however the effect أکثر

  rade control structures are used to control bed erosion in steep small rivers mostly in the mountains. Scour downstream of this structure can lead to failure. Over the past years, the effect of different variables on this phenomena have been studied, however the effect of upward seepage which is common due to head difference of the banks water table or water surface level between the upstream and downstream reaches of a grade control structure has not been studied. In this paper, results of an experimental investigation on the maximum scour depth downstream of a grade control structure with and without upward seepage through bed sediments are presented. Experiments were run for the conditions of free falling jets, over sedimentary beds (median sizes = 1.5, 2.4 and 3.15 mm). Our data for the case of existing upward seepage shows that D' Agostino and Ferro (2004) expression significantly overestimates the scour depth. New finding of this study indicates that with the presence of upward seepage the scour depth decreases significantly which confirms the results of Sarker and Dey (2006) on scour downstream of horizontal jet with no horizontal apron. تفاصيل المقالة
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  8 - Introducing a Relationship for Estimation of the Sediment Transport Rate through Rockfill Structures
  J Chapokpour E Amiri Tokaldany
  Rockfill dams are accounted as useful measures in watershed management projects. How-ever, the sediment transport through the rockfill materials, could impact their lifetime duration. Previously, researches have been conducted to describe the various hydraulically issue أکثر

  Rockfill dams are accounted as useful measures in watershed management projects. How-ever, the sediment transport through the rockfill materials, could impact their lifetime duration. Previously, researches have been conducted to describe the various hydraulically issues of the flow passing through these structures However; there is no general relationship to estimate the sediment transport rate passing through the of rockfill structures. In this research, by using several sets of data provided from three various sources, we introduced a more general rela-tionship to estimate the sediment transport passing through the rock materials. We compared the predicted results from the new equation with those estimated from the other equations. We found that the accuracy of the new relationships is much more than previously introduced equ-ations. Using more measured data, we found that the mean relative error of the predicted re-sults is %21 showing the reasonable accuracy of the present relationship. تفاصيل المقالة
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  9 - Sediment Transport in Unsteady Flow Conditions
  Seyed Amin Salamatian Amir Reza Zarrati Mojtaba Karimaee
  Sediment transport under unsteady flow condition is studied experimentally. In the first step, sediment transport under different steady flow conditions was measured and an empirical equation was derived for its calculation. In the next step, two continuous and three st أکثر

  Sediment transport under unsteady flow condition is studied experimentally. In the first step, sediment transport under different steady flow conditions was measured and an empirical equation was derived for its calculation. In the next step, two continuous and three stepwise hydrographs were generated in the flume, and their sediment transport rate was measured. The continuous hydrographs were then approximated by different number of steps. Sediment transport for the hydrographs was then calculated by assuming a steady state condition in each step employing the empirical equation derived in the first step of the study. Results showed that in continuous as well as the stepped hydrographs the difference between the calculated and measured sediment rates is less than 10%. This shows that in the range of the tested hydrographs which conforms to many rivers in Iran, approximating the hydrograph with steady state steps for sediment transport calculations leads to acceptable results. In the next step, the flow and sediment transport in the flume under the tested hydrographs were simulated by using HEC-RAS software. Various sediment transport equations were used and calculated results were then compared with experimental measurements. Results showed that by increasing the number of steps in stepped hydrograph in HEC-RAS, calculated sediment transport rates by each equation tend to constant values. تفاصيل المقالة
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  10 - تعیین پروفیل رسوب گذاری در کف مخزن سد اکباتان با استفاده از شبکه های عصبی مصنـوعی
  محسن ایراندوست هدایت فهمـی امید طیاری
  در شبکه‌های عصبی مصنوعی (ANN) روش‌های موجود آموزش و واسنجی عصبی بر اساس ساختار پرسپترون چندلایه‌ای می باشد، لیکن این روش‌ها دارای مشکلات ناشی از عدم همگرایی در روش‌های یادگیری، عدم ثبات اوزان شبکه در شرایطی که طیف داده های ورودی دارای انحراف معیار بزرگ بوده و بالاخره نی أکثر

  در شبکه‌های عصبی مصنوعی (ANN) روش‌های موجود آموزش و واسنجی عصبی بر اساس ساختار پرسپترون چندلایه‌ای می باشد، لیکن این روش‌ها دارای مشکلات ناشی از عدم همگرایی در روش‌های یادگیری، عدم ثبات اوزان شبکه در شرایطی که طیف داده های ورودی دارای انحراف معیار بزرگ بوده و بالاخره نیاز به داده و اطلاعات فراوان جهت آموزش شبکه می باشند. برای غلبه بر مشکلات فوق در این تحقیق روش جدید ترکیبی شبکه عصبی مصنوعی – بهینه سازی ریاضی غیرخطی ارایه شده و شبکه عصبی مصنوعی که با استفاده از روش پس انتشار خطا طراحی گردیده بهعنوان ابزارقدرتمندی برای برآورد میزان رسوب مخزن سد اکباتان معرفی شده است. بر این اساس با استفاده از معادله بین دبی رسوب و جریان آب رودخانه آبشینه و آمار ایستگاه یالفان مدل طراحی شده ANN با گره های مختلف در لایه ها ورودی ها و لایه مخفی اجرا گردید. نتایج واسنجی نشان می دهد برای توزیع رسوب در مخزن سداکباتان بایستی از شش گره در لایه ورودی و هشت گره در لایه مخفی استفاده نمود. دراین تحقیق رابطه رضایت بخشی بین تعداد مولفه‌های لایه مخفی باتعدادداده های آموزش و تعداد مولفه‌های ورودی تعیین شده است. تفاصيل المقالة